OLSR (Optimized Link State Routing Protocol) is a routing protocol designed especially for MANETs (Mobile Ad hoc Networks) and is currently the most widely deployed for this type of networks. OLSR uses multipoint relay (MPR: MultiPoint Relay) flooding mechanism to optimize topology control messages broadcasting throughout the network. Each node of the network selects a subset of nodes (MPR) among its neighbors to disseminate control messages. Reducing topology control packets (TC) is the key functionality of OLSR. In the Ad hoc network, the number of TC depends on the choice of MPR. In this paper, we propose a new cooperative MPR selection algorithm with the aim to reduce TC packets. We implemented this algorithm in NS2 and three other algorithms are known to be performant in the domain. Simulation results show that our algorithm reduces TC packets relative to other algorithms. This reduction is reflected positively on other performance parameters.
Optimized Link State Routing (OLSR) protocol is one of the most popular routing protocols for Mobile Ad hoc Networks. In OLSR, each node disseminates Topology Control (TC) packets throughout the ad hoc network. Individual nodes use this information to compute routes to all destinations. OLSR uses a Multipoint Relays (MPR) selection algorithm to reduce the TC packets overheads by marking subset of neighbors as MPR. In this paper, we propose an enhancement of the MPR selection algorithm which can take advantage of the original algorithm and introduces an additional decision parameter for choose MPR based on local databases of neighbor nodes extended to three hops. Our goal is to reduce further the number of TC packets. The new proposed scheme is used to select MPR by using a simple modification in OLSR protocol without additional signaling overheads. Implementation and simulation experiments with NS2 network simulator are presented to validate the stated goal. The results show that our enhanced OLSR variants outperform original OLSR in term of Number of TC packets, Routing Cost and Efficiency.
Multipath Optimized Link State Routing Protocol (MP-OLSR) is a multipath extension of OLSR, a well knows proactive routing protocol developed especially for Mobile Ad hoc Networks (MANETs). To find multiple paths, MP-OLSR uses the multipath Dijkstra's algorithm. The algorithm obtains considerable flexibility and scalability by using the cost functions, route recovery and loop detection mechanisms in order to improve MANETs performances. However, MP-OLSR presents some drawbacks. First, data packets are distributed into different paths by using Round-Robin (RR) scheduling algorithm. RR is incapable to balance load among heterogeneous multiple paths. Second, the cost functions return fixed values without adaptability to network conditions. To overcome these drawbacks, we proposed, in this paper, to integrate Weighted Round-Robin (WRR) scheduling algorithm to MP-OLSR for supporting heterogeneous multiple paths with different hop count. And, we proposed also a Fuzzy Logic Controller (FLC) to adapt the cost functions as function of hop count metric. Implementation and simulation experiments with Network Simulator NS2 are presented in order to validate our proposed goals. The results show that our enhanced MP-OLSR outperforms original MP-OLSR in terms of packet delivery ratio, end to end delay, jitter and routing cost.
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