Title :
DS-CDMA system with joint channel estimation and MAP detection in time-selective fading channels
Author :
Tsai, Shiauhe ; Wong, Tan F. ; Lehnert, James S.
Author_Institution :
Ericsson Wireless Commun., San Diego, CA, USA
fDate :
1/1/2001 12:00:00 AM
Abstract :
In this paper, maximum a posteriori (MAP) detection is applied to a direct-sequence code-division multiple-access (DS-CDMA) system jointly with identification and estimation of time-selective fading channels. By sampling the outputs of the matched filter and combining antenna array elements, strong and time-varying multiple-access interference (MAI) is characterized and suppressed instantaneously. The decision statistics for MAP detection are obtained from the conditional probability density function of the prediction error. The prediction is accomplished by approximating the fading channel with a constrained nonlinear state model. Unknown parameters such as auto-regressive (AR) process coefficients, noise covariance matrices, and the antenna array vector are estimated based on received sample vectors only. Also, differential modulation is applied to eliminate the need for pilot insertion. Through computer simulations, near-optimum bit error rates (BERs) are found
Keywords :
array signal processing; autoregressive processes; cellular radio; code division multiple access; covariance matrices; error statistics; fading channels; filtering theory; interference suppression; matched filters; modulation; multiuser channels; noise; parameter estimation; radiofrequency interference; signal detection; signal sampling; spread spectrum communication; AR process coefficients; BER; MAP detection; S-CDMA system; antenna array elements; antenna array vector; auto-regressive process coefficients; channel estimation; channel identification; computer simulations; conditional probability density function; constrained nonlinear state model; decision statistics; differential modulation; direct-sequence code-division multiple-access; fading channel approximation; interference suppression; matched filter output sampling; maximum a posteriori detection; mobile cellular communications; near-optimum bit error rates; noise covariance matrices; prediction error; received sample vectors; time-selective fading channels; time-varying multiple-access interference; Antenna arrays; Channel estimation; Error analysis; Fading; Interference suppression; Matched filters; Multiaccess communication; Multiple access interference; Sampling methods; Time varying systems;
Journal_Title :
Selected Areas in Communications, IEEE Journal on