ISSN: 2277 – 9043                                               International Journal of Advanced Research in Computer Sci...
ISSN: 2277 – 9043                                        International Journal of Advanced Research In Computer Science an...
ISSN: 2277 – 9043                                          International Journal of Advanced Research in Computer Science ...
ISSN: 2277 – 9043                                 International Journal of Advanced Research In Computer Science and Elect...
ISSN: 2277 – 9043                                                 International Journal of Advanced Research in Computer S...
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10 14

  1. 1. ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 4,June 2012 Performance Evaluation of Digital Modulation Techniques in a WCDMA-based Radio-over- Fiber Communication System Amanjot Kaur, Jasbir Singh Abstract-The demand of mobile communications in the The distributed antenna system (DAS) provides anmodern world is increasing day by day and subscribers infrastructure that brings the radio interface veryfor the mobile communication technologies are growing close to the users. It gives the benefit such as betterrapidly. The data transfer rate should be maximum for coverage, higher capacity and easier installation.uninterruptable communication .Therefore, the Radioover fiber system along with wireless communication, is Other benefits are low attenuation loss, largerused for the high speed data transfer. This combination bandwidth and immunity to radio frequency. One ofwill increase the capacity for the cellular base stations the most promising approaches to 3G is to combine ato change dynamically and meet the traffic Wideband CDMA (WCDMA) air interface with therequirements. To better understand the M-ary PSK radio over fiber technology. Several proposalsystem, a Simulink-based simulation system is designed supporting WCDMA were submitted to thefor M-ary PSK for M=64 using communication toolbox International Telecommunication Union (ITU) and itsin Simulink. In this paper we propose the suitability of International Mobile Telecommunications for the64 PSK Digital Modulation Technique for transmission year 2000(IMT2000) initiative for 3G. All theseand the results are analyzed on the basis of BER, scatterplot and eye diagram like performance measures. schemes try to take advantage of the WCDMA radio techniques. The standard that has emerged is based on ETSIs Universal Mobile TelecommunicationIndex Terms---Digital Modulation Techniques,EyeDiagram, Scatter Plot and 64 psk using rof. System (UMTS) and is commonly known as UMTS Terrestrial Radio Access (UTRA). WCDMA signal modulation & conversion of electrical to optical I. INTRODCTION signal happen in central station. After transmission through various length of step index single modeRadio over fiber (RoF) is an analog optical link fiber (SI-SMF), the receiver signal is analysed.PINtransmitting modulated RF signals. It serves to photo diode is used to detect the optical signal&transmit the RF signal downlink and uplink, to and convert it back to electrical signal. Demodulationfrom central station (CS) to base station (BS) called then performed. Fig. 1 shows the Simulink diagramalso radio ports. The main requirements of radio over of WCDMA using Radio over fiber.fiber Link architecture are duplex operation (i.e.downlink-uplink), reasonable length (a few tens ofkilometers), and need a few millimeter-wavecomponents only in the base stations and also need ofonly few high-performance Optical components. RoFsystems are now being used extensively for enhancedcellular coverage inside buildings such as offices,shopping malls and airport terminals.Amanjot Kaur, Department of Electronics and communicationEngg., Yadavindra College of Engineering, Talwandi Sabo, India,Phone/MobileNo.09465504021.(email:amanjotmann.04@gmail.co Fig.1: Block Diagram for WCDMA using RoFm). The combination of wireless and optical networks isJasbir Singh, Department of Electronics and communication a potential solution for increasing capacity andEngg., Yadavindra College of Engineering, Talwandi Sabo, India, mobility as well as decreasing costs in the accessMobile No.09501011864.(jasbirsingheng@yahoo.com). network. The concept of RoF means to transport information over optical fiber by modulating the light 10 All Rights Reserved © 2012 IJARCSEE
