Wireless Mesh Networks (WMNs), is an emerging wireless technology which attracts more and more attention of service providers and enterprises. The main advantage of this new class of network is to offer a flexible and economical way to expand internet access. Their major concern is to improve the flow and to preserve the bandwidth, while minimizing the interference. Using multi-channel in multi-radio WMNs can enhance their throughput and performances significantly. This paper is to propose a formal modeling approach, based on bigraphs for maintaining channels assignment in order to minimize interference in WMNs.