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09-10-2010, 05:32 PM
4 - Wireless Communication.doc (Size: 264.5 KB / Downloads: 191)
Wireless communication is the transfer of information over a distance without the use of electrical conductors or "wires". The distances involved may be short (a few meters as in television remote control) or long (thousands or millions of kilometers for radio communications). Wireless communication is generally considered to be a branch of telecommunications.
It encompasses various types of fixed, mobile, and portable two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of wireless technology include GPS units, garage door openers and or garage doors, wireless computer mice, keyboards and headsets, satellite television and cordless telephones.
Wireless operations permits services, such as long-range communications, that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refer to telecommunications systems (e.g. radio transmitters and receivers, remote controls, computer networks, network terminals, etc.) which use some form of energy (e.g. radio frequency (RF), infrared light, laser light, visible light, acoustic energy, etc.) to transfer information without the use of wires. Information is transferred in this manner over both short and long distances.
In 1895, Guglielmo Marconi opened the way for modern wireless communications by transmitting the three-dot Morse code for the letter ‘S’ over a distance of three kilometers using electromagnetic waves. From this beginning, wireless communications has developed into a key element of modern society.
From satellite transmission, radio and television broadcasting to the now ubiquitous mobile telephone, wireless communications has revolutionized the way societies function.
Wireless communications and the economic goods and services that utilise it have some special characteristics that have motivated specialised studies. First, wireless communications relies on a scarce resource – namely, radio spectrum. Second, use of spectrum for wireless communications required the development of key complementary technologies; especially those that allowed higher frequencies to be utilised more efficiently. Finally, because of its special nature, the efficient use of spectrum required the coordinated development of standards. Those standards in turn played a critical role in the diffusion of technologies that relied on spectrum use.
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23-12-2010, 02:30 PM
ANB.doc (Size: 2.47 MB / Downloads: 111)
Wireless telecommunications can be divided into two broad categories: mobile communications and fixed wireless communications. The mobile communications market requires mobility or non-tethered communications. The goal of mobility is anytime, anywhere communications. Mobile communications technology must be able to allow roaming - the ability to provide service to a mobile phone users while outside their home system. On the other hand, fixed wireless is simply an alternative to wired communications.
The intelligent network (IN) is an architectural concept that enables the real-time execution of network services and customer applications in a distributed environment consisting of interconnected computers and switching systems. Thus the operator services are automated in INs. These automated services provide directory assistance and is used to provide telephone numbers, addressing information, and so on to the customer. While there are various proprietary-based mobile intelligent network (IN) technologies, the standards based technologies are often of most value to the mobile network operator and their customers. These standards based technologies are referred to as Wireless Intelligent Network (WIN). Wireless Intelligent network is developed to drive intelligent network capabilities such as service independence, separation of basic switching functions from service and application functions and independence of applications from lower-level communication details into wireless networks. The primary weapon for empowering providers to deliver distinctive services with enhanced flexibility is Wireless Intelligent Networks (WINs).
1. WIRELESS INTELLIGENT NETWORK
Wireless intelligent network (WIN) is a concept being developed by the Telecommunications Industry Association (TIA) Standards Committee TR45.2. The WIN standards protocol enables a graceful evolution to an IN without making current network infrastructure obsolete.
Service differentiation and streamlined infrastructure are key factors to winning the battle of competition as customers expand and become more sophisticated and the wireless service becomes more of a commodity. To wireless carriers and service providers, this means leveraging equipment, systems and customer service initiatives across all services and markets. Wireless providers who are first-to-market with customers-oriented services will have an immense advantage in securing dominant market share. One of the vital solutions for this highly competitive and increasingly demanding market is to build a sophisticated Wireless Intelligent Network infrastructure that can flexibly support existing and new services. This approach can reduce the load on the wireless switches.
The Wireless Intelligent Network (WIN) intends to take advantage of the Advanced Intelligent Network (AIN) concepts and products developed from wireline communications. However, progress of the AIN deployment has been slow due to the many barriers that exist in the traditional wireline carriers’ deployment procedures and infrastructure. The success of AIN has not been truly demonstrated. The AIN objectives and directions are applicable to the wireless industry although the plans and implementations could be significantly different. In order to succeed, the technology driven AIN concept has to be reinforced by the market driven WIN services. An infrastructure suitable for the WIN contains elements that are foreign to the wireline network.
WIN, borrowing the concept of AIN, is viewed to bring competitive edges in terms of:
• Mobility services beyond wireline AIN
• Reduced time for service deployment
• Multiple vendor expertise
• Increased customization
• Computerized service creation and implementation tools.
However commercial AIN services have not proven successful. There have been doubts that AIN might only theoretically address the carrier’s needs.
Today's wireless subscribers are much more sophisticated telecommunications users than they were five years ago. No longer satisfied with just completing a clear call, today's subscribers demand innovative ways to use the wireless phone. They want multiple services that allow them to handle or select incoming calls in a variety of ways.
Enhanced services are very important to wireless customers. Enhanced services will also entice potentially new subscribers to sign up for service and will drive up airtime through increased usage of PCS or cellular services. As the wireless market becomes increasingly competitive, rapid deployment of enhanced services becomes critical to a successful wireless strategy.
Intelligent network (IN) solutions have revolutionized wireline networks. Rapid creation and deployment of services has become the hallmark of a wireline network based on IN concepts. Wireless intelligent network (WIN) will bring those same successful strategies into the wireless networks.
