Transmeta released its Very Long Instruction Word (VLIW) processor Known as the Crusoe processor, it is a hardware-software hybrid that uses a code morphing technique to emulate the x86 architecture. Here software known as Code Morphing Software converts the normal x86 instructions into the native VLIW code. In this technique, software is loaded from the ROM upon boot up and used to control the scheduling of instructions. Compatibility with x86 applications is assured because this software is able to insulate programs from the hardware engine s native VLIW instruction set.
The code morphing technique keeps the core logic design of the Crusoe processor simple and provides a solution for the problems posed by traditional architectures. Avery low power consumption is one of the resultant benefits and this makes the Crusoe most suited for internet appliances and mobile applications.
As modern CPUs became more complex, they tend to have more hardware, and perform more functions than their early RISC predecessors. All that hardware requires lots of power though, and the more power a CPU draws the hotter it gets. When Transmeta designed the Crusoe system they went back to basics. They looked at the entire picture they did not just say how fast could we make this system they said, How efficient can we possibly make this, and still have it run x86 applications acceptably . So instead of having in the past one primary directive they had two. So certain things would have to be traded off to make this the best system possible. The three main things they wanted the system to have was:
1. Full x86 compatibility
2. The lowest possible power consumption
3. A level of x86 application performance that provides for a reasonably good user experience.
Showing posts with label SEMINAR. Show all posts
Showing posts with label SEMINAR. Show all posts
Friday, February 20, 2009
imode
The imode is the NTT Do Como s new Internet access system. It is an advanced intelligent messaging service for digital mobile phones and other mobile terminals that will allow you to see Internet content in special text format on special imode-enabled mobile phones. Enabling information access from handheld devices requires a deep understanding of both technical and market issues that are unique to the wireless environment. The imode specification was developed by the industry s best minds to address these issues. Wireless devices represent the ultimate constrained computing device with limited CPU, memory and battery life and a simple user interface. Wireless networks are constrained by low bandwidth, high latency and unpredictable availability and stability.
The imode specification addresses these issues by using the best of existing standards and developing new extensions when needed. The imode solution leverages the tremendous investment in web servers, web development tools, web programmers and web applications while solving the unique problems associated with the wireless domain. The specification ensures that this solution is fast, reliable and secure. The imode specification is developed and supported by the wireless telecommunication community so that the entire industry and its subscribers can benefit from a single, open specification.
NTT DoCoMo: The Creators of imode
NTT DoCoMo is a subsidiary of Japan s incumbent telephone operator NTT. The majority of NTT-DoCoMo s shares are owned by NTT, and the majority of NTT s shares are owned by the Japanese government. NTT-DoCoMo s shares are separately listed on the Tokyo Stock Exchange and on the Osaka Stock Exchange, and NTT-DoCoMo s market value (capitalization) makes it one of the world s most valued companies.
Goals of the imode.
The goals of the imode forum are listed as follows. >>To bring Internet content and advanced data services to wireless phones and other wireless terminals.
>>To develop a global wireless protocol specification that works across all wireless network technologies.
>>To enable the creation of content and applications that scale across a wide range of wireless bearer networks and device types, i.e. to maintain device and bearer independence.
>>To embrace and extend existing standards and technology whenever possible and appropriate.
The imode specification addresses these issues by using the best of existing standards and developing new extensions when needed. The imode solution leverages the tremendous investment in web servers, web development tools, web programmers and web applications while solving the unique problems associated with the wireless domain. The specification ensures that this solution is fast, reliable and secure. The imode specification is developed and supported by the wireless telecommunication community so that the entire industry and its subscribers can benefit from a single, open specification.
NTT DoCoMo: The Creators of imode
NTT DoCoMo is a subsidiary of Japan s incumbent telephone operator NTT. The majority of NTT-DoCoMo s shares are owned by NTT, and the majority of NTT s shares are owned by the Japanese government. NTT-DoCoMo s shares are separately listed on the Tokyo Stock Exchange and on the Osaka Stock Exchange, and NTT-DoCoMo s market value (capitalization) makes it one of the world s most valued companies.
Goals of the imode.
The goals of the imode forum are listed as follows. >>To bring Internet content and advanced data services to wireless phones and other wireless terminals.
>>To develop a global wireless protocol specification that works across all wireless network technologies.
>>To enable the creation of content and applications that scale across a wide range of wireless bearer networks and device types, i.e. to maintain device and bearer independence.
>>To embrace and extend existing standards and technology whenever possible and appropriate.
Web Spoofing
This paper describes an Internet security attack that could endanger the privacy of World Wide Web users and the integrity of their data. The attack can be carried out on today s systems, endangering users of the most common Web browsers, including Netscape Navigator and Microsoft Internet Explorer.
1.1 HISTORY
The concept of IP spoofing was initially discussed in academic circles in the 1980 s. It was primarily theoretical until Robert Morris, whose son wrote the first Internet Worm, discovered a security weakness in the TCP protocol known as sequence prediction. Another infamous attack, Kevin Mitnick s Christmas day, crack of Tsutomu Shimomura s machine, employed the IP spoofing and TCP sequence prediction techniques. While the popularity of such cracks has decreased due to the demise of the services they exploited, spoofing can still be used and needs to be addressed by all security administrators.
1.2 WHAT IS SPOOFING?
Spoofing means pretending to be something you are not. In Internet terms it means pretending to be a different Internet address from the one you really have in order to gain something. That might be information like credit card numbers, passwords, personal information or the ability to carry out actions using someone else’s identity.
IP spoofing attack involves forging one s source address. It is the act of using one machine to impersonate another. Most of the applications and tools in web rely on the source IP address authentication. Many developers have used the host based access controls to secure their networks. Source IP address is a unique identifier but not a reliable one. It can easily be spoofed.
Web spoofing allows an attacker to create a shadow copy of the entire World Wide Web. Accesses to the shadow Web are funneled through the attacker s machine, allowing the attacker to monitor the all of the victim s activities including any passwords or account numbers the victim enters. The attacker can also cause false or misleading data to be sent to Web servers in the victim s name, or to the victim in the name of any Web server. In short, the attacker observes and controls everything the victim does on the Web.
The various types of spoofing techniques that we discuss include TCP Flooding, DNS Server Spoofing Attempts, web site names, email ids and link redirection.
1.1 HISTORY
The concept of IP spoofing was initially discussed in academic circles in the 1980 s. It was primarily theoretical until Robert Morris, whose son wrote the first Internet Worm, discovered a security weakness in the TCP protocol known as sequence prediction. Another infamous attack, Kevin Mitnick s Christmas day, crack of Tsutomu Shimomura s machine, employed the IP spoofing and TCP sequence prediction techniques. While the popularity of such cracks has decreased due to the demise of the services they exploited, spoofing can still be used and needs to be addressed by all security administrators.
1.2 WHAT IS SPOOFING?
Spoofing means pretending to be something you are not. In Internet terms it means pretending to be a different Internet address from the one you really have in order to gain something. That might be information like credit card numbers, passwords, personal information or the ability to carry out actions using someone else’s identity.
IP spoofing attack involves forging one s source address. It is the act of using one machine to impersonate another. Most of the applications and tools in web rely on the source IP address authentication. Many developers have used the host based access controls to secure their networks. Source IP address is a unique identifier but not a reliable one. It can easily be spoofed.
Web spoofing allows an attacker to create a shadow copy of the entire World Wide Web. Accesses to the shadow Web are funneled through the attacker s machine, allowing the attacker to monitor the all of the victim s activities including any passwords or account numbers the victim enters. The attacker can also cause false or misleading data to be sent to Web servers in the victim s name, or to the victim in the name of any Web server. In short, the attacker observes and controls everything the victim does on the Web.
The various types of spoofing techniques that we discuss include TCP Flooding, DNS Server Spoofing Attempts, web site names, email ids and link redirection.
DELAY tolerant networks
Increasingly, network applications must communicate with counterparts across disparate networking environments characterized by significantly different sets of physical and operational constraints; wide variations in transmission latency are particularly troublesome. The proposed Interplanetary Internet (IPN), which must encompass both terrestrial and interplanetary links, is an extreme case. An architecture based on a protocol that can operate successfully and reliably in multiple disparate environments would simplify the development and deployment of such applications.
The Internet protocols are ill suited for this purpose. They are, in general, poorly suited to operation on paths in which some of the links operate intermittently or over extremely long propagation delays. The principle problem is reliable transport, but the operations of the Internet’s routing protocols would also raise troubling issues.
It is this analysis that leads us to propose an architecture based on Internet-independent middleware: use exactly those protocols at all layers that are best suited to operation within each environment, but insert a new overlay network protocol between the applications and the locally optimized stacks. This new protocol layer, called the bundle layer, ties together the region-specific lower layers so that application programs can communicate across multiple regions.
The DTN architecture implements store-and-forward message switching.
A DTN is a network of regional networks, where a regional network is a network that is adapted to a particular communication region, wherein communication characteristics are relatively homogeneous. Thus, DTNs support interoperability of regional networks by accommodating long delays between and within regional networks, and by translating between regional communication characteristics.
The Internet protocols are ill suited for this purpose. They are, in general, poorly suited to operation on paths in which some of the links operate intermittently or over extremely long propagation delays. The principle problem is reliable transport, but the operations of the Internet’s routing protocols would also raise troubling issues.
It is this analysis that leads us to propose an architecture based on Internet-independent middleware: use exactly those protocols at all layers that are best suited to operation within each environment, but insert a new overlay network protocol between the applications and the locally optimized stacks. This new protocol layer, called the bundle layer, ties together the region-specific lower layers so that application programs can communicate across multiple regions.
The DTN architecture implements store-and-forward message switching.
A DTN is a network of regional networks, where a regional network is a network that is adapted to a particular communication region, wherein communication characteristics are relatively homogeneous. Thus, DTNs support interoperability of regional networks by accommodating long delays between and within regional networks, and by translating between regional communication characteristics.
Java Ring
A Java Ring is a finger ring that contains a small microprocessor with built-in capabilities for the user, a sort of smart card that is wearable on a finger. Sun Microsystem s Java Ring was introduced at their JavaOne Conference in 1998 and, instead of a gemstone, contained an inexpensive microprocessor in a stainless-steel iButton running a Java virtual machine and preloaded with applets (little application programs). The rings were built by Dallas Semiconductor.
Workstations at the conference had ring readers installed on them that downloaded information about the user from the conference registration system. This information was then used to enable a number of personalized services. For example, a robotic machine made coffee according to user preferences, which it downloaded when they snapped the ring into another ring reader.
Although Java Rings aren t widely used yet, such rings or similar devices could have a number of real-world applications, such as starting your car and having all your vehicle s components (such as the seat, mirrors, and radio selections) automatically adjust to your preferences.
