Performance of DS-CDMA System with Diversity Combining Schemes in a Land-Mobile Satellite Channel

• Main Authors: Chang, Chih-Hung, 張志鴻
• Other Authors: Mu-King Tsay
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/02717873345487693315

碩士 === 國立中央大學 === 電機工程學系 === 85 === The effects of three kinds of diversity combining techniques, namely selection, maximal ratio and distributed decisions combining, on the bit error probability are investigated for direct-sequence code-division multiple access (DS-CDMA) in a land-mobile satellite channel using coherent binary-phase shift keying (BPSK) with power control scheme and forward error correcting (FEC) code. It is assumed that the channel consists of a lognormally shadowed line-of-sight signal plus Rayleigh distributed multipath signals. The open-loop power control is implemented on the uplink and the control error can be approximated by a lognormally distributed random variable. The system also uses convolutional code as the FEC code to improve the bit error performance. Numerical results are presented for the land-mobile satellite channel under light, average and heavy shadowing. The results indicate that maximal ratio combining has the best bit error performance and the distributed decisions combining is superior to selection combining under a large number of branches, small power control error and weak shadowing. It also shows that convolutional code is effective against the shadowing channel, and the combined coding and diversity is the best way to improve the bit error performance.