Analysis and optimization of pilot symbol-assisted rake receivers for DS-CDMA systems

被引:3
作者
Cui, Tao [1 ]
Tellambura, Chintha [1 ]
机构
[1] Univ Alberta, Dept Elect & Comp Engn, Edmonton, AB T6G 2V4, Canada
基金
加拿大自然科学与工程研究理事会;
关键词
channel estimation (CE); direct-sequence code-division multiple access (DS-CDMA); maximal ratio combining (MRC); Wiener filter;
D O I
10.1109/TVT.2006.877699
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
The effect of imperfect channel estimation (CE) on the performance of pilot-symbol-assisted modulation (PSAM) and MRC rake reception over time- or frequency-selective fading channels with either a uniform power delay profile (UPDP) or a nonuniform power delay profile (NPDP) is investigated. For time-selective channels, a Wiener filter or linear minimum mean square error (LMMSE) filter for CE is considered, and a closed-form asymptotic expression for the mean square error (MSE) when the number of pilots used for CE approaches infinity is derived. In high signal-to-noise ratio (SNR), the MSE becomes independent of the channel Doppler spectrum. A characteristic function method is used to derive new closed-form expressions for the bit error rate (BER) of rake receivers in UPDP and NPDP channels. The results are extended to two-dimensional (2-D) rake receivers. The pilot-symbol spacing and pilot-to-data power ratio are optimized by minimizing the BER. For UPDP channels, elegant results are obtained in the asymptotic case. Furthermore, robust spacing design criteria are derived for the maximum Doppler frequency.
引用
收藏
页码:1159 / 1170
页数:12
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