Mobile TV/IPTV


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Mobile TV/IPTV

  1. 1. Session 8A Mobile TV/IPTV
  2. 2. Delivering Quadruple Play with IPTV over IMS Bruno Chatras, Mikhaël Saïd France Telecom Research & Development 38-40 rue du Général Leclerc F-92794 Issy Moulineaux Cedex 9 Email: {bruno.chatras,mikhael.said} 1 Introduction Integrating IPTV in NGN aims at enabling IPTV functions to interact with relevant NGN The interest in IPTV services is increasing as subsystems and use the capabilities they provide, these are perceived as a potential source of new namely dynamic network attachment and revenues by telecommunications service management of transport resources with quality providers. IPTV services are actually already of service control. Two variants are being being deployed by many of them around the considered in standardisation bodies. The first globe and tend to be packaged as "triple play" way, called "IPTV dedicated subsystem", solutions, including telephony and Internet or focuses on the integration of existing market even "quadruple play" with wireless aspects. solutions in an NGN environment. Its prime objective is to take advantages from NGN Current solutions are essentially vendor-specific environment without replacing existing IPTV and the services they provide are inherited from systems. The second way, called "IMS-based", those available with terrestrial, cable and satellite consists in using the IMS as a control plane for television, augmented with features enabled by IPTV services as for any other multimedia the availability of an upstream channel such as services. video on demand (VoD), personal video recorder (PVR), and live TV with trick mode (e.g. pause, The IMS-based solution addresses not only basic fast forward …). However, new needs are broadcast (e.g. Live TV) and streaming (e.g. emerging along with "quadruple play": access VoD) services but also aims at combining them independent solutions, integration in a multi- with communication services (conversational services environment, availability of enhanced services, presence services and messaging services combining features from every services) so as to provide end-users with a new component of the "quadruple play" bundle, etc. multimedia experience. Examples of combined A common control plane managing both IPTV services are "click-to-dial from TV", where a services and other multimedia communication user can initiate a call to a number shown on the services would ease responding to these new TV screen (e.g. during a TV show); "Caller ID needs. The IP Multimedia Subsystem (IMS) [1] on TV", where the identity of the calling party is defined by 3GPP and extended by ETSI TISPAN displayed simultaneously on the TV screen and provides one possible answer and standardisation on the phone sets; call forwarding (to a mailbox) bodies such as ETSI TISPAN and ITU-T are when watching TV/VOD; remote parental already working on such an approach. control using short messages, etc. Section 2 of this paper further discusses the Besides its ability to ease the design and motivations and benefits of using IMS-based implementation of combined services the IMS- solutions in support of IPTV. Section 3 based approach brings additional inherent highlights a number of technical challenges that benefits: an IMS-based solution has to face. Section 4 provides a technical description of the IMS- - Common infrastructure: Almost all large based solution under standardisation in ETSI Telcos have plans to deploy an IMS TISPAN [2]. infrastructure in support of the replacement of their TDM-networks. Indeed, according 2 IMS-based solutions design and to Gartner, in 2010, 77% of all investment motivations for call control layers is forecast to be based The integration of IPTV services in an NGN on the IMS. The IMS-based approach will environment is one the key features that the leverage this investment by enabling the ETSI TISPAN technical body will deliver as part support of IPTV services on the same of the second release of its NGN standards. network infrastructure than VoIP services. 1
  3. 3. - Common identity and authentication DVD-IPI or OMA-BCAST for mobile access). mechanisms: The IMS identification and However, the IMS specifications do not authentication framework provides an currently include explicit support for such opportunity to extend the features of procedures. existing IPTV services with multi-user 3.2 Control of media flows subscription capabilities. This will make Specific time constraints related to media flows possible allocating different public identities control have to be taken into account. Channel- and service profiles to different users hopping delay is one of the major ones for sharing the same IMS / IPTV subscription. broadcast services. Trick mode operations (e.g. Such capabilities will typically be used to fast forward) in VoD and PVR are also subject to manage different lists of subscribed time constraints. In order to avoid that IMS channels associated to different users in the signalling procedures bring extra delays, it is same family. necessary to draw a clear separation between service/session control performed at the IMS - Common resource management: The IMS level and media flow control handled end-to-end relieves IPTV application servers from the between the user equipment and the content task of interacting with transport control servers. functions for the purpose of reserving transport resources. 3.3 Applicability of session concepts to - Multi-access solution: IMS is designed to broadcast services be access-independent. Using the IMS as a Most of the current broadcast services are control plane will therefore allow users to session-free: once the list of subscribed channels access their IPTV services whatever the is fetched, the client can perform channel- access they are connected to. Moreover, the hopping without running any session-related multi-access capability brought by the IMS preamble or postamble procedure. With the IMS, comes with the support of service roaming introducing the notion of session enables and service continuity when moving from adapting network resources to the services and one access to another. therefore increases the efficiency of transport resources management. The initiation of the - Common charging mechanisms: As a session provides IPTV services with the ability result of using the IMS for session control to request and reserve transport resources and IPTV services will benefit from generic modify these at a later stage (e.g. when zapping charging mechanisms and interfaces from SD channels to HD channels). Explicit applicable to other types of multimedia termination of IMS sessions enables releasing services. This will facilitate unified billing these resources, making them available for other for multi play solutions. services/users. Moreover, the existence of an explicit session provides criteria for triggering 3 Technical Issues the publication of events to be used for presence Although the IMS was originally designed as a services purposes. generic platform for supporting multimedia services, IPTV services bring specific technical 3.4 Negotiation of media properties during challenges that have not yet been fully tackled by session establishment IMS standards. IMS procedures for negotiating media properties 3.1 Service Discovery and Selection during session establishment follow the Service Discovery and Selection (SD&S) refers offer/answer model defined in RFC 3264. to a set of procedures that a user needs to go According to this model, the offerer provides a through before invoking any IPTV service. This description of the set of media streams and enables the user to discover available services codecs it wishes to use, while the answerer and retrieve the necessary parameters to activate responds by indicating whether these streams are the selected service. Electronic Program Guides accepted or not, and which codecs will be used. (EPG) and VoD catalogues are part of the A stream description in an offer may include a service selection information. They can be bandwidth attribute, in which case it indicates unicasted (e.g. retrieved by the user from a portal) the desired bandwidth that the offerer is prepared or multicasted (e.g. received on the user to receive. This model is suitable for equipment in the form of a specific broadcasted conversational services and is not followed today channel). There exist several competing for streaming services where bandwidth standards for the specification of SD&S information relates to the bandwidth required to procedures and associated information (e.g. transmit a particular content rather than to the capabilities of the two ends of the 2
