A multi-hop polling service with bandwidth request aggregation in IEEE 802.16j networks

The IEEE 802.16j protocol for a multi-hop relay (MMR) WiMAX network is being developed to increase data rates and extend service coverage as an enhancement of existing WiMAX standards. The IEEE 802.16j protocol supports transparent and non-transparent modes. In the transparent mode, only data traffic is relayed by an intermediate relay station (RS) between a mobile station (MS) and the base station (BS), while in the non-transparent mode, both signaling and data traffic are forwarded by RSs. Furthermore, non-transparent mode is either distributed or centralized with regard to scheduling. The difference between them resides in that distributed scheduling enables RSs to participate in bandwidth allocation (BWAlloc), while centralized scheduling leaves all BWAlloc coordinated by the BS. In this paper, we propose a novel multi-hop polling service (mPS) for non-transparent centralized scheduling in a multihop 802.16j environment. Our model is adaptive to the traffic pattern so as to provide bandwidth efficiency over access and relay links. Besides, aggregation of bandwidth requests (BWReq) from MSs is conducted at the RS to further save bandwidth. The performances of mPS with BWReq aggregation is evaluated via simulations which demonstrate our approach outperforms the current multi-hop bandwidth request mechanism in terms of overall spectrum efficiency.