Localisation is one of the most important issues in wireless sensor networks, because the location information is typically useful for coverage, deployment, routing, location service, target tracking and rescue operations in wireless sensor networks. The localisation protocols are classified into two categories: range-based protocol and range-free protocol. The range-based protocols employ distance or angle estimation techniques to achieve fine accuracy, which require the use of expensive hardwares. On the other hand, the range-free techniques depend on the contents of received messages to support coarse accuracy. This study describes mobile anchor positioning, a range-free localisation method, which makes use of the beacon packets of mobile anchor and the location packets of neighbour nodes to calculate the location of the nodes. The anchor node, which is equipped with global positioning system, broadcasts its coordinates to the sensor nodes as it moves through the network. As the sensor nodes collect enough beacons, they are able to calculate their locations locally.

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This paper handles the issues related to centralized scheduling in multi-channel WiMAX mesh network. We have used the clique partitioning approach for scheduling. The scheduling algorithm optimizes the length of the scheduling cycle, as well as the buffer size requirement of each node. If sufficient number of channels is present to avoid secondary interference in the network, the static channel assignment strategy is followed whereby each link is assigned a channel that remains fixed throughout the scheduling. If not, channels will be allocated dynamically, i.e., channels for links may change during scheduling. The simulation result shows that our scheduling algorithm minimizes the length of the schedule as well as requires unit buffer in case sufficient number of channels is available.

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