An Interference Aware Distributed MAC Scheme for CDMA-Based Wireless Mesh Backbone

In this paper, based on a cross-layer design prin- ciple, we propose an interference aware distributed medium access control (MAC) scheme for a code-division multiple access (CDMA)-based wireless mesh backbone. Specifically, benefiting from the fixed location of wireless routers, the power allocation is based on the length of the transmission path, so as to ensure some level of fairness in resource allocation among the routers. For call admission and slot/rate allocation, based on the maximum sustainable interference concept, we propose to estimate the interference from the viewpoint of the receiver (rather than the transmitter). Each receiver estimates its experienced interference level for the hypothesis that one or more new calls are admitted. If the interference is not tolerable, the receiver rejects the new call(s). The main advantages of our proposed scheme are the low control message overhead for easy implementation, and the accurate interference estimation. Simulation results are presented to evaluate the performance of our scheme. router. In such a backbone, fine-granularity QoS provisioning is desired or required. Carrier sense multiple access (CSMA)- based random access schemes, the major stream for traditional ad hoc networks, may not be a choice, due to their limited QoS provisioning capability. Thus reservation-based MAC schemes should be more suitable for the wireless mesh backbone. When resources are reserved for each active flow, fine-granularity QoS can be achieved. This paper presents an effective distributed MAC scheme for the wireless mesh backbone, taking into account the unique networking characteristics. Specifically, we consider a wireless mesh backbone based on code-division multiple access (CDMA) technology, and propose a MAC scheme based on the cross-layer design principle. The merits of our proposed scheme are four-fold: 1) it is fully distributed; 2) each link does not need to have the dynamic information of other links in terms of transmission power, tolerable interference, etc., thus requiring a low information exchange overhead and increasing the robustness and scalability of the MAC scheme; 3) accurate interference estimation can be achieved for each receiver; and 4) fine-granularity QoS can be achieved by burst- based resource reservation. If a traffic burst is admitted into the network, it can use the reserved resources until the completion of the burst.