| Nowadays, the number of transmission equipments and the scale of transmission networks in communication industry are increasing constantly. Besides, it is more and more urgent to meet the requirements of evaluating and facilitating transmission systems. In this essay, research is conducted to the network structure of transmission systems which are under 2.5G in Changchun district, with the purpose to provide basis for further optimization study and application of transmission networks in Changchun district.Transmission networks, as the basic networks to supply load bearing in communication business, shoulder more than 80% of the flowing information volume. However, typically local transmission networks own problems in some degree. These problems include poor safety and expansibility in network structure; rationality needs promoting; shortages in circuit dispatch and web operation controlling; low using efficiency of transmission resource, etc. Facing with these troubles, communication corporations certainly need to optimize and integrate the present transmission networks if they intend to meet the competition and take the preemptive opportunities in future telecommunication market. The optimized networks can guarantee the opening of services and further turn to be the striker to build new businesses and grab new users. Moreover, the optimization gives full play to the resource potentiality of transmission networks, and then integrates the existing advantages and problems all around finally establishing a transmission network. This transmission network possesses a clearer net structure, higher efficiency in circuit production as well as a more reasonable facility environment, supports more services, promotes capacity enhancement more smoothly and is easier to operate and maintain. The evaluation of transmission network is the premise of network optimization, no wonder it is particularly important to conduct all-sided, objective and rigorous assessment of current networks. By evaluating, the bottle-necks and hidden troubles could be found out. In that case, the next step of optimizing and supervising is possible. Therefore exploring the evaluation modes of transmission networks actively is an effective way to solve the problems above.The optimization technology of transmission networks is to put forward the reasonable planning scheme for new-built networks as well as the optimization and supervision program which direct at the present networks. It analyzes current networks situation and business models in depth, consequently bring about the plans above from many aspects such as load bearing business types, bandwidth allocation, network survivability and maintenance failure analysis, etc. Thus brings the benefits below. The network resource utilization is promoted, shouldering more businesses; network survivability is enhanced; maintaining efficiency is higher, lowering the cost of repairing; management gets more convenient and faster. Based on the analysis of existing transmission networks technology, as well as the research on the local transmission networks structure which Changchun communications companies own on hand, the study finds problems in transmission networks and the cause that influences network quality. It also explains the necessity to optimize the local transmission networks in Changchun Mobile, and studies the applied techniques in the process of optimizing transmission networks, especially the networking forms in them. Then in full collection and analysis of various business needs, realize effectively, comprehensively and well using the transmission network resources according to the resource situation in Changchun. Thus to maximize the efficiency of transmission networks, reduce the operation and management cost, and improve the quality of service and businesses. These above have enormous economic value and practical significance.In this paper, research is conducted on the optimization of transmission networks, consulting a large number of literatures on the transmission system. On the basis of previous studies, the major work of this paper is as follows:1. First of all, the basic principle of SDH transmission system is discussed in this paper. It introduces the basic characteristics of SDH all-around, including business interface, reuse patterns, operation and maintenance as well as compatibility. On SDH network structure and the whisper principle, it states in details.SDH network system sets unified criterions to network nodal interface (NNI) and optical interface, making it easier to achieve interconnection in various manufacturers. As a result of the synchronous multiplexing method and flexible mapping structure, low-speed branch could be isolated directly from SDH signals with increased reliability, reduced signal damage and more convenient businesses. The frame structure of SDH signal has been arranged abundant overhead bytes for operation and maintenance (OAM), enhancing the monitoring function greatly. SDH owns strong compatibility, ensuring the smooth transition the network from PDH to SDH and the network from SDH to ATM. As to SDH self-healing rings, according to the business level of protection, SDH self-healing rings can be divided into two categories as path protection ring and multiplex section protection ring. For the protection of business, it is based on path in path protection ring, while multiplex section in multiplex section switching ring. Whether to switch depends on the quality of signals under transmission on multiplex section of the ring.2. This essay introduces line of evaluation and optimization of transmission resources. Through the presentation of evaluation and optimization assessment indexes, such as network resources utilization efficiency, network survivability, spare parts, network management system, multiple business support ability, synchronization, maintenance failure analysis, the specific items of evaluation and optimization of transmission networks are defined.3. This essay analyzed the topological situation of transmission network less than 2.5G in Changchun area. By collecting the data on port, slots utilization and the remaining amount of scheduling loop 1,2,3 in Changchun region and suburban loop 1,2,3,4, analyzed the transmission network expansion ability. Based on the evaluation of cross timeslot and path utilization efficiency in each plane, analyzed the remaining amount of transmission path and work out the amount of businesses to be opened in every looped networks. Through gathering the data of protection proportion of network elements in each plane, protection proportion of light plate and key nodes, analyzed transmission network security in Changchun. In the evaluation of network structure, emphasis is put on the analyzing of rationality in configuration of network elements in looped networks and branches. Thus determine the goal of taking apart rings. This essay proceeded assessment in clock source and network management systems, forwarding the optimization scheme for clock and network management. In the end, the article analyzed the optimization result of transmission networks less than 2.5G in Changchun region, pointing out the deficiencies still existing in the optimization and follow-up ideas about improvement. |
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