  2. 2. ISSN: 2277 – 9043 International Journal of Advanced Research In Computer Science and Electronics Engineering Volume 1, Issue 4, June 2012with the radio signal. This modulation can be done techniques have proposed in recent years for ultradirectly with the radio signal or at an intermediate long distance digital optical transmission. Because offrequency. Radio-over-Fiber (RoF) system is a fiber- it’s easy to modulate and demodulate.fed distributed antenna network which is expected tobe a fundamental supporting technique for 3G III. PSKdevelopment. Greater end user demand for improved3G services .It provides wider coverage & better Phase shift keying is another form of angleindoor broadband quality. It supports high data rate modulated, constant amplitude digital modulation.transmission. The goal for the next generation with Psk is an M-ary digital modulation scheme.64 psk ismobile communication system is to seamlessly an M-ary encoding technique where M=64; there areintegrate a wide variety of communication services 64 different output phases possible. With 64-psk sixsuch as high speed data, video & multimedia traffic bits are combined, producing 32 different outputas well as voice signals. This was a topic of phases. With 64 PSK, n=6 and M=64; therefore, theinvestigation Khasjori and H.S A.I Raweshidy. minimum bandwidth and baud equal one –sixth theDescription of the MATLAB simulation of multiuser bit rate (fb/6).detection in code division multiple access (CDMA)Hailil Tanyer Eyyuboglu ,to reach low bit error rate IV. PERFORMANCE MEASURES(BER) levels within reasonable computation times,the method of sampling is utilized. Sonia Aissa and The right choice of the performance evaluationMartin Maier demonstrated the ultimate goal of criteria for the characterization of opticalnetworks providing access to information when transmission links represents one of the key issues forneeded, wherever needed and in whatever format it is an effective design of future long-haul opticalneeded. The vision of technological convergence of systems. The evaluation criteria should provide awireless and optical networks is not only becoming a precise determination and separation of dominantnecessity but also plays a key role in future system limitations, making them crucial for thecommunications networks. suppression of propagation disturbances and a performance improvement. The most widely used II. DIGITSL MODULATION TECHNIQUES performance measures for performance evaluation are the BER and eye opening.To meet the explosive demands of high-capacity andbroadband wireless access, radio over fiber (RoF) A. EYE DIAGRAMtechnology has been proposed to be the best solutionsfor the implementation of the reduced cell size and The Discrete-Time Eye Diagram Scope blockcost-effective system. For the high speed data rate displays multiple traces of a modulated signal tolike 10 GB/s or 40 GB/s per channel linear and produce an eye diagram. In telecommunication, annonlinear degrading effects will be severe. The eye pattern, also known as an eye diagram, is anPerformance Evaluation of Digital Modulation oscilloscope display in which a digital data signalTechniques for WCDMA using Radio over fiber from a receiver is repetitively sampled and applied toselection of a suitable optical modulation format is a the vertical input, while the data rate is used to triggerkey issue to ensure optimum system the horizontal sweep. It is so called because, forperformance[1].An optimal modulation format which several types of coding, the pattern looks like a seriesis more tolerant to linear and nonlinear impairments of eyes between a pair of rails. Several systemcan improve dramatically the capacity of light wave performance measures can be derived by analyzingsystem, bit rate-distance product.[2] To combat both the display. If the signals are too Long, too short,the linear and the nonlinear impairments over the poorly synchronized with the system clock, too high,transmission fiber, an optimal modulation format is too low, too noisy, or too slow to change, or have toodesired. The advanced modulation schemes with much undershoot or overshoot, this can be observedother key technologies, like low noise optical from the eye diagram. An open eye patternamplifiers, new advanced optical fibers and forward corresponds to minimal signal distortion. Distortionerror correction techniques, can realize high spectral of the signal waveform due to intersymbolefficient, high-capacity optical transport networks[3].several advanced optical digital modulation 11 All Rights Reserved © 2012 IJARCSEE
  3. 3. ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 4,June 2012interference and noise appears as closure of the eye D. SCATTER PLOTdiagram. The Discrete-Time Scatter Plot Scope block displaysB. BIT ERROR RATE (BER) scatter plots of a modulated signal, to reveal the modulation characteristics, such as pulse shaping or channel distortions of the signal. The Discrete-TimeIn digital transmission the number of bit errors is the Scatter Plot Scope block has one input port.number of received bits of a data stream over acommunication that have been altered due to noise, V. SYSTEM DESCRIPTION AND RESULTSinterference Distortion bit or synchronization errors.The BER can be estimated from following equation. In this system we will use matlab Simulink. Fig2.The BER gives the upper limit for the signal because Shows the Matlab simulation model of the 64 PSKsome degradation occurs at the receiver end. digital modulation technique. The Performance of 64 PSK is measured and Eye diagram, signal trajectory,BER is scatter plot and BER graph for 64 PSK is evaluated. 