The Modulation And Demodulation In Gsm Marketing Essay

The chanting And De intonation In Gsm Marketing EssayGSM (Global System for Mobile communications) is the most common standard for restless ph unitarys in the world . In GSM aiming and reference channels be digital and info communication is easy to name into the systemGSM is a cellular network,and mobile ph superstars connect to it by distinct for cells in the immediate vicinity.There ar five different cell sizes in a GSM network-macro, micro, pico, femto and umbrella cells. The coverage area of each(prenominal) cell varies fit in to the implementation environment.GSM networks operate in a compute of different frequence ranges (separated into GSM frequence ranges for 2G and UMTS frequency plentys for 3G). Most 2G GSM networks operate in the 900 megacycle per trice or 1800 megahertz bands. Most 3G GSM networks in Europe operate in the 2100 MHz frequency band.900MHz GSM uses a combination of TDMA and FDMA. It uses eight beat slots, hence one carrier basin support ei ght full rate or sixteen half rate channels. line of reasoning separation is 200kHz with mobile lead channels in the range 890 to 915MHz and mobile receive channels in the range 935 to 960MHz. Peak output personnel of the glowters dep terminates on the class of the mobile station and can be 0.8, 2, 5, 8, or 20 watts.GSM is based on digital cellular networks which suck some advantages as listed below great spectrum usage efficacy compared to analogue approaches.Improved service quality for users in the form of amend speech quality, improved security through constitutional encryption (there is none at present), and in high spiritser connection reliability.Larger number of advanced user services and easier linkage to private and public ISDN networks.CHAPTER 2GENERAL PROPERTIES OF GSMGSM uses multiple access technology like FDMA/TDMA and CDMATDMA. With time sectionalisation multiple access simultaneous conversations are supported by users transmittal in short bursts at differ ent times or slots.FDMA. In frequency sectionalisation multiple access, the total band is split into peg down frequency subbands and a channel is allocated exclusively to each user during the grade of a call. One is use for transmission and one for reception.CDMA. Code division multiple access allows all users access to all frequencies with the allocated band. A wiz user is extracted from the mayhem by looking for each users individual enactment using a correlator. Although not selected for the current generation of mobile digital technologies, CDMA holds untold promise as the future technology of choice for GSM second-stringer in the next century. GSM uses frequency division duplexing. Channel for uplink is from 890 915 MHz Channel for downlink is from 935 960 MHz Distance b/w the frequencies used for uplink and downlink (duplex distance) is 45 MHz Frequency difference between adjacent allocations in a frequency plan(channel spacing) is 200khz. Total number of frequencies are equal to 124 Bit rate of each channel is 270.9 kbit/s Duration of data frame in GSM is 4.615 millisecond Number of time slots are 8 and each slot is of (4.615 / 8) 0.577 m secSpeech bit rate is 13 kbits /seccomputer architecture OF GSM NETWORKThe GSM network can be shared out into four important partsThe Mobile Station (MS).The Base Station Subsystem (BSS).The Network and faulting Subsystem (NSS).The Operation and Support Subsystem (OSS).CHAPTER 3BACKGROUND OF GSMThe first GSM system stipulation was published in July 1991 and was immediately followed by several false starts. This was brought some by a combination over-optimism, difficulties in type approval testing, and inescapable changes to the GSM specification. The first terminals appeared on the grocery in June 1992.A combination of high demand for mobile services and a lack of capacity in the installed analogue network, has