Title :
Performance analysis of multicarrier CDMA systems with frequency offsets and random spreading under optimum combining
Author :
Chien, Feng-Tsun ; Hwang, Chien-Hwa ; Kuo, C. -C Jay
Author_Institution :
Dept. of Electron. Eng., Nat. Chiao Tung Univ., Hsunchu, Taiwan
fDate :
4/1/2006 12:00:00 AM
Abstract :
The carrier-frequency offset effect on the performance of asynchronous multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA) systems with aperiodic random spreading and correlated Rayleigh fading is studied in this paper. We obtain the optimum combining filter that maximizes the signal-to-interference-plus-noise ratio (SINR) of the combined statistics and exploits correlated information among subchannels. A closed-form expression for the unconditional covariance matrix of the interference-plus-noise vector, which forms the basis of our theoretical analysis of the maximum SINR and the average bit error probability formula, is derived by averaging several random parameters including asynchronous delays, correlated Rayleigh fading, and signature sequences. The analytic results obtained are applicable to MC-CDMA with appropriate modifications. Furthermore, we show that the MC-CDMA system with a common random signature sequence over all subcarriers for a given user outperforms that with distinct sequences over different subcarriers. Finally, the performance of MC-CDMA systems using the optimum combining technique is compared with that of different combining filters in the simulation.
Keywords :
Rayleigh channels; code division multiple access; covariance matrices; error statistics; mobile radio; spread spectrum communication; SINR; aperiodic random spreading; asynchronous multicarrier CDMA systems; average bit error probability formula; carrier-frequency offset; correlated Rayleigh fading; covariance matrix; direct-sequence code-division multiple-access; optimum combining filter; signal-to-interference-plus-noise ratio; signature sequences; Closed-form solution; Frequency; Information filtering; Information filters; Multiaccess communication; Multicarrier code division multiple access; Performance analysis; Rayleigh channels; Signal to noise ratio; Statistics; Asynchronous transmission; carrier-frequency offset (CFO); code-division multiple access (CDMA); multicarrier CDMA (MC-CDMA); random signature sequence;
Journal_Title :
Communications, IEEE Transactions on
DOI :
10.1109/TCOMM.2006.873094