INTRODUCTION

Since the fabrication of MOSFET, the minimum channel length has been shrinking continuously. The motivation behind this decrease has been an increasing interest in high speed devices and in very large scale integrated circuits. The sustained scaling of conventional bulk device requires innovations to circumvent the barriers of fundamental physics constraining the conventional MOSFET device structure. The limits most often cited are control of the density and location of dopants providing high I on /I off ratio and finite subthreshold slope and quantum-mechanical tunneling of carriers through thin gate from drain to source and from drain to body. The channel depletion width must scale with the channel length to contain the off-state leakage I off. This leads to high doping concentration, which degrade the carrier mobility and causes junction edge leakage due to tunneling. Furthermore, the dopant profile control, in terms of depth and steepness, becomes much more difficult. The gate oxide thickness tox must also scale with the channel length to maintain gate control, proper threshold voltage VT and performance. The thinning of the gate dielectric results in gate tunneling leakage, degrading the circuit performance, power and noise margin.

Alternative device structures based on silicon-on-insulator (SOI) technology have emerged as an effective means of extending MOS scaling beyond bulk limits for mainstream high-performance or low-power applications .Partially depleted (PD) SOI was the first SOI technology introduced for high-performance microprocessor applications. The ultra-thin-body fully depleted (FD) SOI and the non-planar FinFET device structures promise to be the potential “future” technology/device choices.

In these device structures, the short-channel effect is controlled by geometry, and the off-state leakage is limited by the thin Si film. For effective suppression of the off-state leakage, the thickness of the Si film must be less than one quarter of the channel length. The desired VT is achieved by manipulating the gate work function, such as the use of midgap material or poly-SiGe. Concurrently, material enhancements, such as the use of a) high-k gate material and b) strained Si channel for mobility and current drive improvement, have been actively pursued.

As scaling approaches multiple physical limits and as new device structures and materials are introduced, unique and new circuit design issues continue to be presented. In this article, we review the design challenges of these emerging technologies with particular emphasis on the implications and impacts of individual device scaling elements and unique device structures on the circuit design. We focus on the planar device structures, from continuous scaling of PD SOI to FD SOI, and new materials such as strained-Si channel and high-k gate dielectric.

PARTIALLY DEPLETED [PD] SOI

The PD floating-body MOSFET was the first SOI transistor generically adopted for high-performance applications, primarily due to device and processing similarities to bulk CMOS device.

The PD SOI device is largely identical to the bulk device, except for the addition of a buried oxide (“BOX”) layer. The active Si film thickness is larger than the channel depletion width, thus leaving a quasi-neutral “floating” body region underneath the channel. The V T of the device is completely decoupled from the Si film thickness, and the doping profiles can be tailored for any desired VT .

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ABSTRACT

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.

INTRODUCTION

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 InterSymbol 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. .

Traditional synchronous CDMA systems employ almost exclusively Walsh-Hadamard orthogonal codes, jointly with PN sequence, and Gold codes, Kasami codes, etc. In these systems, due to the difficulty in timing synchronization and the large cross-correlation values around the origin, there exists a “near far” effect, such that in some typical system, fast power control has to be employed in order to keep an uniform received signal level at the base station. On the other hand, in forward channel all the signals’ power must be kept at an uniform level. Since the transmitting power of a user would interfere others and even may interfere itself, if one of the users in the system increases its power unilaterally, all other users power should be simultaneously increased; otherwise the controlled system power regime will be destroyed, and the capacity would be drastically decreased. This is because any radio channel, especially mobile channel, is a random time-varying time dispersion channel due to the multi-path effect, so that the received signal can not be reached at the receiver simultaneously.

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ABSTRACT

Real-time systems play a considerable role in our society, and they cover a spectrum from the very simple to the very complex. Examples of current real-time systems include the control of domestic appliances like washing machines and televisions, the control of automobile engines, telecommunication switching systems, military command and control systems, industrial process control, flight control systems, and space shuttle and aircraft avionics.

