ST-TDMA: A Satellite Timing Based MAC Protocol In Long Distance Wireless Mesh Networks

Long-distance IEEE802.11wireless mesh networks (LDmesh) are composed oflinks as long as tens of even hundreds of kilometers. It can be applied broadly in ruralareas or sparse-populated areas offering high-bandwidth Internet access, or large-areanatural reserve surveillance, because of its features of high-bandwidth, low-cost andlarge-coverage. The research on LDmesh is not only of great academic value, butsignificant on the development of society.The MAC protocol is the key technique that determines the performance ofLDmesh. Based on the feature of LDmesh, it is only TDMA protocol can be adopted.Recently, there have been several advances in the design of MAC protocols suitablein LDmesh. However, how to guarantee the synchronization of different nodes inLDmesh remains a big challenge for every researcher. As an effective timingtechnique, satellite timing owns good accuracy of time, which can be adopted in thedesign of MAC protocols suitable in LDmesh.In this paper, we propose ST-TDMA, a Satellite Timing Based TDMA MACProtocol in Long Distance Wireless Mesh Networks, to guarantee the synchronizationof each node or each interface on a certain node. Thanks to the accurate time that GPSreceiver receives, ST-TDMA obtains the improvement of performance in LDmesh.First of all, we give an introduction of the primary hardware environment andsoftware environment of satellite timing module and then describe the design ofsatellite timing module. Next, we verify the availability and the accuracy of satellitetiming module, laying a good foundation for the implementation of ST-TDMA. Inaddition, with the massive amounts of modifications on the original source code ofMadwifi, we implement ST-TDMA on WiZiTJU-GPS platform. The experiments onthe availability of ST-TDMA show that ST-TDMA runs normally on WiZiTJU-GPSplatform.