# Minimum Interference Channel Assignment Algorithm for Multicast in a Wireless Mesh Network
## 1 Introduction  
Wireless networks are a common communication environment these days. Wireless devices are widely spread out and we can use them every day. Especially, wireless mesh networks (WMNs) [1] are the most recently emerging technology that provides more reliability than mobile ad hoc networks (MANET). Typical WMNs usually consist of mesh clients, mesh routers, and gateways. The mesh clients are often laptops, cell phones, and other wireless devices, while the mesh routers forward data packets to and from the gateway nodes which usually connect to the Internet. WMNs can be implemented with various existing wireless technologies, including 802.11, 802.16, ZigBee, or cellular technologies. Multicast communications can be useful for exchanging information between physical devices, such as wireless sensors. An individual physical device sends control or data packets to some control devices. These control nodes can collect and aggregate this information and send them to multipleinterested devices or users. In addition, whenever the control machines receive packets, they distribute them to some destination devices or users. It is well known that multicast can transmit the same data flow to multiple destinations without producing the duplicated flow and wasting bandwidth. One of the greatest challenges of applying multicast in machine-to-machine (M2M) communications [2; 3; 4] is how to deal with network interference between machines. Wireless mesh routers in WMNs are typically equipped with multiple network interfaces operating on different channels to increase network throughput. In a multi-radio multi-channel WMN, when two nearby nodes transmit on the same channel, they may interfere with each other and cause throughput decreases. Therefore, we need an efficient solution to reduce network interference to improve network throughput significantly. One of the best ways to decrease interference in WMNs is always to assign a different channel to each wireless device instead of the same channel. However, we do not have enough available channels to use at the same time. As a result, we need an efficient channel assignment mechanism to diminish the overall network interference in the network. In this work, we have proposed a minimum interference channel assignment (MICA) algorithm for multicast that accurately models the interference relationship between pairs of multicast tree nodes using the concept of the interference factor and assign channels to tree nodes to minimize interference within the multicast tree. There are many studies on how to assign channels to nodes in WMNs [5; 6; 7; 8; 9; 10; 11; 12; 13; 14]. All of these studies concentrate on unicast communications. On the other hand, channel assignment for multicast has been addressed recently [15; 16; 17; 18; 19; 20; 21; 22; 23]. In addition, there are emerging studies of resource allocation for small cell networks, called femtocell networks [24; 25; 26; 27; 28]. The femtocell network is a small coverage network to support home users. Femtocell networks suffer from cross-tier interference between macrocell and multiple femtocells as well. The channel assignment algorithm named multi-channel multicast (MCM) [17] suffers from low throughput caused by the hidden channel problem (HCP) [15]. Our proposed algorithm in this paper can get rid of HCP by considering every pair of nodes in the network. This algorithm allows nodes in a multicast tree to work with minimum interference. Our simulation results show that MICA achieves higher throughput and lower end-to-end packet delay compared with MCM. In addition, MICA accomplishes much lower throughput variation among the destination nodes than MCM.