The Advantages of Broadband Services

Transcription

1 Broadband Services Using Databroadcasting and Point-to-Point Networks Hans-Jörg Vögel, Peter Krummenacher, Erik Troelsen The Fantastic Corporation, Tel , Abstract. An ever-growing demand for rich multimedia services puts enormous strain on servers and transport network under the current centralized delivery paradigms of the Internet. Consequently, they often fail to deliver a broadband user experience. Delivery models based on digital broadcast transport mechanisms can effectively bypass these bottlenecks. Broadcast networks are able to efficiently convey large volumes of data, delivering it either directly to end-consumers or replicating it across servers and caching engines, which are deployed at the network s edge for the scalable delivery of this content. Such a combination of broadcast services and point-to-point access to information residing in entities on the network edge is considered the ideal environment for the definition and delivery of new service offerings, effectively combining push- and pull- models for the delivery of a rich multimedia user experience, including live-streaming events and on-demand services. This paper defines broadband services and then describes the enabling technologies involved in realizing that experience. We continue discussing the aspects involved in broadcast and point-to-point delivery models, raging from transport issues, to functionalities required in the aggregation, playout and caching/storage domain. Broadcasting requires scheduling and bandwidth management mechanisms. Subscriber management, protection and billing functionalities are required for broadcasting services as well as for point-to-point delivery services. We conclude by describing a fully converged network with the IP protocol as the central layer of convergence and describe its applications in a special realization of the Multimedia Car Platform project of the European commission. 1 Introduction Content owners and network operators on the Internet are faced with an increasingly difficult task: to offer compelling services while satisfying an ever-growing demand for rich multimedia. This demand puts enormous strain on central servers and the transport networks, often resulting in a disappointing user experience that doesn t live up to the expectations of a Broadband access link. The answer in the Internet so far lies in the deployment of content distribution networks, putting the content on serving and caching engines on the network edge close to the user. This then speeds up individual web access and reduces Internet bottlenecks, but also requires content to be efficiently replicated across a large number of servers. Effectively bypassing these bottlenecks are delivery models based on digital broadcast transport mechanisms. These broadcast networks offer a broadband, always-on stream of information, be it video/audio or data. They are very well suited for scalable delivery of high-quality services like live audio-video streaming to a mass-audience. Moreover, 1

2 through their high data rate and constant availability, broadcast networks are able to convey large amounts of data, which at the end-user side can provide a very rich multimedia experience. When locally cached, these data are instantenously available upon user request with a minimum of further latency. The caching appliance can be deployed in the end-consumer s home as well as within the access network, making the network edge a floating concept offering some flexibility. Therefor, broadcast networks not only can serve as a content delivery network for broadcast content, they can also provide efficient distribution services for the future broadband version of the Internet s content delivery networks. Push-delivery services based on broadcast transport are an efficient means to distribute large volumes of information to a mass-audience concurrently. They scale very well, if this is information shared by all consumers, even when profiling techniques are being used to personalize the set of information. On-demand and transactional services can be implemented through the pull-delivery paradigm best served by telecommunication networks, however. Therefor, a combination of broadcast transport and point-to-point access to information residing in entities on the network edge is considered the ideal environment for the definition and delivery of new service offerings, effectively combining push- and pull- models for the delivery of a rich multimedia user experience, including live-streaming events and on-demand services. In this paper, we define broadband services and then describe the enabling technologies involved in realizing that experience. We continue discussing the aspects involved in broadcast and point-to-point delivery models. Beside the transport issues, there are functionalities required in the aggregation, playout and caching/storage domain. Broadcasting requires scheduling and bandwidth management mechanisms, whereas content providers want to be able to pro-actively manage the content on remote edge devices and retain full control over who gets access to what and when. The same or similar subscriber management, protection and billing functionalities are required for broadcasting services. We conclude by describing a fully converged network with the IP protocol as the central layer of convergence and describe its applications in a special realization of the Multimedia Car Platform project of the European commission. 2 Broadband services There are many services and applications that come to mind when speaking of broadband systems. The term comprises high-bitrate backbone transport and routing services, as well as rich multimedia messaging, high-performance content replication, audio-video streaming offered by Internet Service Providers, and also as dedicated an application as videoconferencing in companies. Virtual universities, distance learning, powerful corporate presentations, multimedia guidance services, car entertainment, virtual city tours, and networked gaiming are only a few more examples to illustrate the buzzwords of the broadband domain. One should emphasize though, that the term broadband must not be used in an Internet-focussed fashion alone, as currently is mostly the case. Broadband applies as much to television broadcasting as well, as it does apply to all other areas mentioned above. There, broadband is a term classically used when referring to the television cable infrastructure, but with the advent of digital broadcasting also is being used to describe the sheer physical bitrate of the transmission channel. This 2