All of these involve gathering data from the environment, processing of gathered data, and providing timely response. A concept of time is the distinguishing issue between real-time and non-real-time systems. When a usual design goal for non-real-time systems is to maximize system’s throughput, the goal for real-time system design is to guarantee, that all tasks are processed within a given time. The taxonomy of time introduces special aspects for real-time system research. Real-time operating systems are an integral part of real-time systems. Future systems will be much larger, more widely distributed, and will be expected to perform a constantly changing set of duties in dynamic environments. This also sets more requirements for future real-time operating systems. This seminar has the humble aim to convey the main ideas on Real Time System and Real Time Operating System design and implementation.

INTRODUCTION

Timeliness is the single most important aspect of a real -time system. These systems respond to a series of external inputs, which arrive in an unpredictable fashion. The real-time systems process these inputs, take appropriate decisions and also generate output necessary to control the peripherals connected to them. As defined by Donald Gillies “A real-time system is one in which the correctness of the computations not only depends upon the logical correctness of the computation but also upon the time in which the result is produced. If the timing constraints are not met, system failure is said to have occurred.”

It is essential that the timing constraints of the system are guaranteed to be met. Guaranteeing timing behavior requires that the system be predictable. The design of a real -time system must specify the timing requirements of the system and ensure that the system performance is both correct and timely. There are three types of time constraints:

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ABSTRACT

The seminar is about polymers that can emit light when a voltage is applied to it. The structure comprises of a thin film of semiconducting polymer sandwiched between two electrodes (cathode and anode).When electrons and holes are injected from the electrodes, the recombination of these charge carriers takes place, which leads to emission of light .The band gap, ie. The energy difference between valence band and conduction band determines the wavelength (colour) of the emitted light.
They are usually made by ink jet printing process. In this method red green and blue polymer solutions are jetted into well defined areas on the substrate. This is because, PLEDs are soluble in common organic solvents like toluene and xylene .The film thickness uniformity is obtained by multi-passing (slow) is by heads with drive per nozzle technology .The pixels are controlled by using active or passive matrix. The advantages include low cost, small size, no viewing angle restrictions, low power requirement, biodegradability etc. They are poised to replace LCDs used in laptops and CRTs used in desktop computers today. Their future applications include flexible displays which can be folded, wearable displays with interactive features, camouflage etc.

INTRODUCTION

Imagine these scenarios
- After watching the breakfast news on TV, you roll up the set like a large handkerchief, and stuff it into your briefcase. On the bus or train journey to your office, you can pull it out and catch up with the latest stock market quotes on CNBC.
- Somewhere in the Kargil sector, a platoon commander of the Indian Army readies for the regular satellite updates that will give him the latest terrain pictures of the border in his sector. He unrolls a plastic-like map and hooks it to the unit’s satellite telephone. In seconds, the map is refreshed with the latest high resolution camera images grabbed by an Indian satellite which passed over the region just minutes ago.
Don’t imagine these scenarios at least not for too long.The current 40 billion-dollar display market, dominated by LCDs (standard in laptops) and cathode ray tubes (CRTs, standard in televisions), is seeing the introduction of full-color LEP-driven displays that are more efficient, brighter, and easier to manufacture. It is possible that organic light-emitting materials will replace older display technologies much like compact discs have relegated cassette tapes to storage bins. .

The origins of polymer OLED technology go back to the discovery of conducting polymers in 1977,which earned the co-discoverers- Alan J. Heeger , Alan G. MacDiarmid and Hideki Shirakawa – the 2000 Nobel prize in chemistry. Following this discovery , researchers at Cambridge University UK discovered in 1990 that conducting polymers also exhibit electroluminescence and the light emitting polymer(LEP) was born!.

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ABSTRACT

Nowadays the number of people who are using Internet is dramatically increasing. With no hesitation, it can be said that the Internet is indeed the most popular media of communication prevailing in the present world scenario. But many of the users are nowadays facing the problem of failure in maintaining the connection with the cyber world.

