Reinforcement of Privacy in 802.16 MAC Common Part Sublayer using the Principle of Circularity

R. Bhakthavathsalam (India)


WiMax, MAC CPS, Circularity, Contention Resolution, Access Delay, and Uplink Transmission.


Owing to the addition of various security overheads at different layers, the cumulative encapsulation causes more access delay in the uplink data transmission in WiMax resulting in low throughput. The upstream channel is a stream of minislots with a dynamic mix of contention and reservation based opportunities affording privacy between transmitter and receiver. The contention resolution algorithm used in WiMax is based on a truncated binary exponential backoff, maintaining privacy between Base Station and Subscriber Stations, with initial backoff window and maximum backoff window controlled by the Base Station. The performance of the system is affected by the collisions of bandwidth request messages in uplink transmission. In this paper, we introduce a new paradigm of circularity by selectively dropping appropriate control messages in order to obviate the overall bandwidth request collisions with some modifications of the same backoff overheads for supporting privacy. This new mechanism reduces the uplink access delay and thereby yields higher uplink throughput resulting in better utilization of available bandwidth.

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