3 also is the usage of the term broadband in the telecommunications domain, usually meaning a channel data rate of at least 2 Mbit/s or above. But what really is broadband? When looking at all aspects, broadband is not only a bitrate or an application alone. And certainly, it is much more than just faster Internet. It is all of that and none of that basically, we like to call it a user experience. This user experience is composed of a number of factors: live streaming video and audio of superior broadcast quality, large amounts of data (including stored audio-video) and software packages being available with a minimum of access latency (preferrably subsecond, but in any case lower than the average web page response time of 4 to 7 seconds), and on-demand services (pull) paired with the sensory experience, drama and emotion of broadcasting (push). And of course, all needs to be carried on an access network providing the necessary throughput (Fig. 1). Pull Services Push Services Video on Demand Service Cached Content Service Live AVS Storage Streaming Access Network Fig. 1 Broadband services classification It should be noted, that with ongoing evolution in signal processing and source coding methods and the continuing progress in processing power, the threshold bitrate necessary to deliver a broadband experience is sinking. Nevertheless, a rapidly growing number of subscribers and an exploding range of applications and services cause the bandwidth demand to rise, overall. 3 Converged broadband content delivery With the penetration of digital, broadband access networks constantly growing, we finally start seeing and ever growing diversity of services and applications. This development is facilitated by digital networks evolving from service-specific, dedicated systems (e.g. fixed/mobile voice networks, data networks, broadcast networks) towards generic, service-independent platforms. Network operators, therefore, need to closely cooperate with content creators and service providers to make the most compelling use of their network s capacity. These need to create compelling content and applications to serve the growing and challenging demand. This will on the one hand lead to a highly fragmented value chain, with a multitude of players. Content will be king and branding will be a must to differentiate offerings from a competitor s. On the other hand, these 3

4 applications and the corresponding rich content cannot be served from a single, centralized server any more, like it they used to be in the traditional Internet model. For scalability and performance reasons, they need to be moved close to the user requesting them, to be replicated across a large number of physical hosting locations and to be served from the network edge. This drives the further development of content delivery network services, as they already have started to appear now for a couple of years for improving and speeding up traditional Internet services. A new type of service provider has appeared, offering content delivery and distribution services to content providers, enabling them to efficiently resell high quality content to consumers, accessing it from the nearest hosting point on the network edge (Fig. 2). Provides raw content Aggregation, DRM,... Content Creator Content Provider Content Consumption Subscription, Billing,... Consumer Single Point of Contact Operate CDN components Provide CDN Service CDN Distribution Provider Operator Services Service Provider Provide Distribution Telco Capacity Network Operator Operate Access Network Fig. 2 Roles and relationships in content delivery Access Network Subscription These content delivery models will be refined and enhanced in the future in order to be able to accommodate truly broadband services. Traditional broadcasting companies are considered to be among the prime users of these broadband content delivery services or even operating their own broadband content delivery networks, constantly seeking out new ways to re-sell valuable content and re-package it in new services and delivery models. This valuable, high quality content needs not only a broadband distribution network with its replication, distribution and hosting services, it also needs protection with encryption and rights management functionality as well as efficient mechanisms to bill for its distribution and consumption (Fig. 3). 4

5 OAM (reporting...) Billing Integration with DRM... Replication Distribution User Redirection CDN network operation Fig. 3 Elements of content delivery 3.1 Content Aggregation After its creation, the raw content needs to be aggregated for delivery. This involves the usual steps of encoding or transcoding, of publishing and framework integration. Watermarking and rights management data need to be added and the proper measures to protect against unauthorized consumption and copying of the content. Content aggregation also involves the management of assets and the integration of authentication and certification mechanisms. Of growing and in the future highest importance during the content aggregation will be the capability to add and handle metadata. In addition to multimedia content (e.g. pictures/videos, audio, product descriptions, animations, prices etc.), additional information may be embedded in the content as metadata including preferred broadcast times, number of repetitions, expiration date, geographic area of broadcast, size of files, content rating, billing currency, content duration, and required bandwidth. Once an endto-end metadata signalling mechanism has been introduced and properly standardized, basically any information can be conveyed together with content. This metadata controls and enhances the content delivery and distribution process. 3.2 Playout, transport, caching ad storage As mentioned above, we believe the ideal vehicle for broadband multimedia distribution to be a hybrid combination of broadcast and point-to-point networks. There are a number of transport technologies either already available or currently under development, facilitating these scenarios. Among them are Digital Video Broadcasting DVB, 3rd generation mobile, Digital Subscriber Line xdsl, broadband coaxial cable and a number of others. Play-out of multimedia content must seamlessly support a mixture of streaming, cached, schedule-based, location-based, narrowband and broadband content. The enduser should experience a seamless service and not be aware of the different delivery networks involved. Content may either be streamed from the network head-end, or directly from the Content Provider (in the case of a live sports event). Content may also be sourced from access network cache, or from a local cache installed in the endconsumer premises, like e.g. a set-top box, home gateway or even a car s dashboard. Content from all sources may be combined into a single presentation. A few examples: 5

