Abstract-The aggregate capacity of wireless mesh networks can be increased by the use of multiple channels. Stationary wireless routers are equipped with multiple network interface cards (NICs). Each NIC is assigned with a distinct frequency channel. In this paper, we formulate the Joint Optimal Channel Assignment and Congestion Control (JOCAC) as a decentralized utility maximization problem with constraints that arise from the interference of the neighboring transmissions. Unlike other previous work, the JOCAC algorithm is able to assign not only the non-overlapping (orthogonal) channels, but also the partiallyoverlapping channels within the IEEE 802.11 frequency bands. Using 802.11b with 3 non-overlapping channels, simulation results show that our algorithm provides a higher aggregated goodput than the recently proposed load-aware algorithm by 20%. The goodput is further increased by 40% when all the 11 partially-overlapping channels are being used.
Abstract-Random access has been studied for decades as a simple and practical wireless medium access control (MAC). Some of the recently developed distributed scheduling algorithms for throughput or utility maximization also take the form of random access, although extensive message passing among the nodes is required. In this paper, we would like to answer this question: is it possible to design a MAC algorithm that can achieve the optimal network utility without message passing? We provide the first positive answer to this question through a simple Aloha-type random access protocol. We prove the convergence of our algorithm for certain sufficient conditions on the system parameters, e.g., with a large enough user population. If each wireless node is capable of decoding the source MAC address of the transmitter from the interferring signal, then our algorithm indeed converges to the global optimal solution of the NUM problem. If such decoding is inaccurate, then the algorithm still converges, although optimality may not be always guaranteed. Proof of these surprisingly strong performance properties of our simple random access algorithm leverages the idea from distributed learning: each node can learn as much about the contention environment through the history of collision as through instantaneous but explicit message passing.
In a wireless mesh network (WMN) with a number of stationary wireless routers, the aggregate capacity can be increased when each router is equipped with multiple network interface cards (NICs) and each NIC within a router is assigned to a distinct orthogonal frequency channel. In this paper, given the logical topology of the network, we formulate the joint channel allocation, interface assignment, and media access control (MAC) problem as a cross-layer non-linear mixed-integer network utility maximization problem. An optimal joint design, based on exact binary linearization techniques, is proposed which leads to a global maximum. A near-optimal joint design, based on approximate dual decomposition techniques, is also proposed which is of more interest in terms of practical deployment. Performance evaluation is given through a number of numerical examples in terms of network utility maximization and aggregate network throughput.
Abstract-The aggregate capacity of wireless mesh networks can be increased by the use of multiple frequency channels and multiple network interface cards in each router. Recent results have shown that the performance can further be increased when both non-overlapped and partially overlapped channels are being used. In this paper, we propose a linear model for a joint channel assignment, interface assignment, and scheduling design. We propose the channel overlapping matrix and mutual interference matrices to model the non-overlapped and partially overlapped channels. Since the model is formulated as a linear mixedinteger program with a few integer variables, the computation complexity is low and it is feasible for implementation. Simulation results show that the aggregate network capacity increases by 90% when all partially overlapped channels within the 802.11b frequency band are being used.
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