Effect of constrained fast power control on cellular DS-CDMA systems with base station diversity - Electronics Letters

Numerical examples: We consider a TDMA system with a quaternary phase shift keying (QPSK) constellation and N,. = 4 receive antennas. Following a Rayleigh-fading assumption, the channel coefficients {h,Jl)} are generated as Gaussian random variables with zero mean and equal variance which are independent for different n, and/or 1; also, {hn,(l)} are fixed within one frame and changed independently from frame to frame. In the following examples, we set L = 1 (a 2-ray channel), N = 162 (frame length), M = 18 (number of pilots within a frame), K = 18 (sub-frame size for detection), and the system is assumed to have one co-channel interferer, which is generated using a similar method to the desired user. We compare the proposed scheme with linear zero-forcing (ZF) and minimum mean-squared error (MMSE) receivers. The ZF and MMSE receivers are implemented as follows: first a channel estimate for the desired user is obtained via a least-squares (LS) fitting using the pilot symbols; the LS channel estimates are next substituted in the standard linear ZF and MMSE receivers for symbol demodulation. Note that with only the CSI of the desired user, the ZF receiver is able to suppress ISI, but not CCI.