  4. 4. communication. Therefore, its applicability to 2) Connection to these servers (known as IPTV needs to be carefully considered and may Service Selection Functions, SSF) to get require adaptation. information on available services; 3) Retrieval of relevant information (e.g. 4 Architecture, procedures and content identifier, media parameters) protocols required to initiate a session for accessing the selected service. The principle of the IMS-based solution lies on the use of IMS architecture and procedures. This After a service is selected, the relevant content section provides further details on the identifier is inserted in the SIP session initiation implementation of this principle in ETSI message sent towards the IPTV Service Control TISPAN standards. Function (SCF) that provides access to this service. IMS compliant SIP/SDP procedures are used to establish, modify and release sessions between IPTV Service Control Functions perform service the user equipment and the content servers. authorisation during session initiation and Session initialisation provides the ability to modification, which includes checking IPTV negotiate the characteristics of content channels users' profiles in order to allow or deny access to and possibly of an associated control channel, the service. IPTV Service Control functions may and reserve the required transport resources. As also perform credit control and select the far as streaming services are concerned, the relevant IPTV media functions. They act as protocol running over the control channel is standard IMS Application Servers, using the ISC expected to be RTSP (or a subset of it). interface to communicate with the core IMS. 4.1 Architecture This architecture is designed to make media Service Service Service Control flows control out of the IMS scope, in order to Selection Discovery Functions cope with the issue highlighted in §3.2. Media flows control is therefore supported by other Session initialisation UPSF means, using existing protocols: RTSP for trick Modification and termination mode operation during streaming services and Media Functions IGMP for channel zapping during broadcast CORE IMS User services. Equipment Resource and Admission control Flow control and media delivery RACS IPTV media functions are in charge of controlling and delivering media flows to the Transport User Equipment. They are split into Media Control Functions (MCF), handling media flow control and managing interaction with the UE Figure 1: IMS-based solution functional architecture (e.g. handling of trick-mode), and Media Delivery Functions (MDF) sourcing the actual The IMS-based approach relies on a functional media flows. architecture centred on the core IMS (i.e. the IMS Call Session Control Functions). When For the purpose of implementing combined processing session signalling, as for any other services IPTV service control functions may multimedia service supported over the ETSI interact with Presence Servers or with TISPAN NGN architecture, the Core IMS Application Servers hosting the logic of interacts with the UPSF (User Profile Server communication services, using IMS capabilities Function) to download service profile such as third-party registration, event information and with the RACS (Resource and notification… For example, existing IMS Admission Control Subsystem) to request and presence capabilities can be enhanced with reserve transport resources related to the session. IPTV-specific information such as an indication of the "currently watched channel", allowing Before initiating a session, the user has to user's contacts to share experiences and third- proceed to the selection of a service using party applications to develop specific services Service Discovery and Selection (SD&S) based on IPTV presence information. procedures. SD&S includes three steps: 1) Retrieval from a Service Discovery 4.2 User Data Function (SDF) of service providers' server The provision of IPTV services involves two addresses (e.g. addresses of service portals); categories of user data: 3
  5. 5. - IMS user profile data: These data are When looking at the above figure, it is worth required for the IMS to operate and are not noticing that only the service discovery step goes related a specific service. They include, through the IMS. amongst other parameters, triggering filters (i.e. Initial Filter Criteria - IFC) towards 4.4 Streaming session application servers hosting services the user Streaming session initiation is composed of three has subscribed to. logical steps: - IPTV user profile data: these data are specific to IPTV services. They typically - Establishment of a dialogue between the UE include the list of subscribed channels for a and the IMS: this step encompasses the broadcast service or the parental control processing of the SIP session setup, the level and language preferences for video on execution of a service logic by the SCF (e.g. demand services. checking of user's rights, determination of appropriate charging rules…) and the The IMS user profile data are always stored in selection of the relevant media function; the UPSF while IPTV user profile data may be - Negotiation of the control channel between stored at a different location. They may be stored the UE and the media function necessary to transparently in the UPSF as enabled by the IMS support trick mode operation; specifications or nearer to the Service Control - Negotiation of one or more content Function, if frequent accesses are needed during channel(s) between the UE and the media the processing of service sessions. Such data function necessary to deliver the requested have to be available to the SCF and may also content. need to be available to the SD&S functions in order to customise the information they present The three steps can be executed in sequence or in to the user. parallel depending on the parameters available at 4.3 Service discovery and Selection the UE to initiate the session. If the UE has As described in a previous paragraph (see § 4.1), enough parameters to make an offer for control Service Discovery and Selection comprises three and content channels at this stage, it can combine steps. During the first step, users contact the the session initiation request with the offered Service Discovery Function to retrieve the control and content channels descriptions in a addresses of the servers (Service Selection single message, as illustrated in the figure 3. Function) that can provide them with a However, if the only piece of information description of the available services. This three- available to the UE when initiating a session is a step approach allows the network to provide content identifier, the control and content access to services and contents from several channels offers have to be sent from the media service providers. function