I. INTRODUCTION IJSER

INTERNATIONAL JOURNAL OF SCIENTIFIC & ENGINEERING RESEARCH, VOLUME 7, ISSUE 8, AUGUST-2016ISSN 2229-5518Implementation of Digital Modulation Technique andCalculate the Bit Error Rate Performance using MatlabAli Kamal Taqi 1Abstract— With the increasing demand in communication, it has become necessary to give better and efficient service to users by using bettertechnique. This paper demonstrates different modulation technique including Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), PhaseShift Keying (PSK) and analyze the Bit Error Rate (BER) for different modulation schemes such as Binary Phase Shift Keying (BPSK), QuadraturePhase Shift Keying (QPSK), Octal Phase Shift Keying (8PSK), and Trellis Coded Modulation (TCM). By Choosing a reliable modulation schemeand better coding technique the enhancement of the performance can be obtained in transmitter and receiver of the system. Simulated result isshown to analyze and compare the performance of these systems by using additive white Gaussian noise channel (AWGN). Finally, the differentmodulation schemes are compared on the basis of BER and best modulation scheme is determined. From analysis of modulation techniques, thesystem could use more appropriate modulation technique to suit the channel quality, thus we can deliver the optimum and efficient systemparameters. Both Matlab Code and Simulink have been used for simulation.Index Terms— Digital Modulation, ASK, FSK, PSK, Bit Error Rate (BER), TCM.—————————— ——————————I. INTRODUCTIONIn the simplest type, a transmission-reception system may bea three-block system, consisting of a) a transmitter, b) atransmission medium and c) a receiver. If we predict of amix of the transmission device and reception device withinthe sort of a ‘transceiver’ and if (as is sometimes the case)the transmission medium permits signal each ways that, wetend to are in an exceedingly position to consider a both-way(bi-directional) communication system. For simpledescription, we are going to discuss a few unidirectionaltransmission-reception systems with the implicit assumptionthat, once understood, the concepts are used for developing/ analyzing two-way communication systems. So, ourrepresentative communication system, in an exceedinglystraightforward type, once more consists of 3 completelydifferent entities, viz. a transmitter, a channel and a receiver.A data communication system has many distinctive optionswhen put next with associate analog communication system.each analog (such as voice signal) and digital signals (suchas knowledge generated by computers) is communicatedover a digital gear mechanism. once the signal is analog innature, constant discrete-time discrete-amplitude illustrationis feasible when the initial process of sampling andquantization. So, each a digital signal and a quantal analogsignal are of comparable kind, i.e. discrete-time-discreteamplitude signals. A key feature of a data communicationsystem is that a way of ‘information’, with acceptable unitof live, is related to such signals. This image, attributable toClaude E. Shannon, ends up in many fascinating schematicdescription of a data communication system. parenthetically,take into account Fig.1.1 that shows the signal supply at thetransmission finish as constant ‘Information Source’ andalso the receiving user as associate ‘Information sink’. thegeneral purpose of the data communication system is ‘tocollect data from the supply and perform necessary signalprocess specified the data is delivered to the top user(information sink) with acceptable quality’. One could noteof the compromising phrase ‘acceptable quality’ andsurprise why a digital gear mechanism mustn't deliverprecisely the same data to the sink as accepted from thesupply. A broad and general answer to such question at nowis: well, it depends on the designer’s understanding of the‘channel’ (Fig. 1.1) and the way the designer will translatehis data to style the signal process algorithms / techniqueswithin the ’Encoder’ and ‘decoder’ blocks in Fig. 1.1 wetend to hope to select up many basic nonetheless smartapproaches to amass the higher than skills. However,pioneering add the 1940-s and 1950-s have established abottom-line to the look for ‘a unflawed (equivalently, ‘errorless’) data communication system’ delivery out manyprofound theorems (which currently get into the name ofknowledge Theory) to ascertain that, whereas error-lesstransmission of knowledge will ne'er be secured, the other‘acceptable quality’, haphazardly getting ready to error-lesstransmission could also be doable. This ‘possibility’ ofvirtually error-less data transmission has driven importantanalysis over the last 5 decades in multiple connected areassimilar to, a) digital modulation schemes, b) errormanagement techniques, c) optimum receiver style, d)modeling and characterization of channel so forth. As aresult, varieties of electronic communication systems aredesigned and place to use over the years and therefore theoverall performance has improved considerably �——1 ComputerEngineering Department, University of Technology, IraqEmail: alikamal1@yahoo.comIJSER 2016http://www.ijser.org1

