A memory-lite time synchronization protocol for wireless sensor networks

Wireless sensor networks (WSNs) used in distributed surveillance commonly requires network-wide time synchronization. Most existing time synchronization protocols assume that the clock with each node can be modeled by a linear equation at + b with t being the universal time, a the clock drift (skew) coefficient, and b the clock offset. Some protocols assume that a = 1, hence the synchronization target is the parameter b while others assume that a could deviate from one and both parameters a and b are the synchronization targets. In the latter case algorithmic synchronization details become complicated, requiring either involved computation or memory use. For example, the recently proposed Average TimeSync (ATS) protocol demands expensive use of memory within each WSN node. In this work a memory-lite time synchronization (MLTS) protocol is proposed, which can achieve synchronization of both drift and offset just by sending synchronization packet including the past time stamps received by the sender node, but the number of such past stamps is minor. Both simulation and hardware experimental results justify that the proposed memory-lite protocol is still capable of effective distributive time synchronization with robustness but at the slight price of a little slowed down synchronization speed.