in subsequent SIP messages. The communication between the user equipment The session initiation is performed using the SIP and the SDF relies on the SIP SUBSCRIBE and INVITE method. Negotiation of the content and NOTIFY methods. The user equipment can control channel descriptions is achieved by acquire the knowledge of the Service Discovery exchanging SDP descriptions embedded in SIP Function address through provisioning or rely on messages, following the SDP offer/answer model. the IMS to route the SUBSCRIBE request to the This procedure is very similar to the one already appropriate SDF, based on initial filter criteria existing for conversational services. However, as (IFC) contained in the user profile (See figure 2). explained in one of the above paragraphs (§ 3.4), the offer/answer model is indeed suitable for use Service Discovery with conversational services but may require Server adaptation for use in the context of IPTV services, especially regarding the conveyance of bandwidth information. Work is in progress at 1. Suscribe/Notify the IETF to extend this model with an indication Procedure : retrieval of service selection CORE IMS IFC : triggering to the of the bandwidth required by an application. servers' addresses Service Discovery function Messages exchanged over the control channel for User Equipment Service trick mode operation are imported from RTSP. Selection Server They do not go through the IMS, thereby 2. Service information and selection answering to the constraint delay as explained in § 3.2. Figure 2: Service Discovery and Selection 4
  6. 6. IMS procedures also allow the user or the media - To provide the RACS with information function to modify an established session. For required to enable multicast access control example, on receipt of RTCP reports indicating to be performed in the access node: during downgrade of the network resources, the media session initiation the RACS downloads in function can decide to modify the media flows the access node a set of filters related to the properties in order to adapt them to network subscribed channels. This way, when the changes. Session modification may also be used access node receives an IGMP join request with SVC (Scalable Video Coding) when from the UE, it can autonomously allow or enhancement layers are added or removed during forbid access to the requested channel by a session. preventing or enabling packets received from the corresponding source to be Figure 3 gives an example of a session initiation forwarded to the UE. procedure where the three logical steps identified above are combined. Figure 4 gives an example of the broadcast session initiation. User User Equipment CORE IMS SCF MF Equipment CORE IMS SCF INVITE (SDP offer for RTSP and content) INVITE (service package id) INVITE (service package id) RACS interactions INVITE (SDP offer) 183 Session Progress (SDP offer) INVITE (SDP offer) Resources control 200 OK (SDP answer for RTSP and content) 183 Session Progress (SDP offer) 200 OK (SDP answer) PRACK (SDP answer) Resources control : RACS interactions download filters 200 OK (SDP answer) in the access node for multicast control ACK () PRACK (SDP answer) ACK () ACK () 200 OK () 200 OK () RTSP 200 OK () 200 OK () Figure 3: Streaming session initiation example Figure 4: Broadcast session initiation example When looking at the above figure, it is worth As already mentioned, after session initiation, noticing that RACS mechanisms required to the UE can use IGMP to perform channel- reserve transport resource and perform hopping without going through the IMS. In case admission control for streaming flows are previously allocated resources are not sufficient, identical to those required in support of an IMS session modification procedure may take conversational media flows. place in parallel with the IGMP join. However, 4.5 Broadcast session this procedure can become heavy and inefficient if frequent modifications are required. ETSI The broadcast session spirit differs from the TISPAN is currently studying an alternative unicast one since media functions are not part of solution where receipt of an IGMP message by the initiation process. However, a session can be an access node can trigger a request to modify a initiated between the UE and the SCF to allow resource reservation. This requires extensions to the later to perform appropriate service checking the RACS capabilities and is known as a "pull" (e.g. user's rights). Moreover, during session procedure. initiation, media parameters related to subscribed channels are exchanged via SIP/SDP messages. This information can be used by the core IMS 4.6 Use of IMS for Network Personal Video for two purposes: Recorder and Time shifting Network Personal Video Recorder (N-PVR) - To build a request to the RACS for allows the user to record a particular live content reserving transport resources in the last-mile and watch it later on. The registered content is segment of the network at service session stored in the network. From a user's point of initiation time. Here, it is worth noticing that view, this service involves two steps: IMS-initiated mechanisms are not sufficient to perform admission control beyond the 1) The user decides to record a live content. access part of the network since multicast Specific interactions between the user flows are shared between users. Additional equipment and the AS are necessary to mechanisms are currently being studied in identify the sequence the user wants to ETSI TISPAN to enable admission control record. Such interactions do not rely on to be applied to other segments of the IMS session-based procedures and may be network. achieved using HTTP. 5
  7. 7. 2) The user accesses the recorded content. 5 Conclusion Since this is a registered content such as a IMS is really promising in terms of IPTV VoD, the procedures described in § 2.1 for services evolution. IPTV session management streaming session initiation apply. re-uses existing IMS procedures with very few adaptations as described in this paper. Because Network Time Shifting (N-TS) allows trick these procedures are identical or similar to those mode operation to be supported on a live used in support of conversational services, this program. This procedure relies on the solution facilitates offering advanced services by assumption that the contents of the live programs combining features from the two worlds. are continuously recorded in the networks for a Moreover this type of solution benefits from certain period of time. Therefore, in order to be mobility management procedures that are able to use trick modes, the user equipment just inherent to the IMS and opens the door to IPTV needs to turn the broadcast session into a service continuity when moving from one streaming session with the server that contains network access to another. the corresponding recorded content. This is achieved by sending a re-INVITE request from IMS-based IPTV will offer a well-standardised the UE to the SCF with an indication of the solution to provide not only basic IPTV but also currently watched channel (since the SCF may quadruple play and enhanced services. It is an not know it unless the procedures described in § opportunity for the IMS to demonstrate its 4.7 are used). When the streaming session is commercial value and will likely be at the centre established, the UE can use RTSP to perform of multimedia services infrastructure trick mode commands on the unicast streams as mutualization. defined in § 2.1. Going back to a live mode is possible and would imply the reverse procedure from streaming to broadcast session. 6 References [1] 3GPP TS 23.228. IP Multimedia Subsystem (IMS); stage 2. 