An Experimental Study On Wireless Mesh Networks

Wireless Mesh Network (WMN) is a new broadband wireless network structure. It's a high-capacity high-speed distributed network which is different from traditional wireless networks. It can be seen as the integration of WLAN and Mobile Ad hoc networks. Now, WMNs have become a research focus in the area of next generation wireless networks. The original testbed of our research group focuses mainly on multimedia transmissions in small-scale Ad hoc networks. But the application environment of Mesh networks and Ad hoc networks is quite different. The application and traffic in WMNs have higher requirements in available bandwidth, delays etc. In the paper, we establish a new Mesh network testbed based on the original experimental study of Ad hoc network testbed. Through modifying the DSR protocol, we try to improve the performance of network transmissions.The Internet access traffic in WMNs requires high bandwidth. First, without adding new hardware, we fully used IEEE 802.11 non-overlapping frequency channels and designed a tiered Mesh architecture. We made multi-channel expansion to DSR, amend the route discovery and maintenance process, and introduced the concept of multi-channel gateway. Through channel interference and multi-hop scene experiments, we found that the available bandwidth improved significantly. Second, in order to banlance the load among different IGWs in WMNs and reduce packet loss caused by gateway congestion, we modified the original IGW discovery and maintenance process, designed new gateway selection algorithm. The new algorithm, firstly, selects highest priority gateway nodes and then chooses the node which has maximum available bandwidth as the optimal gateway node. Through experiment in testbed, we found that the new protocol had got great improvement in throughput, packet delivery ratio, delay jitter and end-to-end delay.Finally, we have done a comprehensive experiment in our Mesh testbed. Experimental results demonstrate the new DSR can well satisfy the transimission needs of a variety of traffic including video transmissions in WMNs...