Adaptive transmission in spatial multiplexing system with zero forcing receiver

Spatial multiplexing is a promising technique to achieve high capacity of multiple-input multiple-output (MIMO) communication systems. The spatial multiplexing system using zero forcing (ZF) receiver offers relatively low computation complexity. A new transmission parameter in such systems - number of transmission substreams is introduced. After that, an adaptive transmission scheme, which adjusts the number of transmission substreams according to channel conditions, is presented to obtain both efficiency and reliability under fading channel. Then we present two adaptive algorithms for the proposed adaptive transmission scheme to guarantee the symbol error rate and maximize spectral efficiency respectively. A numerical example is given to demonstrate the performance improvement of the proposed adaptive transmission scheme.