Performance Analysis and PAPR Calculation of OFDM System Under Different Modulation schemes

Transcription

1 SSRG International Journal of Electronics andoncommunication 2017) - Secial 2nd ndinternational Conference Innovations and- (2'ICEIS Solutions -(2'ICEIS )Issue - Aril International Conference on Innovations and Solutions (2 ICEIS -2017) Performance Analysis and PAPR Calculation of OFDM System Under Different Modulation schemes 1 K.Rajasekar Deartment of ECE IFET College of Villuuram, India rajakeerthivasan@gmail.com Abstract The redominant focus of this aer is to observe the erformance of PAPR(Peak-to-Average Power Ratio) distortion in OFDM by using cliing and filtering aroach with channel state estimation. The roosed aroach is very easy to imlement and reduces the maximum amount of PAPR distortion with the aid of cliing the eak of high intensity ower signal. Moreover, PAPR distortion is decreased via tuning secific arameters like linear channel estimators, the Least Square Error () and DFT Minimum Mean Square Error (). The roosed aroach is analyzed with different modulation strategies like QPSK, 16 QAM, 64QAM with 128 subcarriers. Channel state information is useful at receiver to remove effect of noisy channel in received signal for efficient recovery of data Here, DFT - is used instead of () because of its simlicity as well as it retain criteria but the constrain is linear. The roosed aroach shows tremendous overall erformance develoment over existing strategies in hrases of PAPR reduction and bit blunders rice (BER). keywords OFDM,PAPR,,,BER. A.Jayakumar 2,S.Sundaresan3 Associate rofessor2, Assistant rofessor3 Deartment of ECE IFET College of Villuuram, India 2 jayangce@gmail.com estimators[2], the Least Square Error() and DFT-based Minimum Mean Square Error() OFDM system under different modulation like QPSK,16QAM,64QAM and 256QAM as well as with equalizer at receiver. Channel state information is useful at receiver to remove effect of channel in received signal for efficient recovery of data and at transmitter it is useful to vary modulation order and ower allocation according to channel for efficient wireless system. For erformance analysis, is used instead of least square() because of its simlicity as well as it retain criteria but the constrain is linear. The erformance is tested in matlab simulation software version 2013A.The simulation results shows significant erformance imrovement in cliing and filtering method over existing method and the comares is based on BER erformance and PAPR reduction under various modulation scheme for Reed Solomon encoder with different sub carriers. shown that cliing and filtering technique outerforms all existing techniques.erformance and PAPR reduction under various modulation scheme for Reed Solomon encoder with different sub carriers.it is shown that cliing and filtering technique outerforms all existing techniques. INTRODUCTION I. PROPOSED METHOD Orthogonal Frequency Division Multilexing (OFDM) is a multi-carrier transmission method which is most widely used in the field of communication. One of the major drawbacks of this system is Peak to Average Power Ratio (PAPR). This thesis highlighting mainly on the PAPR reduction of OFDM system using cliing filtering[1] method with channel estimation.the main focus of this aer is to study erformance of two linear channel The OFDM signal Xn is bought by using due to the fact that information block Xn of N symbols every the lace n = [1, 2,.., N-1] and each and every symbol is modulated by way of a subcarrier which is taken from a suite of subcarriers, and these subcarriers are chosen such that they're orthogonal to each other. The discrete time area sign of OFDM is generated by means of alying N-factor IFFT on ISSN : Seventh Sense Research Grou Page Page3296

2 2nd on Innovations Innovationsand andsolutions Solutions(2 ICEIS (2'ICEIS ) 2ndInternational International Conference Conference on -2017) frequency domain OFDM sign Xk, which can also be written as x[ n] 1 N x[k ] ex j 2 nk. N BLOCK DIAGRAM PAPR reduction scheme using cliing and filtering In this OFDM signal is clied at a exact threshold worth before amlification. Nonetheless, cliing exlanations in-band distortion and out-ofband noise a good way to indirectly degrades the bit error rate erformance and the sectral effectively. Direct cliing suresses the timedomain OFDM sign of which the signal ower exceeds a articular threshold value. The enalty is the significant increase of out-of-band energy. Peak windowing or filtering after direct cliing can be used to reduce the out of- band energy. But after filtering oeration, the eak of the time-domain signal may increase. x FIGURE NO.1 The L-times interolated version as x ' [ m] 1 L.N L. N 1 K 0 X '[k ]. ex j j m fk L.N c [m] x if x A Hence, recursive cliing and filtering (RCF) can be used to suress both the out-of-band energy and the PAPR RCF can also be modified by way of restricting the neighborhood of distortion to obtain elevated error erformance, filtering is comleted after cliing in an effort to do away with unwanted frequencies triggered through the cliing system. [m]. A x [ m] x [ m] x m = 0, 1;... NL-1 c II.PAPR in MIMO-OFDM System The rationale why PAPR raises is, in a multicarrier rocess at each instant of time the subcarriers at different hases should be different with resect to each other. But generally due to resence of large number of indeendently modulated subcarrier.[4]the eak value of those subcarriers could achieve highest worth at the same time considering of which the more than one sinusoids are brought together which exlanations the outut enveloe to shoot u immediately. So the PAPR reduction system reduces the chance of simultaneous occurrence of eaks of these subcarriers. In ractice, comlementary cumulative distribution function (CCDF) is used as a size index to calculate the chance of PAPR exceeding a articular threshold rice and it is mathematically reresented. PAPR[ x] max x(t ) 2 E[ x(t ) 2 otherwise cliing ratio (CR) as the cliing level normalized by the RMS value s of OFDM signal[4], such that CR A III.CHANNEL ESTIMATION The DFT-based channel estimation technique has been derived to imrove the erformance of or channel estimation by eliminating the effect of noise outside the maximum channel delay. Let the estimate of channel gain at the kth subcarrier, obtained by either or channel estimation method[7].clear that the estimation shows better erformance than the estimation does at the cost of requiring the additional comutation and information on the channel characteristic Ignoring the coefficients {h[ n]} that contain the noise only, define the coefficients for the maximum channel delay L as ISSN : Seventh Sense Research Grou Page Page