The Java Ring is an extremely secure Java-powered electronic token with a continuously running, unalterable real-time clock and rugged packaging, suitable for many applications. The jewel of the Java Ring is the Java iButton -- a one-million transistor, single chip trusted microcomputer with a powerful Java Virtual Machine (JVM) housed in a rugged and secure stainless-steel case.
The Java Ring is a stainless-steel ring, 16-millimeters (0.6 inches) in diameter, that houses a 1-million-transistor processor, called an iButton. The ring has 134 KB of RAM, 32 KB of ROM, a real-time clock and a Java virtual machine, which is a piece of software that recognizes the Java language and translates it for the user s computer system.
The Ring, first introduced at JavaOne Conference, has been tested at Celebration School, an innovative K-12 school just outside Orlando, FL. The rings given to students are programmed with Java applets that communicate with host applications on networked systems. Applets are small applications that are designed to be run within another application. The Java Ring is snapped into a reader, called a Blue Dot receptor, to allow communication between a host system and the Java Ring.
Designed to be fully compatible with the Java Card 2.0 standard the processor features a high-speed 1024-bit modular exponentiator fro RSA encryption, large RAM and ROM memory capacity, and an unalterable real time clock. The packaged module has only a single electric contact and a ground return, conforming to the specifications of the Dallas Semiconductor 1-Wire bus. Lithium-backed non-volatile SRAM offers high read/write speed and unparallel tamper resistance through near-instantaneous clearing of all memory when tampering is detected, a feature known as rapid zeroization.
Data integrity and clock function are maintained for more than 10 years. The 16-millimeter diameter stainless steel enclosure accomodates the larger chip sizes needed for up to 128 kilobytes of high-speed nonvolatile static RAM. The small and extremely rugged packaging of the module allows it to attach to the accessory of your choice to match individual lifestyles, such as key fob, wallet, watch, necklace, bracelet, or finger ring.
Workstations at the conference had ring readers installed on them that downloaded information about the user from the conference registration system. This information was then used to enable a number of personalized services. For example, a robotic machine made coffee according to user preferences, which it downloaded when they snapped the ring into another ring reader.
Although Java Rings aren t widely used yet, such rings or similar devices could have a number of real-world applications, such as starting your car and having all your vehicle s components (such as the seat, mirrors, and radio selections) automatically adjust to your preferences.
The Java Ring is an extremely secure Java-powered electronic token with a continuously running, unalterable real-time clock and rugged packaging, suitable for many applications. The jewel of the Java Ring is the Java iButton -- a one-million transistor, single chip trusted microcomputer with a powerful Java Virtual Machine (JVM) housed in a rugged and secure stainless-steel case.
The Java Ring is a stainless-steel ring, 16-millimeters (0.6 inches) in diameter, that houses a 1-million-transistor processor, called an iButton. The ring has 134 KB of RAM, 32 KB of ROM, a real-time clock and a Java virtual machine, which is a piece of software that recognizes the Java language and translates it for the user s computer system.
The Ring, first introduced at JavaOne Conference, has been tested at Celebration School, an innovative K-12 school just outside Orlando, FL. The rings given to students are programmed with Java applets that communicate with host applications on networked systems. Applets are small applications that are designed to be run within another application. The Java Ring is snapped into a reader, called a Blue Dot receptor, to allow communication between a host system and the Java Ring.
Designed to be fully compatible with the Java Card 2.0 standard the processor features a high-speed 1024-bit modular exponentiator fro RSA encryption, large RAM and ROM memory capacity, and an unalterable real time clock. The packaged module has only a single electric contact and a ground return, conforming to the specifications of the Dallas Semiconductor 1-Wire bus. Lithium-backed non-volatile SRAM offers high read/write speed and unparallel tamper resistance through near-instantaneous clearing of all memory when tampering is detected, a feature known as rapid zeroization.
Data integrity and clock function are maintained for more than 10 years. The 16-millimeter diameter stainless steel enclosure accomodates the larger chip sizes needed for up to 128 kilobytes of high-speed nonvolatile static RAM. The small and extremely rugged packaging of the module allows it to attach to the accessory of your choice to match individual lifestyles, such as key fob, wallet, watch, necklace, bracelet, or finger ring.
NAS
Information Technology (IT) departments are looking for cost-effective storage solutions that can offer performance, scalability, and reliability. As users on the network increase and the amounts of data generated multiply, the need for an optimized storage solution becomes essential. Network Attached Storage (NAS) is becoming a critical technology in this environment.
The benefit of NAS over the older Direct Attached Storage (DAS) technology is that it separates servers and storage, resulting in reduced costs and easier implementation. As the name implies, NAS attaches directly to the LAN, providing direct access to the file system and disk storage. Unlike DAS, the application layer no longer resides on the NAS platform, but on the client itself. This frees the NAS processor from functions that would ultimately slow down its ability to provide fast responses to data requests.
In addition, this architecture gives NAS the ability to service both Network File System (NFS) and Common Internet File System (CIFS) clients. As shown in the figure below, this allows the IT manager to provide a single shared storage solution that can simultaneously support both Windows*-and UNIX*-based clients and servers. In fact, a NAS system equipped with the right file system software can support clients based on any operating system.
NAS is typically implemented as a network appliance, requiring a small form factor (both real estate and height) as well as ease of use. NAS is a solution that meets the ever-demanding needs of today s networked storage market.
The benefit of NAS over the older Direct Attached Storage (DAS) technology is that it separates servers and storage, resulting in reduced costs and easier implementation. As the name implies, NAS attaches directly to the LAN, providing direct access to the file system and disk storage. Unlike DAS, the application layer no longer resides on the NAS platform, but on the client itself. This frees the NAS processor from functions that would ultimately slow down its ability to provide fast responses to data requests.
In addition, this architecture gives NAS the ability to service both Network File System (NFS) and Common Internet File System (CIFS) clients. As shown in the figure below, this allows the IT manager to provide a single shared storage solution that can simultaneously support both Windows*-and UNIX*-based clients and servers. In fact, a NAS system equipped with the right file system software can support clients based on any operating system.
NAS is typically implemented as a network appliance, requiring a small form factor (both real estate and height) as well as ease of use. NAS is a solution that meets the ever-demanding needs of today s networked storage market.
DNA Computing in security
In today’s world where no modern encryption algorithms are spared of the security breach, the world of information security is on the look out for fresh ideas. Thus came up the new theory of DNA computing in the fields of cryptography and steganography.
Though researches have been done to demonstrate DNA computing and its use in the areas of cryptography, steganography and authentication, the limitations of sophisticated lab requirements, along with high labour cost has still kept DNA computing at bay from today’s security world. But on the other hand DNA authentication has become a great boon.
Though researches have been done to demonstrate DNA computing and its use in the areas of cryptography, steganography and authentication, the limitations of sophisticated lab requirements, along with high labour cost has still kept DNA computing at bay from today’s security world. But on the other hand DNA authentication has become a great boon.
LonWorks Protocol
A technology initiated by the Echelon Corporation in 1990, the LonWorks provides a platform for the for building industrial, transportation, home automation and public utility control networks to communicate with each other. Built on the Local Operating Network, it uses the LonTalk protocol, in order to have a peer to peer communication with each other, with out actually having a gateway or other hardware.
CELL PHONE VIRUSES AND SECURITY
As cell phones become a part and parcel of our life so do the threats imposed to them is also on the increase. Like the internet, today even the cell phones are going online with the technologies like the edge, GPRS etc. This online network of cellphones has exposed them to the high risks caused by malwares viruses, worms and Trojans designed for mobile phone environment. The security threat caused by these malwares are so severe that a time would soon come that the hackers could infect mobile phones with malicious software that will delete any personal data or can run up a victim s phone bill by making toll calls.
All these can lead to overload in mobile networks, which can eventually lead them to crash and then the financial data stealing which poises risk factors for smart phones. As the mobile technology is comparatively new and still on the developing stages compared to that of internet technology, the anti virus companies along with the vendors of phones and mobile operating systems have intensified the research and development activities on this growing threat, with a more serious perspective.
All these can lead to overload in mobile networks, which can eventually lead them to crash and then the financial data stealing which poises risk factors for smart phones. As the mobile technology is comparatively new and still on the developing stages compared to that of internet technology, the anti virus companies along with the vendors of phones and mobile operating systems have intensified the research and development activities on this growing threat, with a more serious perspective.
Thursday, February 19, 2009
imode
Definition
The imode is the NTT DoCoMo's new Internet access system. It is an advanced intelligent messaging service for digital mobile phones and other mobile terminals that will allow you to see Internet content in special text format on special imode-enabled mobile phones. Enabling information access from handheld devices requires a deep understanding of both technical and market issues that are unique to the wireless environment. The imode specification was developed by the industry's best minds to address these issues. Wireless devices represent the ultimate constrained computing device with limited CPU, memory and battery life and a simple user interface.
Wireless networks are constrained by low bandwidth, high latency and unpredictable availability and stability. The imode specification addresses these issues by using the best of existing standards and developing new extensions when needed. The imode solution leverages the tremendous investment in web servers, web development tools, web
programmers and web applications while solving the unique problems associated with the wireless domain. The specification ensures that this solution is fast, reliable and secure. The imode specification is developed and supported by the wireless telecommunication community so that the entire industry and its subscribers can benefit from a single, open specification.
NTT DoCoMo is a subsidiary of Japan's incumbent telephone operator NTT. The majority of NTT-DoCoMo's shares is owned by NTT, and the majority of NTT's shares is owned by the Japanese government. NTT-DoCoMo's shares are separately listed on the Tokyo Stock Exchange and on the Osaka Stock Exchange, and NTT-DoCoMo's market value (capitalization) makes it one of the world's most valued companies.
Goals of the imode
The goals of the imode forum are listed as follows.
To bring Internet content and advanced data services to wireless phones and other
wireless terminals.
To develop a global wireless protocol specification that works across all wireless
network technologies.
To enable the creation of content and applications that scale across a wide range
of wireless bearer networks and device types, i.e. to maintain device and bearer
independence
To embrace and extend existing standards and technology whenever possible and
appropriate.
The Technology:
imode consists of three technologies:
1.a smart handset
2.a new transmission protocol
3.a new markup language.
The above mentioned three technologies together make the brand name, imode
The imode is the NTT DoCoMo's new Internet access system. It is an advanced intelligent messaging service for digital mobile phones and other mobile terminals that will allow you to see Internet content in special text format on special imode-enabled mobile phones. Enabling information access from handheld devices requires a deep understanding of both technical and market issues that are unique to the wireless environment. The imode specification was developed by the industry's best minds to address these issues. Wireless devices represent the ultimate constrained computing device with limited CPU, memory and battery life and a simple user interface.
