Research On Time Synchronization Protocol For Wireless Body Sensor Networks

Along with the development of microelectronic technology, body sensor technology and wireless sensor network, low power, small size and low price wireless body sensor networks(WBSNs) has arisen worldwide concerns in the areas of health monitoring and medical treatment. Time synchronization is an important supporting technology of WBSNs, while the existing time synchronization algorithm for wireless sensor network can't be used in WBSNs directly, because they don't meet the WBSNs'requirements for low energy consumption, high precision. Only according to the particular requirements for WBSNs, to select the appropriate time synchronization algorithm, WBSNs can be better used in areas of medical and health care, and then to provide reliable protection for people's health.In this paper, architecture, characteristics and the requests of time synchronization of wireless body sensor networks are firstly analyzed. And then some researches are made on typical timing synchronization algorithms and time deviation and drift in time synchronization problems. At last, TPSN (Timing-sync protocol for sensor networks) with higher synchronization accura is selected as the algorithm to be improved, by comparative analyzing the performance of accustomed time synchronization algorithms. After the algorithm TPSN is selected, the TPSN algorithm is improved in two sides that synchronization error and energy consumption. First of all, it uses least squares estimation to reduce the synchronization error, and after that, it adopts variable-cycle synchronization to reduce energy consumption based on the synchronization error fluctuations of the algorithm improved by least squares estimation. Finally, in NS2 simulation environment, simulation experiments are made on different time algorithms that TPSN, FTTS(Fault Tolerant Time Synchronization) and TPSN-LS(Time Synchronization for Senor Network with Least Square Method) from the performances of synchronization error, accumulated error, energy consumption and so on.From the simulation results analysis, the performaces of improved algoritm TPSN-LS are better than that of TPSN and FTTS in synchronization error, accumulated error, energy consumption and so on. Especially in energy consumption, the improved algorithm consumes about half energy of TPSN. So it significantly reduces energy consumption, and prolongs the the network life cycle, better meeting the WBSNs requirements of high precision and low energy consumption...