4.7 Presence enablers Presence enablers are already specified in IMS [2] ETSI TISPAN TS 182 027: IPTV but do not currently include IPTV specific Architecture; IPTV functions supported by information. However, existing procedures can the IMS subsystem. easily be used and extended with such information. This is particularly relevant in 7 Glossary broadcast services where the presence feature AS Application Server can be used to publish the channel/program HD High Definition currently watched by the user (See Figure 5). IFC Initial Filter Criteria This capability can be required by particular IGMP Internet Group Management applications combining IPTV features with other Protocol IMS services (see § 2). It could also be used in IMS IP Multimedia Subsystem IPTV IP Television instant messaging applications where a user NASS Network Attachment Subsystem would then be able to see what his/her contacts NGN Next Generation Network are watching (very much like some existing PVR Personal Video Recorder instant messaging applications already enable RACS Resource and Admission Control users to publish the music they currently listen). Subsystem However, in order to cope with numerous RTSP Real Time Streaming Protocol channel-hoppings potentially causing overloads SD Standard Definition in the network, a minimum time interval between SDP Session Description Protocol publications can be set to limit the number of SD&S Service Discovery and Selection SIP Session Initiation Protocol messages sent into the network. SVC Scalable Video Coding VoD Video on Demand User Equipment Access Node CORE IMS AS TS Time Shifting UPSF User Profile Server Function Session initiation already done Join (xcast channel 1) Zapping timer PUBLISH (channel 1) IFC PUBLISH (channel 1) Figure 5: presence for broadcast services 6
  8. 8. IMS and IPTV Service Blending – Lessons and Opportunities Andre Beck, Bob Ensor, Jairo Esteban, {abeck, jre, esteban} Bell Labs Research / Alcatel-Lucent 791 Holmdel-Keyport Rd Holmdel, NJ 07733 Abstract modules is provided through Session Initiation Protocol Blended services are composite services created by combining (SIP) [1] message exchanges with elements of an IP simpler, more basic component services under the control of Multimedia Subsystem (IMS) [2]. Access to the TV coordinating software. The authors have created several services is provided through Hyptertext Transfer services that blend telephony and digital TV service Protocol (HTTP) [3] message exchanges with Hypertext components. The paper presents the major challenges faced Markup Language (HTML) [4] browsers that are part of by the authors as they built these services. It also presents the the service provider software executing on subscriber key lessons taught by these experiences, and it highlights set-top boxes. The coordinating software is unique to opportunities for building further combined telephony-TV each service blend and exchanges messages with the services with even greater efficiency and economy. component services through appropriate protocols. Introduction The paper next introduces the architecture of blended Blended services are composite services created by telephony and digital TV services. It then describes a combining simpler, more basic component services blended service that the authors developed. The paper under the control of coordinating software. For continues by describing the major challenges posed by example, a blended service providing TV viewers with this service’s implementation and the lessons learned by on-screen notification of incoming telephone calls and solving these problems. It ends by noting some the opportunity to handle those calls through remote- opportunities for new blended services and for control commands can be created by combining existing improving their development and deployment telephone call components with TV viewing environments. components. Since component services interact with one another as part of blended services, service blending Architecture of IMS-IPTV Blended Services is a powerful way to create many interesting and To blend IMS telephony services and IPTV services, the distinctive new services. In particular, service blending coordinating software makes use of both IMS and IPTV is a much more powerful means of service creation than architectural elements. The coordinating software service bundling, which is simply the association of one accesses the component service elements through the service with another. interfaces provided by those elements. While the coordinating software could possibly be implemented as Blended services have a common abstract architecture. an element of one or both component subsystems, it can They are built as collections of software modules that be viewed more generally (and more clearly) as a provide the component services plus one or more distinct architectural element. Figure 1 illustrates the modules that create coordinating software. This relationship among the key elements found in the coordinating software provides the blending logic for authors’ blended service implementations. the new service; that is, it controls the interactions of the component services to create the composite service Key IMS Elements behavior. It performs this control by scheduling The IMS architecture is an open standard defined by execution of component functions and by regulating 3GPP and other organizations. It describes an IP core their access to shared data. Development of the network surrounded by various access networks. In this coordinating software is made simpler when base architecture, a request for a call or other service moves components have standard interfaces and when these from a user’s communication device through an access components can be re-used for multiple service blends. network to an IMS instance. The device determines which access network is used for each session request. The authors have created several services that blend For example, when the user makes a call request with a telephony and digital TV service components. Each cellular phone, the access network is a wireless service is built from three sets of components— telephone network. Similarly, other parties involved in telephony service modules, IPTV service modules, and a call or service session are connected to the IMS coordinating software. Access to the telephony service through appropriate access networks. In Figure 1, users
  9. 9. Coordinating Software Interface to IPTV IPTV Elements Interface to IMS Service Components Service Components Video Coordination Web Server Server Infrastructure SCIM TV EPG Stream VoD GUI User Profile Call/Session Data Controllers Signaling and Media Gateways IMS Elements Set-Top Box Alice Bob Figure 1: Key Architectural Elements of Blended IMS-IPTV Services Alice and Bob are connected to an IMS through (which are connected through one or more networks) telephone access networks. and consumers’ STBs. Live content is usually streamed to consumer STBs for immediate display on the When a call/session control request is made, signals and consumers’ TVs. Video-on-demand content also may be associated media move from the access network to an streamed, but it is more often transferred IMS through signaling and media gateways. Within an asynchronously as files, which are stored on consumer IMS, these signals are transmitted as SIP messages. STBs for later display. Service management has two Call/session control signals go from signaling gateways aspects—consumer control of content delivery and to call/session control elements. These control elements management of service subscription records. Consumer examine the call request and determine whether any controls include displays of available content, e.g., applications should be executed in association with the Electronic Program Guides (EPGs), program (channel) call processing. If