Coverage extension by means of non-conventional multi-hop communications

This paper analyzes the benefits that can be obtained by using opportunistic multi-hop extensions in terms of coverage extension of traditional network deployments. We assume that there are some devices acting as relaying entities, so as to allow others reaching an Access Element, in those situations in which a direct connection is not possible. Two different network deployments are used for this analysis: in the first one, an a priori planning is not assumed and, therefore, the Access Elements are randomly deployed, thus leading to a rather poor connectivity; on the other hand, in the second case, the Access Elements are placed according to an array deployment, thus maximizing the covered area. The paper finds analytical expressions for the probability of a user to be disconnected, i.e. she is not able to reach an Access Element, or the outage probability, for both scenarios, when either one or two hop paths can be used. These results are assessed, first, and complemented later, by means of an extensive simulation-based analysis, which brings about the possibility of extending the results when more than two hops are considered. The results provide helpful insights for aiding network dimensioning processes, since they allow establishing sensible bounds on the maximum number of hops which should be used to connect to the network; in the two complementary deployments which are used throughout the paper, there was not much additional benefit for paths longer than three/four hops, regardless of the probability for a user terminal to behave as a forwarding node. (C) 2011 Elsevier B.V. All rights reserved.