The Research Of WCDMA R4 Network Bearer Panel Call Control Method

1. IntroductionAs far as Core Network (CN) is concerned, traditional PSTN network cannot satisfy and adapt new development trend of network no matter that servicedesign, service capacity, and network organization mode. It is must be a trend forthe telecom network to develop softswitch technology. There are R99,R4,R5WCDMA CN editions in the layout of the 3rd Generation Partnership Plan (3GPP)which is an international standard organization. R4 edition puts forward bearerand control separation conception, namely softswitch conception. R4 softswitchtechnology architecture improves network organize agility, expansibility,administrable ability and abundance 3G services. The CN CS field is split intoMSC Server and MGW two parts, the network can be build up by TDM/ATM/IPbearer. The separation of beare and control introduces new bearer and resourceoperation mechanism. The softswich which is an element of CN provides realtime call control and connection control function for service layer. It is key devicefor CN to realize call control function. Media gateway realizes media formatconversion function and the connection between PSTN and IP network.Softswitch and MGW realize interface by H.248 protocol. Our national networkand softswitch standard research have finished the whole technology requirementframework of softswitch related technology architecture. Some softswitch isbringing out to the market. How to realize current network services and abundant3G services, how to realize the call control of R4 network bearer panel bearer andresource are the urgent question of R4 network construction procession at present.2. Research ContentThe paper aims at the new bearer and resource operation mechanismintroduced by R4 network bearer and control separation architecture researchesWCDMA R4 network bearer panel call control method. Firstly, the paper analysessoftswitch technology architecture, 3GPP edition evolution relation, R4 softswitcharchitecture, hardware and software design scenario, softswitch communicationmechanism. Secondly, the paper combines R4 softswitch function requirement,constructs high reliability softswitch call and control unit, gives out servicesdistribution procession, load sharing and software fault tolerant arithmetic. Lastly,the paper gives out softswitch bearer panel bearer and resource call and controlmethod. The basic call, call wait, send tone,3 part conference call and controlprocess bearer and resource operation realizing scenario.(1) The Analysis of H.248 ProtocolIncluding softswich call and control connection model, termination, context,H.248 command set, transaction processing of media gateway register, basic callset up and release flow.(2) The Total Architecture of R4 SoftswitchIncluding the choice of softswitch hardware platform, the whole softswitchhardware scenario design, the SMU, ALU, BFI processing board hardwarescenario design. CCU process board's distributing process scenario. Softswitchsoftware platform choose, the inner communication mechanism of softswitch.(3) The Design of Softswitch Call and Control UnitThere are many CCUs in softswitch which realize service bearer setup,maintain, release and resource(Send tone, DTMF) operation. As the keyprocessing board of softswitch, CCU supports many kind of protocol. The workof the paper including the application program architecture design, BRO relatedmodule, BRO sub-module structure and function, the design of softswitch call andcontrol module. The paper also debates services prallel processing, mediagateway dual-ascription, rubbish reclaim scenario and so on. Beside somesoftswitch basic fuction requirement the paper acquires the following aims:As far as the hardware architecture is concerned, the processing boardshould has redundancy, That is Softswitch switches atomaticly to anotherwhen peocessing board meet with malfunction.User's services should not interrupt when one softswitch arise problemsor the bearer break off.The CCU should have validiate mechanism to inssure that the MGC canrelease reated resource when MG exites service and the system do notappear "resource hand up" phenomenon.CCU should adopts modularize strcture and the commucation betweensubmodule should obey the regulations of interface. The maintaince andupdate of any layer and any module should not affect other module.CCU must attach or excess 99.999% reliability(4) Bearer Panel Call and Control realizationAfter CN realizes the separation of bearer and control, MGC providescontrol fuction for the setup, maintain and release of basic call, including theprocessing of call request, connection control, IN call and resource control. MGCcontrols all kind of media gateways and devices including relay media gateway,user connect media gateway, all kind of wireless user media gateway. MGWrealizes media connect in and media format conversion and other function. Thesoftwtich should identify user hand on, dail-up, hand off event reported by mediagateway;MGW control media gateway to send all kinds of audio-sigal such asdail up tone, ring tone, ring back tone for user. In additional, softswitch shouldsupport two part call and multi-part call function, Such as special logicrelation,call member join, exit, separation, audit and so on.The paper gives out the software realization of softswitch's basic call flow,the function of SM module, BRO module and H.248 module during the callprocessing, softswitch bearer panel bearer and resourece call and control method.The basic call, call wait, send tone, 3 part conference call and control processbearer and resource operation realizingscenario.3. ConclusionThe paper realizes high reliability R4 softswitch call and control unit. Thedistributive process arithmetic relives system load and raises softswitch faulttolerant ability, realize the basic call, call wait, send tone,3 part conference calland control process bearer and resource operation witch provide an new referencescenario for softswitch bearer and control operation.gives out the software andhardware architecture design of 3GPP R4 network, realizes basic function of playtone, call hold, three partner conference, listen service. The paper takes distributeprocess arithmetic to relieve system payload and increase softswitch fault tolerantability.The paper tests softswtich CCU function according to national H.248 MGCtest criterion. The result shows that CCU satisfies the function of connectioncontrol, media resource control, bearer resource control and realize good supportfor basic call, call wait, 3 part conference,listen in services. The paper has greatsignificance for WCDMA R4 network bearer and resource operating, realizingabundance 3G services, accelerating 3G CN constrctionIt is hoped that through softswitch technology discussion of this paper, thesoftswitch call and control theory can be further optimized, and realizes a functionof motivation and inspiration.(1) Further perfect R4 network architecture softswitch call and control uintsyetem design, optimize basic call service control and bearer resource softwaredesign, impove the whole system performance.(2) Search for more practical and fitful R5 network call and control functionsolutions.