張建生

（中國(guó)有線電視網(wǎng)絡(luò)有限公司，北京 100036）

1 INTRODUCTION

The Local Application Service Delivery Platform（LASDP）is a conceptual platform which resides within the home network to provide programming interfaces and functionalities to enable the cable service provider and third party entities to deliver advanced and innovative applications and services to cable subscribers in the home network.The LASDP can communicate and interwork with Network Service Delivery Platforms（NSDP）to create more value for customers and the service provider[1].

From a business perspective,a LASDP will facilitate the creation and delivery of new and advanced local applications and services.New and advanced local applications and services will potentially generate more revenues and increase competitiveness of the service provider.Furthermore,if the programming interface to the LASDP is open and standardized to facilitate applications and services creation by third parties,more innovative and advanced local services will be made available to consumer.Such situation will benefit the cable service provider and the consumer alike.Similar third party business models,e.g.Apple's App-store for iPhone or NTT DoCoMo's i-mode,have proved to be very successful financially for the service provider[2].

With the development of triple play on digital TV,telecommunication and Internet,it is a successful key for network operator to win home users that have the advantage of service delivery platform,which delivery the rich applications and value-added services,on home services entrance.

Based on these observations,an open and standard LASDP is important for user-need on-demand response,service agility,service convergence and service ecosystem.The work for standardize the LASDP with open APIs will encourage faster application and service creation for home users and reduce the cost of cable network operators.

For open and standard LASDP,a number of issues related to the LASDP will be identified and studied.These issues should include,but not limited to：

1）Use cases and scenarios for local applications and services;

2）Architectural and functional requirements;

3）Application programming interfaces（APIs）;

4）Application and service creation environment;

5）Interfaces with service provider network,e.g.interface with network-based service delivery platform and so on.

The functional architecture of LASDP over broadband cable home networks is studied in this article.

2 MARKET DEMANDING AND CHALLENGES

2.1 Technology trends

The technology trends are listed below:

1）Capability and flexibility increased at the device/appliance;

2）Open standards,open architecture and open APIs for applications/services innovation;

3）Open applications/services offering for users and providers;

4）Seamless network integration/convergence on the implementation of infrastructure;

5）Service oriented economy ecological environment.

2.2 M arket demanding

2.2.1 Home user's demanding

The main demands of home customer include but not limited to:

1）Multi-screen sharing the video,content and data;

2）Remote access to home contents and control the home devices;

3）Mobility to connect home anywhere and anytime;

4）Low cost and low maintenance for home equipment and devices;

5）QoE improving.

The new user experience requirement:

1） Interactive experience，such as linear TV with trick model,personal broadcast service,linear TV with multi-view,video on-demand with multi-view service,interactive content on video,audio,text,image and Web,interactive control;

2）Flexible content choice;

3）Integrate TV service,internet service and communication service.

2.2.2 Network operator's demanding

The main demands of MSOs include but not limited to:

1）Increase service innovation ability;

2）Smooth new service introduction;

3）Raise network efficiency;

4）Reduce CAPEX;

5）Reduce OPEX.

2.2.3 Applications/services provider's demanding

The main demands of Applications/services providers include but not limited to:

1）Useful applications/services,such as good performance,fast connect to users,fast response to user's new demands;

2）Intelligent user interfaces,such as friendly awareness interface,personalization,video/audio/date integration;3）Acceptable cost,such as flexible price policy;4）Security.

2.3 Challenge in meeting the demands

The MSOs have challenges in meeting the demands of home users and applications/services provides.These challenges include but not limited to:

1）Provide unlimited TV channels with trick model,multi-view,high-definition and 3D;

2）Provide winning increasing value-added applications and services;

3）Provide rich interactive video applications and services;

4）Respond quickly to market increasing demanding;

5）Attract"top in class"third-party developers of applications;

6）Achieve superior performance and reliability;

7）Reduce cost and risk on deployment.

3 CONSIDERATION OF SERVICE DELIVERY PLATFORM

3.1 SDP

In the past,individual services have typically been built as"stovepipes"——each tied to a particular equipment vendor's protocols in a particular type of network,and each with own creation,provisioning and control environment.This duplication of technology is costly and prevents operators from easily bundling or combining services into new offerings.

