Capacity enhancements in IEEE 802.16J systems using MIMO-relay multiplexing

This paper presents the analysis of relay multiplexing configuration for IEEE 802.16j systems employing MIMO antennas. The availability of multiple relay paths in IEEE 802.16j motivates two relay configurations: relay diversity and relay multiplexing. Existing works have focused on the relay diversity method. In this paper, we explore the relay multiplexing alternative. Using the concept of code-division multiple relay access (CDMRA), where relay stations (RS) are assigned unique access codes for parallel relaying of independent data streams from source to destination, we derive the capacity of the relay multiplexing system in comparison with the relay diversity methods. We show that while the capacity of the diversity methods grows with the log of the system SNR, the capacity of the relay multiplexing approach grows linearly with the number of parallel relay paths created in the system for iid channel case. Relay multiplexing thus provides affordable means of realizing high-speed multihop communications.