so, the session control element selection, etc. Management of subscription records invokes application servers to execute the appropriate includes billing and payment, feature subscription applications. Once these applications have been updates, etc. Figure 1 presents a simplified view of executed, the call request may be passed through IPTV service elements, representing each part as a gateways and then through an access network to the single server connected to the consumer’s STB. called party’s device or to call/session control elements associated with the called party (in the same or in Various parts of an IPTV service may be used to create another IMS), which can also invoke application a blended service. For example an IMS-IPTV blended servers. (In the simplified illustration of Figure 1, only service might use IPTV content delivery functions, an one IMS and one set of application servers are shown.) EPG, and IPTV billing and payment functions, but not use IPTV feature update functions. Multiple application servers can be associated with a single session. Call/session controllers can invoke these Coordinating Software servers directly, but have only limited means of The coordinating software for blended services interacts controlling interactions among the invoked applications. with distinct component services, each with its own The IMS specifications include a SCIM (Service interface. In fact, the coordinating software for the IMS- Capability Interaction Manager) function [5], which can IPTV service blends must typically manage support more robust control of application interactions. relationships among messages of multiple protocols. An IMS SCIM behaves as a specialized application Therefore, development of this coordinating software server. It uses SIP to communicate with an IMS can be aided by a specialized software infrastructure, call/session controller and SIP-based application servers which provides a framework for writing and executing to coordinate applications within the context of IMS coordination logic and which handles communications sessions. In Figure 1, the SCIM is shown as part of a between the coordinating software and the component coordination infrastructure (see below). services. Figure 1 illustrates a case in which the coordinating software runs in an environment provided Key IPTV Elements by a coordination infrastructure. In this instance, the Typically, an IPTV service is based on two fundamental infrastructure includes protocol handlers for both SIP— parts—content delivery and service management. used to communicate with call/session controllers—and Content delivery involves moving TV programming HTTP—used to communicate with the IPTV service material from producers to consumers. These data provider software executing on the susbcriber’s STB. transmissions generally involve multiple media servers
  10. 10. often, these interfaces offer service developers Service Blending Example—TV Caller ID application program interfaces (APIs), and they may also have associated software development kits (SDKs). with Call Handling Less frequently, IPTV service elements can be accessed TV caller ID is a service that responds to incoming indirectly through interfaces with the service telephone calls by displaying caller ID information on subscriber’s STB. (This case is illustrated in Figure 1.) the subscriber’s TV screen. The authors implemented a version of this service that also lets subscribers control The authors created a software module to provide the the handling of these incoming calls; subscribers issue coordinating software with a single interface for call control commands using their STB remote controls. multiple IPTV service implementations. This module, The call control commands provided by this service which is called the IPTV interface client, provides a include signals to accept the call and to send the call to common abstraction of various IPTV components, voicemail. thereby insulating the coordinating software from the differences among these base systems. The client This service blend demonstrates how events originating manages input/output for the service subscriber; it in the IMS service domain (e.g., an incoming call) can creates information displays for subscriber TV screens trigger actions in the IPTV service domain (e.g., TV and collects commands entered through subscriber STB screen-based menu displays). It also shows how events remote controls. The client communicates with originating in the IPTV service domain (e.g., a remote coordinating software through HTTP message control command) can trigger actions in the IMS service exchanges. domain (e.g., call routing decisions). Finally, it illustrates how events from the two service domains can In its most general form, the IPTV interface client interleave. For example, if the subscriber picks up the would abstract IPTV services, whether accessed through phone while the caller ID is displayed on the TV screen, IPTV APIs or subscriber STBs. However, the authors the incoming call is answered and the message is did not build an IPTV interface client to interface with removed from the screen. proprietary APIs. Instead, they developed an IPTV interface client that interfaces with various subscriber The authors have implemented this IMS-IPTV service STBs. This client is based on the Web (HTML) browser blend using commercially available IMS and IPTV found in most IPTV STBs. These browsers are used by components. The implementation is based on service service providers to render a graphical user interface on logic coded within coordinating software, which, in the subscriber’s TV. For example, IPTV service turn, makes use of the component IMS and IPTV providers often implement their EPGs as Web service instances. applications. This approach to building the interface client provides an abstraction of STBs since the client is written to Web standards such as HTML and JavaScript. IMS Software Component IMS specifications provide well-defined interfaces Coordinating Software between application servers (including those that act as In the authors’ service implementation, the coordinating SCIMs) and core IMS elements (including call/session software executes on the Alcatel-Lucent Service Broker. controllers and media resource controls). The This platform acts as a coordination infrastructure by coordinating software in the authors’ service providing a framework for the definition and execution implementation uses these standard IMS interfaces to of the service blending logic of the coordinating access session state descriptions and necessary media software. It also helps the coordinating software resources for controlling call progress during blended communicate with the remaining software by providing IMS-IPTV interactions. Meanwhile, call/session SCIM capabilities and handling key protocols, including controllers within a component IMS evaluate SIP and HTTP. expressions from the user profile data to determine when to send messages to the coordinating software. With the support of the Alcatel-Lucent Service Broker, the coordinating software provides the blending logic to IPTV Software Component • bridge functions from IMS and IPTV service IPTV service implementations are not standardized, nor elements, are they constructed to a standard functional • coordinate processing of SIP messages architecture. Blended services that include IPTV (associated with telephone calls) and HTTP elements must use the interfaces and functions provided messages (to/from service clients in the IPTV by the component IPTV service. Typically, IPTV domain), and service elements are accessed through proprietary • keep track of telephone call state during service interfaces supplied by IPTV service providers. Most invocation.
