mANNUAL pract CT325 Mobile communication---am.docx

EE101: BASIC ELECTRONICS Odd Term 2010-11

CT325 MOBILE COMMUNICATION LAB

Even Term 2012-13

Faculty DetailsCourse Teacher: Prof. A.Meshram,Prof. S. LachureOffice: Computer Technology Department.Office Hours : 9 a.m. to 4 p.m.Phone: 9325159812Email: [email protected] Course Website:

Required Textbook for practical 1. Mobile communication by Jochen Schiller (Addison Wesley pub) 2. Mobile Communication Systems by Krzysztof Wesolowski (Wiley Publication) 3. Wireless Communication principles & Practice by T. S. Rappaport (PHI pub)

Course Objective This course provides an in depth understanding of wireless access and core networks and mobility in cellular and wireless networks using the important standards of the industry like GSM, CDMA, GPRS and IEEE 802.11 technologies. The course will focus on understanding the quantitative techniques to evaluate the different, protocols, network architecture.

Course AssessmentTotal 100 marks practical is divided into two components Continuous Assessment:40% End semester examination: 60%

1. Grading for Continuous assessment is based on the following components that are weighted for each practical as described below:a. Execution of practical: 2%b. Viva: 1%c. Regular Submission/Attendance:1%2. Grading for End semester examination is based on the following components as described below:a. Execution :20%b. Writing Work: 10%c. Viva : 30%

ExaminationsThere will be 1 scheduled End semester examination at the end of semester. The schedule of this examination is given in the Academic Calendar for the session published by the Dean (Academic matters)..

CT325 MOBILE COMMUNICATION LABEven Term 2013-14

List of practical

1. To Study Wireless Application Protocol.2. Write a WML script to establish connectivity between two cards.3. Write a WML page to display an image and to accept input from the user.4. A write WML page using various tags such as select and option tags.5. To study MATLAB commuictaion tool .6. Write a MATLAB Program for representing Analog Signal.7. Implement Analog Modulation in MATLAB.8. Write a program for generating random symbol and create Noisy Signal.9. Case Study on 4G Technology.

Beyond Syllabus1. Implementation of android application on android.

Signature of the teachers Signature of the HOD

Prof. A.Meshram Prof. A. R. Bhagat PatilProf. S. Lachure

Practical No.1Aim: To Study Wireless Application Protocol.Theory:What is WAP?Wap is the short form for Wireless Application Protocol. It is an open, global specification that empowers mobile users with wireless devices to easily access and interact with information and services instantly. It is targeted to bring Internet content and advanced services to digital cellular phones and other wireless terminals. BriefingWAP empowers mobile users of wireless devices to easily access from the screens of mobile phones live interactive information services and applications including email, customer care, call management, unified messaging, weather and traffic alerts, news, sports and information services, electronic commerce transactions and banking services, online address book and directory services, as well as corporate intranet applications. The WAP specification was based on existing Internet standards, such as XML and IP, for all wireless networks. It utilizes HTTP 1.1 Web servers to provide content on the Internet or intranets, thereby leveraging existing application development methodologies and developer skill sets such as CGI, ASP, NSAPI, JAVA and Servlets. WAP defines an XML (eXtensible Markup Language) syntax called WML (Wireless Markup Language). All WML content is accessed over the Internet using standard HTTP 1.1 requests. To leverage today's extremely large market penetration of mobile devices, WML's user interface components map well onto existing mobile phone user interfaces. This means end-users can immediately use WAP-enabled mobile phones and services without re-education. WAP specifications enable products which employ standard Internet technology to optimize content and airlink protocols to better suit the characteristics and limitations of existing and future wireless networks and devices.

WAP TechnologyGoals of WAP Architecture and DesignWAP is intended to be modeled after existing, known Internet technologies and Internet protocols (for example, WML is based on HTML, XML and WAP uses familiar URL addressing to request services). WAP also extends many common Internet technologies for better usage on more restricted wireless networks. The reason is that wireless networks tend to be plagued with:1. lower bandwidth 2. higher latency (high latency refers to a higher amount of time that it takes a packet to travel to a remote server and return again to the client) 3. less connection stability 4. less predictable availability When looking at this topic, it was impressive to see the many efficiency improving techniques used to make WAP better suited for the more restricted wireless network infrastructure. WAP LayersThe WAP protocol stack optimizes web protocols, like HTTP, for wireless networks.WAP sits on top of existing wireless networks so that WAP can be successfully used over any wireless network. This is very useful because wireless networks often use different standards depending on geographical areas. So in order to allow WAP to be universally available, even when your telephone services are not, it is designed to run over any air interface.

