Channel assignments using constrained greedy algorithm, T-coloring and simulated annealing in mesh and cellular networks

Channel assignment is an important step in communication networks. The objectives of minimizing networks interference and the channels used are the problems in the channel assignments of the networks. In real environments, some difference will be expected in the performance of the networks when the channel allocation algorithms under more accurate interference models are deployed. In this research, the wireless mesh networks represent dynamic networks while static networks are represented by the cellular networks. In the wireless mesh networks, communication between a pair of nodes happens when both nodes are assigned with channels. The cellular networks are the radio network distributed over land areas called cells, each served by at least one fixed-location transceiver. Channel assignments in the networks is an application of the vertex coloring in graph theory. Previously, the Greedy Algorithm was used for link scheduling but only the adjacent channel constraint was considered. Here, an algorithm called Improved Greedy Algorithm was proposed to solve the channel assignments by considering the adjacent channel and co-channel constraints which is an improvement to the algorithm. Besides, Simulated Annealing and T-coloring problem are combined to minimize the channels used. The algorithms are applied for single and multiple channels communications in the wireless mesh networks and cellular networks to show the different results of the channel assignments. Further improvement is made on the multiple channels case where the Improved Greedy Algorithm is applied by considering the cosite constraint in addition to the co-channel and adjacent channel constraints. The Improved Greedy Algorithm has been tested in a series of simulations. Results for the simulations prove that the Improved Greedy Algorithm perform significantly well for the channel assignment problem

Performance issues in cellular wireless mesh networks

This thesis proposes a potential solution for future ubiquitous broadband wireless access networks, called a cellular wireless mesh network (CMESH), and investigates a number of its performance issues. A CMESH is organized in multi-radio, multi-channel, multi-rate and multi-hop radio cells. It can operate on abundant high radio frequencies, such as 5-50 GHz, and thus may satisfy the bandwidth requirements of future ubiquitous wireless applications. Each CMESH cell has a single Internet-connected gateway and serves up to hundreds of mesh nodes within its coverage area. This thesis studies performance issues in a CMESH, focusing on cell capacity, expressed in terms of the max-min throughput. In addition to introducing the concept of a CMESH, this thesis makes the following contributions. The first contribution is a new method for analyzing theoretical cell capacity. This new method is based on a new concept called Channel Transport Capacity (CTC), and derives new analytic expressions for capacity bounds for carrier-sense-based CMESH cells. The second contribution is a new algorithm called the Maximum Channel Collision Time (MCCT) algorithm and an expression for the nominal capacity of CMESH cells. This thesis proves that the nominal cell capacity is achievable and is the exact cell capacity for small cells within the abstract models. Finally, based on the MCCT algorithm, this thesis proposes a series of greedy algorithms for channel assignment and routing in CMESH cells. Simulation results show that these greedy algorithms can significantly improve the capacity of CMESH cells, compared with algorithms proposed by other researchers

Optimization of load balance link layer protocol for nodes with multiple channels and interfaces in wireless mesh networks: A comprehensive review

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