Uplink Capacity of 802.16j Mobile Multihop Relay Networks with Transparent Relays

This paper analyzes the potential uplink capacity gains of a two-hop 802.16j relay network operating in transparent mode. Detailed channel models and adaptive modulation and coding (AMC) in the physical layer are developed. To mitigate the capacity loss due to multihop communications, multi-input multi-output (MIMO) transmission is applied in the relay link. We derived the cell coverage and average spectral efficiency, as well as the system Erlang capacity supporting both voice and data traffic. The numerical results show that MIMO transmission in the relay link can significantly improve the end-to-end spectral efficiency. Furthermore, the position and the number of relay stations (RSs) have a great impact on the capacity gain. These results are further verified in the evaluation of the system Erlang capacity. The study demonstrates that with proper deployment of RSs and use of MIMO transmission in the relay link, significant capacity gains can be achieved with a two-hop 802.16j relay system compared to the conventional single-hop 802.16e system.