Throughput-Optimal Configuration of Fixed Wireless Networks

Abstract

Abstract-In this paper, we address the following two questions concerning the capacity and configuration of fixed wireless networks: (i) given a set of wireless nodes with arbitrary but fixed locations, and a set of data flows, what is the max-min achievable throughput? and (ii) how should the network be configured to achieve the optimum? We consider these questions from a networking standpoint assuming point-to-point links, and employ a rigorous physical layer model to model conflict relationships between them. Since we seek capacity results, we assume that the network is operated using an appropriate schedule of conflict-free link activations. We develop and investigate a novel optimization framework to determine the optimal throughput and configuration, i.e., flow routes, link activation schedules and physical layer parameters. Determining the optimal throughput is a computationally hard problem, in general. However, using a smart enumerative technique we obtain numerical results for several different scenarios of interest. We obtain several important insights into the structure of the optimal routes, schedules and physical layer parameters. Besides determining the achievable throughput, we believe that our optimization-based framework can also be used as a tool, for configuring scheduled wireless networks, such as those based on IEEE 802.16.Index Terms-Capacity, fixed wireless networks, IEEE 802.16, mesh networks, optimal scheduling and routing.

Engineering wireless mesh networks

“…The descriptions are based on the assumptions made earlier (single power, single rate, etc.). The models proposed and analyzed in [9], [10] are much more general.…”

“…Note that since we have assumed that all nodes use the same transmit power and the same modulation/coding scheme, this class of problems does not include power control (see [9] for a more general version of this problem). While the network operation was described above in terms of time slots and packets, the JRSP is based on a fluid model.…”

“…The detailed mathematical formulation of the joint routing and scheduling problem (JRSP) is omitted; interested readers are referred to our previous work [9] in which we focus on maximizing the minimum flow rate. In the following, rather than focusing on how to solve JRSP, we investigate in detail the engineering insights provided by the solutions of JRSP for different network topologies that are described in the next section.…”

“…However, most of the studies usually stop short of showing the engineering insights that such models can provide to WMN operators. In [9], we have formulated and solved a joint routing, power and rate control and scheduling problem based on max-min throughput. In [10], we have developed very powerful computational tools to solve this joint problem.…”

“…These tools allow us to present here optimal configuration results for networks of up to 50 nodes, which we believe is a first. It is the objective of this paper to present the main engineering insights that were obtained as a results of our studies reported in [9] and [10]. We limit our scope to networks that are single rate and in which all nodes use the same transmit power.…”