Wireless networks are constrained by low bandwidth, high latency and unpredictable availability and stability. The imode specification addresses these issues by using the best of existing standards and developing new extensions when needed. The imode solution leverages the tremendous investment in web servers, web development tools, web
programmers and web applications while solving the unique problems associated with the wireless domain. The specification ensures that this solution is fast, reliable and secure. The imode specification is developed and supported by the wireless telecommunication community so that the entire industry and its subscribers can benefit from a single, open specification.
NTT DoCoMo is a subsidiary of Japan's incumbent telephone operator NTT. The majority of NTT-DoCoMo's shares is owned by NTT, and the majority of NTT's shares is owned by the Japanese government. NTT-DoCoMo's shares are separately listed on the Tokyo Stock Exchange and on the Osaka Stock Exchange, and NTT-DoCoMo's market value (capitalization) makes it one of the world's most valued companies.
Goals of the imode
The goals of the imode forum are listed as follows.
To bring Internet content and advanced data services to wireless phones and other
wireless terminals.
To develop a global wireless protocol specification that works across all wireless
network technologies.
To enable the creation of content and applications that scale across a wide range
of wireless bearer networks and device types, i.e. to maintain device and bearer
independence
To embrace and extend existing standards and technology whenever possible and
appropriate.
The Technology:
imode consists of three technologies:
1.a smart handset
2.a new transmission protocol
3.a new markup language.
The above mentioned three technologies together make the brand name, imode
DNA Based Computing
Definition
Rediscovering Biology
Biology is now the study of information stored in DNA - strings of four letters: A, T, G, and C for the bases adenine, thymine, guanine and cytosine - and of the transformations that information undergoes in the cell. There were mathematics here? DNA polymerase is the king of enzymes - the maker of life. Under appropriate conditions, given a strand of DNA, DNA polymerase produces a second "Watson-Crick" complementary strand, in which every C is replaced by a G, every G by a C, every A by a T and every T by an A. For example, given a molecule with the sequence CATGTC, DNA polymerase will produce a new molecule with the sequence GTACAG. The polymerase enables DNA to reproduce, which in turn allows cells to reproduce and ultimately allows you to reproduce. For a strict reductionist, the replication of DNA polymerase is what life is is all about.
DNA polymerase is an amazing little nanomachine, a single molecule that "hops" onto a strand of DNA and slides along it, "reading " each base it passes and "writing" its complement onto a new, growing DNA strand. This was in similarity to the Turing machine (toy computer) suitable for mathematical investigation on the study of the notion of "computability" which preceded the advent of actual computers by about a decade and led to some of the major mathematical results of the 20th century. The most striking was that Turing's toy computer had turned out to be universal and could be programmed to compute anything that was computable at all. In other words, one could programme a Turing machine to produce Watson-Crick complementary strings, factor numbers, play chess and so on.
To build a DNA computer, tools were essential such as (1) Watson-Crick pairing (2) polymerases (3) Ligases (4) Nucleases (5)Gel electrophoresis, and (6) DNA synthesis.
To build a computer, only two things are really necessary - a method of sorting information and a few simple operations for acting on that information.
DNA Computer Building
The Unrestricted model of DNA computing:
To build a DNA computer, the tools were essentially the following -
1. Watson-Crick pairing - every strand of DNA has its Watson-Crick complement.
2. Polymerases - to copy information from one molecule into another.
3. Ligases - to bind molecules together.
4. Nucleases -to cut nucleic acids.
5. Gel electrophoresis - a process to separate DNA by length
6. DNA synthesis - to write a DNA sequence on a piece of paper.
Since Adleman's original experiment, several methods to reduce error and improve efficiency have been developed. The Restricted model of DNA computing solves several physical problems with the Unrestricted model. The Restricted model simplifies the physical obstructions in exchange for some additional logical considerations. The purpose of this restructuring is to simplify biochemical operations and reduce the errors due to physical obstructions
Rediscovering Biology
Biology is now the study of information stored in DNA - strings of four letters: A, T, G, and C for the bases adenine, thymine, guanine and cytosine - and of the transformations that information undergoes in the cell. There were mathematics here? DNA polymerase is the king of enzymes - the maker of life. Under appropriate conditions, given a strand of DNA, DNA polymerase produces a second "Watson-Crick" complementary strand, in which every C is replaced by a G, every G by a C, every A by a T and every T by an A. For example, given a molecule with the sequence CATGTC, DNA polymerase will produce a new molecule with the sequence GTACAG. The polymerase enables DNA to reproduce, which in turn allows cells to reproduce and ultimately allows you to reproduce. For a strict reductionist, the replication of DNA polymerase is what life is is all about.
DNA polymerase is an amazing little nanomachine, a single molecule that "hops" onto a strand of DNA and slides along it, "reading " each base it passes and "writing" its complement onto a new, growing DNA strand. This was in similarity to the Turing machine (toy computer) suitable for mathematical investigation on the study of the notion of "computability" which preceded the advent of actual computers by about a decade and led to some of the major mathematical results of the 20th century. The most striking was that Turing's toy computer had turned out to be universal and could be programmed to compute anything that was computable at all. In other words, one could programme a Turing machine to produce Watson-Crick complementary strings, factor numbers, play chess and so on.
To build a DNA computer, tools were essential such as (1) Watson-Crick pairing (2) polymerases (3) Ligases (4) Nucleases (5)Gel electrophoresis, and (6) DNA synthesis.
To build a computer, only two things are really necessary - a method of sorting information and a few simple operations for acting on that information.
DNA Computer Building
The Unrestricted model of DNA computing:
To build a DNA computer, the tools were essentially the following -
1. Watson-Crick pairing - every strand of DNA has its Watson-Crick complement.
2. Polymerases - to copy information from one molecule into another.
3. Ligases - to bind molecules together.
4. Nucleases -to cut nucleic acids.
5. Gel electrophoresis - a process to separate DNA by length
6. DNA synthesis - to write a DNA sequence on a piece of paper.
Since Adleman's original experiment, several methods to reduce error and improve efficiency have been developed. The Restricted model of DNA computing solves several physical problems with the Unrestricted model. The Restricted model simplifies the physical obstructions in exchange for some additional logical considerations. The purpose of this restructuring is to simplify biochemical operations and reduce the errors due to physical obstructions
Autonomic Computing
Definition
The millions of businesses, billions of humans that compose them, and trillions of devices that they will depend upon all require the services of the IT industry to keep them running. And it's not just a matter of numbers. It's the complexity of these systems and the way they work together that is creating a shortage of skilled IT workers to manage all of the systems. It's a problem that is not going away, but will grow exponentially, just as our dependence on technology has.
The solution is to build computer systems that regulate themselves much in the same way our autonomic nervous system regulates and protects our bodies. This new model of computing is called autonomic computing. The good news is that some components of this technology are already up and running. However, complete autonomic systems do not yet exist. Autonomic computing calls for a whole new area of study and a whole new way of conducting business.
The Benefits
Autonomic computing was conceived to lessen the spiraling demands for skilled IT resources, reduce complexity and to drive computing into a new era that may better exploit its potential to support higher order thinking and decision making. Immediate benefits will include reduced dependence on human intervention to maintain complex systems accompanied by a substantial decrease in costs. Long-term benefits will allow individuals, organizations and businesses to collaborate on complex problem solving.
The Problem
Within the past two decades the development of raw computing power coupled with the proliferation of computer devices has grown at exponential rates. This phenomenal growth along with the advent of the Internet have led to a new age of accessibility - to other people, other systems, and most importantly, to information. This boom has also led to unprecedented levels of complexity.
The simultaneous explosion of information and integration of technology into everyday life has brought on new demands for how people manage and maintain computer systems. Demand is already outpacing supply when it comes to managing complex, and even simple computer systems. Even in uncertain economic times, demand for skilled IT workers is expected to increase by over 100 percent in the next six years.
As access to information becomes omnipresent through PC's, hand-held and wireless devices, the stability of current infrastructure, systems, and data is at an increasingly greater risk to suffer outages and general disrepair. IBM believes that we are quickly reaching a threshold moment in the evolution of the industry's views toward computing in general and the associated infrastructure, middleware, and services that maintain them. The increasing system complexity is reaching a level beyond human ability to manage and secure.
This increasing complexity with a shortage of skilled IT professionals points towards an inevitable need to automate many of the functions associated with computing today.
The Solution
IBM's proposed solution looks at the problem from the most important perspective: the end user's. How do IT customers want computing systems to function? They want to interact with them intuitively, and they want to have to be far less involved in running them. Ideally, they would like computing systems to pretty much take care of the mundane elements of management by themselves.
The most direct inspiration for this functionality that exists today is the autonomic function of the human central nervous system. Autonomic controls use motor neurons to send indirect messages to organs at a sub-conscious level. These messages regulate temperature, breathing, and heart rate without conscious thought. The implications for computing are immediately evident; a network of organized, "smart" computing components that give us what we need, when we need it, without a conscious mental or even physical effort.
IBM has named its vision for the future of computing "autonomic computing." This new paradigm shifts the fundamental definition of the technology age from one of computing, to one defined by data. Access to data from multiple, distributed sources, in addition to traditional centralized storage devices will allow users to transparently access information when and where they need it. At the same time, this new view of computing will necessitate changing the industry's focus on processing speed and storage to one of developing distributed networks that are largely self-managing, self-diagnostic, and transparent to the user.
The millions of businesses, billions of humans that compose them, and trillions of devices that they will depend upon all require the services of the IT industry to keep them running. And it's not just a matter of numbers. It's the complexity of these systems and the way they work together that is creating a shortage of skilled IT workers to manage all of the systems. It's a problem that is not going away, but will grow exponentially, just as our dependence on technology has.
The solution is to build computer systems that regulate themselves much in the same way our autonomic nervous system regulates and protects our bodies. This new model of computing is called autonomic computing. The good news is that some components of this technology are already up and running. However, complete autonomic systems do not yet exist. Autonomic computing calls for a whole new area of study and a whole new way of conducting business.
The Benefits
Autonomic computing was conceived to lessen the spiraling demands for skilled IT resources, reduce complexity and to drive computing into a new era that may better exploit its potential to support higher order thinking and decision making. Immediate benefits will include reduced dependence on human intervention to maintain complex systems accompanied by a substantial decrease in costs. Long-term benefits will allow individuals, organizations and businesses to collaborate on complex problem solving.
The Problem
Within the past two decades the development of raw computing power coupled with the proliferation of computer devices has grown at exponential rates. This phenomenal growth along with the advent of the Internet have led to a new age of accessibility - to other people, other systems, and most importantly, to information. This boom has also led to unprecedented levels of complexity.
