Multi-channel and cognitive radio approaches for wireless sensor networks

In traditional wireless sensor networks communicating on a single channel data throughput measured at the sink is constrained by the radio capability, interference, and collisions. Enabling a multi-channel transmission is a potential solution to alleviate the above problem and improve the network performance. Many approaches have been proposed to exploit multiple channels on unlicensed frequencies. The advanced development of cognitive radio enables wireless sensor networks to use vacant licensed channels. Cognitive radio wireless sensor networks enable a dynamic channel selection with the restriction of releasing a channel when a primary user is present. When nodes are set on different channels, coordination has to be carefully designed to ensure a successful transmission. This issue is mainly addressed at the MAC and network layers. In this paper, we provide an intensive survey on various aspects of traditional and cognitive multi-channel wireless sensor networks. Different approaches are categorized based on their underlying topology. Major developments are discussed and drawbacks of the existing approaches are identified.