Interference-aware Robust Wireless Mesh Network Design Farah Kandah, Weiyi Zhang, Yashaswi Singh, Juan Li Department of Computer Science, North Dakota State University, Fargo, ND 58105 Abstract—Interference has been proven to have an effect on the performance in wireless mesh networks (WMN). Using multi- channels can improve the performance of WMNs by reducing interference influence. In this paper, we study how to design a robust WMN for a set of mesh nodes, each with Q Networking Interface Cards (NICs) and pre-defined connection requests. Our scheme aims to construct an interference-aware network topology for the nodes, then set up a pair of link-disjoint paths for each request with fault-tolerant capability. We propose two novel schemes to improve the network design. First, we embrace the network interference for providing resource-efficient protections. Second, protection links are shared and reused by multiple connections for protection, which further improves the efficiency of network resource usage. Our simulation results show that our scheme outperformed previous schemes. Keywords: Wireless Mesh Network, multipath routing, network interference, channel assignment. I. I NTRODUCTION Wireless Mesh Networks (WMNs) have attracted much research attention due to the capabilities including, fault tol- erance, self configuration and scalability [13]. A wireless mesh network [1][8][9][13] is a multihop wireless network that consists of a large number of wireless devices, such as mesh gateways (which are connected with a wired network to the Internet), mesh routers (which can relay packets through wireless channels), and mesh end users. Multiple channels usage in multihop wireless networks has been shown to be able to improve the network throughput [8][9]. IEEE 802.11b and IEEE 802.11a standard [3][4] offer 3 and 12 non-overlapping channels respectively. An example of WMN with multi-channel design is shown in Fig. 1. Note that, two neighboring mesh nodes can communicate with each other if they have their network interface cards (NIC)s using the same channel. One of the first IEEE 802.11-based multi-channel multi- hop wireless mesh network architectures was proposed and evaluated in [9]. The authors developed a set of centralized algorithms for channel assignment, bandwidth allocation, and routing. They also presented distributed algorithms utilizing only local traffic load information to dynamically assign chan- nels and to route packets in [8]. Besides network throughput, another important design issue in WMNs is the reliability [6][12]. In [13], the authors studied robust network topology design with consideration of interfer- ence. On the induced K-connected topology, they presented bandwidth-aware routing algorithms. The research developed in this paper is supported by NSF ND EPSCoR under the Infrastructure Improvement Program FAR-0015846. Fig. 1. Wireless mesh network architecture Multipath routing has been shown to be able to provide better reliability in WMNs [12]. The idea of multipath routing is finding several disjoint paths for a specific connection [6]. In [5], the authors showed that multi-path routing can improve the reliability of packets delivery by providing alternate loop- free paths to destination. Tsai and Moors in [12] studied a multi-path routing design and focused on the concurrent use of multi-paths. Another approach for the multipath design was studied in [10]. The authors studied the problem of finding minimum energy disjoint paths in wireless ad-hoc networks. Hu and Lee in [2] proposed a multipath routing protocol named AODV-DM. After finding a primary path, an insulating reign is formed around the primary path, which contains all the nodes within the interference range of each node on the primary path. A protection path must be selected outside the insulating reign to reduce potential network interference with the found primary path. To provide an interference-aware robust WMN design, we define the INterference-Aware Robust Wireless Mesh Network DesIgn (INARI) problem in this paper. We assume that a static traffic model in the networks, where all traffic requests are given in advance. To provide good network throughput and increase network capacity, we in this work need to pre- serve the network connectivity and support robustness through providing a channel assignment design in a way that, the channels assigned to the NICs in a common neighborhood to be as different as possible such that interference influence can be reduced. To provide good reliability, each request is accommodated by two disjoint paths, a primary path (P a ) and a protection path (P b ). While a protection path is reserved (not actively used) for a request until the primary path fails, it is possible to use a same link to protect multiple primary paths if some criteria are satisfied. We denote such ability of protecting multiple paths with one link as reusability of a protection link. To the best of our knowledge, this work is the first to discuss the reusability of protection links in wireless mesh networks.