RESEARCH OF SDH UNIDIRECTIONAL SHR
SDH单向复用段自愈环的研究

This paper reviews the SDH SHR, summarily depicts the architecture of U-SHR. Two APS methods of U-SHR are compared. Finally, this paper addresses the problems of lowering the cost of ADM device, timing manners in the U-SHR and working mode of the network element.