A low complexity space-frequency BICM MIMO-OFDM system for next-generation WLANs

We propose a low complexity Space-Frequency Bit Interleaved Coded (SF-BICM) Multiple-Input Multiple-Output (MIMO) OFDM system as a promising candidate for Next Generation Wireless LANs, expected to operate in excess of 100Mb/s. A MIMO overlay on a 64-QAM OFDM system can increase computational complexity exponentially if Maximum Likelihood performance is desired. In this paper, we present two schemes for reducing implementation complexity without compromising PER performance. First, we show that multiplexing OFDM symbols across multiple antennas achieves the best performance, and also leads to the most cost effective implementation. Second, we propose a novel ad-hoc scheme for MIMO soft-symbol demapping that uses hard-decision feedback to perform interference cancellation and maximal ratio combining. Our proposed low-complexity architecture offers a throughput of 108Mb/s at the comparable SNR of an IEEE 802.11a/g-compliant 54Mb/s transmission with 1% PER.