made Germany the most advanced country for GSM deployment. In the UK, Vodafone have said that they now cover 60-70% of the UK population with their GSM service and expect 90% coverage by mid 1993.GSM has also been accepted for use by over s even upteen European countries and several others including New Zealand and Hong Kong ending a period of diverse and proprietary standards.Some of the problems which were faced by the Europians when implementing these grass new technology wereIn many countries there is no candid demand or need for GSM. Analogue services are ready(prenominal) and under employed.GSM coverage needs to be as wide as analogue before users will swap over.The current generation of GSM excrete portables are not as small or as wake as analogue variants. This will limit the interest of many users, even though a better service may be provided by GSM technology.Terminal prices for digital technologies are high compared to analogue.It is likely that it will be very difficult to get users to pay higher call charges for an improved service so GSM cannot be positio ned as a higher quality/higher price service.CHAPTER 4IMPLEMENTATIONModulation scheme which is used in GSM is GMSK which is based on MSK.MSK uses linear cast changes and is spectral efficient. bar diagram of GMSK generatorSome of the properties of the GMSK areImproved spectral efficiencyPower Spectral DensityReduced main lobe over MSKRequires much power to transmit data than many comparable modulation schemes forward the GMSK can be explained, some fundamentals of Minimum Shift Keying (MSK) mustiness be known.MSK (MINIMUM SHIFT-KEYING)MSK uses changes in phase to represent 0s and 1s, but unlike most other keying schemes we have get holdn in class, the pulse sent to represent a 0 or a 1, not only depends on what information is being sent, but what was previously sent.Following is the pulse used in MSKWhereif a 1 was sentif a 0 was sentTo turn around how this works assume that the data being sent is 111010000, then the phase of the signal would fluctuate as seen belowIn order to see the signal constellation diagram consider the following equationswhich can be simplefied aswhereandThus the equations for s1 and s2 depend only on andwith each victorious one of two possible economic values. Therefore there are 4 different possibilitiestherefore the signal constellation diagram will beAdvantages of MFSKMSK produces a power spectrum density that travel off much fast-paced compared to the spectrum of QPSK. While QPSK falls off at the inverse square of the frequency, MSK falls off at the inverse fourth power of the frequency. Thus MSK can operate in a smaller bandwidth compared to QPSKGMSK(GAUSSIAN-MINIMUM SHIFT-KEYING)Even though MSKs power spectrum density falls quite fast, it does not fall fast bounteous so that interference between adjacent signals in the frequency band can be avoided. To take care of the problem, the original binary signal is passed through a Gaussian shaped drop before it is play with MSK.The principle parameter in designing an appropr iate Gaussian filter is the time-bandwidth product WTb.Following figure shows the frequency response of different Gaussian filters.MSK has a time-bandwidth product of infinityAs can be seen that GMSKs power spectrum drops much quicker than MSKs. Furthermore, as WTb is decreased, the roll-off is much quickerIn the GSM standard a time-bandwidth product of 0.3 was chosen as a compromise between spectral efficiency and intersymbol interference. With this value of WTb, 99% of the power spectrum is within a bandwidth of 250 kHz, and since GSM spectrum is divided into 200 kHz channels for multiple access, there is very trivial interference between the channelsThe speed at which GSM can transmit at, with WTb=0.3, is 271 kb/s. It cannot go faster, since that would cause intersymbol interferenceCHAPTER 5FUTURE OF GSMThe tough demand for GSM is continuing. Today, GSM is used by 2.3 billion people worldwide and the unwavering growth is expected to be maintained. Most of the expansion occurs in high-growth markets, where the toll of mobile calls and terminals is crucial.With the success of GSM and to meet the demanding requirements of the subscribers,GPRS, HSCSD and EDGE has been introduced which offer high data rates for the transmission. 