Digital Convergence and Innovation of Chinese Telecommunication Enterprises

Liu Yunj ie

(China Unicom Co. Ltd., Beijing 100032, China）

Abstrac t:This article introduces the development background of the digital convergence,analyzes the challenges facing the convergence,and suggests that Chinese telecommunication enterprises should use the chance of the digital convergence to become the mainstay of technological innovation.It thinks that the digital convergence brings a set of advantages such as reducing the cost for network construction and maintenance,and quickening the pace of the new service development.However,it points out that the convergence has to undergo profound network and technology transformation and improvement in order to be realized,which should be promoted together by the transmission network,bearer network,core service network,MAN and access network.

D igital convergence is the trend of technology development,and has been the common pursuit in the telecommunication industry for decades.In China,the digital convergence is a domestic demand and effective method for building a harmonious and economicalsociety.However,the convergence is a gradually improving process full of challenges from every side.Accordingly,a significant strategy at present is to employ concrete solutions for every layer to promote the convergence.

1 Development Background of Digital Convergence

Digital convergence does not mean simply merging the broadcasting and television network and the telecom network into a single network.It will be completed gradually and in phases.The first phase will provide mutualservicelayer access between the broadcasting and television and the telecom networks,that is,the broadcasting and television network is capable of offering traditional telecommunication services like voice and Internet；and the telecommunication network can offer broadcasting services such as video services,including Internet Protocol Television(IPTV).The mutual access to the two networks helps enhance the efficiency of network resources and cost return,enrich service content,improve service quality,and promote the development of technologies.In the second phase,the telecommunication network and the broadcasting and television network are,according to the direction of the Next Generation Network(NGN)technology evolution,improved to offer multi-services respectively.Therefore,the convergence of the networks and that of the services will really be fulfilled in this phase.

As the trend of technology development,network convergence has become a common development direction under the drive of various factors and effective efforts from allparts of the industry.In China,network convergence has not only obtained clear support from the government,but also become the focus of the industry's concern.The 11th Five-Year Development Guidelines of China clearly points out that basic infrastructure such as the broadband communication network,digital television network and next generation Internet shall be strengthened to promote digital convergence.All these prove that digital convergence has realistic driving forces.

Firstly,digital convergence is a requisite for building a harmonious and economical society.It willsave much resource.Today,more than 80 percent of the broadcasting and television Metropolitan Area Networks(MAN)has implemented Fiber to the Zone(FTTZ).Broad bandwidth enables easy provisioning of various services.Meanwhile,the number of telecommunication network users had reached 77 million by July 2006,and the bandwidth resource is rather rich.In this case,the prohibition of mutual access to the two networks certainly leads to a great waste of network resources and causes duplication of network establishment as well.Making the corresponding policies,such as the access network's unbinding policy,shall reduce redundant investment,improve the efficiency of network resource,and help fulfill the goal of building a harmonious and economical society of China.

Secondly,digital convergence shall meet the increasing demands of users.First came the simple voice services,then video service occurred,which changed people's communication habit,and finally,various and colorful multimedia services have come.People's communication ideal is being realized step by step.Nowadays,users expect to enjoy all services conveniently and quickly,while to avoid complex operations of different networks.Such requirements can be appeased through the convergence of networks on the access and service layers.From this viewpoint,so,the digital convergence is the result propelled by users and the market requirement.

Lastly,digital convergence is a good breakthrough point of the evolution from existing networks to the NGN.Actually,the network convergence is an ideal goal pursued by global telecommunication operators,equipment vendors and terminal subscribers for decades.In the 1970s,the Integrated Service Digital Network(ISDN)emerged to offer integrated services including voice and video through a single network.In the 1980s,the Broadband Integrated Service Digital Network(B-ISDN)arose from the Asynchronous Transfer Mode(ATM)technology to offer a solution for network convergence.In the 1990s,provisioning all telecommunication services via the Internet showed a new attempt in the field of network convergence.Although prospective goals have not been reached,the above efforts stand for the mission of network convergence.Today,the definition of the NGN views network convergence as another key objective.The International Telecommunication Union-Telecommunication Standardization Sector(ITU-T)defines the NGNin five aspects:the NGNis a packet-based network；it is able to provide multi-services including telecommunication services；it fulfills the separation of bearer,control and service functions,and offers broadband capabilities and Quality of Service(QoS)enabled transport technology；it enables users to enjoy services from different providers as they please；it supports wide mobility and unified service provisioning.Therefore,the network convergence has been the trend and an important goal in the development and evolution of the telecommunication technology since the 1960s.

