Design And Implementation Of Routing Metric With Partially Overlapping Channels In Wireless Mesh Networks

Wireless Mesh Networks (WMN) has been applied in wireless communication withadvantages such as self-configuration, self-healing, low cost and easy establishing. In orderto improve the performance of WMN, scholars have designed a variety of routing metricmethods. Reasonable design of routing metric can make the communication nodes avoidthe area with high load and strong interference, then select the optimal path forcommunication. At present, routing metrics are based on the orthogonal channel, design ofrouting metric for partially overlapped channels is still in early stage. So research onrouting metric for partially overlapped channels has a certain value in further enhanceWMN performance, and improve customer satisfaction.In order to verify the performance of the routing metric, designers need to do simulateexperiments. Network simulation can be divided into build the actual network test platformand software simulation in two ways. The former is affected by high cost and low scaleexpansion, therefore it is difficult to generalize; the latter have been widely used for its lowcost and unlimited network size etc. As one of the major network simulation software NS2,with its open source features, has been welcomed by the network simulation experimenterThis paper foucus study on the design of routing metric for partially overlappingchannel, and NS2simulations software is used to simulate the proposed routing metric, theresearch work in this paper mainly includes the following parts:(1) Compare some performance of hop count routing metric under orthogonal channel(HOPS_OC) with hop count routing metric under partially overlapping channel(HOPS_POC).The performance are regional channel busy time (CBT) and average networkthroughput, packet loss rate, average end to end delay. We validated the use of partiallyoverlapping channels can bring network performance improvement. Simulation resultsshow that the region CBT of HOPS_POC is lower than the regional CBT of HOPS_OC, thenetwork performance of HOPS_POC is better than that of HOPS_OC.(2) Routing metric under partially overlapping channels was proposed. Since theintroduction of partially overlapping channels cause interference relationship changesamong wireless mesh network nodes and links, so the design of routing metric has toconsider the interfering nodes or links and the degree of interference to the communicationnode. By considering interfering nodes, links, node’s interface queue length, the actualtransfer rate (AR) of the link and other factors, an POCs-based Load andInterference-aware Transmission Time routing metric P_LITT is proposed. This routingmetric consider intra-flow interference and inter-flow interference uniformly, theinterfering nodes’ buffer queue expected time is used to capture interference to communication node.(3) Implementation P_LITT with NS2software. Because NS2software defined nodemodel can only perceive the interference of nodes using the same channel, beforeimplementation P_LITT, we need to expand NS2into partially overlapping channels.Firstly, by modifying the code to the physical layer and the routing layer in NS2, node cansense interfering nodes which use the adjacent channel; then, modify NS2on the basis ofthe original code to obtain the interfering nodes, interfering links, node buffer queue andthe AR, and so on, thusrealize the P_LITT; finally, by contrast HOPS_POC, P_LITT(PP_LITT) which using probes to obtain the AR and P_LITT (CP_LITT) which using ofregional CBT to get AR, we obtained PP_LITT outperforms HOPS_POC, CP_LITT’sperformance is better than PP_LITT’s.The design and simulation of the routing metric under partially overlapping channelsin this paper, not only provides a reference for design and research of the partiallyoverlapping channel routing metric, but also enriched the code resources on open sourcesoftware NS2.