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The wireless mesh network is emerging as a promising technology in providing economical and scalable broadband Internet accesses to communities. The backbone of the wireless mesh network consists of mesh routers, which connect each other in an ad hoc manner via wireless links. The presence of backbone mesh routers and utilization of multiple channels and interfaces allow the wireless mesh network to have better capacity than that of the infrastructure-free ad hoc network formed by mesh clients directly. A special type of the mesh routers, referred to as gateway nodes, is capable of Internet connection, and other mesh routers and associated terminal clients have to access the Internet through the gateway nodes. In this paper, we present the analytically traceable stochastic models to characterize the average delay and throughput performance in wireless mesh networks. We model the forwarding mesh routers as an open queuing network. The analytical model takes into account the mesh router density, the random packet arrival process, the degree of locality of traffic and the collision avoidance mechanism of the IEEE802.11 DCF random access MAC. Our simulation results suggest that the analytical results are quite accurate, which can provide valuable insights in system performance and an effective guideline for the scalable design and optimization in wireless mesh networks.

In this paper, we propose a novel load-balancing scheme for the Birkhoff-von Neumann input-queued (BvN-IQ) switch, which we call the cyclic exchange. According to the cyclic exchange scheme, in each time slot each linecard transfers a cell from its non-empty VOQ to the empty VOQ of another linecard which is destined for the same output. In order to guarantee the cell sequence in this procedure, we propose a simple rule of selecting the cells to be transferred for load balancing, and prove the sequence guarantee by the proposed rule. Since the cyclic exchange is performed locally between two linecards, its communication and computation overhead is not too heavy to implement. To be specific, the communication overhead of the proposed scheme is the transmission of N bits and its computation overhead corresponds to a priority encoder with a fixed highest priority. The simulation results show that the proposed scheme achieves 100% throughput asymptotically and shorter delay than the two-stage switch.

In this paper, we present an accurate throughput model of the IEEE 802.11e enhanced distributed coordination function (EDCF). Compared to the previous models, we newly consider a delay bound by predicting an effective retry limit and applying the retry limit to our model. To support this, the accurate description of the performance in a non-saturation condition is necessary, which is achieved by newly considering a queue length and a queue limit in the Markov chain. Simulation results show that our model is accurate in predicting the system throughput.