Signaling analysis of heterogeneous bandwidth request for WiMAX multihop relay networks

In this paper, we investigate signaling overhead with heterogeneous bandwidth request (BR) for WiMAX multihop relay networks. The code division multiple access (CDMA) contention based BR suffers from high signaling overhead in WiMAX relay networks. Hence, we suggest heterogeneous bandwidth request in which the mobile stations (MSs) with relay connectivity exhibits message based BR and relay stations (RSs) with BS connectivity undergoes CDMA based BR. Further, we investigate the signaling overhead with `m´ retransmission attempts since the contention based BR may take more than one attempt for successful transmission. Simulations confirm that the signaling overhead with heterogeneous BR is reduced by 23.84% without retransmission and 29.71% with four retransmission attempts (with two hops in both cases) compared to CDMA based BR. Similar overhead reduction is observed with three hop (17.56% 20.59%) and four hop (13.90% and 15.77%) WiMAX relay.