MAC Retransmissions for Multiple Antena Systems

While many studies have focused on capacity improvement through MIMO/BLAST technologies at physical layer, few have investigated the possibility of utilizing properties of MIMO technologies at MAC layer for performance improvement. One candidate MIMO technology provides capacity achieving performance by transmitting a separately encoded signal substream at each transmit antenna, which encounters different error statistics. Upon channel loss, conventional MAC retransmission mechanism retransmits all the substreams although some substreams might be received successfully. Our work integrates MAC retransmission design with underlying MIMO technology to apply separate retransmission process for each substream to explore partial statistical independence among substreams. This not only avoids retransmitting correctly received substreams but also facilitates interference cancellation using re-encoded versions of reliable post-MAC retransmission symbols. Simulations show that this integrated approach achieves more than 30% of link throughput improvement.

Multiple ARQ Processes for MIMO Systems
Haitao Zheng, Angel Lozano, M. Haleem
EURASIP Journal on Applied Signal Processing
Special Issue on MIMO Systems and Signal Processing,
Vol. 2004, No. 5, pp.772-782, May 2004. [Abstract, PDF]

Talks: coming soon!
Haitao Zheng, April 16, 2005