Wireless Application Environment (WAE)WML and WMLScript are examples of the application layer in WAP. WAE is built into the micro-browser present in the WAP device and handles WML and WMLScript in a similar fashion to how current web browsers handle HTML and Javascript. To make WAP more efficient at this layer though, WML and WMLScript are translated in binary code at the gateway (the gateway is the link from the air interface to the Internet). WAP also utilizes binary data converting algorithms to convert cumbersome HTTP text headers to a more compressed binary form before HTTP headers are transmitted on wireless networks.Wireless Session Protocol (WSP)WSP implements the session services of WAP. Sessions can be connection-oriented and connectionless and they may be suspended or resumed with little overhead. To be more specific, this layer has mechanisms to allow suspending and resuming of connections without the overhead of initial connection establishment.Wireless Transaction Protocol (WTP)The WTP is responsible for facilitating reliable communication between the communicating WAP device and the gateway. WTP deconstructs data into packets for sending and reconstructs received packets into useful data. WTP guarantees similar reliability that TCP does, but with more efficient behavior. For example, WTP cuts down on header size because it does not have header information for handling out of order packets since wireless networks only have one route from gateway to WAP device. WTP eliminates the need for the TCP to be installed on the phone and therefore decreases the amount of resources needed on the phone to support data transmission.Wireless Transport Layer Security (WTLS)WTLS is modeled after the Secure Sockets Layer (SSL). WTLS allows for the transmission of data along a secure connection. Many Internet applications require a secure connection and WTLS allows WAP to provide the necessary security abilities to users with WAP devices. WTLS handles authentication, denial of service and ensures privacy through crypting and decrypting. Again, WTLS has been optimized for use over wireless networksWireless Markup Language (WML) WML is a strong typed markup language, similar to HTML and XML, that is used to author WML pages primarily for download on wireless networks. Strongly typed refers to the fact that WML must always have opening and closing tags. WML code looks fairly similar to HTML, but there are fewer tags available. WML also provides some dynamic characteristics, not found in HTML, allowing the WML page designer to play around with variables, which therefore gives WML a flexible extension comparable to XML. WML pages are organized into multiple cards (WML sub-pages) contained in a WML deck (WML page). WML cards provide a simple document to be easily scrolled through on the minimal screen size of most WAP devices. Each WML card must be contained in a WML deck and so WML decks are downloaded from servers.Keeping the comparison with current Internet technologies, WML has an available scripting language similar to JavaScript. It is called Wireless Markup Language Script (WMLScript) and is similar in syntax to JavaScript, but a little more restricted. It was designed to allow the WML page to validate user input without going to the server, give access to facilities on the wireless device that WML does not have access to (i.e. the ability to make a phone call or send a text message) and generate messages and dialogs locally without having to go to the server. It therefore provides many advantages to WML that Javascript provides to HTML. One major difference between WMLScript and JavaScript though is that WMLScript code must be kept in a separate file and cannot be included in the WML file via inline tags.A WAP browser is required to view pages written in WML so WML pages cannot be viewed with a standard web browser. Several WAP browser emulators are available in order to view WML pages on your home PC.As mentioned before, WML documents are divided into a set of units of user interaction called cards. Cards are well suited to be viewed on the limited screen size of WAP devices. A WML deck is located within the tags. Each individual card that is then displayed on the WAP device is set apart by the tags. The content of the card and any functionality is contained within the CARD tags. Users can then scroll through WML cards on their WAP devices.Wireless Bitmap (WBMP)WBMP is the default picture format for WAP. WBMPs are uncompressed, monochrome black/white bitmaps intended for use in devices with small screens and a narrow bandwidth connection. This makes WBMPs well suited for use with WAP devices.WAP ServersMost web servers can handle WAP content. To be sure if your web server can handle WAP content, the following MIME types must be available:1. text/vnd.wap.wml for .wml files (WML source files) 2. application/vnd.wap.wmlc for .wmlc files (WML compiled files) 3. text/vnd.wap.wmlscript for .wmls files (WMLScript source files) 4. application/vnd.wap.wmlscriptc for .wmlsc files (WMLScript compiled files) 5. image/vnd.wap.wbmp for .wbmp files (wireless bitmaps)

