A digraph is a graph in which each edge has an orientation. A linear directed path, , is a path whose all edges have the same orientation. A linear simple graph
介绍了一种基于智能电表的3层分布式无线居民用户自动抄表系统。系统第1层为RS-485通信网络,负责智能电表中的用电信息采集,系统第2层为ZigBee Pro无线传感器网络,负责用电信息及设置参数的路由,系统第3层为通用无线分组业务GPRS(General Packet Radio Service)通信网络,负责数据的远距离可靠传输。分析了设计中的关键问题,如无线通信方案设计、无线传感器网络参数配置