Sharma, GVV and Chockalingam, A (2004) Performance Analysis of Maximum-Likelihood Multiuser Detection in Space-Time Coded CDMA with Imperfect Channel Estimation. In: IEEE 59th Vehicular Technology Conference, 2004. VTC 2004-Spring, 17-19 May, Milan,Italy, Vol.3, 1664-1668.
In this paper, we analyze the performance of maximum likelihood (ML) multiuser detection in space-time coded CDMA systems with imperfect channel estimation. A K-user synchronous CDMA system which employs orthogonal space-time block codes with M transmit antennas and N receive antennas is considered. A least-squares estimate of the channel matrix is obtained by sending a sequence of pilot bits from each user. The channel matrix is perturbed by an errror matrix which depends on the thermal noise as well as the correlation between the signature wave forms of different users. Using the characteristic function of the decision variable, we derive an exact expression, in closed-form, for the pairwise error probability (PEP) of the joint data vector of hits from different users. Using this exact PEP expression, we obtain an upper bound on the average bit error rate (BER). The analytical BER bounds are compared with the BER obtained through simulations. The BER bounds are shown to be increasingly tight far large SNR values. It is shown that the degradation in BER performance due to imperfect channel estimation can he compensated by using more number of transmit/receive antennas.
|Item Type:||Conference Paper|
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|Keywords:||MI. multiuser detection;Space-time codes;CDMA.imperfect channel estimation|
|Department/Centre:||Division of Electrical Sciences > Electrical Communication Engineering|
|Date Deposited:||11 Jan 2007|
|Last Modified:||19 Sep 2010 04:21|
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