Reduction of Relay Overhead in IEEE 802.16j Mobile Multi-Hop Relay (MMR) Networks

In IEEE 802.16j standard, relays are added to increase coverage and improve throughput. However, some overhead results from the inclusion of the relays. One typical example is an addition of R-MAP (relay MAP) to be included in the header of the frames transmitted from BS (base station) to RS (relay stations) in non-transparent mode [1]. The R-MAP conveys transmission schedules for the burst data from BS to an RS. Since R-MAP is mostly modulated by the lower MCS (Modulation and Coding Scheme) level (QPSK 1/2 for example), the bandwidth consumption is considerable. Compared with higher MCS level (64QAM 3/4 for example) used by data bursts, it uses 5 times the bandwidth. In this paper, we propose a scheme to compress the R-MAP and show its efficiency through simulation. We also show how to reduce the CID (connection identifiers) information in MAC headers to further reduce the overhead from relaying. Compression of R-MAP will greatly reduce the overhead from relaying. In other words, we reduce the overhead from relaying in control plane (R-MAP) as well as in data plane (MAC header). As confirmed by the performance evaluation, MAC efficiency of the proposed schemes is higher than that of the Standard schemes by approximately 11%.