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A Proper Startup for Network Transformation
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A Proper Startup for Network Transformation
Huawei Softswitch + SHLR + MSAN solution

I. Network Transformation -- Challenges and Opportunities for Network Carriers

Traditional carriers are now facing three main challenges:
A. Saturation in fixed-line and wireless voice markets.
B. Continued erosion of TDM service revenue by IP and VoIP telephony.
C. Lack of an effective strategy and sufficient profit margins for broadband services.

The need for transformation
The prevalent trend in the telecom market exhibits wireless technologies replacing fixed-line telephony, voice services giving way to non-voice services, and ICT convergence superseding traditional business services. The fixed network market has undergone substantive, structural changes in terms of increasingly demanding market requirements, the impact of technological progress and fresh challenges due to increased competition. Telecommunications is now focused on the integration of multimedia information and the convergence of IT and CT in corporate applications. Furthermore, there now exists a greater emphasis on mobility and personalized and customized services. Technological advancements have given rise to lost cost new technology, more rapid deployment methods and an unprecedented ease of market entry. IP and mobile technologies are the fastest developing applications and, compounded by polarized competition, cheap mobile voice and VoIP telephony and VoIP services are shattering the tried and tested "license + voice" service delivery pattern. Structural transformation is therefore inevitable for network carriers, and this is in fact necessary to guarantee survival in the marketplace.

The nature of transformation and NGN
This of course raises the question of defining clear goals relative to the nature of this transformation. Some common viewpoints have been found after analyzing the cases and strategic plans of various globally leading carriers, including BT's 21st Century plan, Telstra's Future Network Evolution and NTT's Resonant Communication Network Architecture. It is the belief of these companies that traditional carriers must shift perspective to become more holistic and integrated information service providers in order to reflect the fact that networks are moving inexorably towards convergence, broadband and network intelligence.

'Convergence' can be defined as multiple networks of services being combined into a single network providing multiple services; 'broadband' refers to the evolution of narrowband networks to broadband networks; 'intelligence' means the transition of intelligent networks to network intelligence. Traditional to NGN network evolution occurs in two stages. Firstly, NGN is used re-construct PSTN. Secondly, corporate and home subscribers are provided with converged Information Communication Technology (ICT) services.


II. Network Transformation: Starting from Softswitch + SHLR + MSAN

Based on an understanding of future network transformation, Huawei proposes a solution utilizing "Softswitch + SHLR + MSAN", as shown in Figure 1.

Figure 1

There are four layers to this solution:
1. A service and management layer.
2. The network control layer.
3. The core-switching layer.
4. The edge access layer.

The service and management layer is an open and integrated service platform that provides service logic processing in terms of creation, logic definition, programming interfacing and management. The network control layer consists of softswitch and SHLR (Smart Home Location Register). The softswitch comprises the network's service control center, which provides control functionality, control and command of media gateways and access devices, signaling protocols' processing and CDR generation. The SHLR in these terms encapsulates a user profile center that acts as the central database detailing every network subscriber, their attributes and subscription service properties. Additionally, the SHLR can store subscriber profiles in networks other than NGN, such as PSTN or PLMN, as well as storing logical and physical number maps. The SHLR, softswitch and service platform are designed to enhance service provision across the entire network (NGN, PSTN, and PLMN).

The core-switching layer adopts packet switching technology, and provides a highly reliable, guaranteed large-bandwidth integrated switching platform. The edge access layer contains MSAN (Multi-Service Access Network), an integrated access gateway solution that provides various kinds of access interfaces including POTS, ISDN and xDSL.

Combining softswitch and SHLR in terms of the solution as a whole brings intelligence to the whole network. MSAN is positioned as the access layer, thus enabling the provision of new broadband services by broadening last mile bandwidth. The features of convergence, broadband, and intelligence are reflected in all four layers of the network.

  • Convergence oriented Network

At the access layer, the existing multiple access equipment - traditional switch, DSLAM and AN - are replaced by one MSAN, which embodies a unified access platform and significantly decreases the required number of access nodes. Diversified access service needs are met including ADSL 2+, VDSL, LAN, FTTH, WiMAX , PBX, POTS and ISDN.. At the core-switching layer, legacy PSTN, data and Internet networks are replaced by a shared IP network.
The service layer enables centralized user profile storage and network call control, which realizes the goals of service convergence and rapid service deployment. Voice, mobility, multimedia and Internet converged services are readily expedited.

  • Broadband oriented Network

MSAN introduces various broadband access methods at the access layer and increases last mile bandwidth to meet user broadband service requirements. At the core-switching layer, the network is constructed utilizing sufficient, guaranteed core bandwidth to ensure high quality and the ability to meet growing service needs.

  • Intelligence-oriented Network

At the service layer, the existing separated intelligent networks - fixed, mobile and APP server - are replaced by one unified, intelligent service platform. The centralized subscriber data center and service-switching center brings intelligence to the whole network and supports speedy and unified service deployment.