A service delivery platform（SDP）is a system framework or environment for service creation,deployment,execution,orchestration and management.It is key characteristic that the exposure by open application program interfaces（APIs）and integration between heterogeneous networks such as wireline,wireless and IP multimedia subsystem（IMS）based on service oriented architecture（SOA）.In SOA which used for integrating various kinds of business services,systems are divided into basic service component,services are distinct unit that can be independently reusable.

SDPs are applicable to both consumer and business applications.The business objective of implementing the SDP is to enable rapid development and deployment of new converged multimedia services.

3.2 NSDP and LASDP

The service delivery platforms are commonly considered for the network environments as a core system which interconnects the service provider's headend infrastructure or home-user's terminal infrastructure.SDPs in this context are usually associated to a particular service regime or converged services.For discussion purposes,a service delivery platform that resides in the service provider domain is categorized as network service delivery platform（NSDP）.A service delivery platform which provides an application and service execution environment that resides in the home network domain is categorized as local application and service delivery platform（LASDP）.The interconnection and interaction between the NSDP and LASDP would make the deployment of applications and services.

3.3 Featuresof LASDP

The LASDP is the home network platform environment for sharing the services and applications,based on the residential gateway（RGW）or hybrid set-top-box（HSTB）,which interconnecting and interworking the personal computer,mobile terminals and domestic appliances.

The LASDP is the key parts of family clouds.The primary features of LASDP include but not limited to:

1）Base on RGW/HSTB,that is the center and outlet of home network;

2）Interconnect and interwork the STB,PC,mobilephone,tablet,storage and domestic appliances;

3）Share the services,application and content of family;

4）Centralized storage of family contents;

5）Remote access to the family contents and controls the domestic appliances;

6）Reallocate resources based on services and application;

7）Shorten interval to roll-out new services;

8）Allow self-services for subscribers[3].

4 HIGH-LEVEL FUNCTIONAL ARCHITECTURES

The high-level functional architecture on overall end-toend systems is shown as Figure 1.The overall architecture include 3rd party developer domain,service provider domain and home user domain.The network service delivery platform resides in service provider domain.The local application and service delivery platform resides in home user domain.

4.1 Functional b locks

4.1.1 Local application and service delivery platform

The local application and service delivery platform functions block resides in home user domain.This functional block provides necessary functions and application programming interfaces（APIs） to applications and services via reference point APa.Application and service developers use application programming interfaces provided by this functional block to access the facilities and functions provided by the home network and its devices to realize advanced and sophisticated applications and services that bring value to customers,service providers and developers.

Fig.1 high-level functional architecture on NSDP and LASDP

Functions in this block include:

1）Service management function.This function provides necessary capabilities for managing local applications and services developed by third party developers.

2）Service execution function.Local applications and services use functionalities provided by this function to run,in order to provide values to the customers.

3）Service access function.Home network users access local applications and services by using functionalities provided by this function.

This functional block can reside in a Residential Gateway（RGW）,hybrid set-top-box（HSTB）or on a different computing platform on the home network.

4.1.2 Home network and devices

This functional block represents the functions and facilities of the home network and its devices.The local application and service delivery platform interfaces with this block via reference point Luto provide local applications and services with necessary APIs to invoke functions provided by the home network and its devices.

Functions in this block include but not limited to:

1）Residential gateway;

2）Hybrid set-top-box;

3）Network storage;

4）Smart-phone;

5）Tablet.

4.1.3 Network service delivery platform

The network service delivery platform functions block resides in the service provider domain.Functions related to local applications and services that need to be provided by a service provider are included in this block.The contents distribution network（CDN）function block and the network transport function block also resides in the service provider domain.The network transport function includes but not limited to：

1）Optical Transport Network（OTN）;

2）Passive Optical Network（PON）;

3）Hybrid Fiber Cable（HFC）.

The network service delivery platform functions in this block include:

1）Service management function

Service providers use functionalities provided by this function to manage local applications and services that run on the home network.

