REDUCTION IN BER AND PAPR USING WP BASED IMPROVED SLM METHOD IN MIMO-OFDM TECHNIQUE

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1 Volme 119 No , ISSN: (o-lie versio) rl: ijpam.e REDUCTION IN BER AND PAPR USING WP BASED IMPROVED SLM METHOD IN MIMO-OFDM TECHNIQUE Ms. Keerthiga.K 1, Mr. Sagaya Selvaraj.A 2 1 Departmet of ECE, IFET College of Egieerig ad Techology, Villpram, Idia Abstract : Geerally, MIMO-OFDM(Mltiple Ipt Mltiple Otpt- Orthogoal Freqecy Divisio Mltiplexig) is attractive method i high data rate trasmissio. Bt, this method is affected by high peak to average power ratio ad high bit error rate. I this paper, Wavelet Packet based improved SLM(Selected Mappig) method is sed to redce both BER ad PAPR. Wavelet Packet is sed for Wavelet Packet Trasform istead of Fast Forier Trasform. Improved SLM method, the sigals are trasformed by Hadamard matrix. The the row vector of Hadamard matrix is sed as phase seqece ad sperimposed to sigal seqece. The simlatio reslts show that better performace i BER ad PAPR tha the other methods. Keywords: MIMO-OFDM(Mltiple Ipt Mltiple OtptOrthogoal Freqecy Divisio Mltiplexig), WP(Wavelet Packet), SLM(Selected Mappig), PAPR(Peak to Average Power Ratio), BER(Bit Error Rate). 1. Itrodctio I geeral, MIMO-OFDM (mltiple ipt mltiple otpt orthogoal freqecy divisio mltiplexig) is sed for high data rate trasmissio i wireless system. MIMO method is sed for mltiple ateas for trasmittig ad receivig the data ad OFDM method is created by iverse discrete Forier trasform ad discrete Forier trasform. There are some disadvatages i MIMO-OFDM system, high PAPR, BER ad it caot be localized i both time ad freqecy. To overcome this problem, we go for wavelet packet trasform(wpt) istead of Forier trasform i OFDM system. WPbased OFDM sigals are also sffered from high peak to average power ratio becase of icreased spply of arrowbad sigals. A high PAPR evet cases oliear distortio of sigals ad redces the power efficiecy of a high power amplifier. The se of a HPA trasmitter with wide liear regio will lead to a cosiderable cost ad icrease overall system complexity; hece PAPR redctio is good alterative. Several methods have bee proposed to miimize PAPR, icldig PTS (Partial Trasmit Seqece), PTS with embedded side iformatio data, clippig ad filterig, geetic algorithm, block codig scheme, selective mappig. These methods are redcig PAPR, bt icrease the BER. I this paper, WP based improved SLM method i MIMO-OFDM system performace is better iboth PAPR ad BER. The improved SLM method is sed Hadamard matrix to redce PAPR ad achieve good BER performace. The the row vectors of Hadamard matrix are sed as phase seqece ad sperimposed o the origial data sigals. The simlatio reslt shows, PAPR ad BER performace are better tha the other methods at complemetary cmlative distribtio fctio of level of The rest of paper is orgaized as follows. Sectio II covetioal SLM. Sectio III The proposed system of WP based improved SLM method i MIMO-OFDM techiqe.sectio IV Simlatio Reslts.Sectio V Coclsio. 2. Covetioal Slm Method The SLM method is basically implemeted from symbol scramblig. I this method, a set of ipt sigals are created to represet the same iformatio, the the sigal with lowest PAPR is selected for trasmissio. The iformatio abot the selectio of these ipt sigals eed to be explicitly trasmitted alog with the selected sigal as side iformatio. Selected mappig techiqe eeds to trasmit the iformatio to receiver, with the selected sigal, as side iformatio. If there is ay error i the received iformatio, the it is difficlt for the receiver to recover the iformatio from the trasmitted selected sigal. De to this problem a strog protectio is eeded regardig side iformatio. If the receiver has these side iformatio the the process of decodig become very simple. SLM PAPR redctio techiqe ca be employed for larger mber of sb-carriers with moderate complexity. 837