Initiating network transformation with Softswitch + SHLR + MSAN offers users a plethora of benefits:

1. Simplified network architecture
Serving as independent call control nodes in the traditional local network, the legacy switch can be defined as an all-inclusive, small capacity piece of equipment. In order to actualize large-scale deployment, numerous offices are usually established in a small area to build a layered network such as C1, C2, C3 and so on. This can give rise to over-complicated network dynamics, rendering PSTN hard to maintain, update and expand.

Large capacity softswitch + MSAN denote the most practical and cost efficient solution to solve this problem. The softswitch contains a powerful processing capability to support local subscribers, and the different Media Gateways bundled with this solution offer different capacities and circumstantial adaptability. MSAN, which can support thousands of subscribers, possesses an internal switching function that is suitable for relatively densely populated areas or significant subscribers. If the bearer network between softswitch and the MSAN fails, MSAN subscribers can still communicate. Furthermore, the 'MSAN Outdoor Cabinet' boasts an all-in-one design incorporating power supply, MDF, battery and air-conditioning system for outdoor application.

With this solution, one Softswitch system is capable of covering a very large area. Not only is the structure of the network simplified, call failures are greatly reduced. The system as a whole offers unequalled robustness and a dramatic reduction in terms of total investment expenditure in equipment, external lines and maintenance. Moreover, by adopting optical fiber transmission, this solution can satisfy the requirements of both today and the future.

Figure 2

As Figure 2 illustrates, the Softswitch + MSAN solution reduces the number of host switches from 10 to 1. All subscribers receive centralized softswitch control that is accessed through MSAN, and switch coverage is extended from 3km to tens of kilometers. Given that the MSAN receives centralized control and monitoring from the Softswitch, this aspect of maintenance expenditure is considerably lessened. Since the lower-level, small capacity legacy switches are replaced by an MSAN, the local network is unified. Therefore, call connection times are shortened, call completion rates are increased, network safety and integrity is enhanced, and the cost of upgrading and overall maintenance reduced.

2. Bringing intelligence to the whole network
The SHLR operates in a similar manner to the HLR in a mobile network and the HSS in IMS. It functions as the central database for all subscribers in the network and stores the mapping between logical numbers and physical numbers, as well as recording subscriber attributes and subscription service properties. This methodology delivers operators the following benefits:

  • Quick and low-cost network-wide coverage of IN services. All calls in the network are controlled and billed via the softswitch, which acts as the service control center. All subscriber data is stored and managed by the SHLR, the subscriber data center. The development and deployment of services are no longer limited by physical lines, and numbers located in the LEs are scattered over different geographical locations. The solution can provide IN services such as Colorful RBT, ONLY, PPS, WAC, new intelligent phones, MVN (Multiple Virtual Number) to all subscribers without upgrading the LEs. Thus network profitability is boosted.
  • OPEX is reduced by centralized management, maintenance and subscriber data authorization

3. Investment protection
Huawei's "Softswitch + SHLR + MSAN" solution can consolidate all PSTN service capabilities and facilitate development without losing current subscribers. It therefore supports service transformation in a manner that is forward-looking, proactive and reactive to the future direction of the industry. The access network is a key component of the local network, requiring the greatest portion of CAPEX, and it forms the access and transfer platform for all service networks including PSTN, ISDN, DDN, FR, ATM, and IP. At the moment, voice service is still the principal network service, but with the rapid development of packet services, packet traffic will ultimately exceed TDM traffic levels. The access network provides access to all service and local telephone networks and inherently possesses the capacity for evolution to NGN. The use of MSAN in the NGN's access network reduces CAPEX and OPEX and allows future service integration and deployment to take place.

MSAN – key benefits

  • MSAN is an integrated access device that can access services such as POTS, DDN, FR, ATM, and IP. Therefore, carriers do not have to build and maintain multiple service networks.
  • Huawei fully considers the trend of future service development in MSAN system design. It is designed with a triple-bus structure - ATM, TDM, and IP. All access modes are supported, as is the deployment of the ANY PLAY service. Carriers are not required to upgrade MSAN to support new future services.
  • The MSAN provides high-density, narrowband and broadband hybrid boards, increasing port density, reducing cabinet size; simplifying cabling and minimizing cabling space. OAM is simplified, reducing CAPEX and OPEX.

4. Enhancing service capabilities
With MSAN's broadband access capability, the network control center softswitch and the SHLR data center provide richer services spanning multimedia, third-party and network management. Service provision takes place together with the ENIP, a comprehensive service platform. The development cost of Softswitch's new services is only 20% that of traditional telecom networks, and the development period is only 10% that of PSTN.

Services and capabilities

1. Traditional PSTN/ISDN basic services, supplementary services and Centrex services. This covers traditional phones as well as SIP and H.323 multimedia phones.

