Joint Discovery in Synchronous Wireless Networks

Given a synchronous wireless network with N nodes uniformly located at random on a finite plane, we consider the problem of distributed peer discovery: all nodes want to discover as many other nodes as possible. We assume that there are a total of K physical resources dedicated for the discovery purpose. Each node can pick one resource to transmit its node identifier on, and can receive on the remaining. K - 1 resources. We assume that node identifiers are broadcast via coded transmission on one single physical resource. This paper addresses link level strategies to increase the average number of discovered devices when N similar or equal to aK, where a is the degree of density of the network. A classical strategy of discovering one node per resource would lead to a maximum of K - 1 nodes being discovered. We focus on a multiple-access channel (MAC) scernario where multiple interferer users are jointly decoded. We propose a scheme to improve the performance. The method, based on iterative belief propagation on factor graph, is called joint iterative decoding (JID). It is shown, through system simulations, that JID may gain by significantly more than 100% over the classical single-user decoding, and by 20-25% over the successive interference cancellation (SIC).