The evolution of wireless networks to a WIN concept of service deployment delivers the following advantages, similar to the IN benefits reaped by wireline providers:
• Multivendor product offerings that foster competition
• Uniform services to subscribers across service areas
• Efficient network utilization
• Service creation and deployment
2. INTELLIGENT NETWORK
An intelligent network (IN) is a service-independent telecommunications network. That is, intelligence is taken out of the switch and placed in computer nodes that are distributed throughout the network. This provides the network operator with the means to develop and control services more efficiently. New capabilities can be rapidly introduced into the network. Once introduced, services are easily customized to meet individual customer's needs. Many of the desirable properties of the modern IN architecture are based on three major principles of independence:
1. Service independence (meaning that a wide variety of services can be composed using a set of common building blocks),
2. Separation of basic switching functions from service and application functions
3. Independence of applications from lower-level communication details.
As the IN evolves, service providers will be faced with many opportunities and challenges. While the IN provides a network capability to meet the ever-changing needs of customers, network intelligence is becoming increasingly distributed and complicated. For example, third-party service providers will be interconnecting with traditional operating company networks. Local number portability (LNP) presents many issues that can only be resolved in an IN environment to meet government mandates. Also, as competition grows with companies offering telephone services previously denied to them, the IN provides a solution to meet the challenge.
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31-12-2010, 04:24 PM
Course Instructor: Dr. Zubair Shaikh
Wireless Communication-Lect 1.ppt (Size: 667.5 KB / Downloads: 161)
The communication does not require physical cables
Can be classified into:
Fixed Wireless Network
Wireless Network with Fixed Access Points
Ad hoc network
4G of Mobile Communication
Fully Packet switched IP network
Flexibility and Personalized Services
Mobile Multimedia, Anytime Any where, Global Mobility Support, Integrated Wireless Solution and Customized Personal Services – MAGIC
Software Defined Radios
Ad hoc Networking
Acoustic Modems for Ubiquitous Computing
Sound waves are characterized by:
Comparatively Low data rate
Sound waves can be localized within rooms
Can be exposed to Humans
Digital Voices project and implimentation explores device communication using sound
It analyzed common modulation techniques and the sounds they produce
Applications of Accoustic Modems
Can easily be deployed in the existing voice infrastructure
Benefits from human awareness of the communication
Requires short-range broadcasts enclosed within walls and windows
Agencies conducting secret operations might be interested in such an application, given that these sounds can be broadcast by traditional media and can be picked up anywhere in the world with a laptop or PDA.
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24-03-2011, 12:33 PM
11.ppt (Size: 5.07 MB / Downloads: 167)
Fundamentals of Wireless Communication
• Past decade has seen a surge of research activities in the field of wireless communication.
• Emerging from this research thrust are new points of view on how to communicate effectively over wireless channels.
• The goal of this course is to study in a unified way the fundamentals as well as the new research developments.
• The concepts are illustrated using examples from several modern wireless systems (GSM, IS-95, CDMA 2000 1x EV-DO, Flarion's Flash OFDM, ArrayComm systems.)
• In free space, received power attenuates like 1/r2.
• With reflections and obstructions, can attenuate even more rapidly with distance. Detailed modelling complicated.
• Time constants associated with variations are very long as the mobile moves, many seconds or minutes.
• More important for cell site planning, less for communication system design.
Small-scale multipath fading
• Wireless communication typically happens at very high carrier frequency. (eg. fc = 900 MHz or 1.9 GHz for cellular)
• Multipath fading due to constructive and destructive interference of the transmitted waves.
• Channel varies when mobile moves a distance of the order of the carrier wavelength. This is 0.3 m for Ghz cellular.
• For vehicular speeds, this translates to channel variation of the order of 100 Hz.
• Primary driver behind wireless communication system design.
• We wish to understand how physical parameters such as carrier frequency, mobile speed, bandwidth, delay spread impact how a wireless channel behaves from the communication system point of view.
• We start with deterministic physical model and progress towards statistical models, which are more useful for design and performance evaluation
• Communication over a flat fading channel has poor performance due to significant probability that channel is in deep fading.
• Reliability is increased by provide more signal paths that fade independently.
• Diversity can be provided across time, frequency and space.
Name of the game is how to expoited the added diversity in an efficient manner
Joined: Jul 2011
28-01-2012, 10:54 AM
to get information about the topic securing wireless communication full report ,ppt and related topic please refer link bellow
http://topicideas.org/how-to-wireless-co...or-project and implimentations-for-ece
http://topicideas.org/how-to-wireless-co...on-project and implimentations-for-final-year-engineering-students
Joined: Apr 2012
26-06-2012, 04:54 PM
Wireless communication has been evolving and growing rapidly during the last few years. In order to meet the demand of this growth researchers as well as industry have been working for new techniques and new standardizations. Usually wireless communications performance is badly affected by channel fading. Diversity technique is used to reduce the impact of fading on wireless channel by conveying data over multiple independent fading channel paths and combine them at the receiver.
Cooperative diversity is novel transmission technique where multiple terminals use their resources in cooperative manner to form a virtual array that realizes spatial diversity gain in a distributed fashion. Cooperative system can obtain reliable communications, capacity gain and energy saving by mutual relaying among users of wireless network.
In this project and implimentation we examine the performance of a cooperative system and its ability to realize the advantages and the ideas behind its invention. We model a simple decode and forward, amplify and forward repetition-based cooperative system consisting of three nodes representing source, destination and relay, which communicate cooperatively between the source and the destination. To evaluate the performance of cooperative system we measure the probability of error of cooperative system using computer simulation. Our results show that a better performance of a communication system could be achieved by allowing wireless network partners to communicate cooperatively.