Process of Connecting a WAP device to a WWW siteWAP phones use the in-built browser to:1. Make a request in WML 2. This request is passed to a WAP Gateway that then retrieves the information from an Internet server either in standard HTML format or WML/JWMLScript directly prepared for WAP devices. If the content being retrieved is in HTML format, a filter in the WAP Gateway may try to translate it into WML. 3. The requested information is then sent from the WAP Gateway to the WAP client, using the underlying wireless infrastructure. Area of ApplicationThe following list is extracted from a presentation by WAP Forum in M-commerce World London Feb 2001:M-commerceShopping, ticket purchase, reservation, comparison shoppingFinanceStatements, fund transfer, shares tradingM-billingNotification, presentation and payment of billsEnterprise AccessInventory, shipment/sales update, email accessM-careCustomer service, payment status, other backroom operationsEntertainmentGames, gambling, interactive multi-player eventsMessagingCommunication and collaborationTravelScheduling, advisories, reservationsLocation-smart services . Traffic reports, parking information, store discounts, event recommendations

Practical No. 2Aim:- Write a WML script to establish connectivity between two cards.Theory:WML Used to create the cards for mobile application (s) Two versionsWML 2.x and WML 1.x WML 2.x includes XHTML-MP which includes XHTML WML 1.x does not include XHTML

Information in WML A collection of decks and cards A WML deck is saved in a file with extension wml Each file contains one deck For example, a welcome deck can be saved in a WML file welcome.wml

WML deck Can have number of cards There is a navigational link from one card to another WML provides for management of the navigation between cards and decks

WML card A scaled down set of procedural elements Used to control navigation between cards A card represents an interaction with the user and the deck contains the cards Provides the content (for example, a program, command, data, string, or image) Supports variety of formatting commands as well as layout commands Commands are defined by tags and attributes Provides user interface for mobile devices with constraints as mentioned in the preceding text Organizes similar to deck and cards

WML parser Parses the tags, attributes, and underlying text within the tags present within the deck or card The parser is a part of a browser or serverThe format of a WML deck and card

WML card First validated against its declared document type using WML 1.3 DTD (document type definition) before parsing Parsed data, information, and contents used to give input to a Java program for the application or server which runs method(s) at the browser or server Browser program runs at the client

WinWAP WinWAP has an Emulator which is an alternative program used for emulating the actual run at the mobile client and runs on a PC WinWAP is for a computing system running on PocketPC, WindowsMobile 2003, or Windows operating system

Application Running using WML Card A WML card containing a client-request is transmitted and response is received from server Element do is used to process the text within the do tags The element label is an attribute which defines a text, the purpose of which is simply to specify the incoming text or action

URLs are used to call WML Script functions from a WML card. The URL specifies the location of the WML Script file and the name of the function to be called. It should be in the form:

http://domain_name/path/wmlscript_filename#function_name(argument1, argument2, ...)

The URL can be in absolute or relative form.The following example demonstrates how to use anchor links to call WMLScript functions from a WML card. Suppose we have a WML Script file called wmlscript.wmls, which contains the following script:extern function wmlscript_function(){WMLBrowser.setVar("message", "Welcome to our WMLScript tutorial");}To call wmlscript_function() from a WML card, create an anchor link using the following WML markup. The script will be executed if you click the anchor link.Execute ScriptOr

Execute Script

Another way to call wmlscript_function() in a WML card is to place the URL in a WML event handler. The script will be executed when the WML event occurs. For example, the following markup instructs the WAP browser to call wmlscript_function() when the ontimer event is triggered:

Four event types are supported in WML. They are ontimer, onenterbackward, onenterforward and onpick. Details about them can be found in the "WML Events and the Tag" section of our WML tutorial.

Passing Arguments to FunctionsThe wmlscript_function() function above does not take any arguments. Now let's see how to pass arguments to functions. Suppose there is another function called addition() that takes two numbers as its arguments:extern function addition(number1, number2){WMLBrowser.setVar("message", number1 + number2);}

To call addition() from a WML card, we need to include two arguments in the URL. For example, to pass two integers 10 and 11 to addition(), we can make use of the following WML markup:Execute ScriptIn some situations, what you want to pass into a WMLScript function is not a fixed value but is a WML variable. The following WML markup demonstrates how to pass two WML variables, wmlVar1 and wmlVar2, to the addition() function:

Execute Script

...

When the WAP browser comes across the terms $(wmlVar1) and $(wmlVar2), it will substitute them with their stored value. So, the WML markup:Execute Scriptwill become:Execute ScriptNote that if the value of wmlVar1 and wmlVar2 contains non-numeric characters, $(wmlVar1) and $(wmlVar2) have to be enclosed in quotes so that the values are passed into the function as string literals, like this:Execute ScriptSuppose the values of wmlVar1 and wmlVar2 are still 10 and 11 respectively. After substitution, the above WML markup will become:Execute Script

