双向报文交换同步的原子性约束与解决

Atomicity-caused restriction on two-way packets exchanging synchronization and its resolution

针对经典的双向报文交换同步因存在原子性约束致使应用范围受限的问题,对双向报文变换机制提出了两处改进:对非同步期内由时钟飘移导致的误差进行补偿;对非同步期内由节点时间突变导致的误差进行补偿,从而突破了原子性约束,并结合实际的桥梁健康监测项目背景,针对线状拓扑的无线传感器网络,基于上述两处改进提出了线状传感器网络时间同等协议(TPLSN)。在全局可达智能接点(GAINs)上的实验表明,单跳同步精度可达10μs左右,同步误差随跳数的增长率为1μs/跳;同步一个长度为n的线状网络只需2n个报文,该值也是全程采用双向报文交换同步机制最少需要的报文数。

Aiming at the application restriction caused by the atomicity of the classic two-ay packets exchanging synchronization scheme, this paper introduces two creative improvements on it as follows： compensating time error during the non-syn- chronization period caused by clock skew, and compensating time error caused by abrupt time mutation during the non- synchronization period. Combined with a real bridge-health monitoring application and based on the above two improve- ments, a time synchronization protocol named timing-sync protocol for linear sensor networks （TPLSN） is proposed for wireless sensor networks with lihear topology. The experiments on global accessible intelligent nodes（GAINs） reveal that the synchronization error of TPLSN is about 10 microseconds in a single-hop network, and its increase ratio is less than 1 microsecond per hop. To synchronize all nodes in a network with n-hop linear topology, only 2n packets am needed in total, which is also the minimum number of packets required by any synchronization protocol that employs the scheme of two-way synchronization on every hop.