2 Challenges Facing Digital Convergence

Challenges from the administration regulations and the technology field urge the digital convergence to find out their corresponding solutions.

As the telecommunication technology continues to progress,and the process of the digital convergence speeds up,the administrative system is supposed to advance with the times.Nowadays,the mutual admittance of bidirectional services of telecommunication and cable television has been allowed in many countries and guaranteed by law.More and more countries are integrating the regulations for both telecommunication and broadcasting into a unified regulating framework and separate the content regulation from the network regulation.As for China,on the basis of fully learning from foreign experience,the administration is suppose to ensure the content security first,helping the stability and unity of the country and meeting the demands of building a harmonious society.Moreover,the administration is required to advance with the times,and should be favorable to the technical progress and development of digital convergence.The manageability of both the broadcasting and the telecommunication networks is able to assure the security of transported content.Therefore,it is a feasible target for the administrative system's reform to effectively unify content security and technology development.This target will greatly promote the process of digital convergence.

Contrary to what people say,the administrative system is not the only problem that the digital convergence is facing.In fact,challenges from technology lay another significant task before the digital convergence,which relies on innovation of technology and reconstruction of network.As the breakthrough point of evolution from existing networks to the NGN,the digital convergence must take this precious opportunity.Multi-service provisioning based on various existing separated networks will only make services stay low-level and become redundant.This makes no progress.The reformation of the existing networks is necessary for continuous technology development.Generally speaking,an essential principle is to utilize the advantages and characteristics of the broadcasting and television and the telecommunication networks to the greatest extent during the process of network reformation and technology innovation.Meanwhile,services should be offered selectively and new services be rolled out according to market demands.As a complicated system engineering,digital convergence is the accomplishment of the common efforts of the optical transmission network,bearer network,core service network,MANand access network.

The reformation and improvement of the optical transmission network lays ground for the digitalconvergence.One important goal of the digital convergence is to offer diversified services like voice,data and video over a unified network.Broad bandwidth of the optical transmission network is indispensable for offering video services,especially for transmitting a large number of television programs because the bandwidth demand is enormous,with which the available voice service cannot be compared.Moreover,digital convergence requires the optical transmission network to have more flexible dispatching and stronger management capabilities.The rapid increase of demand for network bandwidth requires the optical transmission network to offer better supervision and dispatching function,as well as the function of fault localization,diagnosis and elimination.For example,more intelligent and unified network management systems are needed to guarantee normalnetwork operation and service provisioning.

The convergence of bearer networks is the key to the digitalconvergence.The opportunity of network convergence should be actively taken to make plans and deployment for the evolution of the bearer network to the NGN.Technology advancement plays an important role in propelling the bearer network to get out of the“crossroads”of development directions.In the bearer network,it becomes feasible to provision diversified services on a unified physical network platform.

There was a more than 10 years argumentation about the selection of technologies and equipment for the bearer network to fulfillthe evolution from the circuit switched to the packet switched in the process of the digital convergence.The ATM and router were the choices.However,due to the unsuitability to IP,the ATM has no future development.On the other hand,the traditional router cannot guarantee QoS of real-time services,and not to mention,simultaneous transmission of multi-services since it does not have such functions as Traffic Engineering(TE),Operation and Maintenance(OAM),and resource control and management.To guarantee QoS,light load was tried in order to provide broad bandwidth with lesser traffic.However,it was proved to be impractical.On one hand,it is impossible to test the router network and perceive its real-time status；information about real-time status cannot be exchanged among routers.Besides,the Open Shortest Path First(OSPF)algorithm,developed for the IPnetwork,is only based on the static topological database of the network.On the other hand,the bearer network is dynamic in operation,and the congestion of network nodes and instantaneous interruption of links occur randomly.Without the capability of knowing real-time network congestion and link situation,the router is unable to ensure QoS.To sum up,neither ATM nor Router technology alone can satisfy the demand of digital convergence.However,there is no third choice,so the solution to the bearer network became a“crossroads”that cornered the development of the bearer network.

At present,the common recognition of a new solution has been reached,that is,bringing TEand OAM functions of the ATM technology into the router or reforming the router according to ATM,like adding the Bidirectional Forwarding Detection(BFD)function into the router,to offer QoSgaurantee.The idea is very inspiring because it acquired a generalized recognition in the industry；thus,practical action has been taken to reconstruct the router.