2. Multimedia Application Services, including point-to-point video services, video conferencing, IP TV, interaction between multimedia phones and 3G handsets, and various types of multimedia integrated services

3. Value added services include new intelligent phones, iCard integrated account cards, IN public phones, colorful dial, background and ring back tones (CRBT), instant billing, remote handset address, caller authentication, ONLY, VPN, FFPH (family free phone), FPH, voice address books, audio cards, voice SMS, voice mailbox, advertisements, designated phone payments and an IP card service.

4. Third-party open API. The softswitch and the ENIP platform provide an open API so a third party may develop customized and personalized services. The softswitch can access the Application Server through standard SIP protocol, and traditional SCP through INAP in order to provide traditional and new value added services.

The ENIP benefits from flexible and versatile network capability opening models, providing openings to CORBA, Web Services (SOAP) and RMI. ENIP supported features include standard Parlay interface; expanding Parlay with carriers and customizing API. This allows a third party to manage the service release based on workflows, and provides a universal Portal for subscribers to query and subscribe to third-party services, for example, SP and CP management, subscriber service orders, and bill settlement.

5. Integrated Information and Communication Technology

The convergence of communication and information technologies underpins network transformation, which will ultimately bring huge benefits to fixed-line operators. Convergence occurs in all aspects of carrier-class services, ICT devices, software and IT services, outsourcing included. In the network layer, the softswitch + SHLR + MSAN open network structure provide a basis for ICT. The network can provide broadband access and interconnectivity, IP Centrex, UC, web800 services for corporate subscribers and, for personal subscribers, IPTV and digital home services.

IP Centrex: A wide area IP Centrex grouping can be established for a single enterprise, inclusive of its HQ and branches. It enables both analog and video subscribers to communicate with each other in the same Centrex group, even if the subscribers are located in different cities. Additionally, U-Path is provided to ease self-service management.

UC: UC takes advantage of both real-time communications systems and easy-to-use IT platforms, and can provide click to dial/fax, instant messaging, intelligent routing, unified messaging, directory services and self-service for high-end business subscribers with OA systems.

Web800: This allows subscribers to call an enterprise's call center or helpdesk by clicking the web800 icon on the web page. The service is targeted at the manufacturing, service, financial and logistics industries.

Digital home: With the increased move towards broadband network construction, fixed terminals, otherwise unchanged over decades, are afforded new opportunities. By taking advantage of broadband, new home terminals – in other words the digital home gateway - will integrate telephone, PC, and TV to provide an all inclusive user service.


III Further Network Development

Proposed by 3GPP and widely accepted by international institutions, IMS research into the wireless and fixed-line fields is helping steer the advent of network evolution. The features and benefits of IMS include an open service environment, mobility, flexible service deployment and unified home service settings. IMS facilitates a seamless convergence of fixed-line and wireless networks, and provides ICT services. It is designed to allow all services to share the same core network, subscriber database, background billing system and service development platform. Subscriber data management and roaming capacities are subsequently enhanced.

The IMS is the future of fixed-line and wireless networks, and the IMS-based fixed-line/wireless converged network is generally regarded as the best solution. Nevertheless, the mobile-oriented IMS still requires conclusive research with respect to access models, service provision and fixed-line network subscriber migration. There is still a long way to go before IMS standards are completed, and consequently before the first commercial IMS network is deployed. Equally, sufficient maturity of the entire telecommunications industry is a tangent yet inextricable aspect of the transformation process.

The softswitch and IMS are regarded as the two stages of NGN development. The softswitch has present applications, solving high OPEX and inadequate service capability issues in legacy PSTN networks. Conversely, IMS application will occur in the future: the system is set to provide IP multimedia services and shoulder the convergence capability of fixed-line and wireless networks. The softswitch-based network shares the same network topology as IMS, including Access, IP Bearer, Session&Call control. The evolution from softswitch to IMS is therefore smoothly handled and realized.

Huawei's Softswitch + SHLR + MSAN solution offers flawless evolution capabilities to IMS with minimum network impact. Below is an illustration of the evolution process:

Figure 3

The Softswitch can be upgraded to provide the IMS AGCF/MGCF function without adding any hardware. This approach requires SHLR to provide the IMS HSS function. The IMS is intended as an NGN subsystem that can act as an SIP based multimedia system and provide new value added services for all network subscribers. Existing POTS users must still access the NGN via MSAN and can enjoy traditional PSTN/ISDN services provided by AGCF/MGCF. AGCF/MGCF will share the same HSS user database with other IMS components.


IV Summary

As fixed-line operators are evolving from traditional network carriers to integrated information service providers, a sustainable network is required to support convergence, broadband and intelligence. Huawei "Softswitch + SHLR + MSAN" is the best choice to initiate this transformation and guide future network direction.

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