A contention-based service scheduling protocol for multi-node multi-server wireless sensor networks

Many protocols designed for wireless sensor networks require the existence of special purpose nodes distributed throughout the network to perform such services as aggregation, access coordination, etc. To avoid inter-node interference, it is desirable to schedule beforehand the nodes that will interact with the servers in a given time interval. Previous solutions either assume a fully connected network with a single server or clustered architecture with one server per cluster and no inter-cluster interference. In this paper, we propose a contention-based protocol for scheduling service requests by nodes in environments with multiple servers without any assumption about clustering. We describe two versions of our protocol: one based on random backoff and the other on truncated binary exponential backoff. Results show that a high number of requests can be fulfilled within a reasonable response delay and its performance is better than TDMA-like clustering-based schemes when the interference between clusters is taken into account.