2 PAPR redctio will be better i covetioal SLM method. Bt, this will icrease BER of the ipt sigal. 3. Proposed Wp Based Imrpoved Slm Method I Mimo-Ofdm Techiqe x ( v) arg mi 0UU[ PAPR ( X )] Fig1. block diagram of covetio SLM method This method cotais codes oly for PAPR redctio ad does ot iclde error correctio. The complexity is icreased i this scheme de to the mltiple mbers of IFFT operatios. The eed for trasfer of side iformatio to the receiver withot ay margi for trasmissio errors is very crcial der the fadig chaels. I this proposed system, Wavelet Packet based Improved SLM (Selective Mappig) method i MIMO-OFDM techiqe. Wavelet Packet is sed for Wavelet Packet Trasform istead of Fast Forier Mathematical expressio for PAPR redctio i SLM method: Let the ipt sigal is defied as, X [ X, X,..., X ] T 0 1 N 1 Each data block is mltiplied with U differet phase factor. The phase rotated seqece de to phase rotatio factor Bv ca be writte as, Where, v ( v) X IFFT( X B ) B [ bv, bv,..., bv ] T 0 1 vn 1 With phase seqece with bv ( 0,1,..., N 1) We are sig ±1 for avoidig complexity for complex mltiplicatio or to add modified data ito modified data. After that mltiply ipt data with U differet phase factor the modified data for U phase seqece ca be writte as: X [ X bv, X bv,..., X bv ] 0,0 1,1 N1, N1 =0,1,.,U-1. After the PAPR comparisos amog the U data seqece x(),the optima mapped oe x with the miimm PAPR is selected for trasmissio. Fig2.block diagram for trasmitter Trasform i OFDM. Wavelet Packet Trasform sed i discrete form, becase this will be good compressio, deoisig ad it ca be represeted i both time ad freqecy tha the cotios form. The ipt sigal seqece (X) is coverted from serial to parallel form. Each sigal seqece is mltiplied ito Hadamard matrix (H) to get Hadamard Trasform. This Trasform is maily sed for error correctio ad also the rows are mtally orthogoal. The the row vector of Hadamard matrix is sed as phase seqece (H ). The sigal seqece is sperimposed oto phase seqece, which is called as sperimposed process. This sperimposed sigal seqece is chose from Hadamard matrix.the phase seqece is added ito power ratio factor (β) at 0 to 0.1 levels, which is sed to icrease the performace of the system withot ay hardware chage. After the sperimposed process, the phase seqece ismltiplied itoprocessed sigal to prodce alterate sigal seqece. Fially, this seqece with low PAPR is trasmitted after the IDWPT block. I receiver, the received sigal is set to DWPT block ad the otpt of 838

3 DWPT block is mltiplied ito iverse Hadamard matrix to recover the origial sigal with low PAPR ad BER. This sperimposed sigal seqece is mltiplied ito phase seqece, which is prodce the alterative sigal seqece is, X X X X 0 1 U [,,..., ] After the IDWPT process, the sigal seqece is x IDWPT [ X ] x x x x 0 1 U [,,..., ] The the low PAPR is selected by, x arg mi [ PAPR( x )] 0UU This will be redcig the PAPR tha the existig methods. I receiver, the iverse Hadamard matrix is sed to recover the origial sigal with low BER. Fig3. Block diagram for receiver Mathematical expressio for PAPR redctio i WP based Improved SLM method: Let the ipt sigal seqece is defied as, X X0 X1 X N [,,..., ] A Hadamard Matrix is the matrix of 1 s ad -1 s whose colms are orthogoal. So, a Hadamard Matrix (H) of order satisfies the followig eqatio: 4. Simlatio Reslts The proposed Wavelet Packet based improved SLM method i MIMO-OFDM techiqe is simlated to aalyze ad compare its performace tha the other methods by sig MATLAB 2016a tool. It is ivestigated the PAPR ad BER redctio ca be achieved throgh the proposed system. The MIMO- OFDM techiqe is mostly sed i wireless commicatio system. HH =I Where, I = idetity matrix H = traspositio of H The the partitioed matrix of Hadamard matrix i order H H of 2 are defied as H H The row vector of Hadamard Matrix is sed as Phase Seqece is H, [=0,1,,U] ad this will be sperimposed oto sigal seqece are, X H 1 X Fig4. Simlatio reslt for WP based improved SLM method PAPR redctio 839