Multiple Protocol Label Switching(MPLS)is recognized as the core technology for both fulfilling digital convergence and ensuring QoS.When the MPLSresource control and management function is added into the router,the network will know how the resources are used；the network resources can be timely adjusted if failure,congestion or calls for new resources occur.Moreover,the intensive DS-TEtechnology distributes corresponding resources to different kinds of services in the bearer network,and defines different service levels in a single Label Switched Path(LSP).The fulfillment of QoSin the bearer network does not depend only on MPLS,but also on the reformation of the router,which makes the IPnetwork controllable,manageable and capable of guaranteeing QoS.This is an effective solution,and other solutions such as improvement of network architecture,are stillpossible in the future.

In order to guarantee the

charateristics and quality of different services as being transported over a unified physicalnetwork,multiple Virtual Private Networks(VPN),which are independent in logic,are set up to carry different services.Besides,every VPN has its own routing table and QoSlevel and are separate from each other.

The convergence of core service networks is an engine for fulfilling the digital convergence.The IPMultimedia Subsystem(IMS)represents the future development of telecommunication networks,and is regarded as a preferred solution to solve the vertical independence of the service system；it enables a completely layered architecture.It has widely been adopted by many international standardization organizations and industrial institutes.The IMSmay follow the concept of NGN to fulfill the separation of bearing and control functions,as well as that of control and service functions.It may also implement the separation of control functions from access modes and terminals,enabling users to access the network and enjoy diversified multimedia applications and entertainment services with different terminals(like the handset,Personal Digital Assistant(PDA),fixed phone and PC),and at different places(such as at home,in the office or on the road).With these advantages,IMShelps create a harmonious network application environment for enjoying various applications with different terminals,by different access modes and in different networks.Moreover,IMSgreatly saves on development resources.For example,a lot of services are allowed to share call control,database resources,and request and use of new services and relevant services,which results to providing users with convenient and speedy personalized communication experience.Although the Softswitch technology fulfills the separation of bearing,control and service functions,it makes little devotion to the provisioning of multi-services.Therefore,the lifespan of Softswitch will greatly shrink with the rapid development of the IMS,High Speed Downlink Packet Access(HSDPA)and High Speed Uplink Packet Access(HSUPA),which is an inevitable outcome of technology advancement.

The convergence of MANs and access networks plays an important role in the fulfillment of digitalconvergence.Nowadays,MAN is developing towards network convergence.Besides the available technologies,the development of telecommunication-class Ethernet is worthy of particular attention.Having the same idea for development as the bearer network,telecommunication-class Ethernet uses TEand OAM to guarantee QoS,making itself really telecommunication-class and possible to evolve into MAN.

The access network is devoted to Fixed Mobile Convergence(FMC).The Unlicensed Mobile Access(UMA)technology is expected to quicken the pace of FMC.The UMA enables the integration of the fixed network with the Wireless Local Area Network(WLAN),Bluetooth,and mobile networks,making full use of the infinite resources of the fixed network,as well as resolving the contradiction between the finite bandwidth resources and the infinite application of the mobile network.

Therefore,digital convergence brings a set of advantages such as reducing the cost for network construction and maintenance,and quickening the pace of the new service development.However,the convergence has to undergo profound network and technology transformation and improvement in order to be realized,which should be promoted together by the transmission network,bearer network,core service network,MAN and access network.As a good breakthrough point of evolution from the existing networks to the NGN,digital convergence shall make extraordinary accomplishments as long as such opportunity is seized.

3 Chinese Telecommunication Enterprises Become Mainstay of Technological Innovation with Opportunity of Digital Convergence

China has drawn up a national technological innovation strategy in its long-term national interest.According to the development guidelines of China,it plans to be an innovation-oriented country by 2020,and the Information Technology(IT)field is regarded as a breakthrough of China's technological innovation in the near future.It is a precious opportunity as well as a huge challenge for universities,research institutes and enterprises that specialize in the ITfield.Moreover,digital convergence,together with the continuous rapid increase in the services of mobile,broadband and Internet,provides a good chance for technological innovation in this field.China has made it clear to support enterprises as the mainstay of technological innovation.If the issues of the relevant administrative system,and the driving force and environment for innovation,are solved,Chinese telecommunication enterprises can lead the innovation system and will make it come true that the ITfield becomes a breakthrough of China's innovation strategy.