  11. 11. Single Web Browser Window Challenges In order to insulate the IPTV interface client from the The authors’ implementation of a caller ID blended IPTV service provider software, the authors originally service created several noteworthy challenges. Most of intended to use separate windows for displays of caller these problems were created directly or indirectly by ID information and displays of IPTV service provider nonstandard interfaces of the IPTV service component. information. However, many STBs have limited More precisely, they were created by the authors’ processing power, and their Web browsers typically attempt to avoid basing blended services on proprietary support only one window. IPTV APIs—an attempt that led them to build the service with an STB-based Web client. This restriction forced the authors to use a single window for both the IPTV interface client and the IPTV Web Push service provider code, and, at the same time, prevent unintended interactions between these modules. The Web applications typically follow a pull model in which authors solved this problem through the use of an users, through their Web browsers, request data from IFRAME, an internal frame that provides a distinct Web servers. However, in the caller ID service, display region within a Web page. The IPTV interface telephony events must be sent to subscriber STBs client creates an IFRAME for the display of caller ID asynchronously (i.e., without explicit Web requests information, thereby maintaining some separation from from the subscribers). Hence, the authors used a Web IPTV service displays. Unfortunately, IFRAMEs are not programming technique that is commonly known as supported by all STB Web browsers; therefore, the “Web Push.” With this approach, the Web browser current IPTV interface client implementation only runs behaves conventionally; it establishes an HTTP on a subset of the available browser-based STB models. connection to a Web server. However, the Web server not only accepts the connection but also keeps it open persistently. It then uses this persistent connection to Cross-Domain Scripting Limitations send asynchronous events to the browser. In this Web browsers typically limit the ability of Web blended service implementation, the coordinating applications to manipulate properties of Web pages that software (executing on the Alcatel-Lucent Service are retrieved from different domains, which is Broker) sends JavaScript commands to the STB’s Web commonly known as cross-domain or cross-site browser. In the case of an incoming call, for example, scripting. The cross-domain scripting limitations of the the coordinating software sends a JavaScript command STB Web browser provide a challenge to service to the STB that contains the phone number and name of blending. Since the IPTV interface client receives the calling party and triggers the display of the caller JavaScript commands from the coordinating software, ID. the STB Web browser prevents this code from manipulating Web pages from other domains, e.g., those To ensure that the STB creates an HTTP connection to from the IPTV provider’s Web server. While the Web the Alcatel-Lucent Service Broker, appropriate actions browser considers the IFRAME that contains the caller must be performed by the STB Web browser. During its ID display to be part of the IPTV domain (because the boot sequence, this browser automatically loads a pre- JavaScript code to create it was called from the IPTV configured home Web page, which is typically created service provider’s home page), it considers JavaScript and managed by the IPTV service provider. To generate from the coordinating software to be part of a different the necessary actions by the browser, the authors domain. The authors were able to work around this modified the IPTV service provider’s home page limitation with the help of JavaScript statements that (thereby creating a dependency on this page). The declared the IPTV service provider Web pages and the inserted JavaScript causes the browser to load the IPTV coordinating software Web pages to be part of a single interface client code from a specified Web server. sub-domain. The author’s easily added this statement to the coordinating software Web pages. However, they To maintain this connection, messages must be were also forced to add this statement to each IPTV exchanged periodically between its endpoints. The service provider Web page that contained JavaScript. IPTV interface client on the STB and the coordinating These later modifications introduced another software on the Alcatel-Lucent Service Broker dependency on the provider’s software that the authors exchange heartbeat messages and check to detect loss of had sought to avoid. connectivity. Upon link failure, the IPTV interface client reestablishes connectivity. This client reconnects Interference between ID Displays and IPTV Content with the original connection parameters, resulting in a When the blended service displays a caller ID over the transparent operation to the end user, with no re- subscriber’s currently displayed IPTV content, the authentication required. service blend is interfering with one of its component services. The caller ID information obscures at least
  12. 12. part of the IPTV content, and the associated call- Security handling menus intercept remote control events— Security of a distributed service is based on control of temporarily blocking commands for the underlying the flow of information between service elements (both IPTV service. To address this problem in their computing and data servers) and service subscribers. implementation of the caller ID service blend, the The security of a blended service also involves the flow authors used the operations provided by software on the of information between the coordination software and subscriber’s STB. In one case they created a full-screen component service elements. These component window for the caller ID information and menu elements may have their own distinct security displays, allowing the underlying video to show on mechanisms; therefore, the coordination software might selected portions of the screen. This technique is be required to manage interaction of multiple security enabled through the chroma key operation provided by domains using multiple mechanisms. the STB core software. In a second case they used a small window to display caller ID information and To control information flow between service elements menus; the video underlying this screen region is visible and service subscribers, subscribers must be reliably with partial transparency. This approach is enabled identified. IMS user identification and authentication through alpha-blending operation provided by the STB mechanisms are standardized and, in the author’s IMS- core software. In a third case, both chroma keying and IPTV service blend, work with the coordinating alpha-blending were used. In each case, the core software within a SIP domain. IPTV user identification software is accessed through proprietary JavaScript and authentication are not standardized; therefore, the extensions provided by the STB vendor, which, author’s coordinating software had to be modified to unfortunately, creates STB-specific commands within work with the security mechanisms and policies of each the IPTV interface