The simultaneous explosion of information and integration of technology into everyday life has brought on new demands for how people manage and maintain computer systems. Demand is already outpacing supply when it comes to managing complex, and even simple computer systems. Even in uncertain economic times, demand for skilled IT workers is expected to increase by over 100 percent in the next six years.
As access to information becomes omnipresent through PC's, hand-held and wireless devices, the stability of current infrastructure, systems, and data is at an increasingly greater risk to suffer outages and general disrepair. IBM believes that we are quickly reaching a threshold moment in the evolution of the industry's views toward computing in general and the associated infrastructure, middleware, and services that maintain them. The increasing system complexity is reaching a level beyond human ability to manage and secure.
This increasing complexity with a shortage of skilled IT professionals points towards an inevitable need to automate many of the functions associated with computing today.
The Solution
IBM's proposed solution looks at the problem from the most important perspective: the end user's. How do IT customers want computing systems to function? They want to interact with them intuitively, and they want to have to be far less involved in running them. Ideally, they would like computing systems to pretty much take care of the mundane elements of management by themselves.
The most direct inspiration for this functionality that exists today is the autonomic function of the human central nervous system. Autonomic controls use motor neurons to send indirect messages to organs at a sub-conscious level. These messages regulate temperature, breathing, and heart rate without conscious thought. The implications for computing are immediately evident; a network of organized, "smart" computing components that give us what we need, when we need it, without a conscious mental or even physical effort.
IBM has named its vision for the future of computing "autonomic computing." This new paradigm shifts the fundamental definition of the technology age from one of computing, to one defined by data. Access to data from multiple, distributed sources, in addition to traditional centralized storage devices will allow users to transparently access information when and where they need it. At the same time, this new view of computing will necessitate changing the industry's focus on processing speed and storage to one of developing distributed networks that are largely self-managing, self-diagnostic, and transparent to the user.
Short Message Service (SMS)
Definition
Short message service (SMS) is a globally accepted wireless service that enables the transmission of alphanumeric messages between mobile subscribers and external systems such as electronic mail, paging, and voice mail systems. The benefits of SMS to subscribers center around convenience, flexibility, and seamless integration of messaging services and data access. From this perspective, the benefit is to be able to use the handset as an extension of the computer. SMS also eliminates the need for separate devices for messaging, as services can be integrated into a single wireless device-the mobile terminal. SMS provides a time stamp reporting the time of submission of the message and an indication to the handset of whether there are more messages to send (GSM) or the number of additional messages to send.
SMS appeared on the wireless scene in 1991 in Europe. The European standard for digital wireless, now known as the Global System for Mobile Communications (GSM), included short messaging services from the outset.
In North America, SMS was made available initially on digital wireless networks built by early pioneers such as BellSouth Mobility, PrimeCo, and Nextel, among others. These digital wireless networks are based on GSM, code division multiple access (CDMA), and time division multiple access (TDMA) standards. Network consolidation from mergers and acquisitions has resulted in large wireless networks having nationwide or international coverage and sometimes supporting more than one wireless technology. This new class of service providers demands network-grade products that can easily provide a uniform solution, enable ease of operation and administration, and accommodate existing subscriber capacity, message throughput, future growth, and services reliably.
Short messaging service center (SMSC) solutions based on an intelligent network (IN) approach are well suited to satisfy these requirements, while adding all the benefits of IN implementations handling multiple input sources, including a voice-mail system (VMS), Web-based messaging, e-mail integration, and other external short message entities (ESMEs).Communication with the wireless network elements such as the home location register (HLR) and mobile switching center (MSC) is achieved through the signal transfer point (STP). SMS provides a mechanism for transmitting short messages to and from wireless devices. The service makes use of an SMSC, which acts as a store-and-forward system for short messages.
The wireless network provides the mechanisms required to find the destination station(s) and transports short messages between the SMSCs and wireless stations. In contrast to other existing text-message transmission services such as alphanumeric paging, the service elements are designed to provide guaranteed delivery of text messages to the destination. Additionally, SMS supports several input mechanisms that allow interconnection with different message sources and destinations. A distinguishing characteristic of the service is that an active mobile handset is able to receive or submit a short message at any time, independent of whether a voice or data call is in progress (in some implementations, this may depend on the MSC or SMSC capabilities). SMS also guarantees delivery of the short message by the network. Temporary failures due to unavailable receiving stations are identified, and the short message is stored in the SMSC until the destination device becomes available.
SMS is characterized by out-of-band packet delivery and low-bandwidth message transfer, which results in a highly efficient means for transmitting short bursts of data. Initial applications of SMS focused on eliminating alphanumeric pagers by permitting two-way general-purpose messaging and notification services, primarily for voice mail. As technology and networks evolved, a variety of services have been introduced, including e-mail, fax, and paging integration, interactive banking, information services such as stock quotes, and integration with Internet-based applications. Wireless data applications include downloading of subscriber identity module (SIM) cards for activation, debit, profile-editing purposes, wireless points of sale (POSs), and other field-service applications such as automatic meter reading, remote sensing, and location-based services. Additionally, integration with the Internet spurred the development of Web-based messaging and other interactive applications such as instant messaging, gaming, and chatting.
Short message service (SMS) is a globally accepted wireless service that enables the transmission of alphanumeric messages between mobile subscribers and external systems such as electronic mail, paging, and voice mail systems. The benefits of SMS to subscribers center around convenience, flexibility, and seamless integration of messaging services and data access. From this perspective, the benefit is to be able to use the handset as an extension of the computer. SMS also eliminates the need for separate devices for messaging, as services can be integrated into a single wireless device-the mobile terminal. SMS provides a time stamp reporting the time of submission of the message and an indication to the handset of whether there are more messages to send (GSM) or the number of additional messages to send.
SMS appeared on the wireless scene in 1991 in Europe. The European standard for digital wireless, now known as the Global System for Mobile Communications (GSM), included short messaging services from the outset.
In North America, SMS was made available initially on digital wireless networks built by early pioneers such as BellSouth Mobility, PrimeCo, and Nextel, among others. These digital wireless networks are based on GSM, code division multiple access (CDMA), and time division multiple access (TDMA) standards. Network consolidation from mergers and acquisitions has resulted in large wireless networks having nationwide or international coverage and sometimes supporting more than one wireless technology. This new class of service providers demands network-grade products that can easily provide a uniform solution, enable ease of operation and administration, and accommodate existing subscriber capacity, message throughput, future growth, and services reliably.
Short messaging service center (SMSC) solutions based on an intelligent network (IN) approach are well suited to satisfy these requirements, while adding all the benefits of IN implementations handling multiple input sources, including a voice-mail system (VMS), Web-based messaging, e-mail integration, and other external short message entities (ESMEs).Communication with the wireless network elements such as the home location register (HLR) and mobile switching center (MSC) is achieved through the signal transfer point (STP). SMS provides a mechanism for transmitting short messages to and from wireless devices. The service makes use of an SMSC, which acts as a store-and-forward system for short messages.
The wireless network provides the mechanisms required to find the destination station(s) and transports short messages between the SMSCs and wireless stations. In contrast to other existing text-message transmission services such as alphanumeric paging, the service elements are designed to provide guaranteed delivery of text messages to the destination. Additionally, SMS supports several input mechanisms that allow interconnection with different message sources and destinations. A distinguishing characteristic of the service is that an active mobile handset is able to receive or submit a short message at any time, independent of whether a voice or data call is in progress (in some implementations, this may depend on the MSC or SMSC capabilities). SMS also guarantees delivery of the short message by the network. Temporary failures due to unavailable receiving stations are identified, and the short message is stored in the SMSC until the destination device becomes available.
SMS is characterized by out-of-band packet delivery and low-bandwidth message transfer, which results in a highly efficient means for transmitting short bursts of data. Initial applications of SMS focused on eliminating alphanumeric pagers by permitting two-way general-purpose messaging and notification services, primarily for voice mail. As technology and networks evolved, a variety of services have been introduced, including e-mail, fax, and paging integration, interactive banking, information services such as stock quotes, and integration with Internet-based applications. Wireless data applications include downloading of subscriber identity module (SIM) cards for activation, debit, profile-editing purposes, wireless points of sale (POSs), and other field-service applications such as automatic meter reading, remote sensing, and location-based services. Additionally, integration with the Internet spurred the development of Web-based messaging and other interactive applications such as instant messaging, gaming, and chatting.
Millipede
Definition
Today data storage is dominated by the use of magnetic disks. Storage densities of about more than 5 Gb/cm 2 have been achieved. In the past 40 years areal density has increased by 6 orders of magnitude. But there is a physical limit. It has been predicted that superparamagnetic effects- the bit size at which stored information become volatile as a function of time- will limit the densities of current longitudinal recording media to about 15.5 Gb/cm2 . In the near future century nanometer scale will presumably pervade the field of data storage. In magnetic storage used today, there is no clear-cut way to achieve the nanometer scale in all three dimensions. So new techniques like holographic memory and probe based data storage are emerging. If an emerging technology is to be considered as a serious candidate to replace an existing technology, it should offer long-term perspectives. Any new technology with better areal density than today's magnetic storage should have long-term potential for further scaling, desirably down to nanometer or even atomic scale.
The only available tool known today that is simple and yet offer these long-term perspectives is a nanometer-sharp tip like in atomic force microscope (AFM) and scanning tunneling microscope (STM). The simple tip is a very reliable tool that concentrates on one functionality: the ultimate local confinement of interaction. In local probe based data storage we have a cantilever that has a very small tip at its end. Small indentations are made in a polymer medium laid over a silicon substrate. These indentations serve as data storage locations. A single AFM operates best on the microsecond time scale. Conventional magnetic storage, however, operates at best on the nanosecond time scale, making it clear that AFM data rates have to be improved by at least three orders of magnitude to be competitive with current and future magnetic recording. The "millipede" concept is a new approach for storing data at high speed and with an ultrahigh density.
Millipede Concept
Millipede is a highly parallel scanning probe based data storage that has a real storage densities far beyond superparamagnetic limits and data rates comparable to today's magnetic recording. At the first glance, millipede looks like a conventional 14 X 7 mm 2 silicon chip. Mounted at the center of the chip is a miniature two-dimensional array of 1024 'v'-shaped cantilevered arms that are 70 µm long and 0.5 µm thick. A nano-sharp fang-like tip, only 20 nm in diameter, hangs from the apex of each cantilever. The multiplex drivers, allow addressing of each tip individually. Beneath the cantilever array, is a thin layer of polymer film deposited on a movable, three-axis silicon table. The 2-D AFM cantilever array storage technique called "millipede" is based on a mechanical parallel x/y scanning of either the entire cantilever array chip or the storage medium.
