Channel assignment and its applications in wireless networks

Wireless technologies grow rapidly and benefit almost every aspect of our daily lives. To fulfill various application requirements, researchers have proposed and developed many different communication protocols. The assignments of wireless channels, which are known as the most precious resources in wireless networks, cause intensive research interests from both academic and industrial fields. Every different kind of wireless network has its own feature, which puts extra constraints on the channel assignment. As the emerging technology, wireless sensor networks (WSNs) are well known for its feature of easy deployment, low cost and etc. Since most of the commercial WSNs-oriented products using ISM 2.4GHz band for communications, the communication costs in terms of energy and time become a very challenging issue for real applications. To tackle this problem, we first comprehensively study the channel feature in WSNs. Then proposed Double-Plate, a fair channel assignment algorithm, which aims to ensure high throughput and fairness simultaneously. With the observation of inefficient channel usage among the full spectrum band, the new concept of cognitive radio networks (CRNs) is initiated by researchers, where spectrum users are divided into primary users with license and secondary users without license but can opportunistically use the spectrum. While CRNs calls for spectrums sensing from secondary users before they can use any available pre-assigned channels to primary users, the spectrum sensing technology becomes one key issue for a successful deployment in CRNs. To utilize the WSNs for spectrum sensing, we initiate a cooperative boundary detection algorithm which utilizes WSNs to detect the signal boundary of each primary user. We then also study the more complicated case where multiple primary channels exist. This scenario is more realistic in practice. While more sensors can definitely provide more accurate sensing result per primary channel, we must find a best tradeoff between the sensed number of primary channels and the number of sensors that are needed. By analyzing the sensitivities of the parameters to the sensing performance, we conclud that a regular deployment with more voronoi neighbors can always provide more benefits under a restricted number of sensors. Inspired by the analysis, we then propose SCAS algorithm to solve the problem with promising results. Our proposed approaches can be further replanted to other application areas where WSNs and CRNs are utilized, and we believe employing the proposed channel assignment algorithms will significantly improve the efficiency and performance of the network systems in their practical usage. Keywords: wireless networks, channel assignment, Wireless Sensor Networks, Cognitive Radio Network