Design of a performance management model for wireless local area networks

The amount of Wireless Local Area Network (WLAN) deployments has increased rapidly in recent years. High throughput Internet access and operation without wires enables new innovative applications for communication, information retrieval, and entertainment. Increasingly, these applications set strict requirements for Quality of Service (QoS). Interference, a constantly changing environment, multipath signal propagation, and the movement of networking terminals are characteristic of wireless communication. Such characteristics cause varying bit rates and frequent packet retransmissions and consequently problems for applications requiring high throughput or low delay. Network management has a significant role in managing QoS by providing information from the network and controlling the network operation. Managing QoS would not be possible without information on the network performance. Performance parameters cannot be measured when the network is being planned or only partially deployed, and for cost reasons performance estimates may also be preferred when the network is operational. This thesis presents the development of a performance model that can be utilized in WLAN management tools. The output of the model is a set of metrics that are estimates of the network performance parameters. The model provides feedback on the network performance and allows the network administrator to control network management algorithms. Thus, the performance model facilitates high quality network planning and operational network management based on the preferences of the network administrator. The performance model developed here supports both traditional WLANs and Wireless Mesh Networks (WMN). It is designed specifically for supporting mechanisms utilized in the IEEE 802.11 standard. These include the distributed medium access mechanism, contention between devices, WLAN multirate operation, multi-interface and multi-radio devices, as well as advanced antennas. The performance model has been integrated into a designed planning process. The planning process is a conceptual framework that describes how planning algorithms can use the performance model. The feasibility of both the planning process and the performance model is demonstrated by designing example algorithms for WMN performance optimization that utilize the performance model. Algorithms are collected into two prototype tools, one for WLAN planning and the other for WLAN management. The performance model has been developed on the basis of an analysis of IEEE 802.11 technology operation, existing research results, WLAN throughput measurements and network capacity simulations. The simulation results presented in this thesis provide a significant insight into WMN operation. According to the results, multirate operation, interference aware routing, and the use of multiple evaluation criteria are crucial in WMN deployment planning. The accuracy of the performance model has been validated with simulations, which show that the performance model provides reasonably accurate estimates of the network capacity, even with dense network deployments. The simulation results also show that the performance model can be successfully controlled by the network administrator to achieve the desired planning results. As a result, the performance model is of benefit to the network administrator both in network planning and operational management