2）Application development function

This function provides necessary capabilities of developer toolsets used to build application-level service that execute in network SDP.This function should be 3rd developer friendly capabilities and interfaces.

3）Service orchestration function

This service orchestration function is used by service providers manage the lifecycle of service orchestration.The service orchestration function is part of an emerging SDP based on SOA.The service orchestration environment contains a modeling tool that understands the function available in each function block,and controls communication between all the functional blocks when they are executed as a service.

4）Service control function

5）Service gateway function

Network-based services can be developed by using functions and services provided by this function,which resides in the service provider domain.

4.1.4 Third party developer functions block

This block represents third-party developers'functions that are needed for the realization of local applications and services.One example of those functions is that of service management.Functions in this domain interact with service provider domain.

Functions in this block mainly include service management function,the functionalities provided by this function are used by third party developers to manage local applications and services.

4.1.5 Applications and services

This block represents actual products developed by third party developers using programming interfaces provided by the local application and service delivery platform.These applications and services interact with the local application and service delivery platform via the APareference point.

4.2 Reference points

4.2.1 Reference point APa

Local applications and services are developed using application programming interfaces（APIs）provided by the local application and service delivery platform on this reference point.A standard set of APIs over this reference point will enable fast creation and delivery of local applications and services that take advantage of functions and capabilities of the home network and its devices.

4.2.2 Reference point Lu

This reference point is between service access functions of a local application and service delivery platform with home network and devices.It provides the delivery platform with necessary interfaces to utilize capabilities and functions of home network devices.

4.2.3 Reference point Nu

Network service delivery platform（NSDP）is used to provide network based services to service subscribers.Those services may need to access to functions and capabilities of home network devices.Network based services to be build using NSDP access functions and capabilities of home network devices using interfaces across reference point Nu.

4.2.4 Reference point Ls

One of the key aspects for local applications and services creation and deployment is service management.Local application and service delivery platform needs to provide applications and services developers with necessary functions to manage many aspects of a local service,e.g.service activation,charging,etc.These functions are provided by the Service management function.This functional block interacts with the service management function of the service provider domain to exchange service management information.The interaction is performed using interfaces over the Lsreference point.

4.2.5 Reference point Lp

This reference point is for interaction between network SDP and local application and service delivery platform.Network-based services developed using network SDP and local applications and services developed with local application and service delivery platform can use interfaces defined over this reference point to exchange necessary information for coordination of services and applications.

4.2.6 Reference point N3p

Third party developers need to interact with a service provider to manage services and applications developed using local application and service delivery platform.This interaction can be performed using interfaces defined over this reference point.An example of such interface would be using a web browser to register and change a local service by a third party developer[1].

5 GENERAL CAPABILITIES REQUIREMENTS

5.1 General servicesagility requirements

The LASDP is required the capabilities supporting for applications and services agility.The services agility includes but not limited to:

1）Rapid response to home use's demands;

2）Rapid on-demand response to application and service providers and 3rd developers for service integration and delivery.

5.2 General services convergence capabilities requirements

The LASDP is required to supporting the capabilities of convergence services with digital TV,telecommunication and internet.

The supported convergence services for the example as:

1）Digital TV applications and services.Include but not limited to linear TV and on-demand TV with trick mode,TV with multi-view applications and services,personal video recorder services with applications of client,network mode[4].

2）Multi-devices interacting services.Include but not limited to seamless multi-screen TV watching service,social media assisted-TV watching service,multi-device control service.

3）Communication service.Include but not limited to messaging service,telephony service,video communication service.

4）Value-added lifestyle services.The services based on Internet of Things（IoT）are resided in this scope.Include but not limited to commercial service,medical service,education services,home monitoring services,home automation services,entertainment services,information services.

5）Internet based services.Include but not limited to Internet browser services,application store service.

5.3 General integrated platform capabilities requirem ents

The LASDP is required to supporting the integrated service platform capabilities for the home network capacity,home equipment and appliance resources and service resources.Include but not limited to:

1）Supporting triple-play convergence service;

2）Integrated the capabilities of home network and devices;

3）Supporting the cloud-based applications and services;

4）Integrated the capabilities of TV,IT,CT and IoT/M2M technologies.

