A performance evaluation method of wireless sensor networks based on gray theory is proposed. Firstly the influence factors of performance are analyzed, and the index set in evaluation of wireless sensor networks' performance is built which include index of key performance and reliable characteristics. Based on AHP and gray theory, a model of evaluation of wireless sensor networks performance is given. Finally the results of example show that the evaluation model is rationality and feasibility.

As the rapid development of Wireless Sensor Networks(WSN), the demands of frequency rose sharply, thereby how to deal with the frequency assignment of WSN is a difficult problem. A dynamical and real-time frequency assignment system is proposed, which was based on the network architecture of Internet of Things by the means of Cloud Computing technique. The system assigned the frequency dynamically and real-timely that it can improve the frequency utilization rate. This system is an efficient path to face the frequency needs of WSN.