The prime reason for the problem is that in the existing technology of connection with the Internet, a client is connected to a server through a number of nodes which depends on each other to facilitate the flow of information. The problem with the existing technology is that, even if a single intermediate node malfunctions, the whole system collapses. The solution to the problem is RAIN-Reliable Array Of Independent Nodes developed by the California Institute of Technology (Caltech), in collaboration with NASA’s Jet Propulsion Laboratory and the Defense Advanced Research Projects Agency (DARPA).
RAIN technology was able to offer the solution by minimizing the number of nodes in the chain connecting the client and server and also by making the existing nodes more robust and independent of each other. Also RAIN technology provides the novel feature of replacing a faulty node by a healthy one there by avoiding the break in information flow. In effect with the aid of RAIN connection between a client and server can be maintained despite all the existing problems.

INTRODUCTION

The Internet is changing the way that people manage and access information. In the last five years, the amount of traffic on the Internet has been growing at an exponential rate. The World Wide Web has evolved from a hobbyists’ toy to become one of the dominating media of our society. Ecommerce has grown past adolescence and multimedia content has come of age. Communication, computation and storage are converging to reshape the lives of everyone. Looking forward, this growth will continue for some time. The question is: what can we do to scale the Internet infrastructure to meet this growth?.

There are four trends in the current growth of the Internet:
1. Internet clients are becoming more numerous and varied. In addition to the ever-increasing number of PCs in offices and homes, there are new types of clients, such as mobile data units, (cell phones, PDAs, etc.) and home Internet appliances (set-top boxes, game consoles, etc.) In the next five years, these new types of Internet devices will pervade the Internet landscape.
2. To support these new clients, new types of networks are being designed and implemented. Examples are wireless data networks, broadband networks and voice-over-IP networks. Technologies are being developed to connect these new networks with the existing Internet backbone.
3. The content delivered over the Internet is evolving, partly because of the emergence of the new clients and new networks. There will be a growing presence of multimedia content, such as video, voice, music and gaming streams. The growth in content adds not only to the volume of the traffic, but also to the computation complexity in transporting and processing the traffic, thus accelerating the convergence between communication and computation.
4. New Internet applications emerge, both on the server side and the client side. As the Internet penetrates deeper and deeper into everyone’s life, the demand for security, reliability, convenience and performance sky-rockets. With the popularity of cars comes the invention of traffic lights and stop signs, the gas station and the drive-thru. As Internet makes its way into daily lives, the demand will grow for firewalls and VPNs, intrusion detection and virus scanning, server load balancing and content management, quality of service and billing/reporting applications. The list goes on, and will keep expanding.

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ABSTRACT

Mobile positioning technology has become an important area of research, for emergency as well as for commercial services. Mobile positioning in cellular networks will provide several services such as, locating stolen mobiles, emergency calls, different billing tariffs depending on where the call is originated, and methods to predict the user movement inside a region. The evolution to location-dependent services and applications in wireless systems continues to require the development of more accurate and reliable mobile positioning technologies. The major challenge to accurate location estimation is in creating techniques that yield acceptable performance when the direct path from the transmitter to the receiver is intermittently blocked. This is the Non-Line-Of-Sight (NLOS) problem, and it is known to be a major source of error since it systematically causes mobile to appear farther away from the base station (BS) than it actually is, thereby increasing the positioning error.
In this paper, we present a simple method for mobile telephone tracking and positioning with high accuracy. Through this we will discuss some technology used for mobile positioning and tracking

INTRODUCTION

As shown in Figure 3, the mobile telecommunication network includes a several base stations (BSs) T 1 to T N for providing mobile telecommunication service to a mobile subscriber through a mobile telephone M1, a base station controller (BSC) for controlling the BSs T 1 to T N, and a mobile telephone switching office (MTSO) for connecting the BSC to another BTS or a PSTN (Public Switched Telephone Network).

In a cellular mobile telecommunication network, the whole service area is divided into a several coverage areas having respective base stations (BS). Each BS coverage area is called a “cell.” Each BS is provided with a frequency of a range between 450 to900 MHz. More than one cells can use same frequency. Only condition is that no two adjacent cells must have same frequencies. An MTSO controls these BSs so that a subscriber can continue his call without interruption while moving between different cells. The MTSO can reduce the time required for calling a subscriber by locating the cell of the subscriber. In case of an emergency like a fire, or a patient needing first aid treatment, the mobile subscriber should be accurately located. Tracking the location of a mobile subscriber within the boundary of a cell in a mobile telecommunication network is known as “location based services
Mobile technology includes mainly two functions. They are call fixing and hands-off process. All the BSs are sending a signal of power 25 to 30w to the mobile unit. When a user switches ON his mobile, it will search for the strongest signal and got connected to that BS. Then the mobile unit sends an identification signal to the BS. When he fixes a call, the BS accepts the request and sends the request to the BSC and MTSO. Then the MTSO will searches where the subscriber is and connects the call.

