Partially Overlapped Channel Assignment In Wireless Access Networks

With the rapid development and widespread popularity of handheld mobile terminals,wireless broadband access technology has become a significant method for people to surf the Internet. Wireless Local Area Network(WLAN) and Wireless Mesh Network(WMN) , both based on IEEE 802.11x standards, are two typical kinds of wireless broadband access technologies. They are easy to be deployed and can achieve high bit rate as well as mobility support, all of which make it efficient and convenient for users to get interested information. For now, WLANs have been used extensively and WMNs have also attracted so much attention that they are to be deployed hopefully.For WLAN and WMN, as the network quantities and scales increase, the interference will become the bottle neck of network performance. Channel assignment technology is a key method to eliminate the interference, as it can assign different channels to different nodes. IEEE 802.11b/g/n standards define 11 channels in the 2.4GHz ISM frequency band , but traditional orthogonal channel assignment technologies can only use 3 orthogonal channels, which results in their limited capacity of mitigating the interference and can not meet the requirement of actual deployment. As a result, another kind of channel assignment technologies called partially overlapped channel assignment(POCA) comes to be an intensive research topic, because it can fully use all the channel resources and further improve the network performance. Most proposed POCA algorithms are based on the position information of each network node. In this article, we first improve the interference model of partially overlapped channels and then propose two new position-based POCA algorithms:LPPOCA algorithm and MPPOCA algorithm, which apply to WLAN and WMN respectively. The simulation results show that both two algorithms can achieve much better performance when compared to orthogonal channel assignment algorithms.Furthermore, according to the limitation of position-based POCA algorithms, we design a new POCA algorithm called SPOCA algorithm which is based on the sense information. The simulation results demonstrate that SPOCA algorithm does not rely on the position information and free signal propagation space that are the preconditions for position-based POCA algorithms. At the same time SPOCA algorithm can also achieve high network performance which makes it possible to deploy POCA algorithms in actual network environment efficiently.