Practical No.3Aim:- Write a WML page to display an image and to accept input from the user.Theory:The tag is used to add an image to a WML card. This is the same as in HTML. WAP browsers will display the text assigned to the alt attribute of the tag if it cannot display the image for reasons such as file not found or image format not supported. The URL of the image file is specified with the src attribute.The height and width attributes of the tag, as their names suggested, are used to specify the height and width of an image's display area. WAP browsers may reserve some space on the screen according to the values of these two attributes when the image is still downloading, so that users can know the layout of the card. Also, WAP browsers may scale up or down the size of an image if the height and width attribute values are not the same as the image's real size.Older WAP-enabled wireless devices can only display WBMP images. Newer ones support image formats commonly used on the web such as GIF, JPG and PNG.For example the script can be shown as

Practical No. 4Aim:- A write WML page using various tags such as select and option tags.Theory:The onpick event is used together with the WML tags, which are used to specify an item of a selection list. Before we discuss the onpick event, let us first introduce to you what selection lists are and how to use them in mobile Internet browsing applications.Creating Selection Lists (Radio Buttons): A selection list is a list of options that a user can select. The WML tags are used to define a selection list and the tags are used to define an item in a selection list. Items are presented as radio buttons in some WAP browsers. The tag pair should be enclosed within the tags. The following WML example demonstrates how to create a selection list only tags:

This is a selection list:
WML Tutorial AWML Tutorial BWML Tutorial CIn WML, a selection list is associated with a variable, which stores the value of the item selected. The variable name is specified with the name attribute of the element and the value of an item is specified with the value attribute of the element. In the above WML example, a variable selection_list is associated with the selection list.The value attribute of the tag can be used to set the default option that will be selected initially. The tag that has the same value attribute value as that of the tag will be the default option. Here is an example that shows how to specify the second option "WML Tutorial B" as the default option:

WML Tutorial AWML Tutorial BWML Tutorial C

Experiment No:5

Aim:To study MATLAB commuictaion tool

Theory:What Is the Communications Toolbox?

The Communications Toolbox is a set of MATLAB functions that can help youdesign and analyze advanced communication systems. Functions in the toolboxcan accomplish these tasks:

Random signal production

Error analysis, including eye diagrams and scatter plots

Source coding, including scalar quantization, differential pulse code modulation, and companders

Error-control coding, including convolutional and linear block coding

Analog and digital modulation/demodulation

Filtering of data using special filters

Computations in Galois fields

Random Signals and Error Analysis

Simulating a communication system often involves analyzing its response tothe noise inherent in real-world components. Such analysis aims to illustratethe systems response and possibly to help design a system appropriate for themost likely kinds of noise.

Error Analysis Features of the Toolbox

Error analysis tasks supported in the Communications Toolbox include:Simulating noise or signal sources using random signalsComputing the error rate or number of errorsPlotting an eye diagramGenerating a scatter plotThis section describes these toolbox functions that accomplish error-analysistasks: biterr, eyediagram, randerr, randint, randsrc, scatterplot, symerr,and wgn. Since error analysis is often a component of communication systemsimulation, other portions of this guide provide additional examples.

Random Signals

Random signals are useful for simulating noise, errors, or signal sources.Besides built-in MATLAB functions like rand and randn, you can also use thesefunctions from this toolbox:wgn, for generating white Gaussian noiserandsrc, for generating random symbolsrandint, for generating uniformly distributed random integersranderr, for generating random bit error patternsWhile randsrc and randint are suitable for representing sources, randerr ismore appropriate for modeling channel errors.

White Gaussian Noise

The wgn function generates random matrices using a white Gaussian noisedistribution. You specify the power of the noise in either dB (decibels), dBm, orlinear units. You can generate either real or complex noise.For example, the command below generates a column vector of length 50containing real white Gaussian noise whose power is 2 dB. The functionassumes that the load impedance is 1 Ohm.y1 = wgn(50,1,2);To generate complex white Gaussian noise whose power is 2 watts, across aload of 60 Ohms, use either of the commands below. Notice that the ordering ofthe string inputs does not matter.y2 = wgn(50,1,2,60,'complex','linear');y3 = wgn(50,1,2,60,'linear','complex');To send a signal through an additive white Gaussian noise channel, use theawgn function.

Error RatesComparing messages before and after transmission can help you evaluate thequality of a communication system design or the performance of a specialtechnique or algorithm. If your communication system uses several bits torepresent a single symbol, then counting bit errors is different from countingsymbol errors. In either the bit- or symbol-counting case, the error rate is thenumber of errors divided by the total number (of bits or symbols) transmitted.The biterr function compares two messages and computes the number of biterrors and the bit error rate. The symerr function compares two messages andcomputes the number of symbol errors and the symbol error rate.

Experiment No:6

Aim:Write a MATLAB Program for representing Analog Signal.

