optical_network_of_sdh__graduate__thesiss毕业设计论文(编辑修改稿)

optical_network_of_sdh__graduate__thesiss毕业设计论文(编辑修改稿)内容摘要：

mission is carried out row wise from left to right and from top to bottom. Bits are transmitted serially. The STS1 frame of SDH is posed of section overhead, transport overhead, payload overhead and data part. The frame starts with fixed A1/A2 bit pattern of 0xf628 used for bit/octet synchronization. SDH is referred as octet synchronous. The first three columns of SDH frame is referred as transport overhead. The next 87 columns of the frame are referred as Synchronous payload envelope (SPE). Payload overhead is part of SPE. 本科生毕业设计（论文） 6 Fig. Section overhead STS1 data rate is about Mbps. Let us examine how this has been achieved. Every SDH frame repeats once every 125 microsec. 90 columns in 9 rows and 8000 times per second and 8 bits per octet give us data rate of Mbps. STS is the abbreviation of Synchronous Transport Signal. STS1 is referred as OC1(Optical Carrier) after scrambling is done on STS1. SDH multiplexing step The multiplexing principles of SDH follow: Mapping A process used when tributaries are adapted into Virtual Containers (VCs) by adding justification bits and Path Overhead (POH) information. Aligning This process takes place when a pointer is included in a Tributary Unit (TU) or an Administrative Unit (AU), to allow the first byte of the Virtual Container to be located. Multiplexing This process is used when multiple lowerorder path layer signals are adapted into a higherorder path signal, or when the higherorder path signals are 本科生毕业设计（论文） 2 adapted into a Multiplex Section. Stuffing SDH has the ability to handle various input tributary rates from PDH. As the tributary signals are multiplexed and aligned, some spare capacity has been designed into the SDH frame to provide enough space for all these various tributary rates. Therefore, at certain points in the multiplexing hierarchy, this space capacity is filled with fixed stuffing bits that carry no information, but are required to fill up the particular frame. Functions to achieve include。 reuse the is a lowcost channel layer multiple signals through the code to make it into the highspeed adjustment channel or multiple highspeed channel layer code signals through the process of adjustment to make it into the multiplex layer. Among them, reuse is reuse roadmap, roadmap ITUT has a variety of provisions, but a national and regional use only one. China39。 s use of SDH signals are multiplexed with the line 10 shown in Figure . Fig. . SDH mapping multiplexing principle The figure on the previous page illustrates the ITUT SDH multiplexing structure. The notations in the boxes, such as C1, VC3, and AU4, are explained in the table after the figure. At the lowest level, containers (C) are input to virtual containers (VC). The purpose of this function is to create a uniform VC payload by using bitstuffing to bring all inputs to a mon bitrate ready for synchronous multiplexing. Various containers (ranging from VC11 at Mbit/s to VC4 at Mbit/s) are covered by the SDH 本科生毕业设计（论文） 3 hierarchy. Next, VCs are aligned into tributary units (TUs), where pointer processing operations are implemented. These initial functions allow the payload to be multiplexed into TU groups (TUGs). As the figure illustrates, the xN label indicates the multiplexing integer used to multiplex the TUs to the TUGs. The next step is the multiplexing of the TUGs to higher level VCs, and TUG2 and TUG3 are multiplexed into VC3 (ANSI mappings) and VC4. These VCs are multiplexed with fixed bytestuffing to form administration units (AUs) which are finally multiplexed into the AU group (AUG). This payload then is multiplexed into the Synchronous Transport Module (STM). The information structure level SDH multiplexing step is called Synchronous Transport Module using STMN (Synchronous Transport, N = 14, 16, 64), in fourfold module, the basic module STM1. Four STM1 synchronous multiplexing constitute STM4, 16 个 four STM1 or STM4 synchronous multiplexing constitute STM16, the structure shown in Figure . Fig. Structure of SDH synchronous multiplexing SDH transmission work is posed of different types of work elements connected via fiberoptic cables posed of different work element SDH work to plete the transfer function: up / down operations, crossconnect services, such as selfhealing work failure. TM Terminal Multiplexer Terminal: terminal multiplexer used on the site of the work, such as the two endpoints of a chain which is a dualport device, shown in Fig. . S T M 1155 Mb / sS T M 4622 Mb / sS T M 162 . 5 Gb / sS T M 6410 Gb / s10 Gb / s 4 4 4WDM 本科生毕业设计（论文） 4 Fig. Terminal Multiplexer ADM Add / Drop Multiplexer: add / drop multiplexer for SDH transmission work adapter at the site, such as the chain of intermediate nodes, or SDH node on the ring is the most used online, the most important one work element, which is a threeport device, as shown in Figure . S T M NT UA U 4E 42 M b / s1 4 0 M b / sS T M NE 1S T M NS T M NS T M N S T M N Add/drop multiplexer REG regenerative repeater: optical transmission work, there are two regenerative repeater, and a purely optical regenerative repeater, the main power amplifier to extend the optical distance of the optical transmission。 other is for pulse regeneration shaping the electric regenerative repeater, mainly through the optical / electrical conversion, sampling the electrical signal, reproduction judgment plastic, electrical / optical conversion, line noise does not accumulate in order to achieve and ensure transfer of the signal waveform on line integrity. After talking here is a regenerative repeater, REG is a twoport device, only two line ports W, E,。