Research On Distributed Time Synchronization Method Of Wireless Sensor Networks Based On Firefly Synchronization

Though centralized time synchronization methods for wireless sensor networkshave been further developed those days, its advantages in expandability andinvulnerability and the problem that synchronization errors accumulate with the hopsincreasing cannot be avoided however, which have limited their applied range andflexibility. Fortunately, the appearance of distributed time synchronization methods ofwireless sensor networks provides possibility for these issues above, and among them,those methods that are inspired by the phenomenon that fireflies flashing in a unisonare most suggestive.There are lots of problems since most seminal works based on fireflysynchronization are not specific for wireless sensor networks, among which, theexistence of coupling delay between each node and the complicated topology areinstantly to be solved. Based on creative research of M&S model and Reachback FireflyAlgorithm, we provided a weight based reachback firefly mechanism and a changeablecoupling strength mechanism and took some measures to avoid the influence caused bysaltation of transmission delay. I will introduce my research in the following aspects:1. Describe the process constructing the synchronization simulation model. At first,the network model is built according to positions of randomly distributed nodestogether with random transmission delay; after that, we use the mathematic model todescribe synchronization actions of each node, in which the mathematic regulation weused is based on M&S model and further operations such as linearization anddiscretization are carried out. At last, the variation of some variables and factors areinvolved in the test terminal model.2. Because of the existence of transmission delay and the variation of topology,we propose a weight based reach back firefly mechanism to reduce fluctuation of thenetwork phase state and a changeable coupling strength mechanism to achieve a goodbalance between synchronization accuracy and speed. Besides, some measures to avoidthe influence caused by saltation of transmission delay are taken.3. The last part of my works is to build a hardware platform to test and verify mysynchronization mechanisms. Firstly, a new method regarding to providing an accurate time base is proposed which is mainly utilizing GPS module; then each function moduleis introduced including GPS module, FPGA module and wireless module JN5148.Finally, I do some preliminary verification works using the hardware platform.