Representing Analog SignalsTo modulate an analog signal using this toolbox, start with a real message signal and a sampling rate Fs in hertz. Represent the signal using a vector x, the entries of which give the signal's values in time increments of 1/Fs. Alternatively, you can use a matrix to represent a multichannel signal, where each column of the matrix represents one channel.For example, if t measures time in seconds, then the vector x below is the result of sampling a sine wave 8000 times per second for 0.1 seconds. The vector y represents the modulated signal.Fs = 8000; % Sampling rate is 8000 samples per second.Fc = 300; % Carrier frequency in Hzt = [0:.1*Fs]'/Fs; % Sampling times for .1 secondx = sin(20*pi*t); % Representation of the signaly = ammod(x,Fc,Fs); % Modulate x to produce y.figure;subplot(2,1,1); plot(t,x); % Plot x on top.subplot(2,1,2); plot(t,y)% Plot y below.

As a multichannel example, the code below defines a two-channel signal in which one channel is a sinusoid with zero initial phase and the second channel is a sinusoid with an initial phase of pi/8.Fs = 8000;t = [0:.1*Fs]'/Fs;x = [sin(20*pi*t), sin(20*pi*t+pi/8)];

Experiment No:7Aim : Implement Analog Modulation in MATLAB.Analog Modulation ExampleThis example illustrates the basic format of the analog modulation and demodulation functions. Although the example uses phase modulation, most elements of this example apply to other analog modulation techniques as well.The example samples an analog signal and modulates it. Then it simulates an additive white Gaussian noise (AWGN) channel, demodulates the received signal, and plots the original and demodulated signals.% Prepare to sample a signal for two seconds,% at a rate of 100 samples per second.Fs = 100; % Sampling ratet = [0:2*Fs+1]'/Fs; % Time points for sampling

% Create the signal, a sum of sinusoids.x = sin(2*pi*t) + sin(4*pi*t);

Fc = 10; % Carrier frequency in modulationphasedev = pi/2; % Phase deviation for phase modulation

y = pmmod(x,Fc,Fs,phasedev); % Modulate.y = awgn(y,10,'measured',103); % Add noise.z = pmdemod(y,Fc,Fs,phasedev); % Demodulate.

% Plot the original and recovered signals.figure; plot(t,x,'k-',t,z,'g-');legend('Original signal','Recovered signal');

Experiment No:8Aim:Write a program for generating random symbol and create Noisy Signal.

Theory: Initializing VariablesThe first step is to initialize variables for number of samples per symbol, number of symbols to simulate, alphabet size (M) and the signal to noise ratio. We create a local random stream with known seed and state to be used by random number generators. Using this local stream ensures that the results generated by this demo will be repeatable.nSamp = 8; numSymb = 100;M = 4; SNR = 14;hStr = RandStream('mt19937ar', 'Seed', 12345);Generating Random Information SymbolsNext, use RANDI to generate random information symbols from 0 to M-1. Since the simulation is of QPSK, the symbols are 0 through 3. The first 10 data points are plotted.numPlot = 10;msg_orig = randi(hStr, [0 M-1], numSymb, 1);stem(0:numPlot-1, msg_orig(1:numPlot), 'bx');xlabel('Time'); ylabel('Amplitude');

Phase Modulating the DataUse MODEM.PSKMOD to modulate the data using QPSK modulation and Gray encoding. Updample the symbols to a sampling rate 8 times the carrier frequency using RECTPULSE. Use SCATTERPLOT to see the signal constellation.hMod = modem.pskmod('M', M, 'PhaseOffset', pi/4, 'SymbolOrder', 'Gray');msg_tx = modulate(hMod, msg_orig);msg_tx = rectpulse(msg_tx,nSamp);h1 = scatterplot(msg_tx);

Creating the Noisy SignalThen use AWGN to add noise to the transmitted signal to create the noisy signal at the receiver. Use the 'measured' option to add noise that is 14 dB below the average signal power (SNR = 14 dB). Plot the constellation of the received signal.msg_rx = awgn(msg_tx, SNR, 'measured', hStr, 'dB');h2 = scatterplot(msg_rx);

Experiment No:910. Aim: Case Study on 4G Technology.