5.4 General carrier-grade ecosystem capabilities requirements

The LASDP is required the capabilities of open and standard platforms and the capabilities of ecosystem supporting.Include but not limited to:

1）Reliable end-to-end service operations;

2）Strong media delivery capabilities;

3）Friendly management for service provider,3rd developer and home user;

4）Professional and standard application developing environments for application system integration.

5.5 Examp leof RGW based services capabilities

RGW,as a core device for home ICT service,is expected to deliver the high-grade and interactive services for cable customers with use of internet resources,cooperation between service delivery platform and multiple devices/sensors in HN.Service representation will be processed over the browsers which are embedded in each terminal device connected with HN through Ethernet or WiFi.Figure 2 shows service delivery scheme by RGW.

RGW is required to provide service functions for home automation（light,sun shade and room temperature control,etc.）,home security（fire/smoke detection,security camera,etc.）,mobile device cooperation,home appliance control,energy saving,health care,education and supporting public services et,by the communication between cloud functions and terminal device functions.The services depicted in Figure 2 are examples only,and does not exclude other service capability[5].

6 FUNCTIONAL REQUIREMENTS

The LASDP is an integrated service platform which supported by technologies of TV,IT,CT and IoT.Figure 3 shows the reference layered functional framework of LASDP.

The LASDP is required with 3 function framework flocks of service management functions,service execution functions,service access functions.

Fig.2 Service delivery scheme by RGW

Fig.3 Reference layered functional framework of LASDP[6]

6.1 Service managem ent functional framework block

The service management function in LASDP is the client of service management in NSDP.This block provides necessary capabilities for managing local applications and services developed by third party developers.These management capabilities are required include but not limited to:

1）Application lifecycle management;

2）Service management;

3）Home devices management;

4）Home network management;

5）Service subscription management;

6）Billing management;

7）Security management.

6.2 Serviceexecution function framework block

An application and service execution functional environment provides applications or services,which developed by the service provider or by a third party developer,with necessary resources to run to provide functions intended by the applications or services.

6.2.1 Service orchestration function block

The service orchestration function is required to provide the engine capabilities for application＆service connection,discovery,directory,policy and orchestration,show as application and service connection engine,application and service discovery engine,application and service directory engine,application and service policy engine,application and service orchestration engine.

6.2.2 Service control function block

The service control function is required to provide the engine capabilities for home device discovery,home network communication,session control,resource control and so on,such as home devices discovery engine,home network communication engine,session control engine,resource control engine,

6.3 Serviceaccess function framework block

The service access function provides the LASDP with necessary interfaces to home network and devices.It provides capabilities to access home devices by utilizing the capabilities and functions of home network devices.The service access function framework block is required to contain access adaptor capabilities include but not limited to:

1）Home network communication abstraction adaptor;

2）Home devices access abstraction adaptor;

3）Application and service capability abstraction adaptor.

7 FUTURE WORKS

For benefit to consumer and operator,the broadband cable home network platform,such as LASDP,would aim to support CAPEX（capital expenditures）reduction,OPEX（operating expense）reduction,low maintenance,content security and energy saving.Based on the broadband coax access and connect,the collaborative cover,interconnection and interworking over wire and wireless in home environment should be supported.For LASDP,based on the study of use cases,service scenarios,functional architecture and APIs,the future important work are two scopes.One is the detail description on the requirements of functions and APIs;another is the specification on LASDP.

[1] ITU-T SG09 Contribution C-0105，Proposal of modifying the structure and updating the texts of J.lasdp-req[S].2015.

[2]CHAPPELL C.The future of SDP[J].Heavy Reading，2005，3（19）：1-75.

[3] ITU-T SG09 Contribution C-0061r1，Proposal of considerations on home cloud technology developing[S].2014.

[4] ITU-T Recommendation H.722，TV terminal device:full-fledged model[S].2014.

[5] ITU-T Draft New Recommendation J.rg-spec，Specification for residential gateway[S].2013.

[6] ITU-T SG09 Contribution C-0107，Proposal of updating the key requirements on functions and APIs of J.lasdp-req[S].2015.