Diversity and Multiplexing Switching in 802.11n MIMO Systems

Tremendous interest in multimedia applications such as wireless video streaming drives the need for high throughput WLAN communications. Spatial multiplexing and diversity techniques (such as space-time coding and delay diversity) are adopted in the IEEE 802.11n draft specification to fully exploit the benefit of MIMO channel. In this paper, we propose an efficient and simple algorithm that switches between these modes based on the instantaneous channel state information. The post- detection constellation-coding SNR is calculated at the receiver for each mode and is used to derive the switching criterion. The algorithm is designed for practical 802.11n systems with linear receiver and outer forward error correction codes, and does not require complicated eigen-decomposition. Simulations demonstrate the effectiveness of our switching algorithm.