1.INTRODUCTION

The approaching 4G (fourth generation) mobile communication systems are projected to solve still-remaining problems of 3G (third generation) systems and to provide a wide variety of new services, from high-quality voice to high-definition video to high-data-rate wireless channels. The term 4G is used broadly to include several types of broadband wirelessaccess communication systems, not only cellular telephone systems. One of the terms used to describe 4G is MAGICMobile multimedia, anytime anywhere, Global mobility support, integrated wireless solution, and customized personal service. As a promise for the future, 4G systems, that is, cellular broadband wireless access systems, have been attracting much interest in the mobile communication arena. The 4G systems not only will support the next generation of mobile service, but also will support the fixed wireless networks. This paper presents an overall vision of the 4G features, framework, and integration of mobile communication. The features of 4G systems might be summarized with one word-Integration.The 4G systems are about seamlessly integrating terminals, networks, andapplications to satisfy increasing user demands. The continuous expansion of mobile communication and wireless networks shows evidence of exceptional growth in the areas of mobile subscriber, wireless network access, mobile services, and applications. An estimate of 1 billion users by the end of 2003 justifies the study and research for 4G systems.

2.HISTORY

The history and evolution of mobile service from the 1G (first generation) to fourth generation are discussed in this section. Table 1 presents a short history of mobile telephone technologies. This process began with the designs in the 1970s that have become known as 1G. The earliest systems were implemented based on analog technology and the basic cellular structure of mobile communication. Many fundamental problems were solved by these early systems. Numerous incompatible analog systems were placed in service around the world during the 1980s.The 2G (second generation) systems designed in the 1980s were still used mainly for voice applications but were based on digital technology, including digital signal processing techniques. These 2G systems provided circuit-switched data communication services at a low speed. The competitive rush to design and implement digital systems led again to a variety of different and incompatible standards such as GSM (global system mobile), mainly in Europe; TDMA (time division multiple access) (IS-54/IS-136) in the U.S.; PDC (personal digital cellular) in Japan; and CDMA (code division multiple access) (IS-95), another U.S. system. These systems operate nationwide or internationally and are today's mainstream systems, although the data rate for users in these system is very limited. During the 1990s, two organizations worked to define the next, or 3G, mobile system, which would eliminate previous incompatibilities and become a truly global system. The 3G system would have higher quality voice channels, as well as broadband data capabilities, up to 2 Mbps. Unfortunately, the two groups could not reconcile their differences, and this decade will see the introduction of two mobile standards for 3G. In addition, China is on the verge of implementing a third 3G system. An interim step is being taken between 2G and 3G, the 2.5G. It is basically an enhancement of the two major 2G technologies to provide increased capacity on the 2G RF (radio frequency) channels and to introduce higher throughput for data service, up to 384 kbps. A very important aspect of 2.5G is that the data channels are optimized for packet data, which introduces access to the Internet from mobile devices, whether telephone, PDA (personal digital assistant), or laptop. However, the demand for higher access speed multimedia communication in today's society, which greatly depends on computer communication in digital format, seems unlimited. According to the historical indication of a generation revolution occurring once a decade, the present appears to be the right time to begin the research on a 4G mobile communication system.

3.VISION OF 4G

This new generation of wireless is intended to complement and replace the 3G systems, perhaps in 5 to 10 years. Accessing information anywhere, anytime, with a seamless connection to a wide range of information and services, and receiving a large volume of information, data, pictures, video, and so on, are the keys of the 4G infrastructures. The future 4G infrastructures will consist of a set of various networks using IP (Internet protocol) as a common protocol so that users are in control because they will be able to choose every application and environment. Based on the developing trends of mobile communication, 4G will have broader bandwidth, higher data rate, and smoother and quicker handoff and will focus on ensuring seamless service across a multitude of wireless systems and networks. The key concept is integrating the 4G capabilities with all of the existing mobile technologies through advanced technologies. Application adaptability and being highly dynamic are the main features of 4G services of interest to users. These features mean services can be delivered and be available to the personal preference of different users and support the users' traffic, air interfaces, radio environment, and quality of service. Connection with the network applications can be transferred into various forms and levels correctly and efficiently. The dominant methods of access to this pool of information will be the mobile telephone, PDA, and laptop to seamlessly access the voice communication, high-speed information services ,and entertainment broadcast services. Figure 1 illustrates elements and techniques to support the adaptability of the 4G domain. The fourth generation will encompass all systems from various networks, public to private; operator-driven broadband networks to personal areas; and ad hoc networks. The 4G systems will interoperate with 2G and 3G systems, as well as with digital (broadband) broadcasting systems. In addition, 4G systems will be fully IP-based wireless Internet. This allencompassing integrated perspective shows the broad range of systems that the fourth generation intends to integrate, from satellite broadband to high altitude platform to cellular 3G and 3G systems to WLL (wireless local loop) and FWA (fixed wireless access) to WLAN(wireless local area network) and PAN (personal area network),all with IP as the integrating mechanism. With 4G, a range of new services and models will be available. These services and models need to be further examined for their interface with the design of 4G systems. Figures 2 and 3 demonstrate the key elements and the seamless connectivity of the networks.