client. component IPTV service provider. In one case, the IPTV service provider associated each subscriber with a Scalability static IP address of a STB. This approach was The authors’ blended service implementation was transparent to the subscriber. In another case, the designed to support large numbers of subscribers subscriber was prompted to enter an ID and password, economically. In particular, the coordinating software which caused some subscriber inconvenience. and its infrastructure—the Alcatel-Lucent Service Broker—should not add inordinate equipment cost or IMS user authorization mechanisms are also performance penalties to the underlying telephony and standardized and offer applications well-defined television service platforms. Only modest computing interfaces to user descriptions. ITPV authorization resources are needed to support the coordinating mechanisms are not standard; many approaches to software and its infrastructure; therefore, the equipment storing and accessing service-related data are available. cost is not a problem in large-scale deployment of this For their IMS-ITPV blended service, the authors were blended service. able to use a single database for various ITPV service components. The authors measured resource requirements and performance capabilities of their service blend. The The coordinating software of a blended service must bandwidth needed between the Alcatel-Lucent Service interact with the security mechanisms of the component Broker and the component telephony and IPTV servers services. Typically, the coordinating software will be is very small; that is, the message load on these viewed as an external agent by one or more of these connections is minor. The processing load of the component services. In the case of the authors’ blended coordinating software is also modest. This load is service implementations, the coordinating software is generated primarily through message processing, and it viewed by an IMS as part of its security domain, but it is easily handled by the processors on which the is viewed by the IPTV service elements as outside of its coordinating software executes. The memory required security domain. Therefore, this coordinating software for message input/output was a limiting resource in the and the IPTV service elements viewed each other with initial blended service implementation. The memory mutual distrust. To overcome this problem, they needed by the individual message buffers and link status communicated through a mutually trusted security data structures in the first version of the system was gateway that was established by the IPTV service overwhelming. In the straightforward use of one provider. particular Java environment (Java 1.4 on Sun workstations), the authors measured a memory Lessons and Opportunities allocation of 20KB for every connection, i.e., An obvious theme of this paper is that blended services approximately 200MB for 10K active subscriber are more easily built from components that have connections. By avoiding Java OutputStream operations standard interfaces than from those that lack such and writing messages directly to sockets, the authors interfaces. The caller ID service, which blends IMS and eliminated this excessive memory use.
  13. 13. IPTV components, clearly illustrates this lesson. With a Their coordinating software required only a single well-specified interface between IMS core signaling interface module to interact with multiple IMS elements and application servers, the authors’ instances. They had more difficulty accessing IPTV coordinating software was able to interact with multiple service components. They attempted to create a single IMS instances through a single interface. On the other interface module within their service’s coordinating hand, the lack of standard interfaces between IPTV core software to interact with a non-proprietary IPTV elements and external servers prevented the authors component—Web browsers executing on subscriber from building a single interface between the STBs. However, the authors discovered that they coordinating software and IPTV service components. needed to use proprietary features of these browsers. Furthermore, the authors were not able to build a single Furthermore, they needed to modify proprietary Web interface to subscriber STB-based Web browsers pages to implement their IPTV service interfaces because these browsers lack a standard interface for through the Web browsers. their video operations. Standardization of the interfaces to current IPTV service A standard means of interfacing between IPTV core capabilities and to enhanced capabilities would promote elements and outside servers would create an the development of new TV services and service blends. opportunity for developers to create—more This standardization would create significant new economically—many new blended IPTV services. opportunities for the growth of the IPTV market as well Similarly, a standard interface to STBs would also as associated markets, e.g., IMS and Web applications. promote development of many more digital TV services and blended digital TV services. An encouraging References achievement in this area is the OpenCableTM Application [1] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Platform (OCAPTM) [6] standard currently being adopted Johnson, J. Peterson, R. Sparks, M. Handley, by many cable TV service providers. and E. Schooler, “SIP: Session Initiation Protocol,” IETF RFC 3261, June 2002, Extensions to current IPTV service interfaces would provide additional opportunities for new blended [2] 3rd Generation Partnership Project, “IP services (and, if they were standardized, would make Multimedia Subsystem (IMS), Stage 2 building these new service blends simpler). For (Release 6),” 3GPP TS 23.228, v6.4.1, Jan. example, IPTV service interfaces could make more 2004, information available. As a more particular example, if info/23228.htm subscriber presence information (e.g., the identity of a [3] “Hypertext Transfer Protocol,” IETF RFC TV viewer) and the identity of the currently viewed 2616, June 1999, channel were known, then caller ID displays could be precisely targeted for each user in a household and [4] HTML 4.01 Specification, could be restricted to occur only during the viewing of specified content. [5] 3rd Generation Partnership Project, “Network Architecture (Release 6),” 3GPP TS 23.002, IPTV service interfaces could also be extended through v6.7.0, Mar. 2005, protocols to handle interactions with various new devices. For example, these interfaces could be info/23002.htm expanded to include BluetoothTM [7] protocol handlers. [6] OpenCableTM Platform, Such extensions would allow new ways of interacting with IPTV services and also allow new service blends to [7] Bluetooth, be built. For example, Bluetooth cameras and microphones could be used to create a service that blends video conferencing and TV viewing. Summary Blended services combine more basic component services through coordinating service logic. They offer means to create new and interesting services economically by using existing service elements. The authors built a blended service that combines elements of telephony and IPTV services. They were able to access telephony service components through a standard SIP interface, which was provided by IMS instances.
