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Method and apparatus for transmitting service of synchronous digital system in passive optical network

A technology of synchronous digital system and passive optical network, which is applied in the field of communication and communication based on optical fiber transmission network, can solve the problems of high protocol overhead, complex implementation, and inability to realize byte adjustment, so as to realize the synchronization of business clocks and prevent Clock jitter, the effect of facilitating the synchronization of business clocks

Active Publication Date: 2011-09-14
HUAWEI TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The defect of this method is that: it is necessary to change the mapped service frame structure, it is impossible to realize the direct transmission of SDH frames to the terminal ONT, and it is also impossible to realize the transmission of structured TDM services due to the non-standard structure; and because the virtual container only provides forward and reverse Adjust padding bits, so byte alignment is not possible;
The disadvantage of this method is that although there is no need to modify the existing standard, the TDM service data needs to be mapped three times by VT, Ethernet frame, and GEM frame, which is more complicated to implement, and causes too much protocol overhead and requires a large bandwidth

Method used

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  • Method and apparatus for transmitting service of synchronous digital system in passive optical network
  • Method and apparatus for transmitting service of synchronous digital system in passive optical network
  • Method and apparatus for transmitting service of synchronous digital system in passive optical network

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] Embodiment 1. A method for carrying SDH services in GPON, the process is as follows figure 1 shown, including steps:

[0042] a1. Encapsulate the TU frame loaded with SDH service data into the GEM frame; it may include two steps of mapping and framing:

[0043] a11, mapping the TU frame loaded with SDH service data to the load part of the GEM frame;

[0044] a12, add the frame header of the GEM frame to form the GEM frame;

[0045] The present invention utilizes variable-length GEM frames to carry various types of TU frames in SDH, maps the TU frames to the load part of the GEM frame, and then adds a GEM frame header of 5 bytes to form a GEM frame, such as figure 2 shown. The GEM frame header includes payload length indication (PLI, 12 bits), port identification (Port ID, 12 bits), payload type indication (PTI, 3 bits) and header error control (HEC, 13 bits). The payload length of a GEM frame carrying a TU is fixed and determined by the size of the TU frame structu...

Embodiment 2

[0063] Embodiment 2. A method for receiving SDH services in GPON, the process is as follows Figure 8 As shown, the method of this embodiment is the reverse process corresponding to Embodiment 1, and the SDH service transmitted by the method of Embodiment 1 is received, including steps:

[0064] b1. Receive GEM frame;

[0065] b2, taking out the TU frame loaded in the load part of the GEM frame; since the GEM frame loaded with the TU frame has a fixed load length, the TU type carried by it can be judged according to the PLI of the GEM frame;

[0066] b3. According to the type of TU, ​​send the service to it or obtain the corresponding SDH service data from its load structure;

[0067] If the device implementing the receiving method of the present invention is an office side device, such as an OLT, etc., step b3 can perform service transmission on the TU frame, such as forwarding the TU frame to the connected SDH network. Of course, it can be carried out as needed when forward...

Embodiment 3

[0069] Embodiment 3. A method for receiving SDH services in GPON, the process is as follows Figure 9 As shown, the method of this embodiment is basically the same as that of Embodiment 2, the difference is that the TU type carried by the GEM is negotiated through OMCI before the data is received, including steps:

[0070]c1. Negotiate through OMCI to obtain an indication of the TU type carried by the GEM;

[0071] c2. Receive the GEM frame;

[0072] c3, taking out the TU frame loaded in the payload part of the GEM frame;

[0073] c4. Send the service according to the type of the TU or acquire the corresponding SDH service data from its load structure.

[0074] The system applied to the above transmission method will be described in detail below.

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Abstract

The invention discloses a method for transmitting SDH service in a passive optical network. The core concept of the method is to directly map an SDH branching unit carrying the SDH service in load of a GEM frame so as to realize transmission of the SDH service in GPON. Data of the SDH service is stripped, encapsulated and extracted at the receiving end with reverse process. As the method can adopt a standard frame structure of the SDH branching unit to be integrated with an SDH network directly, and VC extract of the SDH service data and synchronization of a service clock can be realized conveniently based on a pointer adjustment mechanism provided by the branching unit.

Description

technical field [0001] The invention relates to the technical field of communication, in particular to the technical field of communication based on optical fiber transmission network. Background technique [0002] Passive Optical Network (PON: Passive Optical Network) is a point-to-multipoint optical fiber access network, which consists of an optical line terminal (OLT: Optical Line Terminal) on the office side, an optical network unit (ONU: Optical Network Unit) / Optical Network Terminal (ONT: Optical Network Terminal) and Optical Distribution Network (ODN: Optical Distribution Network). With the development of PON technology, Gigabit Passive Optical Network (GPON: Gigabit Passive Optical Network) is becoming a research hotspot, how to carry the existing profitable synchronous digital system (SDH: Synchronous Digital Hierarchy) communication service is an important issue that needs to be solved for GPON network to obtain application promotion and support. [0003] In the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04Q11/00H04L29/06H04J3/06H04L12/46
Inventor 弗兰克·埃芬博格赵峻黄伟林薇
Owner HUAWEI TECH CO LTD