4.KEY 4G TECHNOLOGIES

Some of the key technologies required for 4G are briefly described below:

4.1 OFDMA

Orthogonal Frequency Division Multiplexing (OFDM) not only provides clear advantages for physical layer performance, but also a framework for improving layer 2 performance by proposing an additional degree of free- dom. Using ODFM, it is possible to exploit the time domain, the space domain, the frequency domain and even the code domain to optimize radio channel usage. It ensures very robust transmission in multi-path environments with reduced receiver complexity. OFDM also provides a frequency diversity gain, improving the physical layer performance .It is also compatible with other enhancement Technologies, such as smart antennas and MIMO.OFDM modulation can also be employed as a multiple access technology (Orthogonal Frequency Division Multiple Access; OFDMA). In this case, each OFDM symbol can transmit information to/from several users using a different set of sub carriers (sub channels). This not only provides additional flexibility for resource allocation (increasing the capacity), but also enables cross-layer optimization of radio link usage.

4.2 SOFTWARE DEFINED RADIO Software Defined Radio (SDR) benefits from todays high processing power to develop multi-band, multi-standard base stations and terminals. Although in future the terminals will adapt the air interface to the available radio access technology, at present this is done by the infrastructure. Several infrastructure gains are expected from SDR. For example, to increase network capacity at a specific time (e.g. during a sports event),an operator will reconfigure its network adding several modems at a given Base Transceiver Station (BTS). SDR makes this reconfiguration easy. In the context of 4G systems, SDR will become an enabler for the aggregation of multi-standard pico/micro cells. For a manufacturer, this can be a powerful aid to providing multi-standard, multi-band equipment with reduced development effort and costs through simultaneous multi-channel processing.

4.3 MULTIPLE-INPUT MULTIPLE OUTPUT

MIMO uses signal multiplexing between multiple transmitting antennas (space multiplex) and time or frequency. It is well suited to OFDM, as it is possible to process independent time symbols as soon as the OFDM waveform is correctly designed for the channel. This aspect of OFDM greatly simplifies processing. The signal transmitted by m antennas is received by n antennas. Processing of the received signals may deliver several performance improvements:range, quality of received signal and spectrum efficiency. In principle, MIMO is more efficient when many multiple path signals are received. The performance in cellular deployments is still subject to research and simulations.However, it is generally admitted that the gain in spectrum efficiency is directly related to the minimum number of antennas in the link.

4.4 HANDOVER AND MOBILITY

Handover technologies based on mobileIP technology have been considered for data and voice. Mobile IP techniques are slow but can be accelerated with classical methods (hierarchical, fast mobile IP). These methods are applicable to data and probably also voice. In single-frequency networks, it is necessary to reconsider the handover methods. Several techniques can be used when the carrier to interference ratio is negative (e.g. VSFOFDM,bit repetition), but the drawback of these techniques is capacity. In OFDM, the same alternative exists as in CDMA, which is to use macro-diversity. In the case of OFDM, MIMO allows macro-diversity processing with performance gains. However, the implementation of macro-diversity implies that MIMO processing is centralized and transmissions are synchronous. This is not as complex as in CDMA, but such a technique should only be used in situations where spectrum is very scarce.

5.QUALITY OF SERVICE

_ Traffic generated by the different services will not only increase traffic loads on the networks, but will also require different quality of service (QoS) requirements (e.g., cell loss rate, delay, and jitter) for different streams (e.g., video, voice, data).

_ Providing QoS guarantees in 4G networks is a non-trivial issue where both QoS signaling across different networks and service differentiation between mobile flowswill have to be addressed.

_ One of the most difficult problems that are to be solved, when it comes to IP mobility, is how to insure the constant QoS level during the handover.

_ Depending on whether the new access router is in the same or some other subnetwork, we recognize the horizontal and vertical handover.

_ However, the mobile terminal can not receive IP packets while the process of handover is finished. This time is called the handover latency._ Handover latency has a great influence on the flow of multimedia applications in realtime.

_ Mobile IPv6 have been proposed to reduce the handover latency and the number of lost packets.

_ The field Traffic Class and Flow Label in IPv6 eader enables the routers to secure the special QoS for specific packet series with marked priority.

6.SECURITY

_ The heterogeneity of wireless networks complicates the security issue.

_ Dynamic reconfigurable, adaptive, and lightweight security mechanisms should be developed.

_ Security in wireless networks mainly involves authentication, confidentiality, integrity, and authorization for the access of network connectivity and QoS resources for the mobile nodes flow.

_ AAA (Authentication Authorization Auditing) protocols provide a framework forsuch suffered especially for control plane functions and installing security policies in the mobile node such as encryption, decryption and filtering.

