Uplink Capacity of Multi-Class IEEE 802.16j Relay Networks with Adaptive Modulation and Coding

The emerging IEEE 802.16j mobile multi-hop relay (MMR) network is currently being developed to increase the user throughput and extend the service coverage as an enhancement of existing 802.16e standard. In 802.16j, the intermediate relay stations (RSs) help the base station (BS) communicate with those mobile stations (MSs) that are either too far away from the BS or placed in an area where direct communication with BS experiences unsatisfactory level of service. In this paper, we investigate the uplink Erlang capacity of a two-hop 802.16j relay system supporting both voice and data traffics with adaptive modulation and coding (AMC) scheme applied in the physical layer. We first develop analytical models to calculate the blocking probability in the access zone and the outage probability in the relay zone, respectively. Then a joint algorithm is proposed to determine the bandwidth distribution between the access zone and the relay zone, and to derive the Erlang capacity region of the system. The numerical examples show that some capacity gains can be obtained with a relay-enhanced 802.16j system compared to the conventional single-hop 802.16e system.