Search

A distributed algorithm for the scatternet formation problem in Bluetooth networks is proposed, that dynamically constructs and maintains a scatternet based on estimated traffic flow rates between nodes. The algorithm is adaptive to changes and maintains a constructed scatternet for bandwidth-efficiency when nodes come and go or when traffic flow rates change, and simulations reveal the improvements in bandwidth-efficiency and reduction in energy consumption provided by the proposed algorithm.

Channel access scheduling is one of the key components in the design of multihop wireless mesh networks (WMNs). This paper addresses the allocation/demand mismatch problem observed in oblivious WMN channel access scheduling schemes and proposes Utilization-Based Scheduling (UBS). UBS is a Spatial-TDMA- (STDMA-) based dynamic channel access scheduling scheme designed with the aim of increasing the application-level throughput. In UBS, each node has a weight, which is dynamically adjusted in accordance with the node's slot usage history and packet-queue occupancy. UBS is a fully distributed algorithm, where each node adjusts its own weight and makes pseudorandom transmission attempts using only the locally available information. To demonstrate the performance improvements of the dynamic weight adjustment, the performance of UBS is compared against other channel access scheduling schemes through extensive ns-2 simulations under both uniform and nonuniform traffic patterns.

Abstract Multicast routing protocols in wireless sensor networks are required for sending the same message to multiple different destinations. In this paper, we propose two different distributed algorithms for multicast routing in wireless sensor networks which make use of location information of sensor nodes. Our first algorithm groups the destination nodes according to their angular positions and forwards the multicast message toward each group in order to reduce the number of total branches in multicast tree which also reduces the number of messages transmitted. Our second algorithm calculates an Euclidean minimum spanning tree at the source node by using the positions of the destination nodes. The multicast message is forwarded to destination nodes according to the calculated MST. This helps in reducing the total energy consumed for delivering the message to all destinations by decreasing the number of total transmissions. Evaluation results show that the algorithms we propose are scalable and energy efficient, so they are good candidates to be used for multicasting in wireless sensor networks.

In wireless sensor networks (WSNs) that use TDMA-based scheduled channel access, spatial re-use of time-slots is possible among a nonconflicting set of nodes. In this way, data gathering delays can be reduced and aggregate network throughput can be increased. Besides spatial re-use, available multiple channels, which is already an available feature in some sensor node platforms, can be utilized to increase concurrency and minimize the number of time-slots required for a round of communication. In this paper, we propose TDMA-based scheduling algorithms for multi-channel wireless sensor networks. By redefining the conflicts in a multi-channel environment, we extend two existing single-channel TDMA scheduling algorithms into multi-channel structure. We also present two channel assignment schemes (called NCA and LCA) appropriate to use with the extended multi-channel scheduling algorithms. We evaluate our proposed schemes by extensive simulation experiments and compare them with other single-channel and multichannel algorithms from literature. The results show that in large networks our proposed algorithms can provide better performance, more concurrency, and up to 50% less delay compared to other methods. [ABSTRACT FROM AUTHOR]