A novel class of uplink OFDM/SDMA algorithms for WLAN

Wireless LANs (WLANs) still offer low capacity compared to conventional wired LANs. The design of high-capacity WLANs is impeded mainly by the impairments of the indoor channel and by bandwidth and transmit-power restrictions. To mitigate these, Vandenameele et al. (1999) proposed an OFDM/SDMA approach that combines the advantages of orthogonal frequency division multiplexing (OFDM) with those of space division multiple access (SDMA). However, the comparison of two uplink OFDM/SDMA algorithms, respectively based on the minimum-mean-squared-error and maximum-likelihood criterion, revealed a serious performance and complexity gap between them. In this paper, we propose a novel class of uplink OFDM/SDMA algorithms that bridge this gap. To this end, we introduce per-carrier successive interference cancellation and interference-dependent state insertion. Compared to the minimum-mean-squared-error approach, a performance gain of 10 dB is obtained for a BER of 10^-3 This improvement comes at less than three times the initial implementation cost