A Slotted Aloha Message Concentration Protocol for Wireless Sensor Networks
Steven P. Weber · 2017
Wireless sensor network applications, including the Internet of Things (IoT), will benefit from message concentration protocols, which gather messages originating at a large number of spatially distributed nodes (devices) into a small subset of those nodes, each holding a subset of the messages. This concentration facilitates more efficient access to the network or cloud, in the aggregate, than when each device seeks individual direct access. Such protocols must be lightweight and capable of operating without knowledge of the (potentially dynamic) network topology. In this paper we propose an extremely simple multi-round Aloha-based protocol, wherein the set of live nodes in each round randomly partition into transmitters and receivers, and the receivers collect messages from all transmitters within range. The protocol requires judicious choice of both the multi-round contention probabilities and transmission powers to effectively tradeoff between the four performance metrics of interest - the degree of message concentration, the fraction of lost messages, the protocol delay, and the transmission power. We analyze a special case of this protocol using basic results from stochastic geometry and branching processes.