4 sig Hadamard Trasform. The Simlatio reslts show, PAPR ad BER redctio improves tha other methodsat complemetary cmlative distribtio fctio Refereces Fig 5. Simlatio reslt for Compariso of SNR ad BER Fig 6. Simlatio reslt for WP based improved SLM method BER redctio This method is affected by high PAPR ad BER. There are several methods which are sed to redce PAPR ad BER. Bt, the PAPR ad BER are iversely proportioal parameters. So, both caot be redced at the same time. I this method, the PAPR ad BER are redced at the same time tha the other methods at complemetary cmlative distribtio fctio Coclsio PAPR ad BER redctio Scheme based o Wavelet Packet based improved SLM method i MIMO-OFDM techiqe has bee proposed to redce peak-to-average power ratio of trasmitted wavelet packet based MIMO- OFDM sigals ad redce BER of received sigal by [1] LoReze, Li Ri, Dag Yp, Yag Jiao, Li Weihog; Two improved SLM methods for PAPR ad BER redctio i OFDM ROF systems, Optical Fiber Techology (2014) [2] Daod, O.: Performace improvemet of wavelet packet trasform over fast Forier trasform i mltiple-ipt mltiple-otpt orthogoal freqecy divisio mltiplexig systems, IET Comm., 2012, 6, (7), pp [3] G. Kar, R. Kar. "Comparative stdy of SLM ad PTS techiqes for PAPR Redctio of a MC- CDMA system". "Iteratioal Joral of Egieerig Research ad Applicatios". Vol. 2, Isse 4,.Ily-Agst 2012, pp [4] Wali,U.;Bidwai,S., Novel Techiqes to redce PAPR i OFDM Systems Usig Threshold SLM,Advace Comptig Coferece (IACC), 2013 IEEE 3rd Iteratioal, Ghaziabad, Feb. 2013,pp [5] Pakaj Kmar Sharma, A SLM based PAPR Redctio Method sig New VolterraPredistorter Model i the OFDM System, Isse 10, Volme 11, October [6] Pawa Sharma ad SeemaVerma, PAPR Redctio of OFDM Sigals sig Selective Mappig with Trbo codes, Iteratioal Joral of Wireless & Mobile Networks (IJWMN) Vol. 3, No. 4,Agst [7] Park, M., Heeyog, J., Cho, N., Hog, 0, ad Kag, C., "PAPR redctio i OFOM trasmissio sig Hadamard trasform", IEEE Iteratioal Coferece 0 Commicatios, VoU, J 2000, pp [8] Yag, L., Soo, K.K., Li, S.Q., et al.: PAPR redctio sig low complexity PTS to costrct of OFDM sigals withot side iformatio, IEEE Tras. Broadcast., 2011, 57, (2), pp [9] Zakaria, J., Salleh, M.F.M.: O the PAPR redctio techiqe: WP-PTS scheme with embeddig the side iformatio data. IEEE 11th Malaysia It. Cof. o Commicatios (MICC 2013) Mobile ad Wireless Commicatios 2013,

5 [10] Rostamzadeh, M., Vakily, V.T.: PAPR redctio i wavelet packet modlatio. 5th It. Mlti- Cof. o Systems, Sigals ad Devices, IEEE SSD 2008, 2008 [11] Ha, S.H., Lee, J.H.: A overview of peak-toaverage power ratio redctio techiqes for mlticarrier trasmissio, IEEE Wirel. Comm., 2005, 12, (2), pp [12] Patel, V.V., Patil, R.N.: Miimizatio of PAPR i OFDM system sig IDWT/ DWT, clippig ad filterig combied with Hffma codig method. It. Cof. o Commicatios ad Sigal Processig (ICCSP), 2013 [13] Th Ngye, Ph Hoag, Qyet Ngo, Khoa Dag, Phog Ngye H: Wavelet packet trasform i MIMO - OFDM systems 2013 Third World Cogress o Iformatio ad Commicatio Techologies (WICT) [14] Xiaodogzh, Gagxi Zh, Tao Jiag, "Redcig the peak-to-average power ratio sig itary matrix trasformatio. let Commicatios, 2009,3(2),pp

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