INTERNATIONAL JOURNAL OF SCIENTIFIC & ENGINEERING RESEARCH, VOLUME 7, ISSUE 8, AUGUST-2016ISSN 2229-5518Figure 1.1: Basic block diagram of a digital communicationsystemII. DIGITAL COMMUNICATION SYSTEMIt is attainable to expand our basic ‘three-entity’ descriptionof an electronic communication system in multiple ways inwhich. as an example, Fig. 2.1 shows a somewhat elaboratediagram expressly showing the vital processes of‘modulation demodulation’, ‘source coding-decoding’ and‘channel cryptography – decoding’. A reader might havemultiple queries with reference to this sort of abstraction. asan example, once ‘information’ has got to be sent over anoutsized distance, it's a standard information that the signalought to be amplified in terms of power and so began thephysical transmission medium. Diagrams of the kind in Figs.1.1 and 2.1 have no explicit reference to such issues.However, the issue here is more of suitable representation ofa system for clarity rather than a module-by-modulereplication of an operational digital communication system.‘modulation channel’. We will see later that a modulationchannel usually accepts modulated signals as analogwaveforms at its inputs and delivers another version of themodulated signal in the form of analog waveforms. Suchchannels are also referred as ‘waveform channels’. The‘channel’ in Fig. 1.1, on the other hand, appears to acceptsome ‘encoded’ information from the source and deliversome ‘decoded’ information to the sink. Both the figures arepotentially useful for describing the same digitalcommunication system. On comparison of the two figures,the reader is encouraged to infer that the ‘channel’ in Fig.1.1 includes the ‘modulation channel’ and the modulationdemodulation operations of Fig. 2.1 The ‘channel’ of Fig.1.1 is widely denoted as a ‘discrete channel’, implying thatit accepts discrete-time-discrete-amplitude signals and alsodelivers discrete-time discrete-amplitude signals [2].III. MODULATION TECHNIQUEA. Amplitude-Shift Keying (ASK) ModulationThe transmission of digital signals is increasing at a speedyrate. Low-frequency analogue signals area unit typicallyborn-again to digital format (PAM) before transmission. Thesupply signals area unit typically noted as baseband signals.Of course, we will send analogue and digital signals directlyover a medium. From electro-magnetic theory, foreconomical radiation of current from associate degreeantenna it should be a minimum of within the order ofmagnitude of a wavelength in size;c f λ , wherever c is that the rate of sunshine, f is that thesignal frequency and λ is that the wavelength. For a 1kHzaudio signal, the wavelength is three hundred kilometer.associate degree antenna of this size isn't sensible foreconomical transmission. The low-frequency signal iscommonly frequency-translated to the next frequency varyfor economical transmission. the method is namedmodulation. the utilization of the next frequency varyreduces antenna size.In the modulation method, the baseband signals represent themodulating signal and therefore the high-frequency carriersignal may be a curved wave. There are a unit 3 basic waysthat of modulating a undulation carrier. For binary digitalmodulation, they're referred to as binary amplitude-shiftkeying (BASK), binary frequency-shift keying (BFSK) andbinary phase-shift keying (BPSK). Modulation conjointlyresults in the likelihood of frequency multiplexing. in a veryfrequency-multiplexed system, individual signals area unittransmitted over adjacent, non-overlapping frequencybands. they're thus transmitted in parallel and at the sametime in time. If we tend to operate at higher carrierfrequencies, a lot of information measure is obtainable forfrequency-multiplexing a lot of signals.IJSERFigure 2.1: A possible breakup of the pervious diagram(following Shannon’s ideas)To elaborate this potentially useful style of representation,let us note that we have hardly discussed about the thirdentity of our model, viz. the ‘channel’. One can defineseveral types of channel. For example, the ‘channel’ in Fig.2.1 should more appropriately be called as a ‘modulationchannel’ with an understanding that the actual transmissionmedium (called ‘physical channel’), any electromagnetic (orotherwise) transmission- reception operations, amplifiers atthe transmission and reception ends and any other necessarysignal processing units are combined together to form thisIJSER 2016http://www.ijser.org2

INTERNATIONAL JOURNAL OF SCIENTIFIC & ENGINEERING RESEARCH, VOLUME 7, ISSUE 8, AUGUST-2016ISSN 2229-5518A binary amplitude-shift keying (BASK) signal is outlinedbys(t) A m(t) cos2πf c t,0 t TWhere A is constant, m(t) 1 or 0 , f c is the carrierfrequency and T is the bit duration. It has a power P 𝐴𝐴2 /2, so that A 2𝑃𝑃 this equation can be written asS(t) 2𝑃𝑃 cos2πf c t0 t T 𝑃𝑃𝑃𝑃 2/𝑇𝑇 cos2πf c t 𝐸𝐸 2/𝑇𝑇cos2πf c t0 t TFigure 3.2: BFSK Modulation0 t TThe output of the Matlab code for BASK modulationshown in figure (3.1) has the following parameters: Carrierfrequency 8 with Message frequency 4C. Phase-Shift Keying (PSK) ModulationPhase-shift keying (PSK) may be a digital modulationtheme that conveys information by dynamical, ormodulating, the section of a reference signal (the carrierwave). Any digital modulation theme uses a finite range ofdistinct signals to represent digital informationA binary phase-shift keying (BPSK) signal can be definedby0 t Ts(t) A m(t) cos 2πf c tIJSERwhere A is a constant, m (t) 1 or -1, f c is the carrierfrequency, and T is the bit duration. The signal has a powerP A2/2, so that A 2𝑃𝑃 .The output of the Matlab code for BPSK modulation shownin figure (3.3) has the following parameters: Carrierfrequency 8 with Message frequency 4Figure 3.1: BASK ModulationB. Frequency-Shift Keying (FSK) ModulationFrequency-shift keying (FSK) may be a modulation themeduring which digital data is transmitted through distinctfrequency changes of a radio emission. the only FSK isbinary FSK (BFSK). BFSK uses a combine of distinctfrequencies to transmit binary (0s and 1s) dataA binary frequency-shift keying (BFSK) signal can bedefined by𝐴𝐴 𝑐𝑐𝑐𝑐𝑐𝑐2𝜋𝜋𝑓𝑓0 𝑡𝑡S(t) 𝐴𝐴 𝑐𝑐𝑐𝑐𝑐𝑐2𝜋𝜋𝑓𝑓1 𝑡𝑡where A is a constant, f 0 and f 1 are the transmittedfrequencies, and T is the bitduration. duration. The output of the Matlab code for BFSKmodulation shown in figure (3.2) has the followingparameters: 1st Carrier frequency 16, 2nd Carrierfrequency 8 with Message frequency 4IJSER 2016http://www.ijser.orgFigure 3.3: BPSK Modulation3