7.BENEFITS

7.1 CONVERGENCE OF CELLULAR MOBILE NETWORKS ANDWLANS

7.1.1 Benefits for Operators:

Higher bandwidths. Lower cost of networks and equipment. The use of licence-exempt spectrum. Higher capacity and QoS enhancement. Higher revenue.7.1.2 Benefits for Users: Access to broadband multimedia services with lower cost and where mostly needed. Inter-network roaming.

7.2 CONVERGENCE OF MOBILE COMMUNICATIONSAND BROADCASTING

7.2.1 From broadcaster point of view:Introducing interactivity to their unidirectional point-to multipoint Broadcasting systems. That is, a broadband downlink based on DAB/DVB-T and a narrowband uplink based on 3G cellular systems.

7.2.2 From the cellular mobile operator point of view:

_Providing a complementary broadband downlink in vehicular environments to support Ipbased multi-media traffic which is inherently asymmetrical.

7.3 CONVERGENCE BENEFITSBroadcasters will benefit from the use of cellular mobile systems to adapt the content of their multi-media services more rapidly in response to the feedback from customers.

_Cellular operators will benefit from offering their customers a range of new broadband multimedia services in vehicular environments.

_Users will benefit from faster access to a range ofbroadband multi-media services with reasonable QoS and lower cost.

7.4 WIRELESS SYSTEM DISCOVERY

A multimode terminal attaches to the WLAN and scans the available systems.

It can download suitable software manually or automatically.7.5RECONFIGURABLE TECHNOLOGY

In order to use the large variety of services and wireless networks, multimode user terminals are essential as they can adapt to different wireless networks by reconfiguringthemselves. 4G Mobile Communication System Division of Computer Engineering 16

This eliminates the need to use multiple terminals (or multiple hardware components in aterminal).

The most promising way of implementing multimode user terminals is to adopt the software radio approach.

RE-CONFIGURABLE TECHNOLOGYCHALLENGES:

Regulatory and Standardisation issues Business models User preference profiles Inter-system handover mechanisms and criteria Software download mechanisms Flexible spectrum allocation and sharing between operators

RE-CONFIGURABLE TECHNOLOGY

BENEFITS FOR:USERS: Select network depending on service requirements and cost. Connect to any network Worldwide roaming. Access to new services.

OPERATORS:

Respond to variations in traffic demand (load balancing). Incorporate service enhancements and improvements. Correction of software bugs and upgrade of terminals. Rapid development of new personalised and customised services.

MANUFACTURERS:

Single platform for all markets. Increased flexible and efficient production.

PERSONAL MOBILITY:

_ In addition to terminal mobility, personal mobility is a concern in mobility management._ Personal mobility concentrates on the movement of users instead of users terminals,and involves the provision of personal communications and personalized operatingenvironments._ Once the callers agent identifies users location, the callers agent can directly communicate with his agent.

8.APPLICATIONS

8.1 VIRTUAL PRESENCE: This means that 4G provides user services at all times, even if the user is off-site.

8.2 VIRTUAL NAVIGATION: 4G provides users with virtual navigation through which a user can access a database of the streets, buildings etc.

8.3TELEGEOPROCESSING APPLICATIONS: This is a combination of GIS(Geographical Information System) and GPS (Global Positioning System) in which a user can get the location by querying.

8.4TELE-MEDICINE AND EDUCATION: 4G will support remote health monitoring of patients. For people who are interested in life long education, 4G provides a good opportunity.

8.5 CRISIS MANAGEMENT: Natural disasters can cause break down in communication systems. In todays world it might take days or 7 weeks to restore the system. But in 4G it is expected to restore such crisis issues in a few hours.

8.6 MULTIMEDIA VIDEO SERVICES_ 4G wireless systems are expected to deliver efficient multimedia services at very high data rates.

_ Basically there are two types of video services: bursting and streaming video services.

_ Streaming is performed when a user requires real-time video services, in which the server delivers data continuously at a playback rate.

_ Bursting is basically file downloading using a buffer and this is done at the highest data rate taking advantage of the whole available bandwidth.

9.CONCLUSION

As the history of mobile communications shows,attempts have been made to reduce anumber of technologies to a single global standard. Projected 4G systems offer this promise of a standard that can be embraced worldwide through its key concept of integration. Future wireless networks will need to support diverse IP multimedia applications to allow sharing of resources among multiple users. There must be a low complexity of implementation and an efficient means of negotiation between the end users and the wireless infrastructure. The fourth generation promises to fulfill the goal of PCC (personal computing and communication)a vision that affordably provides high data rates everywhere over awireless network.

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