In a ring transmission path, a synchronous multiplexing technique using pointer control is employed. To stabilize pointer values, at least one node is set as a master node. At the master node, the amount of delay by which to delay transmit data is made variable in order to place the transmit...http://www.google.com.hk/patents/US5778188?utm_source=gb-gplus-share專利 US5778188 - System for controlling delays in a ring by assembling subframes with a variable-delay by a master node, and with a fixed-delay by other nodes 
