Effective contention-based bandwidth request scheme for QoS enhancement in IEEE 802.16e

In this paper, we propose an effective contention-based bandwidth request scheme to differentiate the contention scheme of each quality of service(QoS) type in IEEE 802.16e systems. Especially, the scheme is focused on the improvement for extended real-time polling service(ert-PS). The proposed scheme allows the ert-PS to use multicast polling in the normal condition, but to adopt both multicast and broadcast polling under collision. Through the simulation, we show that the proposed bandwidth request mechanism reduces the bandwidth grant delay of ert-PS due to a high probability of successful bandwidth request. Therefore, the ert-PS with the proposed scheme can resolve the contention faster than the conventional mechanism.