Routing Protocols In Wireless Sensor Network Based On Cognitive Technology

Composed by thousands of nodes, wireless sensor networks are used as a tool integrated with new network technologies, such as events monitoring, wireless communications and data processing techniques. Since the sensor nodes are usually built in small chips with limited power supply and storage, energy consumption and transmission power of the nodes in the network become main constraints when designing the protocols of wireless sensor network. In addition, cognitive radio, as a flexible communication method, can improve spectrum efficiency. By detecting "spectrum holes" in the environment, known as "spectrum detection", cognitive users can make use of the idle spectrum channels without affecting the main users. Therefore cognitive radio can be considered as a wireless communication solution for wireless networks and help extend the network lifetime.This paper has a research on the routing protocols of wireless sensor networks and studies the LEACH protocol especially. It delivers two advanced protocols, LEACH-C and LEACH-R, to balance the energy consumption and promote the communication performance. Nodes in LEACH-C no longer generate a random number, but send its location information and residual energy value to the base station. Then the base station will choose the cluster heads in response. This advance relies on some cross-layer adjustments between MAC and network layers. LEACH-R protocol adds cognitive communication technology into original LEACH routing method. Apart from location information and residual energy, another channel quality parameter will be added in calculating the threshold value. Nodes in LEACH-R can find the bit error rates of the surrounded channels by detecting its environment and select the best qualified channel for wireless communication.Finally, simulations and comparisons of the three protocols are made on the NS-2network platform. Results show that LEACH-C protocol reduces the energy consumption significantly and extending lifetime of the whole network, despite a similar communication performance. In a different way, LEACH-R protocol significantly improves the communication performance, but results in a slight increase in energy consumption of nodes. Therefore the LEACH-R protocol applies to the networks requiring higher communication quality.