In addition, a feedback-controlled z-approaching and leveling scheme brings the entire cantilever array chip into contact with the storage medium. The tip-medium contact is maintained and controlled while x/y scanning is performed for read/write. The millipede approach is not based on individual z-feedback for each cantilever ; rather it uses a feedback control for the entire chip, which greatly simplifies the system. However this requires very good control and uniformity of tip height and cantilever bending. Chip approach/leveling makes use of additionally integrated approaching cantilever sensors in the corners of the array chip to control the approach of the chip to the storage medium. Signals from these sensors provide feedback signals to adjust the z-actuators until contact with the medium is established. Feedback loops maintain the chip leveled and in contact with the surface while x/y scanning is performed for write/read operations.
Millipede Is Unique
Conventional data storage devices, such as disk drives and CD/DVDs, are based on systems that sense changes in magnetic fields or light to perform the read/write/store/erase functions. Millipede is unique both in form and the way it performs data storage tasks; it is based on a chip-mounted, mechanical system that senses a physical change in the storage media. The millipede's technology is actually closer to, although on an atomic scale, the archaic punched card than the more recent magnetic media. Using millipede, the IBM scientists have demonstrated a data storage density of a trillion bits per square inch -20 times higher than the densest magnetic storage available today. Millipede is dense enough to store the equivalent of 25 DVDs on a surface of the size of a postage stamp. This technology may boost the storage capacity of handheld devices - personal digital assistants (PDAs) and cell phones - often criticized for their low storage capabilities.
Today data storage is dominated by the use of magnetic disks. Storage densities of about more than 5 Gb/cm 2 have been achieved. In the past 40 years areal density has increased by 6 orders of magnitude. But there is a physical limit. It has been predicted that superparamagnetic effects- the bit size at which stored information become volatile as a function of time- will limit the densities of current longitudinal recording media to about 15.5 Gb/cm2 . In the near future century nanometer scale will presumably pervade the field of data storage. In magnetic storage used today, there is no clear-cut way to achieve the nanometer scale in all three dimensions. So new techniques like holographic memory and probe based data storage are emerging. If an emerging technology is to be considered as a serious candidate to replace an existing technology, it should offer long-term perspectives. Any new technology with better areal density than today's magnetic storage should have long-term potential for further scaling, desirably down to nanometer or even atomic scale.
The only available tool known today that is simple and yet offer these long-term perspectives is a nanometer-sharp tip like in atomic force microscope (AFM) and scanning tunneling microscope (STM). The simple tip is a very reliable tool that concentrates on one functionality: the ultimate local confinement of interaction. In local probe based data storage we have a cantilever that has a very small tip at its end. Small indentations are made in a polymer medium laid over a silicon substrate. These indentations serve as data storage locations. A single AFM operates best on the microsecond time scale. Conventional magnetic storage, however, operates at best on the nanosecond time scale, making it clear that AFM data rates have to be improved by at least three orders of magnitude to be competitive with current and future magnetic recording. The "millipede" concept is a new approach for storing data at high speed and with an ultrahigh density.
Millipede Concept
Millipede is a highly parallel scanning probe based data storage that has a real storage densities far beyond superparamagnetic limits and data rates comparable to today's magnetic recording. At the first glance, millipede looks like a conventional 14 X 7 mm 2 silicon chip. Mounted at the center of the chip is a miniature two-dimensional array of 1024 'v'-shaped cantilevered arms that are 70 µm long and 0.5 µm thick. A nano-sharp fang-like tip, only 20 nm in diameter, hangs from the apex of each cantilever. The multiplex drivers, allow addressing of each tip individually. Beneath the cantilever array, is a thin layer of polymer film deposited on a movable, three-axis silicon table. The 2-D AFM cantilever array storage technique called "millipede" is based on a mechanical parallel x/y scanning of either the entire cantilever array chip or the storage medium.
In addition, a feedback-controlled z-approaching and leveling scheme brings the entire cantilever array chip into contact with the storage medium. The tip-medium contact is maintained and controlled while x/y scanning is performed for read/write. The millipede approach is not based on individual z-feedback for each cantilever ; rather it uses a feedback control for the entire chip, which greatly simplifies the system. However this requires very good control and uniformity of tip height and cantilever bending. Chip approach/leveling makes use of additionally integrated approaching cantilever sensors in the corners of the array chip to control the approach of the chip to the storage medium. Signals from these sensors provide feedback signals to adjust the z-actuators until contact with the medium is established. Feedback loops maintain the chip leveled and in contact with the surface while x/y scanning is performed for write/read operations.
Millipede Is Unique
Conventional data storage devices, such as disk drives and CD/DVDs, are based on systems that sense changes in magnetic fields or light to perform the read/write/store/erase functions. Millipede is unique both in form and the way it performs data storage tasks; it is based on a chip-mounted, mechanical system that senses a physical change in the storage media. The millipede's technology is actually closer to, although on an atomic scale, the archaic punched card than the more recent magnetic media. Using millipede, the IBM scientists have demonstrated a data storage density of a trillion bits per square inch -20 times higher than the densest magnetic storage available today. Millipede is dense enough to store the equivalent of 25 DVDs on a surface of the size of a postage stamp. This technology may boost the storage capacity of handheld devices - personal digital assistants (PDAs) and cell phones - often criticized for their low storage capabilities.
AC Performance Of Nanoelectronics
Definition
Nano electronic devices fall into two classes: tunnel devices and ballistic transport devices. In Tunnel devices single electron effects occur if the tunnel resistance is larger than h/e = 25 K §Ù. In Ballistic devices with cross sectional dimensions in the range of quantum mechanical wavelength of electrons, the resistance is of order h/e = 25 K §Ù. This high resistance may seem to restrict the operational speed of nano electronics in general. However the capacitance values and drain source spacing are typically small which gives rise to very small RC times and transit times of order of ps or less. Thus the speed may be very large, up to THz range. The goal of this seminar is to present the models an performance predictions about the effects that set the speed limit in carbon nanotube transistors, which form the ideal test bed for understanding the high frequency properties of Nano electronics because they may behave as ideal ballistic 1d transistors.
Ballistic Transport- An Outline
When carriers travel through a semiconductor material, they are likely to be scattered by any number of possible sources, including acoustic and optical phonons, ionized impurities, defects, interfaces, and other carriers. If, however, the distance traveled by the carrier is smaller than the mean free path, it is likely not to encounter any scattering events; it can, as a result, move ballistically through the channel. To the first order, the existence of ballistic transport in a MOSFET depends on the value of the characteristic scattering length (i.e. mean free path) in relation to channel length of the transistor.
This scattering length, l , can be estimated from the measured carrier mobility where t is the average scattering time, m* is the carrier effective mass, and vth is the thermal velocity. Because scattering mechanisms determine the extent of ballistic transport, it is important to understand how these depend upon operating conditions such as normal electric field and ambient temperature.
Dependence On Normal Electric Field
In state-of-the-art MOSFET inversion layers, carrier scattering is dominated by phonons, impurities (Coulomb interaction), and surface roughness scattering at the Si-SiO2 interface. The relative importance of each scattering mechanism is dependent on the effective electric field component normal to the conduction channel. At low fields, impurity scattering dominates due to strong Coulombic interactions between the carriers and the impurity centers. As the electric field is increased, acoustic phonons begin to dominate the scattering process. At very high fields, carriers are pulled closer to the Si-SiO2 gate oxide interface; thus, surface roughness scattering degrades carrier mobility. A universal mobility model has been developed to relate field strength with the effective carrier mobility due to phonon and surface roughness scattering:
Dependence On Temperature
When the temperature is changed, the relative importance of each of the aforementioned scattering mechanisms is altered. Phonon scattering becomes less important at very low temperatures. Impurity scattering, on the other hand, becomes more significant because carriers are moving slower (thermal velocity is decreased) and thus have more time to interact with impurity centers. Surface roughness scattering remains the same because it does not depend on temperature. At liquid nitrogen temperatures (77K) and an effective electric field of 1MV/cm, the electron and hole mobilities are ~700 cm2/Vsec and ~100 cm2/Vsec, respectively. Using the above equations, the scattering lengths are approximately 17nm and 3.6nm.These scattering lengths can be assumed to be worst-case scenarios, as large operating voltages (1V) and aggressively scaled gate oxides (10Å) are assumed. Thus, actual scattering lengths will likely be larger than the calculated values.
Further device design considerations in maximizing this scattering length will be discussed in the last section of this paper. Still, the values calculated above are certainly in the range of transistor gate lengths currently being studied in advanced MOSFET research (<50nm). Ballistic carrier transport should thus become increasingly important as transistor channel lengths are further reduced in size. In addition, it should be noted that the mean free path of holes is generally smaller than that of electrons. Thus, it should be expected that ballistic transport in PMOS transistors is more difficult to achieve, since current conduction occurs through hole transport. Calculation of the mean scattering length, however, can only be regarded as a first-order estimation of ballistic transport.
To accurately determine the extent of ballistic transport evident in a particular transistor structure, Monte Carlo simulation methods must be employed. Only by modeling the random trajectory of each carrier traveling through the channel can we truly assess the extent of ballistic transport in a MOSFET.
Nano electronic devices fall into two classes: tunnel devices and ballistic transport devices. In Tunnel devices single electron effects occur if the tunnel resistance is larger than h/e = 25 K §Ù. In Ballistic devices with cross sectional dimensions in the range of quantum mechanical wavelength of electrons, the resistance is of order h/e = 25 K §Ù. This high resistance may seem to restrict the operational speed of nano electronics in general. However the capacitance values and drain source spacing are typically small which gives rise to very small RC times and transit times of order of ps or less. Thus the speed may be very large, up to THz range. The goal of this seminar is to present the models an performance predictions about the effects that set the speed limit in carbon nanotube transistors, which form the ideal test bed for understanding the high frequency properties of Nano electronics because they may behave as ideal ballistic 1d transistors.
Ballistic Transport- An Outline
When carriers travel through a semiconductor material, they are likely to be scattered by any number of possible sources, including acoustic and optical phonons, ionized impurities, defects, interfaces, and other carriers. If, however, the distance traveled by the carrier is smaller than the mean free path, it is likely not to encounter any scattering events; it can, as a result, move ballistically through the channel. To the first order, the existence of ballistic transport in a MOSFET depends on the value of the characteristic scattering length (i.e. mean free path) in relation to channel length of the transistor.
This scattering length, l , can be estimated from the measured carrier mobility where t is the average scattering time, m* is the carrier effective mass, and vth is the thermal velocity. Because scattering mechanisms determine the extent of ballistic transport, it is important to understand how these depend upon operating conditions such as normal electric field and ambient temperature.