When a user moves to another cell the MTSO will change the frequency allotted to it and allots the frequency of the new BS.For both these processes GEOLOCATION of the mobile unit is essential..

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INTRODUCTION

Are you tired of slow modem connections? Cellonics Incorporated has developed new technology that may end this and other communications problems forever. The new modulation and demodulation technology is called Cellonics. In general, this technology will allow for modem speeds that are 1,000 times faster than our present modems. The development is based on the way biological cells communicate with each other and nonlinear dynamical systems (NDS). Major telcos, which are telecommunications companies, will benefit from the incredible speed, simplicity, and robustness of this new technology, as well as individual users.

In current technology, the ASCII uses a combination of ones and zeros to display a single letter of the alphabet (Cellonics, 2001). Then the data is sent over radio frequency cycle to its destination where it is then decoded. The original technology also utilizes carrier signals as a reference which uses hundreds of wave cycles before a decoder can decide on the bit value (Legard, 2001), whether the bit is a one or a zero, in order to translate that into a single character.

The Cellonics technology came about after studying biological cell behaviour. The study showed that human cells respond to stimuli and generate waveforms that consist of a continuous line of pulses separated by periods of silence. The Cellonics technology found a way to mimic these pulse signals and apply them to the communications industry (Legard, 2001). The Cellonics element accepts slow analog waveforms as input and in return produces predictable, fast pulse output, thus encoding digital information and sending it over communication channels. Nonlinear Dynamical Systems (NDS) are the mathematical formulations required to simulate the cell responses and were used in building Cellonics. Because the technique is nonlinear, performance can exceed the norm, but at the same time, implementation is straightforward (Legard, 2001).

This technology will be most beneficial to businesses that do most of their work by remote and with the use of portable devices. The Cellonics technology will provide these devices with faster, better data for longer periods of time (Advantages, 2001). Cellonics also utilizes a few discrete components, most of which are bypassed or consume very little power. This reduces the number of off the shelf components in portable devices while dramatically decreasing the power used, leading to a lower cost for the entire device. The non-portable devices of companies will benefit from the lack of components the machines have and the company will not have to worry so much about parts breaking.

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ABSTRACT

Digital Subscriber Lines (DSL) are used to deliver high-rate digital data over existing ordinary phone-lines. A new modulation technology called Discrete Multitone (DMT) allows the transmission of high speed data. DSL facilitates the simultaneous use of normal telephone services, ISDN, and high speed data transmission, e.g., video. DMT-based DSL can be seen as the transition from existing copper-lines to the future fiber-cables. This makes DSL economically interesting for the local telephone companies. They can offer customers high speed data services even before switching to fiber-optics.

DSL is a newly standardized transmission technology facilitating simultaneous use of normal telephone services, data transmission of 6 M bit/s in the downstream and Basic- rate Access (BRA). DSL can be seen as a FDM system in which the available bandwidth of a single copper-loop is divided into three parts. The base band occupied by POTS is split from the data channels by using a method which guarantees POTS services in the case of ADSL-system failure (e.g. passive filters).

INTRODUCTION

The past decade has seen extensive growth of the telecommunications industry, with the increased popularity of the Internet and other data communication services. While offering the world many more services than were previously available, they are limited by the fact that they are being used on technology that was not designed for that purpose.

The majority of Internet users access their service via modems connects to the Plain Old Telephone System (POTS). In the early stages of the technology, modems were extremely slow by today’s standards, but this was not a major issue. A POTS connection provided an adequate medium for the relatively small amounts of data that required transmission, and so was the existing system was the logical choice over special cabling.