3rd Generation (3G) systems will soon be introduced in Pakistan offering new and interesting services to the users and will bring network to new levelsIn future strong focus of GSM operators will be on maintaining high quality of service, increasing usage and exploring new tax revenue streams on value added services, market visibility through various market initiatives to fulfill subscribers satisfaction and demand and above all to increase the value of investment for the shareholders.MATLAB CODE(IMPLEMENTATION OF GMSK)clear allclose allDRate = 1 % data rate or 1 bit in one secondM = 18 % no. of sample per bitN = 36 % no. of bits for simulation -1818BT = 0.5 % Bandwidth*Period (cannot change )T = 1/DRate % data period , i.e 1 bit i n one secondTs = T/Mk=-1818 % Chens values. More than needed% only introduces a little more delayalpha = sqrt(log(2))/(2*pi*BT) % alpha reason for the gaussian filter responseh = exp(-(k*Ts).2/(2*alpha2*T2))/(sqrt(2*pi)*alpha*T) % Gaussian Filter Response in time domainfigureplot(h)title(Response of Gaussian Filter)xlabel( Sample at Ts)ylabel( Normalized Magnitude)gridbits = zeros(1,36) 1 zeros(1,36) 1 zeros(1,36) -1 zeros(1,36) -1 zeros(1,36) 1 zeros(1,36) 1 zeros(1,36) 1 zeros(1,36)% Modulationm = filter(h,1,bits)% bits are passed through the all pole filter described by h, i.e bits are% shaped by gaussian filtert0=.35 % signal durationts=0.00135 % taste intervalfc=200 % carrier frequencykf=100 % Modulation superpowerfs=1/ts % sampling frequencyt=0tst0 % time vectordf=0.25 % mandatory frequency resolutionint_m(1)=0for i=1length(t)-1 % Integral of mint_m(i+1)=int_m(i)+m(i)*tsendtx_signal=cos(2*pi*fc*t+2*pi*kf*int_m) % it is frequency modulation not the phase modulating with the integral of the signalx = cos(2*pi*fc*t)y = sin(2*pi*fc*t)figuresubplot(3,1,1)stem(bits(1200))title(Gaussian Filtered Pulse Train)gridsubplot(3,1,2)plot(m(1230))title(Gaussian Shaped train)xlim(0 225)subplot(3,1,3)plot(tx_signal)title(Modulated signal)xlim(0 225)% Channel grading%load CCASEDigital_Communicationprojectgmskalichannel.matload channel.math = channelN1 = 700x1 = randn(N1,1)d = filter(h,1,x1)Ord = 256Lambda = 0.98delta = 0.001P = delta*eye(Ord)w = zeros(Ord,1)for n = OrdN1u = x1(n-1n-Ord+1)pi = P*uk = Lambda + u*piK = pi/ke(n) = d(n) w*uw = w + K *e(n)PPrime = K*piP = (P-PPrime)/Lambdaw_err(n) = norm(h-w)endfiguresubplot(3,1,1)plot(w)title(Channel Response)subplot(3,1,2)plot(h,r)title(Adaptive Channel Response)rcvd_signal = conv(h,tx_signal)subplot(3,1,3)plot(rcvd_signal)title(Received Signal)eq_signal = conv(1/w,rcvd_signal)figuresubplot(3,1,1)plot(eq_signal)title(Equalizer Output)subplot(3,1,2)plot(eq_signal)title(Equalizer Output)axis(208 500 -2 2)subplot(3,1,3)plot (tx_signal,r)title(Modulated Signal)% Demodulationeq_signal1 = eq_signal(200460-1)In = x.*eq_signal1Qn = y.*eq_signal1noiseI = awgn(In,20)noiseQ = awgn(Qn,20)I = In + noiseIQ = Qn + noiseQLP = fir1(32,0.18)yI = filter(LP,1,I)yQ = filter(LP,1,Q)figuresubplot(2,1,1)plot(yI)title(Inphase Component)xlim(0 256)subplot(2,1,2)plot(yQ)title(Quadrature Component)xlim(0 256)Z = yI + yQ*jdemod(1N) = imag(Z(1N))demod(N+1length(Z)) = imag(Z(N+1length(Z)).*conj(Z(1length(Z)-N)))xt = -10*demod(1N/2length(demod))xd = xt(42length(xt))figurestem(xd)title(Demodulated Signal)OUTPUTSTABLE OF CONTENTSCHAPTER 1 introductionCHAPTER 2GENERAL PROPERTIES OF GSMCHAPTER 3BACKGROUND OF GSMCHAPTER 4IMPLEMENTATIONMSKGMSKCHAPTER 5FUTURE OF GSMCHAPTER 6MATLAB IMPLEMENTATION