1 Q exp( Q 2 / 2)  erfc( )  2 2 Q 2The bit error rate or bit error ratio (BER) is thenumber of bit errors divided by the total number oftransferred bits during a studied time interval. BER isa unit less performance measure, often expressed as apercentage. The bit error probability pe is theexpectation value of the BER. The BER can beconsidered as an approximate estimate of the bit errorprobability. This estimate is accurate for a long timeInterval and a high number of bit errors. In acommunication system, the receiver side BER maybe affected by transmission channel noise Fig 2.Simulink Model for 64 PSK Digital Modulationinterference, distortion, bit synchronization problems, Technique using WCDMA and RoF.attenuation, wireless multipath fading, etc. In a noisychannel, the BER is often expressed as a function ofthe normalized carrier-to-noise ratio measure denotedEb/N0, (energy per bit to noise power spectraldensity ratio), or Es/N0 (energy per modulationsymbol to noise spectral density).C. SIGNAL TRAJECTORYThe Discrete-Time Signal Trajectory Scope displaysthe trajectory of a modulated signal in its signal spaceby plotting its in-phase component versus itsquadrature component. The Discrete-Time SignalTrajectory Scope block has one input port. The inputsignal must be complex. The block accepts signal oftype double, single, base integer, and fixed-point forinput, but will cast it as double. The input signal mustbe a sample-based scalar in sample-based mode. The Fig 3.Signal Trajectory Scope for 64 pskinput must be a frame-based column vector or ascalar in frame-based mode. 12 All Rights Reserved © 2012 IJARCSEE
  4. 4. ISSN: 2277 – 9043 International Journal of Advanced Research In Computer Science and Electronics Engineering Volume 1, Issue 4, June 2012 Fig 6.BER Graph for 64 psk VI. CONCLUSIONS This paper describes the performance of 64 psk Digital Modulation Technique using the WCDMA and RoF. The Results are carried out using Matlab Simulink. The results include the Eye Diagram, scatter plot, Signal trajectory and BER graph for 64 psk Digital Modulation Technique. REFERENCES [1] Nazem Khashjori, H.S. AI-Raweshidy, A.Bajwa, “Macro diversity Performance in the uplink of WCDMA with radio over fibre access network” PlMRC 2002, Lisbon. [2] Harri Holma, Toskala “WCDMA for UMTS radio Access for the UMTS radio access for the third generation mobile communications,” JOHN WILEY & SONS, LTD, 2000 [3]Theodore S.Rappaport.,“Wireless Communications Principles and Practice”. Prentice Hall, 2000Fig4.Eye Diagram for 64 psk [4] Holma, H., A. Toskala, “WCDMA for UMTS”. New York: Wiley, eds. 2000. [5] Affida M. Zin, Sevia M. Idrus, and Nadiatulhuda Zulkifli, “The Characterization of Radio-over-Fiber Employed GPON Architecture for Wireless Distribution Network”, International Journal of Machine Learning and Computing, Vol. 1, No. 5, December 2011 [6] M. A. Masud, M. Samsuzzaman, M. A.Rahman,” Bit Error Rate Performance Analysis on Modulation Techniques of Wideband Code Division Multiple’, Journal of Telecommunications, volume 1, issue 2, March 2010 [7] Y.BhanupakashReddy, A.Alphones,”Asynchronous W-CDMA Uplink Performance in Double Spread Cascaded RoF systems”, ICICS-PCM, 15-18 Singapore 2003 [8] D.Opatic, "Radio over Fiber Technology for Wireless Access," Ericsson Zagreb, Technology2004 titution of Electrical Engineers,Fig 5.scatter Plot for 64 psk London, 1995, pp 202-227. [9] K.S. Ju, U.S. Goni and A.M.D. Turkmani,” Comparative Evaluation of the Performance of Anti-multipath Modulation Techniques for Digital Mobile Radio Systems”, 1994 IEEE [10] John A. C. Bingham, “Multicarrier Modulation for Data Transmission: An Idea Whose Time Has come”, IEEE Communications Magazine, Vol. 28, Issue 5, pp 5-14, 1990. [11] G. C. Yang, W. C. Kwong, “Performance comparison of multiwavelength CDMA and WCDMA+CDMA for fiber optic Network”, IEEE Trans. Commun., vol. 45, pp. 1426, Nov. 1992 [12] D. K. Mynbaev, L. L. Scheiner, “Fiber-optic communications technology”, Prentice-Hall Inc., New Jersey, USA, 2001 13 All Rights Reserved © 2012 IJARCSEE
  5. 5. ISSN: 2277 – 9043 International Journal of Advanced Research in Computer Science and Electronics Engineering Volume 1, Issue 4,June 2012[13] Y. Luo et al., “Integrating Optical and Wireless Services in Convergence of Optical and Wireless Access Networks, vol. 25,the Access Network,Proc. OFC/NFOEC, Anaheim, CA, Mar. 2006 no. 11, Nov. 2007, pp. 3428–42.[14] L. G. Kazovsky et al., “Next-Generation Optical AccessNetworks,”IEEE/OSA J. Light wave Tech., special issue on Amanjot Kaur received the Bachelor’s degree in E.C.E. from Yadavindra College of Engineering, Talwandi . Sabo, Bathinda, Punjab in 2010. She is currently persuing Masters Degree in Electronics and Communication Engineering from Yadavindra College of Engineering, Talwandi Sabo, Bathinda, Punjab, under Punjabi University Patiala. Her Research area is Communication System. Jasbir Singh is working as Assistant Professor in E.C.E Dept., Yadavindra College of Engineering, Talwandi Sabo. He has done M.E. in Electronics Product Design and Technology From PEC, Chandigarh. His areas of interest include Communication System and Electronics Product Design. He has published 4 papers in national conferences. 14 All Rights Reserved © 2012 IJARCSEE

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