Computationally efficient scheduling with the physical interference model for throughput improvement in wireless mesh networks

Abstract

Wireless mesh networks are expected to be widely used to provide Internet access in the near future. In order to fulfill the expectations, these networks should provide high throughput simultaneously to many users. Recent research has indicated that, due to its conservative CSMA/CA channel access scheme and RTS/CTS mechanism, 802.11 is not suitable to achieve this goal.In this paper, we investigate throughput improvements achievable by replacing CSMA/CA with an STDMA scheme where transmissions are scheduled according to the physical interference model. To this end, we present a computationally efficient heuristic for computing a feasible schedule under the physical interference model and we prove, under uniform random node distribution, an approximation factor for the length of this schedule relative to the shortest schedule possible with physical interference. This represents the first known polynomial-time algorithm for this problem with a proven approximation factor.We also evaluate the throughput and execution time of this algorithm on representative wireless mesh network scenarios through packet-level simulations. The results show that throughput with STDMA and physical-interferencebased scheduling can be up to three times higher than 802.11 for the parameter values simulated. The results also show that our scheduling algorithm can schedule networks with 2000 nodes in about 2.5 minutes.

Complexity in geometric SINR

“…A variety of centralized and decentralized approximation algorithms have been proposed and their quality analyzed for this kind of model [14,20,24,31,32]. Most recently, Brar et al [5] present a scheduling method that is based on a greedy assignment of weighted colors. Although these algorithms present extensive theoretical analysis, they are constrained to the limitations of a model that does not reflect the real nature of wireless networks.…”

A Distributed Channel Access Scheduling Scheme with Clean-Air Spatial Reuse for Wireless Mesh Networks

“…The main factor that limits the network capacity throughput of a wireless mesh network is the interference between neighboring nodes when using a shared medium [1]. The network capacity throughput of a wireless mesh network is determined by the number of non-interfering transmissions that can be achieved at the same time (i.e., transmission concurrency) and their transmission rates.…”

“…Most of the work use some techniques such as compatibility matrix [3] to first find non-interfering transmission pairs and then use centralized algorithms for time slot assignment [4][5] [6] [7]. Various linear programming and heuristic methods are proposed for time slot assignment [8] [1]. These works require prior knowledge of the traffic requirements and the interference relationship between wireless nodes, and assume they do not change frequently.…”

On High Spatial Reuse Link Scheduling in STDMA Wireless Ad Hoc Networks

“…Several innovative algorithms, both centralized [2], [4], [5], [6] and distributed [7], have been proposed in the literature for generating minimum length STDMA link schedules. Existing work on centralized STDMA link scheduling algorithms can be broadly classified into two categories: graph-based scheduling algorithms and SINR-based scheduling algorithms.…”

“…Existing work on centralized STDMA link scheduling algorithms can be broadly classified into two categories: graph-based scheduling algorithms and SINR-based scheduling algorithms. Graphbased scheduling algorithms [2], [4] assume a limited knowledge of the interference and result in low throughput, while SINR-based scheduling algorithms [5], [6] require a complete knowledge of the interference and lead to higher throughput. However, all these algorithms only consider schedule length as their performance metric.…”