| Optical fiber is an excellent transmission medium of communication network.Optical fiber communication is a kind of communication with high frequency(1014Hz)light wave as carrier and optical fiber as transmission medium.The advent of optical fiber communication makes high-speed and large capacity communication possible.At present,it has become the most important information transmission technology.But in the conventional linear optical fiber communication system,fiber loss and dispersion are the main factors limiting the transmission capacity and distance.Due to the continuous improvement of optical fiber manufacturing technology,the fiber loss has been close to the theoretical limit,so the fiber dispersion has become the "bottleneck" to realize ultra large capacity and ultra-long distance optical fiber communication.It has been discussed for a long time.It is found that the optical soliton produced by the nonlinear effect of optical fiber can counteract the effect of fiber dispersion.Using optical soliton to communicate can solve this problem well,thus forming a new generation of optical fiber communication system,which is also the most promising communication mode in the 21 st century.With the advent of the information society,people hope that modern information transmission network can provide various circuits and services quickly,economically and effectively.However,due to the monotony of business,complexity of expansion and limitation of bandwidth,it is no longer helpful to modify or perfect the network technology only in the original framework.SDH(synchronous digital hierarchy)is developed in this context.Among all kinds of broadband optical access network technologies,SDH technology is the most widely used access network system.The birth of SDH solves the bottleneck problem of the access between users and the core network due to the bandwidth limitation of the access medium,which cannot keep up with the development of the backbone network and the user's business requirements.At the same time,it improves the utilization of a large amount of bandwidth on the transmission network.Since the introduction of SDH technology in the 1990 s,it has been a mature and standard technology.It has been widely used in the backbone network,and the price is getting lower and lower.The application of SDH technology in the access network can bring the huge bandwidth advantage and technical advantage of the core network into the access network field,and make full use of SDH synchronous multiplexing,standardized optical interface,powerful network management ability and flexible network extension The capacity and high reliability bring benefits,and benefit in the construction and development of access network in the long term.The optical fiber transmission network of Laos' s power communication system is based on the traditional SDH and PDH,and the system is small in scale and complex in equipment composition.With the development of information technology in electric power industry,the information business transmitted by power communication network is developing towards diversification,data and high speed.The existing communication network of Laos electric power has been unable to meet the current business needs.At present,only part of Laos has laid communication optical cables,and the transmission equipment is backward,so it cannot form a complete power optical transmission network,resulting in the inability to meet the various business transmission requirements of Laos' s power system.Therefore,it is necessary to improve the power optical transmission network in Laos.At the same time,how to upgrade the existing network and achieve the requirements of business development is an urgent problem to be solved in Laos' s power communication network.At present,Laos' s electric power communication optical transmission network mainly adopts traditional SDH technology and PDH technology.The transmission network only covers some substation nodes,and the service side port of substation node transmission equipment is single.Therefore,the construction of power communication network that can adapt to long-term development and integrity must be compatible with the existing technology to ensure smooth upgrading of the network.Therefore,designing a better integration technology of SDH and PDH is also a powerful solution to realize multi service and high-speed transmission of power information in Laos.At present,Laos' s communication industry is spending a lot of manpower and material resources to develop access network,but the standardization of access network is far less than the trunk network.If the standardization of access network is not strengthened at present,with the rapid development of domestic access network construction,it will be more and more difficult to carry out standardization work in the future.Of course,it is difficult to carry out the standardization of access network in an all-round way,but it should be close to a certain standard.Therefore,the standardization of access network is an indispensable link for the continuous development of power communication system in Laos.Laos' s electric power communication system has laid optical cable channels in some parts of the country,and has configured SDH and PDH optical transmission equipment in some substation nodes,and formed a local optical transmission network to realize the transmission of some basic power system business information.With the continuous development of power secondary system,the demand for communication business types(such as relay protection,security and stability system,tele control information,power system informatization,etc.)and bandwidth is further increased,which also puts forward higher requirements for power system communication reliability.However,the current network structure of Laos power system cannot form an effective optical transmission network,which cannot meet the growing business needs.In order to meet the needs of power system business development at present and in the future,it is urgent to reconstruct the power communication network in Laos.On the basis of maintaining the operation of the existing optical transmission network system,it is urgent to build an optical transmission network that can meet the multi service requirements of Laos' s power communication system.Based on the above analysis,the main work and achievements of this paper are as follows:First of all,as a new technology system,SDH has many important advantages compared with PDH.Many countries are studying and developing SDH transmission network.It is obvious that the current PDH network will be gradually replaced by SDH network,but the length of this process will be different according to the current situation and development speed of the network in different countries.During the coexistence of PDH network and SDH network,SDH equipment must be compatible with PDH digital signal and synchronous signal.In this paper,through the analysis of the current situation of Laos power grid and communication network,aiming at the problems existing in the traditional independent single ended,220 V AC power supply PDH access equipment in Laos power communication network,such as unable to manage network,unable to find optical path,unstable power consumption(using AC220 V),power failure without alarm,interruption and other fault problems.The fault is usually that the user interrupts the communication,and the operation and maintenance personnel of the operation and maintenance personnel of the operator service provider will know about the fault,and then start to find the fault,which cannot meet the service commitment of the user SLA at all.Therefore,the use of independent single ended PDH as access transmission must be improved.Combined with the characteristics of SDH technology,this paper proposes a scheme to realize PDH convergence in SDH nodes of local transmission network and network management integration transformation without changing the original SDH structure.In this scheme,the STM-1 electrical signal output from PDH sub-frame is interconnected with the STM-1 interface of SDH sub-rack,only a pair of 155 mbit / s coaxial cable jumper is needed,which saves the traditional PDH 63 pairs of 2Mbit / s coaxial cables are needed for interconnection with SDH,which shows that the scheme is effective.Then,as automatic routing plays an important role in the network fault recovery of Laos' s power system,when a certain path fails,the network management system can automatically select another route according to the network and available resources.The route conforms to the principle of the shortest or fastest routing,and carries the business by the alternative route.Due to the differences between different manufacturers and devices,it is difficult to standardize the shortest route in the industry.Considering the scale of the subnet management system,the centralized method is the best choice.According to the architecture characteristics of SDH network element management software and the characteristics of distributed network element management;this paper proposes a routing algorithm for SDH network management.The experimental results show that the algorithm can calculate the shortest route within2 seconds in the network with less than 10 network elements,which proves that the algorithm is feasible and effective.Finally,the main research results of this paper are summarized. |
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