iosr-JCE   Volume-5 ~ Issue-3

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is digital multicarrier Modulation access system for high data rate transfer .But it has high PEAK To Average Power Ratio which increases complexity of A/D Converter and D/A Converters and lowers the efficiency of power amplifiers. In this paper Repeated Clipping and Filtering (RCF) distortion PAPR Reduction technique of an OFDM signal which is existing technique for reducing high Peak –to –Average Power of an OFDM signal. The basic idea of Repeated Clipping and Filtering(RCF) algorithm is to generate the anti-peak signal for Peak-to-Average Power Ratio (PAPR) reduction by projecting the clipping in-band noise into the feasible extension area while removing the Out-of-Band Interference (OBI), also called as Out-of-Band Distortion with filtering [3]. The Clipping and filtering method suffers from the three major problems like in-band distortion, out-of-band radiation & peak re-growth after digital to analog conversion [24.

Keywords - Orthogonal Frequency Division Multiplexing (OFDM), Peak-to-Average Power Ratio (PAPR), Nonlinear Companding Transform (NCT), Repeated Clipping and filtering (RCF) algorithm Bit Error Rate (BER).

[1] Armstrong. Peak-to-average power reduct ion for OFDM by repeated clipping and frequency domain filtering. Electronics letters, Vol.38, No.5, pp.246-247, Feb.2002

[2] IEEEStandard, 802.11a.Part11: Wireless LAN medium access control (MAC)and physical (PHY)specifications.IEEE,1999

[3] Kitaek Bae, Jeffrey G. Andrews, Edward J. Powers, "Adaptive Active Constellation Extension Algorithm for Peak-to-Average Ratio Reduction in OFDM", IEEE Communications Letters, Vol. 14, no. 1, January 2010.

[4] Tao Jiang, Yang Yang, Yong-Hua Song, "Exponential Companding Technique for PAPR Reduction in OFDM Systems", IEEE Transactions on Broadcasting, vol. 51, no. 2, June 2005.

[5] Jun Hou, Jianhua Ge, Dewei Zhai, and Jing Li, "Peak-to-Average Power Ratio Reduction of OFDM Signals With Nonlinear Companding Scheme", IEEE Transactions on Broadcasting, vol. 56, no. 2, June 2010.

[6] Stephane Y. Le Goff, Samer S. Al-Samahi, Boon Kien Khoo, Charalampos C. Tsimenidis, and Bayan S. Sharif, "Selected Mapping without Side Information for PAPR Reduction in OFDM" , IEEE Transactions on Wireless Communications, vol. 8, no. 7, July 2010 [7] Cristina Ciochina and Hikmet Sari,"A Review of OFDMA and Single-Carrier FDMA"2010,Europian Wireless Conference

[8] Bai, W., Xiao, Y., Li, S. "The peak-to-average power ratio distribution of LFDMA signals"2009 4th International Conference on Communications and Networking in China, CHINACOM 2009 , art. no. 5339758, pp. 945-948

[9] Tao Jiang, " An Overview: Peak –to-Average Power Ratio Reduction Techniques for OFDM signals" IEEE Transactions on broadcasting, vol.54, No.2, June 2008

[9] T. Jiang, W. Xiang, H. H. Chen, and Q. Ni, " Multicast broadcasting services support in OFDMA-based WIMAX systems", IEEE Communications Magazine, vol. 45, no. 8, pp. 7886, Aug.2007

[10] http://searchnetworking.techtarget.com/definition/orthogonal-frequency-divisi on-multiplexing.

Abstract: UWB is a high data rate, short range technology .It transmits the information over a minimum bandwidth of 500 MHZ. Modern UWB systems use Modulation techniques such as OFDM (Orthogonal Frequency Division Multiplexing). The MB-OFDM proposal is selected for UWB system model. Multiband OFDM (MB-OFDM) is a short-range wireless technology that permits data transfers at very high rates, between 53.3 and 480 Mbps. For the requirement of Multiband-OFDM system, the processor should work on a few hundred MHz, which makes it difficult to implement. And since the system targets for the wireless portable devices, small area and low power consumption are also imperative. Therefore a 8-way parallel architecture based on bi-orthogonal encoder is proposed in this paper. In order to satisfy the performance requirement, the proposed architecture reduces the power consumption and utilizes more bandwidth and also detects and corrects both random and burst errors. It is used for multiuser transmission scheme and also works at high speed. The detailed analysis shows that the proposed technique could reduce the gate count by 32.47% on average. With 0.18-μm CMOS process, clock rate of the entire baseband modem was about 66 MHz and BER was 5.57e-138.

Index terms- multi-band orthogonal frequency division multiplexing (MB-OFDM), parallel architecture, ultra wide band (UWB), resource optimization.

