High-speed transmission of LWD signals is difficult to achieve by current technology.The existing downhole mud pulse transmission technology cannot meet the requirements due to its low transmission rate.To cope with this problem, this paper improves while-drilling wireless transmission system with orthogonal frequency division multiplexing (OFDM), which will result in more efficient data transmission.However, the high peak-to-average power ratio (PAPR) of the logging signals in the OFDM will gravely impact its performance.To further improve OFDM drilling wireless transmission system, we propose an SLM algorithm using radix-4 inverse fast Fourier transform (IFFT) to reduce PAPR.In this method, the radix-4-based IFFT performance at point N=4n is partitioned into two stages:transform before k and transform after n-k, between which the phase sequences are multiplied by an input signal.Theoretical analysis shows that, compared with the traditional SLM algorithm, the new SLM reduces the computational complexity almost by 60%.
罗仁泽, 党煜蒲, 李芮, 杨娇, 何国林. 正交频分复用随钻无线传输系统及其SLM算法[J]. 电子学报, 2015, 43(10): 1924-1929.
LUO Ren-ze, DANG Yu-pu, LI Rui, YANG Jiao, HE Guo-lin. Orthogonal Frequency Division Multiplexing While-Drilling Wireless Transmission System and SLM Algorithm. Chinese Journal of Electronics, 2015, 43(10): 1924-1929.
[1] John Proakis,Masoud Salehi.Digital Communications,Fifth Edition[M].McGraw-Hill Companies.2011,516-528.
[2] Mccoy R H,Besser G L,Reed S D,Campbell D B,Knox D L.Systems and Methods for Downhole OFDM Communications[P].US patent:2011047534.2012,7.
[3] Halliburton,"LOGIQ Open-hole Logging Platform"[OL].http://www.halliburton.com/.2013.
[4] Chen Wenxuan,Pei Binbin,Zhao Shuai,et al.Research of networked well logging system based on ethernet technology[J].Well Logging Technology,2012,36(03):286-289.
[5] Mccoy R H,Besser G L,Reed S D,Campbell D B,Knox D L.Systems and Methods for Downhole OFDM Communications[P].US,2011047534. 2012-7-31.
[6] Wang Jianping,Guo Ying,Zhou Xianwei.PTS-clipping method to reduce the PAPR in ROF-OFDM system[J].Consumer Electronics,IEEE Transactions on,2009,55 (2):356-359.
[7] Kim Hyunju,Hong Eon-Pyo,Ahn Chang-Jun J,Har Dong-Soo Soo.A Pilot Symbol Pattern Enabling Data Recovery Without Side Information in PTS-Based OFDM Systems[J].IEEE Transactions on Broadcasting,2011,57 (2):307-312.
[8] Sabbaghian Maryam,Kwak Yongjun,Smida Besma,Tarokh Vahid.Near shannon limit and low peak to average power ratio turbo block coded OFDM[J].Communications,IEEE Transactions on,2011,59 (8):2042-2045.
[9] Eom Seung-Sik,Nam Haewoon,Ko Young-Chai Chai.Low-complexity PAPR reduction scheme without side information for OFDM systems[J].IEEE Transactions on Signal Processing,2012,60 (7):3657-3669.
[10] Seok-Joong Heo,Hyung-Suk Noh,Jong-Seon No,Dong-Joon Shin.A modified SLM scheme with low complexity for PAPR reduction of OFDM systems[J].IEEE Trans.Broadcasting,2007,53(4):804-808.
[11] Chih-Peng Li,Sen-Hung Wang,Chin-Liang Wang.Novel low-complexity SLM schemes for PAPR reduction in OFDM systems[J].IEEE Transactions on Signal Processing,May 2010,58 (5):2916-2921.
[12] Dae-Woon Lim,Jong-Seon,Chi-Woo Lim,Ha-bong Chung.A new SLM OFDM scheme with low complexity for PAPR reduction[J].IEEE Signal Processing Letters,2005,12(2):93-96.
2015, Vol. 43 
