We investigate the problem of joint routing and link scheduling in Time-Division Multiple Access (TDMA) Wireless Mesh Networks (WMNs) carrying real-time traffic. We propose a framework that always computes a feasible solution (i.e. a set of paths and link activations) if there exists one, by optimally solving a mixed integer-non linear problem. Such solution can be computed in minutes or tens thereof for e.g. grids of up to 4x4 nodes. We also propose heuristics based on Lagrangian decomposition to compute suboptimal solutions considerably faster and/or for larger WMNs, up to about 50 nodes. We show that the heuristic solutions are near-optimal, and we exploit them to gain insight on the schedulability in WMN, i.e. to investigate the optimal placement of one or more gateways from a delay bound perspec-tive, and to investigate how the schedulability is affected by the transmission range

No abstract

We discuss the issue of computing resource-optimal routing plans in a network domain. Given a number of known traffic demands, with associated required delays, we discuss how to route them and allocate resources for them at each node so that the demands are satisfied. While a globally optimal routing plan requires joint computation of the paths and of the associated resources (which was claimed to be NP-hard), in this paper we stick to existing approaches for path computation, and use mathematical programming to model resource allocation once the paths are computed. We show that the problem is either convex or non-convex, depending on the scheduling algorithms adopted at the nodes. Our results show that, by computing resources per-path, instead of globally, the available capacity can be exceeded even at surprisingly low utilizations

No abstract

In this paper we investigate link scheduling for Wireless Mesh Networks (WMNs) carrying real-time (i.e., delayconstrained) traffic. We show that the problem of computing a conflict-free link schedule with end-to-end delay constraints can be formulated as a mixed-integer non linear problem that can be optimally solved in reasonable time (i.e., minutes) for relatively large WMNs (up to 20-30 nodes). We use the above result to explore the schedulability region of a WMN with a given routing and input traffic, assessing whether and when aggregating flows which traverse the same path makes a given input flow set schedulable. Furthermore, we devise a heuristic solution strategy, which computes good suboptimal solutions within up to few seconds, thus being amenable for online admission control.