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The paper analyses the intrinsic weak attributes of PDH system which expresses insurmountable defects. Based on the SDH system principle about frame a ...展开
rchitecture, multiplexing, mapping and so on, the paper expound the basical contents and technology specialities of SDH system and point out that PDH does not keep up with the step of developing information society. By contrast, SDH is a thoroughly change. Many of advantages of SDH, such as unified UNI interface, standardlized informational hierarchy, rich overhead bits ect.makes SDH/SONET system become the developing aim that serves for transmission network and Information Superhighway with the huge bandwidth source of optical communications.The paper states schemes that introduce SDH system from the base of PDH system. 收起
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