Performance study of an optical backbone MAC interconnecting WiMAX base stations over a city/county area

WiMAX standard´s medium access control (MAC) protocol supports QoS for real time traffic. Single WiMAX can cover 10 Kms with broad band support of around 22 Mbps in downlink and 6 Mbps in uplink [7]. Multiple WiMAX base stations (BSs) are needed to cover a thickly populated city or county with large diameter (i.e., above 20 kms, which is very common). To maintain QoS for inter WiMAX BSs traffic, it is important to have a supportive MAC protocol on interconnecting network (referred as backbone). In this paper we propose optical backbone connectivity operating at 2.5 Gbps for inter networking several WiMAX BSs located in various location of large cities/county. We propose a novel hybrid- MAC protocol that caters to the QoS needs for real time service with negligible jitter and provides minimum delay for non-real time data traffic of WiMAX. The backbone delay for best effort traffic has been analyzed under various circumstances of real time as well as non-real time traffic. Furthermore, the results reveal that with reasonable load on the backbone there is hardly any impact on packet delay for even Best Effort services.