  14. 14. Next Generation TV – the next step of user experience Łukasz Luzar, Adam Honek Telecommunication Unit - Comarch S.A. Al. Jana Pawła II 39a 31-864 Krakow, Poland TV set in the form of any of the devices mentioned 1 Introduction above. Consequently, joint TV viewing will become an old trend while individual viewing will take center Next generation television is approaching. After the stage. This opens up the possibility to watch and boom of Internet services, TV is again set for becoming comment on the same content individually and interact a center of home entertainment. We are fast with our community friends online. approaching the beginning of a new television era – the era of interactive TV where a user is no longer only a Such a user centric TV trend will give huge possibilities spectator, but takes participation in content generation for advertising companies because it will now be and becomes a vital organ of the TV ecosystem. This possible to enable user specific commercials targeting. television based on Internet protocols is accessible not only through TV, but also PCs, PDAs, mobile phones and soon other personal devices, such as personal DVD 2.2 Device & network convergence or MP4 players. Meanwhile, we can also observe Many years have passed since engineers built the first progress in convergence of IP networks and devices. TV set. This not so trivial device has come a long way These trends give service providers unlimited since then. Progress over the last couple of years has possibilities for innovating. also been significant. Current TVs have sophisticated hardware inside them and offer large and colorful and 2 NGTV fundamentals high-quality displays that are now even wall mountable. TVs are no longer only content receivers – they can be enriched with the use of IP Set-Top Boxes (IP-STBs). By Next Generation TV (NGTV) we understand an With an IP-STB it is possible to offer premium services interactive, IP-based television that can be delivered to subscribers and extend beyond the capabilities of over IP-networks to any IP-enabled device that can act standalone TV’s. as a video-terminal. We can recognize the following devices: While talking about devices that can be used for watching TV, we see that from a business point of view • TV-set with IP-STB they are becoming very similar. Screens have become • 2,5G/3G mobile phones up to 24bit colorful with only their resolution and size • PDAs still different. Some of them can only play the role of a • Personal DVD/MP4 players video-terminal, while some generate the content view • Personal Computers (PC) based on received data, separate to just audio and video. • Video-glasses connected to a PC or a palmtop It seems that for most TV-based services, a typical • Video-kiosks (publicly accessible video- QWERTY keyboard will not be required anymore. All terminals) operation will be performed by a simple numeric keypad and/or pointing device. The TV signal, content and services can be delivered via PSTN, cable, satellite and OTA broadcast to a super head-end or regional head-end before being later delivered as IPTV using IP. The return path required for interactive services is also IP-based which utilizes either Cable DOCSIS or PSTN DSL modems. From the business point of view, the displays capabilities become nearly identical. 2.1 Personal & Interactive TV The same trend is visible in communication between devices. Using IP-based networks it is possible to Due to interactivity, individual content expectations and establish communication between various TV devices. the multiplicity of potential TV terminals, television For example, it will be possible to integrate a fixed will become user centric. Currently, people often sit in PSTN telephone line with a TV set. A user sitting in front of the TV screen to watch channels together. Soon, front of a TV connected to an IP-STB with a webcam, everyone will have the option to use their own personal
  15. 15. will be able to dial a number to a user with a mobile phone, and connect via a video-call. Technical ways of content and services delivery will vary depending on terminal types, content distribution concepts and utilized networks. It is also expected that hybrid methods will appear that for example combine DVB-H and IP. Currently available delivery modes are IPTV, Internet TV, and Mobile TV. Internet TV is usually delivered in two modes: • Centralized – where all content is streamed Sample TV ecosystem from a central server, usually through a dedicated network, We can sensibly state that NGTV will become an • Peer-to-peer – where there is no central global equivalent of the Internet, but such where all content content repository and instead content is and services distribution feature revenue flows as an transmitted over the network in a p2p manner. intrinsic part. It means that network operators will no longer be distant from revenue generated by content and Mobile TV uses a central repository located as part of service distribution over their networks. the mobile operator’s infrastructure either in the super head-end or over various regional head-ends to improve As a result of NGTV, Advertising Companies fall into a coverage, maintain QoS and support area wide load comfort zone to offer NGTV Operators the commercial balancing. . content that particularly addresses the tastes of NGTV subscribers increasing the market impact that these For personal computers, smartphones and IP-STB’s, commercials deliver. NGTV Operators can use profile IPTV content is usually delivered via a DSL enabled data collected about its subscribers to form close joint PSTN line employing copper twisted pair cabling, a ventures with Advertising Companies that take variant of fiber optics (FTTC, FTTB, FTTH ) or a Cable advertising to new levels. broadband DOCSIS connection. Additional roles which will also be formed in TV 2.3 The NGTV ecosystem ecosystem are: • Content aggregators When we look at the future NGTV market, we can • Service aggregators recognize the following roles: Users, NGTV Operators, • Copyright operators Content Providers, Service Providers and Advertising • TV Backbone Carriers Companies. 2.4 The Virtual NGTV Operator Users subscribe to a TV service offered by an operator. Due to natural business desires, large Internet Portals They usually pay monthly fees as a result and all will be interested in participation within a NGTV payments for premium services are also directed to their ecosystem. They can do so by offering their content monthly bill. over an existing NGTV operator’s infrastructure. Such entity we call a Virtual NGTV Operator. Users can NGTV Operators are those Telco operators, who offer become subscribers of a Virtual NGTV operator where NGTV services to their subscribers. We can recognize in fact the service is delivered through a network the following operators that can become an NGTV operator, which itself already may too be a NGTV Operator: PSTN Operators, Internet Service Providers, Operator. In such case, subscribers sign a contract Mobile Operators and Cable TV Operators. agreement with the Virtual NGTV Operator while it in turn shares revenue with its network operator. Content Providers cooperate with multiple NGTV operators and help them deliver a comprehensive 2.5 Who holds the power? offering to their users. They usually provide TV channels, movies, music, audio books, e-learning When we compare NGTV to the Internet, we can see materials, etc. that a characteristic feature of the NGTV’s ecosystem is a closed-circuit business model. All services available to subscribers are delivered by an operator. The operator also decides about the offer its subscribers may receive.