Dependence On Normal Electric Field
In state-of-the-art MOSFET inversion layers, carrier scattering is dominated by phonons, impurities (Coulomb interaction), and surface roughness scattering at the Si-SiO2 interface. The relative importance of each scattering mechanism is dependent on the effective electric field component normal to the conduction channel. At low fields, impurity scattering dominates due to strong Coulombic interactions between the carriers and the impurity centers. As the electric field is increased, acoustic phonons begin to dominate the scattering process. At very high fields, carriers are pulled closer to the Si-SiO2 gate oxide interface; thus, surface roughness scattering degrades carrier mobility. A universal mobility model has been developed to relate field strength with the effective carrier mobility due to phonon and surface roughness scattering:
Dependence On Temperature
When the temperature is changed, the relative importance of each of the aforementioned scattering mechanisms is altered. Phonon scattering becomes less important at very low temperatures. Impurity scattering, on the other hand, becomes more significant because carriers are moving slower (thermal velocity is decreased) and thus have more time to interact with impurity centers. Surface roughness scattering remains the same because it does not depend on temperature. At liquid nitrogen temperatures (77K) and an effective electric field of 1MV/cm, the electron and hole mobilities are ~700 cm2/Vsec and ~100 cm2/Vsec, respectively. Using the above equations, the scattering lengths are approximately 17nm and 3.6nm.These scattering lengths can be assumed to be worst-case scenarios, as large operating voltages (1V) and aggressively scaled gate oxides (10Å) are assumed. Thus, actual scattering lengths will likely be larger than the calculated values.
Further device design considerations in maximizing this scattering length will be discussed in the last section of this paper. Still, the values calculated above are certainly in the range of transistor gate lengths currently being studied in advanced MOSFET research (<50nm). Ballistic carrier transport should thus become increasingly important as transistor channel lengths are further reduced in size. In addition, it should be noted that the mean free path of holes is generally smaller than that of electrons. Thus, it should be expected that ballistic transport in PMOS transistors is more difficult to achieve, since current conduction occurs through hole transport. Calculation of the mean scattering length, however, can only be regarded as a first-order estimation of ballistic transport.
To accurately determine the extent of ballistic transport evident in a particular transistor structure, Monte Carlo simulation methods must be employed. Only by modeling the random trajectory of each carrier traveling through the channel can we truly assess the extent of ballistic transport in a MOSFET.
4G Wireless Systems
Definition
Fourth generation wireless system is a packet switched wireless system with wide area coverage and high throughput. It is designed to be cost effective and to provide high spectral efficiency . The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB),and Millimeter wireless. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.The high performance is achieved by the use of long term channel prediction, in both time and frequency, scheduling among users and smart antennas combined with adaptive modulation and power control. Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.
Wireless mobile communications systems are uniquely identified by "generation designations. Introduced in the early 1980s, first generation (1G) systems were marked by analog frequency modulation and used primarily for voice communications. Second generation (2G) wireless communications systems, which made their appearance in the late 1980s, were also used mainly for voice transmission and reception The wireless system in widespread use today goes by the name of 2.5G-an "in between " service that serves as a stepping stone to 3G. Whereby 2G communications is generally associated with Global System for Mobile (GSM) service, 2.5G is usually identified as being "fueled " by General Packet Radio Services (GPRS) along with GSM. In 3G systems, making their appearance in late 2002 and in 2003, are designed for voice and paging services, as well as interactive media use such as teleconferencing, Internet access, and other services. The problem with 3G wireless systems is bandwidth-these systems provide only WAN coverage ranging from 144 kbps (for vehicle mobility applications) to 2 Mbps (for indoor static applications). Segue to 4G, the "next dimension " of wireless communication. The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB), and Millimeter wireless and smart antenna. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.Frequency band is 2 ]8 GHz. it gives the ability for world wide roaming to access cell anywhere.
Features:
o Support for interactive multimedia, voice, streaming video, Internet, and other broadband services
o IP based mobile system
o High speed, high capacity, and low cost per bit
o Global access, service portability, and scalable mobile services
o Seamless switching, and a variety of Quality of Service driven services
o Better scheduling and call admission control techniques
o Ad hoc and multi hop networks (the strict delay requirements of voice make multi hop network service a difficult problem)
o Better spectral efficiency
o Seamless network of multiple protocols and air interfaces (since 4G will be all ]IP, look for 4G systems to be compatible with all common network technologies, including802.11, WCDMA, Blue tooth, and Hyper LAN).
o An infrastructure to handle pre existing 3G systems along with other wireless technologies, some of which are currently under development.
Fourth generation wireless system is a packet switched wireless system with wide area coverage and high throughput. It is designed to be cost effective and to provide high spectral efficiency . The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB),and Millimeter wireless. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.The high performance is achieved by the use of long term channel prediction, in both time and frequency, scheduling among users and smart antennas combined with adaptive modulation and power control. Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.
Wireless mobile communications systems are uniquely identified by "generation designations. Introduced in the early 1980s, first generation (1G) systems were marked by analog frequency modulation and used primarily for voice communications. Second generation (2G) wireless communications systems, which made their appearance in the late 1980s, were also used mainly for voice transmission and reception The wireless system in widespread use today goes by the name of 2.5G-an "in between " service that serves as a stepping stone to 3G. Whereby 2G communications is generally associated with Global System for Mobile (GSM) service, 2.5G is usually identified as being "fueled " by General Packet Radio Services (GPRS) along with GSM. In 3G systems, making their appearance in late 2002 and in 2003, are designed for voice and paging services, as well as interactive media use such as teleconferencing, Internet access, and other services. The problem with 3G wireless systems is bandwidth-these systems provide only WAN coverage ranging from 144 kbps (for vehicle mobility applications) to 2 Mbps (for indoor static applications). Segue to 4G, the "next dimension " of wireless communication. The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB), and Millimeter wireless and smart antenna. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.Frequency band is 2 ]8 GHz. it gives the ability for world wide roaming to access cell anywhere.
Features:
o Support for interactive multimedia, voice, streaming video, Internet, and other broadband services
o IP based mobile system
o High speed, high capacity, and low cost per bit
o Global access, service portability, and scalable mobile services
o Seamless switching, and a variety of Quality of Service driven services
o Better scheduling and call admission control techniques
o Ad hoc and multi hop networks (the strict delay requirements of voice make multi hop network service a difficult problem)
o Better spectral efficiency
o Seamless network of multiple protocols and air interfaces (since 4G will be all ]IP, look for 4G systems to be compatible with all common network technologies, including802.11, WCDMA, Blue tooth, and Hyper LAN).
o An infrastructure to handle pre existing 3G systems along with other wireless technologies, some of which are currently under development.
NRAM
Definition
Nano-RAM, is a proprietary computer memory technology from the company Nantero and NANOMOTOR is invented by University of bologna and California nano systems.NRAM is a type of nonvolatile random access memory based on the mechanical position of carbon nanotubes deposited on a chip-like substrate. In theory the small size of the nanotubes allows for very high density memories. Nantero also refers to it as NRAM in short, but this acronym is also commonly used as a synonym for the more common NVRAM, which refers to all nonvolatile RAM memories.Nanomotor is a molecular motor which works continuously without the consumption of fuels. It is powered by sunlight. The research are federally funded by national science foundation and national academy of science.
Carbon Nanotubes
Carbon nanotubes (CNTs) are a recently discovered allotrope of carbon. They take the form of cylindrical carbon molecules and have novel properties that make them potentially useful in a wide variety of applications in nanotechnology, electronics, optics, and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized.
A nanotube is a member of the fullerene structural family, which also includes buckyballs. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several millimeters in length. There are two main types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).
Manufacturing a nanotube is dependent on applied quantum chemistry, specifically, orbital hybridization. Nanotubes are composed entirely of sp2 bonds, similar to those of graphite. This bonding structure, stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. Nanotubes naturally align themselves into "ropes" held together by Van der Waals forces. Under high pressure, nanotubes can merge together, trading some sp2 bonds for sp3 bonds, giving great possibility for producing strong, unlimited-length wires through high-pressure nanotube linking.
Fabrication Of NRAM
This nano electromechanical memory, called NRAM, is a memory with actual moving parts, with dimensions measured in nanometers. Its carbon nanotube based technology makes advantage of vaanderwaals force to create basic on off junctions of a bit. Vaanderwaals forces interaction between atoms that enable noncovalant binding. They rely on electron attractions that arise only at nano scale levels as a force to be reckoned with. The company is using this property in its design to integrate nanoscale material property with established cmos fabrication technique.
Storage In NRAM
NRAM works by balancing the on ridges of silicon. Under differing electric charges, the tubes can be physically swung into one or two positions representing one and zeros. Because the tubes are very small-under a thousands of time-this movement is very fast and needs very little power, and because the tubes are a thousand times conductive as copper it is very to sense to read back the data. Once in position the tubes stay there until a signal resets them.
The bit itself is not stored in the nano tubes, but rather is stored as the position of the nanotube. Up is bit 0 and down is bit 1.Bits are switched between the states by the application of the electric field.
The technology work by changing the charge placed on a latticework of crossed nanotube. By altering the charges, engineers can cause the tubes to bind together or separate, creating ones and zeros that form the basis of computer memory. If we have two nano tubes perpendicular to each other one is positive and other negative, they will bend together and touch. If we have two similar charges they will repel. These two positions are used to store one and zero. The chip will stay in the same state until you make another change in the electric field. So when you turn the computer off, it doesn't erase the memory .We can keep all the data in the NRAM and gives your computer an instant boot.
Nano-RAM, is a proprietary computer memory technology from the company Nantero and NANOMOTOR is invented by University of bologna and California nano systems.NRAM is a type of nonvolatile random access memory based on the mechanical position of carbon nanotubes deposited on a chip-like substrate. In theory the small size of the nanotubes allows for very high density memories. Nantero also refers to it as NRAM in short, but this acronym is also commonly used as a synonym for the more common NVRAM, which refers to all nonvolatile RAM memories.Nanomotor is a molecular motor which works continuously without the consumption of fuels. It is powered by sunlight. The research are federally funded by national science foundation and national academy of science.
Carbon Nanotubes
Carbon nanotubes (CNTs) are a recently discovered allotrope of carbon. They take the form of cylindrical carbon molecules and have novel properties that make them potentially useful in a wide variety of applications in nanotechnology, electronics, optics, and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized.
A nanotube is a member of the fullerene structural family, which also includes buckyballs. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several millimeters in length. There are two main types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).