6 Pure walled garden: an interactive city guide is pre-loaded into a car s cache and is browsed locally by the driver and passengers. Connection to the hybrid network is not required after the download. Pure live stream: a live event is monitored by video camera at source, and is encoded and broadcast over the hybrid network and streamed in real-time to the clients. Pre-recorded live stream: a pre-recorded video is broadcast over the hybrid network and appears as a live uninterrupted stream on the client. Reliable delivery: for m-commerce applications where the high reliability of the download is critical (e.g. download of software), a mechanism for data integrity check, and request for re-transmission of corrupted data is necessary. This can be achieved in conjunction with the upstream channel. Mixture of narrowband and broadband content: could consist of a streaming window surrounded by interactive buttons, and a chat window. This page consists of content provided by the broadcast channel (streaming video), integrated into a page containing web content (chat window) and locally cached content (the page framework and hyperlinks). These examples illustrate, how the various push- and pull-components can be combined to deliver a completely new user experience. The remaining chapter will be used to describe a specific research initiative currently underway in Europe to investigate on the prospects of delivering multimedia services over a converged, mobile, fully IPbased network. 4 The Multimedia Car Platform network The Multimedia Car Platform network is based on open network architecture. DAB, DVB-T are examples of broadcast systems and GSM/GPRS, UMTS are examples of mobile telecom systems. All radio access systems in MCP can tunnel IP packets, multicast as well as unicast. However from a spectrum point of view multicast to n users in n times more spectrum efficient with DAB/DVB-T since with these systems multicast can be transmitted using broadcast whereas with telecom systems multicast has to be transmitted via n parallel point-to-point connections. For individual point-to-point communications especially DVB-T offers great capacity and efficiency compared to the telecom systems, because of the large bit rate offering large trunking gains and because of the asymmetry economical area coverage. The system will be simulated and implemented in various test beds for verification, evaluation and demonstration. Fig. 4 shows the MCP Network Reference Architecture. 6

7 The MCP Network is thought as a communications portal offering transport services to Service Providers and to Users, in a way that they are unaware of the technology used to reach the User. The system itself decides how to route the information depending in the current profile of the user (e.g. DAB reception plus GSM connection, or DVB reception plus UMTS connection, and so on...). MCP is as much as possible based on existing protocols and standards (the basis is the TCP/IP stack), but some MCP specific protocols and interfaces (of a higher level) are necessary to communicate all the MCP Servers. We have to take into account that one advantage of the MCP Network is that it keeps track of the current user profile. That means that the user is characterised by a particular profile, like: User has DVB-T reception, UMTS and GSM coverage, but it could change during the day and the profile could change to: User has only UMTS, or User has DAB and GPRS. It also knows where is the user, at least roughly. That permits the system route information coming from a SP to the User without the SP to know how to really reach him/her. MCP Network Traf fi c Ot her MCP I CN DAB BAS DAB cell TV Home Location Register Visit ed Location Register DAB BAS DAB cell Radi o ISP News IP N E T W O R K MCP ICN IP N E T W O R K MMS TS IP N E T W O R K GSM CAS DVB BAS DVB BAS GSM net GPRS net DVB cell DVB cell MCP I nteractive Termi nal( s) Tourism UMTS net Ot hers Ot her MCP I CN Service Providers Fig. 4 MCP Network Architecture 5 Conclusion We have illustrated our view of how converged broadcasting and point-to-point networks serve to deliver the next generation broadband user experience. We outlined a number of aspects in defining a complete content delivery network for broadband 7

8 services and finally described a fully converged network currently in its infant early research stage. This example highlights, how the Internet Protocol IP can be used to integrate content delivery across several physical networks to define a platform for efficient combination of push- and pull-delivery services. 8