C3G-A非直通终端与网关同步算法研究

C3G-A Synchronization Algorithm between Terminals Unable access to Cellular Directly and Gateway

就C3G-A同步的关键点:非直通终端与网关同步,提出了一种既不需借助GPS,也不会增加系统复杂度的同步算法。该算法分为初始同步、闭环同步、同步保持3个过程。非直通终端在转发帧GTS1时隙接收网关广播公告消息,完成初始同步;网关在检测窗搜索非直通终端发送的上行同步码,确定定时提前量,建立闭环同步;网关在转发帧同一时隙测量非直通终端的训练序列,确定同步偏移,实现同步保持。

To solve the key point of synchronization, we propose an algorithm which neither relies on GPS nor increases complexity of system. The algorithm includes three processes： initial synchronization, closed-loop synchronization and synchronization keeping. To establish initial synchronization, terminals unable access to cellular directly receive broadcasting from gateway at GTS1 of forwarding frame. During the process of closed-loop synchronization, gateway searches SYNC_UL in the detection window and determines the advanced time for terminals unable access to cellular directly. To realize synchronization keeping, gateway at the same time slot measures the training sequences of terminals unable access to cellular directly, then determines synchronization shift.