Manufacturing a nanotube is dependent on applied quantum chemistry, specifically, orbital hybridization. Nanotubes are composed entirely of sp2 bonds, similar to those of graphite. This bonding structure, stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. Nanotubes naturally align themselves into "ropes" held together by Van der Waals forces. Under high pressure, nanotubes can merge together, trading some sp2 bonds for sp3 bonds, giving great possibility for producing strong, unlimited-length wires through high-pressure nanotube linking.
Fabrication Of NRAM
This nano electromechanical memory, called NRAM, is a memory with actual moving parts, with dimensions measured in nanometers. Its carbon nanotube based technology makes advantage of vaanderwaals force to create basic on off junctions of a bit. Vaanderwaals forces interaction between atoms that enable noncovalant binding. They rely on electron attractions that arise only at nano scale levels as a force to be reckoned with. The company is using this property in its design to integrate nanoscale material property with established cmos fabrication technique.
Storage In NRAM
NRAM works by balancing the on ridges of silicon. Under differing electric charges, the tubes can be physically swung into one or two positions representing one and zeros. Because the tubes are very small-under a thousands of time-this movement is very fast and needs very little power, and because the tubes are a thousand times conductive as copper it is very to sense to read back the data. Once in position the tubes stay there until a signal resets them.
The bit itself is not stored in the nano tubes, but rather is stored as the position of the nanotube. Up is bit 0 and down is bit 1.Bits are switched between the states by the application of the electric field.
The technology work by changing the charge placed on a latticework of crossed nanotube. By altering the charges, engineers can cause the tubes to bind together or separate, creating ones and zeros that form the basis of computer memory. If we have two nano tubes perpendicular to each other one is positive and other negative, they will bend together and touch. If we have two similar charges they will repel. These two positions are used to store one and zero. The chip will stay in the same state until you make another change in the electric field. So when you turn the computer off, it doesn't erase the memory .We can keep all the data in the NRAM and gives your computer an instant boot.
EDGE
Introduction
EDGE is the next step in the evolution of GSM and IS- 136. The objective of the new technology is to increase data transmission rates and spectrum efficiency and to facilitate new applications and increased capacity for mobile use. With the introduction of EDGE in GSM phase 2+, existing services such as GPRS and high-speed circuit switched data (HSCSD) are enhanced by offering a new physical layer. The services themselves are not modified. EDGE is introduced within existing specifications and descriptions rather than by creating new ones. This paper focuses on the packet-switched enhancement for GPRS, called EGPRS. GPRS allows data rates of 115 kbps and, theoretically, of up to 160 kbps on the physical layer. EGPRS is capable of offering data rates of 384 kbps and, theoretically, of up to 473.6 kbps.
A new modulation technique and error-tolerant transmission methods, combined with improved link adaptation mechanisms, make these EGPRS rates possible. This is the key to increased spectrum efficiency and enhanced applications, such as wireless Internet access, e-mail and file transfers.
GPRS/EGPRS will be one of the pacesetters in the overall wireless technology evolution in conjunction with WCDMA. Higher transmission rates for specific radio resources enhance capacity by enabling more traffic for both circuit- and packet-switched services. As the Third-generation Partnership Project (3GPP) continues standardization toward the GSM/EDGE radio access network (GERAN), GERAN will be able to offer the same services as WCDMA by connecting to the same core network. This is done in parallel with means to increase the spectral efficiency. The goal is to boost system capacity, both for real- time and best-effort services, and to compete effectively with other third-generation radio access networks such as WCDMA and cdma2000.
Technical differences between GPRS and EGPRS
Introduction
Regarded as a subsystem within the GSM standard, GPRS has introduced packet-switched data into GSM networks. Many new protocols and new nodes have been introduced to make this possible. EDGE is a method to increase the data rates on the radio link for GSM. Basically, EDGE only introduces a new modulation technique and new channel coding that can be used to transmit both packet-switched and circuit-switched voice and data services. EDGE is therefore an add-on to GPRS and cannot work alone. GPRS has a greater impact on the GSM system than EDGE has. By adding the new modulation and coding to GPRS and by making adjustments to the radio link protocols, EGPRS offers significantly higher throughput and capacity.
GPRS and EGPRS have different protocols and different behavior on the base station system side. However, on the core network side, GPRS and EGPRS share the same packet-handling protocols and, therefore, behave in the same way. Reuse of the existing GPRS core infrastructure (serving GRPS support node/gateway GPRS support node) emphasizes the fact that EGPRS is only an "add-on" to the base station system and is therefore much easier to introduce than GPRS . In addition to enhancing the throughput for each data user, EDGE also increases capacity. With EDGE, the same time slot can support more users. This decreases the number of radio resources required to support the same traffic, thus freeing up capacity for more data or voice services. EDGE makes it easier for circuit-switched and packet-switched traffic to coexist, while making more efficient use of the same radio resources. Thus in tightly planned networks with limited spectrum, EDGE may also be seen as a capacity booster for the data traffic.
EDGE technology
EDGE leverages the knowledge gained through use of the existing GPRS standard to deliver significant technical improvements. Figure 2 compares the basic technical data of GPRS and EDGE. Although GPRS and EDGE share the same symbol rate, the modulation bit rate differs. EDGE can transmit three times as many bits as GPRS during the same period of time. This is the main reason for the higher EDGE bit rates. The differences between the radio and user data rates are the result of whether or not the packet headers are taken into consideration. These different ways of calculating throughput often cause misunderstanding within the industry about actual throughput figures for GPRS and EGPRS. The data rate of 384 kbps is often used in relation to EDGE. The International Telecommunications Union (ITU) has defined 384 kbps as the data rate limit required for a service to fulfill the International Mobile Telecommunications-2000 (IMT-2000) standard in a pedestrian environment. This 384 kbps data rate corresponds to 48 kbps per time slot, assuming an eight-time slot terminal.
EDGE is the next step in the evolution of GSM and IS- 136. The objective of the new technology is to increase data transmission rates and spectrum efficiency and to facilitate new applications and increased capacity for mobile use. With the introduction of EDGE in GSM phase 2+, existing services such as GPRS and high-speed circuit switched data (HSCSD) are enhanced by offering a new physical layer. The services themselves are not modified. EDGE is introduced within existing specifications and descriptions rather than by creating new ones. This paper focuses on the packet-switched enhancement for GPRS, called EGPRS. GPRS allows data rates of 115 kbps and, theoretically, of up to 160 kbps on the physical layer. EGPRS is capable of offering data rates of 384 kbps and, theoretically, of up to 473.6 kbps.
A new modulation technique and error-tolerant transmission methods, combined with improved link adaptation mechanisms, make these EGPRS rates possible. This is the key to increased spectrum efficiency and enhanced applications, such as wireless Internet access, e-mail and file transfers.
GPRS/EGPRS will be one of the pacesetters in the overall wireless technology evolution in conjunction with WCDMA. Higher transmission rates for specific radio resources enhance capacity by enabling more traffic for both circuit- and packet-switched services. As the Third-generation Partnership Project (3GPP) continues standardization toward the GSM/EDGE radio access network (GERAN), GERAN will be able to offer the same services as WCDMA by connecting to the same core network. This is done in parallel with means to increase the spectral efficiency. The goal is to boost system capacity, both for real- time and best-effort services, and to compete effectively with other third-generation radio access networks such as WCDMA and cdma2000.
Technical differences between GPRS and EGPRS
Introduction
Regarded as a subsystem within the GSM standard, GPRS has introduced packet-switched data into GSM networks. Many new protocols and new nodes have been introduced to make this possible. EDGE is a method to increase the data rates on the radio link for GSM. Basically, EDGE only introduces a new modulation technique and new channel coding that can be used to transmit both packet-switched and circuit-switched voice and data services. EDGE is therefore an add-on to GPRS and cannot work alone. GPRS has a greater impact on the GSM system than EDGE has. By adding the new modulation and coding to GPRS and by making adjustments to the radio link protocols, EGPRS offers significantly higher throughput and capacity.
GPRS and EGPRS have different protocols and different behavior on the base station system side. However, on the core network side, GPRS and EGPRS share the same packet-handling protocols and, therefore, behave in the same way. Reuse of the existing GPRS core infrastructure (serving GRPS support node/gateway GPRS support node) emphasizes the fact that EGPRS is only an "add-on" to the base station system and is therefore much easier to introduce than GPRS . In addition to enhancing the throughput for each data user, EDGE also increases capacity. With EDGE, the same time slot can support more users. This decreases the number of radio resources required to support the same traffic, thus freeing up capacity for more data or voice services. EDGE makes it easier for circuit-switched and packet-switched traffic to coexist, while making more efficient use of the same radio resources. Thus in tightly planned networks with limited spectrum, EDGE may also be seen as a capacity booster for the data traffic.
EDGE technology
EDGE leverages the knowledge gained through use of the existing GPRS standard to deliver significant technical improvements. Figure 2 compares the basic technical data of GPRS and EDGE. Although GPRS and EDGE share the same symbol rate, the modulation bit rate differs. EDGE can transmit three times as many bits as GPRS during the same period of time. This is the main reason for the higher EDGE bit rates. The differences between the radio and user data rates are the result of whether or not the packet headers are taken into consideration. These different ways of calculating throughput often cause misunderstanding within the industry about actual throughput figures for GPRS and EGPRS. The data rate of 384 kbps is often used in relation to EDGE. The International Telecommunications Union (ITU) has defined 384 kbps as the data rate limit required for a service to fulfill the International Mobile Telecommunications-2000 (IMT-2000) standard in a pedestrian environment. This 384 kbps data rate corresponds to 48 kbps per time slot, assuming an eight-time slot terminal.
Delay Tolerant Networking
Introduction
Increasingly, network applications must communicate with counterparts across disparate networking environments characterized by significantly different sets of physical and operational constraints; wide variations in transmission latency are particularly troublesome. The proposed Interplanetary Internet, which must encompass both terrestrial and interplanetary links, is an extreme case. An architecture based on a "least common denominator" protocol that can operate successfully and (where required) reliably in multiple disparate environments would simplify the development and deployment of such applications. The highly successful architecture and supporting protocols of today's Internet are ill suited for this purpose. But Delay Tolerant Networking will crossover this bottle-neck. In this seminar the fundamental principles that would underlie a delay-tolerant networking (DTN) architecture and the main structural elements of that architecture, centered on a new end-to-end overlay network protocol called Bundling is examined.
The US Defense Advanced Research Projects Agency (DARPA), as part of its "Next Generation Internet" initiative, has recently been supporting a small group at the Jet Propulsion Laboratory (JPL) in Pasadena, California to study the technical architecture of an "Interplanetary Internet". The idea was to blend ongoing work in standardized space communications capabilities with state of the art techniques being developed within the terrestrial Internet community, with a goal of facilitating a transition as the Earth's Internet moves off-planet. The "Interplanetary Internet" name was deliberately coined to suggest a far-future integration of space and terrestrial
communications infrastructure to support the migration of human intelligence throughout the Solar System. Joining the JPL team in this work was one of the original designers of the Internet and co-inventor of the "Transmission Control Protocol/Internet Protocol" (TCP/IP) protocol suite. Support for the work has recently transitioned from DARPA to NASA.
