Abstract-We propose an efficient centralized scheduling algorithm in IEEE 802.16 based Wireless Mesh Networks (WMN) to provide high qualified wireless multimedia services. Our algorithm takes special attention on the relay function of the mesh nodes in a transmission tree which is seldom studied in previous research. Some important design metrics, such as fairness, channel utilization and transmission delay are considered in this scheduling algorithm. IEEE 802.16 employs TDMA and the selection policy for scheduled links in a time slot will definitely impact the system performance. We evaluated the proposed algorithm with four selection criteria through extensive simulations and the results are instrumental for improving the performance of IEEE 802.16 based WMNs in terms of link scheduling. I.

IEEE 802.16, popularly known as WiMAX, is at the forefront of the technology drive because of the growing demand for high-speed wireless broadband networks. Multihop WiMAX networks are particularly useful as they increase the coverage area without the need to deploy expensive base stations. There are two kinds of multihop WiMAX networks- WiMAX mesh and Mobile Multihop Relay Networks. Scheduling is very important in both of these multihop WiMAX networks. The links have to be scheduled in such a way so that they do not interfere with each other while maximizing the throughput of the networks. As WiMAX networks are geared towards broadband applications, any scheduling scheme should accomodate the rate, latency and jitter requirements of the applications. This article provides an insight to the scheduling framework presented in the IEEE 802.16 standard. It also presents a few representative research proposals for centralized scheduling in WiMAX networks. We discuss some of the research issues and challenges that need to be addressed for multihop WiMAX networks to realize their full potential. I.

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Abstract—IEEE 802.16 is a new wireless technology standard, it has some advantages, including wider coverage, higher bandwidth, and QoS support. As the new wireless technology for last mile solution, there are designed two models in IEEE 802.16 standard. One is PMP (point to multipoint) and the other is Mesh. In this paper we only focus on IEEE 802.16 Mesh model. According to the IEEE 802.16 standard description, Mesh model has two scheduling modes, centralized and distributed. Considering the pros and cons of the two scheduling, we present the combined scheduling QoS framework that the BS (Base Station) controls time frame scheduling and selects the shortest path from source to destination directly. On the other hand, we propose the Expedited Queue mechanism to cut down the transmission time. The EQ mechanism can reduce a lot of end-to-end delay in our QoS framework. Simulation study has shown that the average delay is smaller than contrasts. Furthermore, our proposed scheme can also

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Abstract—The emerging wireless relay networks (WRNs) are expected to provide significant improvement on throughput and extension of coverage area for next-generation wireless systems. We study an optimization problem for multihop link scheduling with bandwidth and delay guarantees over WRNs. Our optimization problem is investigated under a more general interference model with a generic objective. The objective can be based on various kinds of performance indexes (e.g., throughput, fairness, and capacity), which can be determined by service providers. Through our theoretical analysis, the intractability and inapproximability of the optimization problem are shown. Due to the intractable computational complexity, we present efficient algorithms to provide a reasonable small approximation factor against any optimal solution even for a worst-case input. Furthermore, some experimental results indicate that our algorithms yield near-optimal performance in the average case. Index Terms—Approximation algorithms, link scheduling, quality of service, wireless relay networks. Ç 1

The Wireless Mesh Network (WMN) has become the focus of much research since they allow increased network coverage, low cost and easy deployment. WMN includes the Internet Gateways (IGW), mesh routers and mesh clients forming a three layer architecture. Throughput and fairness are major issues in WMN as the network needs to satisfy increasing network demands and must be fair to all the clients requesting the demand. The gateway may become a bottleneck as all the traffic in WMN is routed to and from the gateway. All these above factors affect the performance of network. Thus the scheduling and load-balancing have become main challenges in WMN. Several scheduling and load balancing schemes have been discussed in this paper. Two scheduling models explored are interference-based and tree-based. Four load balancing schemes discussed are path-based, gateway-based and mesh-router-based.