Research And Logic Design Of Overhead And Multi-lane Distribution In Optical Transport Network

Due to the rapid development of broadband transmission business, the backbone network bandwidth demands of major telecom operators have largely increased. In order to meet the various needs of new services, the optical transport network(OTN) technology has gradually become the main direction of development. OTN,which is designed as a new transmission network technology combining of optoelectronic field, is able to provide bigger bandwidth and more abundant types of business. It not only has a lot of characteristics of traditional transmission technology, but also has other new features, which can undertake more complex customers than the traditional transmission network. With the continuous development of communication services, OTN gradually becomes more advanced, and will have more extensive and in-depth applications in the field of transport networks.According to the ITU-T G.709 Recommendation, and combining with OTN transmission systems carrying 100Gbit/s Ethernet physical layer data, this paper is focused on the 100 G OTN overhead processing and multi-lane distribution system, and conducts a detailed theoretical analysis and FPGA logic design. Through logic design this paper verifies the feasibility of the single channel 100 G high speed OTN lossless transmission, and laies a solid theoretical foundation for the future development of ultra high speed OTN.This paper’s main work involves OTN electric layer’s overhead insertion, overhead extraction, multi-lane distribution, multi-lane recombination and its preprocessing. The specific work is divided into three parts:Firstly, this paper chooses a single-channel 100Gbit/s OTN transmission parallel interface structure OTM-0.4v10, and describes the OTN frame structure and the main features of electric layer’s overheads. Then this paper analyzes the reason for using virtual lane parallel distribution of high-rate OTN, and the multi-lane distribution mechanism of Optical Channel Transport-4. At the same time, this paper analyzes the reasons of preprocessing before receiving end’s multi-lane recombination.Secondly, this paper describes the module design of 100Gbit/s OTN system, especially the function sub-modules involved in this paper. The sending end sub-modules are overhead insertion, BIP-8 calculation, frame-synchronous scrambling, multi-lane distribution and bit multiplexing. The receiving end sub-modules are bit demultiplexing, frame searching, virtual-lane searching, reordering, aligning, multi-lane recombination, descrambling, multi-frame searching, overhead extraction and BIP-8 checking. This paper conducts logic design for each functional sub-modules, and functional simulation of sub-modules.Thirdly, this paper sets up the system-test framework, and compiles top layer testbench including all the sub-modules, in order to simulate transmitting end to receiving end’s system function. The paper analyzes several possible normal or abnormal transmission situations, and observes the states of alarms from CPU reporting, in order to achieve OTN-level network status and data validation monitoring. Meanwhile this paper also evaluates the FPGA post-synthesis / post-implementation utilization rates to ensure the feasibility of logic design.