SUMMARYIn multi-radio multi-channel wireless mesh networks, the design of logical topology is different from that in single channel wireless mesh networks. The same channel assignment algorithm used for various logical topologies will lead to diverse network performance. In this paper, we study the relationship between k-connected logical topology and the maximum number of assigned channels. Meanwhile, we analyze the issues affecting channel assignment performance, and present the lower and upper bounds of the maximum allowable number of assigned channels for k-connected logical topology. We then develop a k-connected logical topology design algorithm based on shortest disjoint paths and minimum interference disjoint paths for each node-pair. In addition, we propose a static channel assignment algorithm according to minimum spanning tree search. Extensive simulations show that our proposed algorithm achieves higher throughput and lower end-to-end delay than fault tolerant topology control algorithms, which validates the involved trade-off between path length and nodal interference. Moreover, numerical results demonstrate that our proposed channel assignment further improves network performance under the context of limited radio interfaces.

Improving the quality of monitoring and guaranteeing target coverage and connectivity in energy harvesting wireless sensor networks (EH-WSNs) are important issues in near-perpetual environmental monitoring. Existing solutions only focus on the utility of coverage or energy efficient coverage by considering target connectivity for battery-powered WSNs. This paper focuses on optimizing the maximum monitoring frequency with guaranteed target coverage and connectivity in EH-WSNs. We first analyzed the factors affecting monitoring quality and the energy harvesting model. Thereafter, we presented the problem formulation and proposed the algorithm for maximizing monitoring frequency and guaranteeing target coverage and connectivity (MFTCC) that is based on graph theory. Furthermore, we presented the corresponding distributed implementation approach. On the basis of the existing energy harvesting prediction model, expensive simulations show that the proposed MFTCC algorithm achieves high average maximum monitoring frequency and energy usage ratio. Moreover, it obtains a higher throughput than existing target monitoring methods.

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Multi-radio and multi-channel wireless mesh networks using directional antenna (MR-MC DWMN) greatly improve the spatial reuse of wireless channels and increase network capacity. However, the number of directional radio interfaces in MR-MC DWMN affects topology reliability and survivability. This article focuses on the construction of robust topology with radio interface constraints in MR-MC DWMN. Because of the limitation of the number of directional radio interfaces, we first formulate this topology optimization problem with directional radio interface constraints to be equivalent to establish k-connected topology with node degree constraints and then propose a robust topology construction algorithm with directional radio interface constraint. We define the link weight based on node degree and then use graph theory to construct the robust topology with node degree constraints. The proposed constructing robust topology with directional radio interface constraint can not only establish k-connected topology but also minimize the maximum node degree and meet the requirement of radio interface constraints. Simulation shows that constructing robust topology with directional radio interface constraint obtains less maximum node degree and average path length than existing kconnected topology control algorithms under the limitation of directional radio interfaces. Moreover, the constructing robust topology with directional radio interface constraint achieves better network performance than other algorithms.