Technological advances have seen these rates increase up to a point where the average Internet user can now download at rates approaching 50Kbps, and send at 33.6Kps. However, POTS was designed for voice transmission, at frequencies below 3kHz, and this severely limits the obtainable data rates of the system. To increase performance of new online services, such as steaming audio and video, and improve general access speed, the bandwidth hungry public must therefore consider other alternatives. Technologies, such as ISDN or cable connections, have been in development for sometime but require special cabling. This makes them expensive to set up, and therefore have not been a viable alternative for most people.

DIFFERENT VARIANTS OF DSL

HDSL- is the pioneering high speed format, but is not a commercially viable option due to its need for two twisted pairs and does not have support for normal telephone services.

SDSL- is symmetric DSL, and operates over a single twisted pair with support for standard voice transmission. The problem with this system is that it is limited to relatively short distances and suffers NEXT limitation due to the use of the same frequencies for transmitting and receiving.

IDSL- stands for ISDN DSL, and is in many ways similar to ISDN technology. It’s disadvantages are the lack of support for analog voice, and that its 128kbps rate is not much greater than that offered by standard 56kbps V90 modems.

VDSL- provides very high bit rate DSL, up to 52Mbps, but requires shorter connections lengths than are generally practical. It has been used in conjunction with an experimental project, FTTC (Fiber to the Curb), but development in this area has slowed due to commercial viability issues.

ADSL- is the most promising DSL technology, proving suitable for personal broadband requirements and allowing for the same channel to still act as a traditional POTS service.

Rate Adaptive DSL, RADSL-, is a further advancement which is able to automatically optimize the ADSL data rate to suit the conditions of the line being used.

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ABSTRACT

This paper discusses the basic concepts and current state of development of EUV lithography (EUVL), a relatively new form of lithography that uses extreme ultraviolet (EUV) radiation with a wavelength in the range of 10 to 14 nanometers (nm) to carry out projection imaging. Currently, and for the last several decades, optical projection lithography has been the lithographic technique used in the high-volume manufacture of integrated circuits. It is widely anticipated that improvements in this technology will allow it to remain the semiconductor industry’s workhorse through the 100 nm generation of devices. However, some time around the year 2008, so-called Next-Generation Lithographys will be required. EUVL is one such technology vying to become the successor to optical lithography. This paper provides an overview of the capabilities of EUVL, and explains how EUVL might be implemented. The challenges that must be overcome in order for EUVL to qualify for high-volume manufacture are also discussed.

INTRODUCTION

Microprocessors, also called computer chips, are made using a process called lithography. Specifically, deep-ultraviolet lithography is used to make the current breed of microchips and was most likely used to make the chip that is inside your computer.

Lithography is akin to photography in that it uses light to transfer images onto a substrate. Silicon is the traditional substrate used in chip making. To create the integrated circuit design that’s on a microprocessor, light is directed onto a mask. A mask is like a stencil of the circuit pattern. The light shines through the mask and then through a series of optical lenses that shrink the image down. This small image is then projected onto a silicon, or semiconductor, wafer. The wafer is covered with a light-sensitive, liquid plastic called photoresist.The mask is placed over the wafer, and when light shines through the mask and hits the silicon wafer, it hardens the photoresist that isn’t covered by the mask. The photoresist that is not exposed to light remains somewhat gooey and is chemically washed away, leaving only the hardened photoresist and exposed silicon wafer. The key to creating more powerful microprocessors is the size of the light’s wavelength. The shorter the wavelength, the more transistors can be etched onto the silicon wafer. More transistors equal a more powerful, faster microprocessor.

DUVL uses a wavelength of 240 nanometers As chipmakers reduce to smaller wavelengths, they will need a new chip making technology. The problem posed by using deep-ultraviolet lithography is that as the light’s wavelengths get smaller, the light gets absorbed by the glass lenses that are intended to focus it. The result is that the light doesn’t make it to the silicon, so no circuit pattern is created on the wafer. This is where EUVL will take over. In EUVL, glass lenses will be replaced by mirrors to focus light and thus EUV lithography can make use of smaller wave lengths. Hence more and more transistors can be packed into the chip. The result is that using EUVL, we can make chips that are upto 100 times faster than today’s chips with similar increase in storage capacity.

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