Research On Failure Detection And Location In The High-speed Railway Optical Transport Network

With the development of high-speed railway and the continuous expansion of railway network,optical transport network as the mainstream technology of optical transmission network,will also carry more and more service.In 12th Five-Year plan,the renewal and transformation of backbone transmission network of the Railway General Company and the 18 railway bureaus has been completed.The backbone layer of the railway adopts the OTN(Optical Transport Network)technology,with the capacity of 40 wavelengths and a single wavelength carry rate of 10Gb/s and 100Gb/s.Optical transport network carries a lot of services that ensure the safety operation of trains,such as train dispatching command and control,train running status monitoring,signal,GSM-R,synchronization and time allocation system,service scheduling communication and so on.Once the optical transport network fails,a lot of information will be lost,which will seriously affect the effective transmission of the service.It will bring huge security risks to the operation of the train.Therefore,when the failure occurs,the network need to adopt failure location mechanism to locate the failure quickly and accurately,and then take corresponding recovery measures to ensure the safety operation of the network.In general,the phenomenon of optical fiber breakage due to human destruction and natural factors is more frequent.Therefore,it is very important to research the link failure location mechanism.This paper mainly studied the single link and multi-link failure location methods in optical transport network.The main contents are as follows:(1)Aiming at the single link failure location in optical transport network,a m-trail allocation algorithm based on RWS(Roulette Wheel Selection)+MTA(Monitoring Trail Allocation)is proposed in this paper.In the MTA algorithm,the maximum weight link will be selected as the next link,which may result in a local optimal situation.The RWS+MTA algorithm can expand the search space through using a probability model when selecting the next link,and can select the best allocation scheme through limited iterations,then can avoid the emergence of local optimum situation.RWS+MTA algorithm is used to design the m-trail allocation scheme of the second and.third ring of the railway backbone layer.The simulation results show that this algorithm can achieve fast and precise location,and it can effectively reduce the running time and the monitoring cost.(2)Aiming at multi-link failure location in optical transport network,a failure location mechanism Parallel Fast-Limited Perimeter Vector Matching(PF-LVM)protocol is proposed in this paper.The failure location mechanism is improved on the basis of the Limited Perimeter Vector Matching(LVM)protocol single link failure location.In order to achieve multi-link failure location,firstly,after identifying the failure,PF-LVM separate every failure link to a limited area,and then use distributed failure location method to locate the failure link.The failure location mechanism not only can locate the failure link at the same time,but also able to locate the link that does not fail at the same time.The simulation results shows that this method has high failure location rate and can realize fast failure location.