Finding more efficient multipoint relay set to reduce topology control traffic of OLSR

Abstract

Multipoint relaying is a key concept adopted in the optimized link state routing protocol (OLSR). It realizes efficient flooding of topology control (TC) messages. It simultaneously supports generating small topology information which is enough to find the shortest path for any pair of nodes. In this paper, we propose a method to find more efficient multipoint relay (MPR) set, in terms of reducing topology control traffic of OLSR. Our method shares MPRs between a node and its neighbor nodes, to reduce the MPR ratio. The MPR ratio is defined as the number of MPR nodes divided by the total number of nodes in the network. By decreasing the MPR ratio, the number of TC message generation is decreased. To overlap the MPR set with MPR sets of the neighbors, each node computes the degree of coverage for each of its MPRs, and appends the degrees into HELLO messages. When a node computes its MPR set, the node intends to share MPRs by referring neighbors' MPR sets and the degrees of their MPRs. Our MPR selection algorithm keeps the size of MPR set no more than that of the conventional MPR selection. Through simulations, the MPR ratio and the number of OLSR packets reduce by 6% and 4%, respectively, in moderately dense networks.