3 nd International International Innovations Solutions (2'ICEIS SSRG International JournalConference ofconference Electronics and Communication - (2'ICEIS ) 2017) ) Secial Issue - Aril nd onon Innovations andand Solutions (2 ICEIS h[n] z[n]n = 0,1,.N - 1 h{n} 0 and transform the remaining L elements back to the frequency domain as follows H DFT [k ] DFT {hdft[n]} the channel estimates obtained by using the various tyes of channel estimation methods with and without Discrete fourier transform technique. IV.RESULT & DISCUSSION FIGURE NO.3 CLIPPED AND FLITERING OF QPSK CLIPPED AND FLITERING OF 16 QAM FIGURE NO.2 While erform the cliing and filtering with DFT e-04 which is greater than CE e-03 shown inanexure_i CLIPPED AND FLITERING OF 8QAM FIGURE NO.4 While erform the cliing and filtering with DFT e-04which is greater than CE e-03 shown inanexure_i While erform the cliing and filtering with DFT e-04which is greater than CE e-03 shown in ANEXURE_I Page 34 Page 98

4 2nd International Conference on Innovations and Solutions (2'ICEIS ) 2nd International Conference on Innovations and Solutions (2 ICEIS -2017) CLIPPED AND FLITERING OF 64 QAM FIGURE NO.7 BER OF 16 QAM FIGURE NO.5 While erform the cliing and filtering with DFT e-04 which is greater than CE e-03shown inanexure_i FIGURE NO.8 BER OF 64QAM BER OF QPSK FIGURE NO.9 FIGURE NO.6 V.CONCLUSION BER OF 8 QAM DFT roved efficient channel estimation technique over and also there will be reduction in PAPR and BER. This outcomes could be efficient to make effective Adative MIMO OFDM rocedure. It could be additionally valuable in adative modulation and ower allocation notion for making better wireless communication aroach. This erformance analysis can erform for different channel models. Page 35 Page 99

5 2nd International Conference on Innovations and Solutions (2'ICEIS ) 2nd International Conference on Innovations and Solutions (2 ICEIS -2017) VI.REFERENCES Hedieh Jahananah and AfroozHaghbin Deartment of Electrical and Comuter, Science and Research Branch, Islamic Azad University, Tehran, Iran SLM-Based Dynamic Cliing and Amlification PAPR Reduction Schemes for Interleaved OFDMA Ulink Systems The 22nd Iranian Conference on Electrical (ICEE 2014), May 20-22, 2014, ShahidBeheshti University Ahmed, E., W. Aziz, S. Saleem and Q. Islam, Performance Analysis of OFDM System for Different Channel Lengths and Multiath Channel Tas. Advances in Electrical Systems 1 (2): Ochiai, H. and K. Imai, Block Coding Scheme Based on Comlementary Sequences for Multicarrier Signals. IEICE Transactions Fundamentals, E80-A (11): Ochiai, H. and K. Imai, On the Distribution of the Peak-to-Average Power Ratio in OFDM Signals. IEEE Transactions on Communications,49 (2): Shang-Kang Deng and Mao-Chao Lin, OFDM PAPR reduction using cliing with distortion control. IEEE International Conference of Communications, Taiei, Taiwan, 4: RajvirsinhRana, and JagdishRathod,"Performance Analysis of VBLAST 2X2 and 4X4 MIMO OFDM System with Different Modulation and Detection Techniques,"IEEE Conference(EESCO-2015), /15/$ IEEE, January S. Coleri, M. Ergan, and A. Puri," A study of channel estimation techniques based on ilot arrangement in OFDM systems," Broadcasting, IEEE Transaction6.s on, Vol.48, No.3, , Yushisen, and Ed Martinez, "Channel Estimation in OFDM Systems," Freescale Semiconductor Alication note, Wen Zhou,and Wong Hing Lam, "A Fast L Channel Estimation Method for OFDM Systems," EURASIP Journal on Wireless Communications and Networking, Hindawi Publishing Cororation, Volume 2009, Article ID Kala Praveen Bagadi, Prof. Susmita Das MIMO OFDM channel estimation using ilot carriers,international Journal of comuter alications,vol 2,no.3,May 2010 Page 36 Page 100

6 2nd International Conference on Innovations and Solutions (2'ICEIS ) 2nd International Conference on Innovations and Solutions (2 ICEIS -2017) VII.ANEXURE_I OFDM DIFFERENT CHANNEL ESTIMATION BPSK QPSK 8 QAM 16 QAM 64 QAM BER at SNR 10 BER at SNR 25 db BER at SNR 40 db BER at SNR 50 db db e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e e-04 Page 37 Page 101