Power Control Technology Of Clusterheads In Degree Adaptive Wireless Sensor Networks

Wireless sensor networks(WSNs) are multiple-hop network self-organized with lots of low-cost sensors with ablities of sensing,data processing and wireless communication.Wireless sensor networks configured automatically are highly valuable in both civil aspect and military aspect. They can be used to collect, process and issue complicated environmental data within a large range.In wireless sensor networks ,The power of the nodes is usually supplied by batteries which energy is limited.It is very difficult, even impossible to replace all batteries used in the wireless sensor networks, which are composed of thousands of nodes.But wireless sensor networks are demanded to have their lifetime persist as long as several months, even several years. Consequently,the most important problem is how can improve validity of networks, increase life of networks.Hiberarchy is mostly used in WSNs,all nodes in same cluster use same channel.The traffic of such nodes is affected by cluster size. Great performance of networks will be represented,when the real number of cluster nodes is close to ideal numbers. The nodes in WSNs broadcasted randomly cause that the distribution density of nodes and the clusters can't be forecasted.The number of cluster nodes is decided by the range of cluster head overlay which is decided by the transmit power of cluster head. Therefore,we expect that the number of cluster nodes is controlled in reasonable range by adjusting the transmit power of cluster heads.Power control mechanism in CDMA comes to maturity.They are similar between 'clusterhead-member'in wireless sensor networks and 'basestation-mobile'in CDMA.Therefore, power control mechanism in CDMA can be used in optimizing Lowest-ID Clustering of wireless sensor network . Improved algorithm is described in detail.Flow chart of controlling clusterhead transmit power is given.In addition ,a power control scheme in wireless sensor networks is proposed,using fuzzy technology to adjust power of the cluster heads for changing framework of topology. Adjust power of the cluster heads according as thedifference between the number of cluster nodes and ideal numbers.While the real number of cluster nodes is far away from ideal numbers,system approaches ideal numbers fastly using long step. While the number of cluster nodes is close to ideal numbers,the step is shorter and shorter.lt can decrease the response time and over adjustment,improve system stability.Finally,simulation and results are shown in the end of paper.The results prove that lifetime and capacity will be increased after controlling the distribution of cluster nodes.