An architecture based on a "least common denominator " protocol that can operate successfully and reliably in multiple disparate environments would simplify the development and deployment of Interplanetary Internet. It is this analysis that lead to the proposal of Delay-Tolerant Network (DTN) architecture, an architecture that can support deep space applications, centered on a new end-to-end overlay network protocol called 'Bundling'. The architecture and protocols developed for the project could also be useful in terrestrial environments where the dependence on real time interactive communication is not possible. The Internet protocols are ill suited for this purpose, while the overlay protocol used in DTN architecture serves to bridge between different stacks at the boundaries between environments in a standard manner, in effect providing a general -purpose application-level gateway infrastructure that can be used by any number of applications. DTN is an architecture based on Internet-independent middleware: use exactly those protocols at all layers that are best suited to operation within each environment, but insert a new overlay network protocol between the applications and the locally optimized stacks.
Research on extending Earth's Internet into interplanetary space has been underway for several years as part of an international communications standardization body known as the Consultative Committee for Space Data Systems (CCSDS). CCSDS is primarily concerned with communications standards for scientific satellites, with a focus more on the needs of near-term missions. To extend this horizon into the future, and to involve the terrestrial internet research and engineering communities, a special Interplanetary Internet study was proposed and subsequently sponsored in the United States by NASA's Jet Propulsion Laboratory (JPL) and DARPA's Next Generation Internet Initiative
Increasingly, network applications must communicate with counterparts across disparate networking environments characterized by significantly different sets of physical and operational constraints; wide variations in transmission latency are particularly troublesome. The proposed Interplanetary Internet, which must encompass both terrestrial and interplanetary links, is an extreme case. An architecture based on a "least common denominator" protocol that can operate successfully and (where required) reliably in multiple disparate environments would simplify the development and deployment of such applications. The highly successful architecture and supporting protocols of today's Internet are ill suited for this purpose. But Delay Tolerant Networking will crossover this bottle-neck. In this seminar the fundamental principles that would underlie a delay-tolerant networking (DTN) architecture and the main structural elements of that architecture, centered on a new end-to-end overlay network protocol called Bundling is examined.
The US Defense Advanced Research Projects Agency (DARPA), as part of its "Next Generation Internet" initiative, has recently been supporting a small group at the Jet Propulsion Laboratory (JPL) in Pasadena, California to study the technical architecture of an "Interplanetary Internet". The idea was to blend ongoing work in standardized space communications capabilities with state of the art techniques being developed within the terrestrial Internet community, with a goal of facilitating a transition as the Earth's Internet moves off-planet. The "Interplanetary Internet" name was deliberately coined to suggest a far-future integration of space and terrestrial
communications infrastructure to support the migration of human intelligence throughout the Solar System. Joining the JPL team in this work was one of the original designers of the Internet and co-inventor of the "Transmission Control Protocol/Internet Protocol" (TCP/IP) protocol suite. Support for the work has recently transitioned from DARPA to NASA.
An architecture based on a "least common denominator " protocol that can operate successfully and reliably in multiple disparate environments would simplify the development and deployment of Interplanetary Internet. It is this analysis that lead to the proposal of Delay-Tolerant Network (DTN) architecture, an architecture that can support deep space applications, centered on a new end-to-end overlay network protocol called 'Bundling'. The architecture and protocols developed for the project could also be useful in terrestrial environments where the dependence on real time interactive communication is not possible. The Internet protocols are ill suited for this purpose, while the overlay protocol used in DTN architecture serves to bridge between different stacks at the boundaries between environments in a standard manner, in effect providing a general -purpose application-level gateway infrastructure that can be used by any number of applications. DTN is an architecture based on Internet-independent middleware: use exactly those protocols at all layers that are best suited to operation within each environment, but insert a new overlay network protocol between the applications and the locally optimized stacks.
Research on extending Earth's Internet into interplanetary space has been underway for several years as part of an international communications standardization body known as the Consultative Committee for Space Data Systems (CCSDS). CCSDS is primarily concerned with communications standards for scientific satellites, with a focus more on the needs of near-term missions. To extend this horizon into the future, and to involve the terrestrial internet research and engineering communities, a special Interplanetary Internet study was proposed and subsequently sponsored in the United States by NASA's Jet Propulsion Laboratory (JPL) and DARPA's Next Generation Internet Initiative
Code Division Duplexing
Introduction
Reducing interference in a cellular system is the most effective approach to increasing radio capacity and transmission data rate in the wireless environment. Therefore, reducing interference is a difficult and important challenge in wireless communications.
In every two-way communication system it is necessary to use separate channels to transmit information in each direction. This is called duplexing. Currently there exist only two duplexing technologies in wireless communications, Frequency division duplexing (FDD) and time division duplexing (TDD). FDD has been the primary technology used in the first three generations of mobile wireless because of its ability to isolate interference. TDD is seemingly a more spectral efficient technology but has found limited use because of interference and coverage problems.
Code-division duplexing (CDD) is an innovative solution that can eliminate all kinds of interference. CDMA is the best multiple access scheme when compared to all others for combating interference. However, the codes in CDMA can be more than one type of code. A set of smart codes can make a high-capacity CDMA system very effective without adding other technologies. The smart code plus TDD is called CDD. This paper will elaborate on a set of smart codes that will make an efficient CDD system a reality. The CDMA system based on this is known as the LAS-CDMA, where LAS is a set of smart codes. LAS-CDMA is a new coding technology that will increase the capacity and spectral efficiency of mobile networks. The advanced technology uses a set of smart codes to restrict interference, a property that adversely affects the efficiency of CDMA networks.
To utilize spectrum efficiently, two transmission techniques need to be considered: one is a multiple access scheme and the other a duplexing system. There are three multiple access schemes namely TDMA, FDMA and CDMA. The industry has already established the best multiple access scheme, code-division multiple access (CDMA), for 3G systems. The next step is to select the best duplexing system. Duplexing systems are used for two-way communications. Presently, there are only two duplexing systems used: frequency-division duplexing (FDD), and time-division duplexing (TDD). The former uses different frequencies to handle incoming and outgoing signals. The latter uses a single frequency but different time slots to handle incoming and outgoing signals.
In the current cellular duplexing systems, FDD has been the appropriate choice, not TDD. Currently, all cellular systems use frequency-division duplexing in an attempt to eliminate interference from adjacent cells. The use of many technologies has limited the effects of interference but still certain types of interference remain. Time-division duplexing has not been used for mobile cellular systems because it is even more susceptible to different forms of interference. TDD can only be used for small confined area systems. Code-division duplexing is an innovative solution that can eliminate all kinds of interference. Eliminating all types of interference makes CDD the most spectrum efficient duplexing system.
CDMA overview
Interference and Capacity
One of the key criteria in evaluating a communication system is its spectral efficiency, or the system capacity, for a given system bandwidth, or sometimes, the total data rate supported by the system. For a given bandwidth, the system capacity for narrow band radio systems is dimension limited, while the system capacity of a traditional CDMA system is interference limited. Traditional CDMA systems are all self-interference system. Three types of interference are usually considered. By ISI we mean Inter Symbol Interference, which is created by the multi-path replica of the useful signal itself; MAI, or Mutual Access Interference, which is the interference created by the signals and their multi-path replica from the other users onto the useful signal; and ACI, or Adjacent Cell Interference, which is all the interfering signals from the adjacent cells onto the useful signal.
Reducing interference in a cellular system is the most effective approach to increasing radio capacity and transmission data rate in the wireless environment. Therefore, reducing interference is a difficult and important challenge in wireless communications.
In every two-way communication system it is necessary to use separate channels to transmit information in each direction. This is called duplexing. Currently there exist only two duplexing technologies in wireless communications, Frequency division duplexing (FDD) and time division duplexing (TDD). FDD has been the primary technology used in the first three generations of mobile wireless because of its ability to isolate interference. TDD is seemingly a more spectral efficient technology but has found limited use because of interference and coverage problems.
Code-division duplexing (CDD) is an innovative solution that can eliminate all kinds of interference. CDMA is the best multiple access scheme when compared to all others for combating interference. However, the codes in CDMA can be more than one type of code. A set of smart codes can make a high-capacity CDMA system very effective without adding other technologies. The smart code plus TDD is called CDD. This paper will elaborate on a set of smart codes that will make an efficient CDD system a reality. The CDMA system based on this is known as the LAS-CDMA, where LAS is a set of smart codes. LAS-CDMA is a new coding technology that will increase the capacity and spectral efficiency of mobile networks. The advanced technology uses a set of smart codes to restrict interference, a property that adversely affects the efficiency of CDMA networks.
To utilize spectrum efficiently, two transmission techniques need to be considered: one is a multiple access scheme and the other a duplexing system. There are three multiple access schemes namely TDMA, FDMA and CDMA. The industry has already established the best multiple access scheme, code-division multiple access (CDMA), for 3G systems. The next step is to select the best duplexing system. Duplexing systems are used for two-way communications. Presently, there are only two duplexing systems used: frequency-division duplexing (FDD), and time-division duplexing (TDD). The former uses different frequencies to handle incoming and outgoing signals. The latter uses a single frequency but different time slots to handle incoming and outgoing signals.
In the current cellular duplexing systems, FDD has been the appropriate choice, not TDD. Currently, all cellular systems use frequency-division duplexing in an attempt to eliminate interference from adjacent cells. The use of many technologies has limited the effects of interference but still certain types of interference remain. Time-division duplexing has not been used for mobile cellular systems because it is even more susceptible to different forms of interference. TDD can only be used for small confined area systems. Code-division duplexing is an innovative solution that can eliminate all kinds of interference. Eliminating all types of interference makes CDD the most spectrum efficient duplexing system.
CDMA overview
Interference and Capacity
One of the key criteria in evaluating a communication system is its spectral efficiency, or the system capacity, for a given system bandwidth, or sometimes, the total data rate supported by the system. For a given bandwidth, the system capacity for narrow band radio systems is dimension limited, while the system capacity of a traditional CDMA system is interference limited. Traditional CDMA systems are all self-interference system. Three types of interference are usually considered. By ISI we mean Inter Symbol Interference, which is created by the multi-path replica of the useful signal itself; MAI, or Mutual Access Interference, which is the interference created by the signals and their multi-path replica from the other users onto the useful signal; and ACI, or Adjacent Cell Interference, which is all the interfering signals from the adjacent cells onto the useful signal.
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