[1] SeokJoong Hwang, Student Member, IEEE, Youngsun Han, SeonWook Kim," Resource efficient implementation of low power Mb-OFDMphy baseband modem with highly Parallel architecture", IEEE Transactions On Very Large Scale Integration (Vlsi) Systems, vol. 20, no. 7, pp.1248-1261,july 2012.
[2] C.-H. Shin, S. Choi, H. Lee, and J.-K. Pack, "A design and performance of 4-Parallel MB-OFDM UWB receiver," IEICE Trans. Commun., vol.E90-B, no. 3, pp. 672–675, Mar. 2007.
[3] W. H. Wu, Y. W. Wu, and H. P. Ma, "A 480 Mbps MB-OFDM-basedUWB baseband inner transceiver," in Proc. IEEE Asia Pacific Conf.Circuits Syst. (APCCAS), 2008, pp. 164–167.
[4] A. Chandrakasan and R. Brodersen, "Minimizing power consumptionin digital CMOS circuits," Proc. IEEE, vol. 83, no. 4, pp. 498–523,Apr. 1995.
[5] A. Safarian, A. Yazdi, and P. Heydari, "Design and analysis of an ultrawide-band distributed CMOS mixer," IEEE Trans. Very Large ScaleIntegr. (VLSI) Syst., vol. 13, no. 5, pp. 618–629, May 2005.
[6] C. Cheng and K. K. Parhi, "High-throughput VLSI architecture for FFT computation," IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 54, no. 10,pp. 863–867, Oct. 2007.
[7] A. Chindapol and J. A. Ritcey, "Design, analysis, and performance evaluation for BICM-ID with square QAM constellations in Rayleigh fading channels," IEEE J. Select. Areas Commun., vol. 19, no. 5, pp.944–957, May 2001.
[8] A. Troya, K. Maharatna, M. Krstic, E. Grass, U. Jagdhold, and R.Kraemer, "Efficient inner receiver design for OFDM-based WLAN systems: Algorithm and architecture," IEEE Trans. Wirel. Commun.,
[9] vol. 6, no. 4, pp. 1374–1385, Apr. 2007.
[10] A. Batra, J. Balakrishnan, G. R. Aiello, J. R. Foerster, and A. Dabak, "Design of a multiband OFDM system for realistic UWB channel environments,"IEEE Trans. Microw. Theory Tech., vol. 52, no. 9, pp.2123–2138, Sep. 2004.

Abstract: This paper proposes a new class of binary zero correlation zone (ZCZ) sequence sets, in which the periodic correlation functions of the proposed sequence set is zero for the phase shifts within the zero-correlation zone. It is shown that the proposed zero correlation zone sequence set can reach the upper bound on the ZCZ codes.

Keywords- Sequence design, theoretical upper bound, zero correlation zone (ZCZ) sequences.

[1] P. Z. Fan, N. Suehiro, N. Kuroyanagi and X. M. Deng, Class of binary sequences with zero correlation zone, IEE Electronic Letters, 35(10), 1999, 777-779.
[2] H. Torii, M. Nakamura, N. Suehiro, A new class of zero-correlation zone sequence, IEEE. Trans. Inf. Theory, 50(3), 2004, 559-565.
[3] H. Torri, M. Nakamura, N. Suehiro, Enhancement of ZCZ sequence set construction procedure, Proc. IWSDA05, 2005, 67-72.
[4] T. Hayashi, A class of zero-correlation zone sequence set using a perfect sequence, IEEE Signal ProcessingLetters, 16(4),2009, 331-334.
[5] Kai Liu, ChengqianXu Gang Li, Binary zero correlation zone sequence pair set constructed from difference set pairs, Proceedings of International Conference on Networks Security, Wireless Communications and Trusted Computing (NSWCTC'09),2, 2009, 543-546.
[6] T. Maeda, S. Kanemoto, T. Hayashi, A Novel Class of Binary Zero-Correlation Zone Sequence Sets, N°978-1-4244-6890-©2010 IEEE, TENCON 2010.
[7] S. Renghui, Z. Xiaoqun, Li. Lizhi, Research on Construction Method of ZCZ Sequence Pairs Set, Journal of Convergence Information Technology, 6(1). January 2011.
[8] A. Rathinakumar and A.K. Chaturvedi, Mutually orthogonal sets of ZCZ sequences, ELECTRONICS LETTERS,40 (18),2004.
[9] T. Hayashi, Limits of the Correlation Function of a Class of Binary Zero-correlation-zone Sequences, ftp://ftp.u-aizu.ac.jp/u-aizu/doc/Tech-Report/2002/2002-1-013.pdf, June 6, 2002.