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volume 5
april 2002

The Networked Digital Home


  Gateway to the future?
by David Baillie and Kenroy Francis
  Much has been written on the convergence of computer, communications and consumer electronics in the home of the near future. Everyone seems agreed that it will happen. We also know all the benefits we will enjoy: high-speed Internet access, video-on-demand (VoD), pausable multi-channel digital TV and intelligent tele/videophone links — all available in every room in the house. What is not certain is how this infrastructure will be enabled in what is set to become a lucrative market for consumer electronics companies. David Baillie and Kenroy Francis investigate the issues of the Networked Digital Home.
1 Bringing the world to your front door. In defining the Networked Digital Home (NDH), the bricks and mortar building in which we live becomes a shell housing the amount of complex electronics which twenty years ago would have been deemed science fiction. This electronic equipment enables us to tap into a worldwide infrastructure capable of delivering a wealth of digital content to our homes. The precise nature of the equipment that will make up the NDH is a matter of much conjecture but it is possible to outline the basic shape and make one definite statement. The shape will involve multiple pipes of digital information — by which we mean everything from voice to video, including data — entering and leaving the home at a single access point and being distributed to many interface devices around the building. The definite statement: all the essential areas of advancement — reception, decoding, transcoding, encoding, storage and transmission — will be enabled by increased integration of silicon integrated circuits (ICs).
  The mechanisms for delivering digital content to the home are via satellite, terrestrial broadcast, cable, and digital subscriber lines (DSL). All are broadband pipes. Though not a two-way pipe yet, it is worth remembering that satellite is one of the broadest pipes available for content delivery and is being combined with POTS technology to provide a back channel. DVD is also a high volume method of content delivery, it just happens to come in big packets of approximately five gigabytes, delivered irregularly via purchase or rental.
  Whether the NDH employs a satellite, DSL or a cable pipe is a variable that may not be down to choice. Geographical constraints may leave many users ultimately without much option. If the choice is available, then the user picks the flavour to match his or her demands. For video without interactivity, satellite provides the best option. For fast Internet access, opt for DSL. Internet access and multichannel interactive broadcast content lend themselves to cable. There is one other interesting option for DSL if both it and cable are available: it can be used to augment satellite. Fast Internet and Video on Demand (VoD) is a key offering, and one that is better suited to a terrestrial and satellite partnership. Although this is a hard sell in terms of infrastructure costs, adding a dish and front end to a box will give tremendously fast access. For those countries with a large satellite distribution in place this could be available within the next few years.
2 The heart of the Networked Digital Home. The heart of the NDH is the gateway that is, in essence, an adaptation point from the broadband pipe to the networking infrastructure and consumer devices in the home. This device can accept digital streams in multiple formats; decode them for use; store them as appropriate; and transcode them into other formats that can be transmitted to, and decoded by, other devices around the home. Why such a functionally demanding piece of equipment is required can be illustrated by looking at some typical situations.
  We can see how a gateway operates when comparing DSL to satellite as a fat pipe for delivering content to the home. DSL will struggle with a single broadcast quality channel over a commercial service line, let alone a consumer line. Set top boxes (STBs) today are based around the MPEG2 coding standard, which requires a throughput of between two and three megabytes per second to deliver broadcast quality content. The challenge currently is that DSL and MPEG2 are not well matched, so MPEG4 is being considered as the likely coding format for DSL. While MPEG4-coded content theoretically could now reach the home, the vast majority of decoders are still MPEG2. So do consumers have to throw all that equipment away? No, intelligent hardware is utilised that recognises and transcodes from one format to another so that the home can deal with it. This is the first and key role a gateway must perform. Another example is if MPEG2 is streaming in from a satellite but the consumer wants to view it on a 3G handset. In this converse situation the gateway obviates the need to transmit an indigestible three MB/s datastream to the phone by transcoding from incoming MPEG2 MP@ML to MPEG4 SP@L1 to view the content.
  So the home gateway offers multiple interfaces for all content delivery methods, allowing the user to select the source. This is technically very demanding and requires some clever electronics to achieve. But the role of the gateway does not end with the manipulation of high-speed data. It will also be required to incorporate storage, initially on hard disk, but in time will employ optical technologies. This aspect of the device is important for adoption. The user interface on a hard disk is impressive. The ability to search, sort and access content is a compelling power. So both in the context of the gateway and selected terminals there will be storage, whether for audio, digital stills or digital video files.
  In fact, the mechanism for delivering content to the home will influence the development of the gateway. If an always-on connection such as DSL is adopted, main storage may well run to the hundreds of gigabytes and so is likely to be held at the head end by the service provider. Consequently, the gateway is referred to simply as an "access terminal" within the telecom industry and its role ends with the delivery of content around the home to the smaller, less powerful terminals, whether they be television STBs, games consoles or mobile communication devices. Within this scenario the silicon providers — the manufacturers of the chips that make all this possible — remain agnostic. While the formats and adoption patterns are uncertain, what is crystal clear is that as convergence increases so to will the need for integration of data coding and transport capabilities.
3 Future styling. Because of the interest groups involved, the nature of the gateway and whether it is most likely to evolve from today's PC or another emerging consumer device is a matter of some debate. However, convergence will probably mean that this argument is irrelevant in the long term. The NDH will be very different to how we view the technology today and in twenty years there will be no perceived difference, as the gateway will have adopted the best elements of both worlds.
  In the short term, the gateway format could depend simply on whether it is purchased through a specialist PC vendor or from the high street retailer. The home entertainment solution is likely to diverge from the PC-centric solution by providing a greater amount of storage, whilst being able to take, process and distribute content to cheap, targeted consumer items designed to use that content. This consumer terminal market, which will be cost driven, is being educated through "Trojans", such as the networked games console and email on television through STBs.
  The makers of these devices are well practised in moving from generation to generation delivering additional functionality whilst preserving backward compatibility — without a massive software overhead. Games consoles that will play your old favourites and DVD systems that play CDs are obvious examples. In many cases the incremental cost of this additional functionality is very much lower than the cost of two separate products with the same capability.
4 Cutting the cords. Another discussion point is where the gateway will live within the Networked Digital Home. However, whether or not the home gateway sits by your television, like an STB, or is hidden away under the stairs like an electricity meter, it will almost certainly use a wireless connection. US homes are often wired for Ethernet, encouraging a PC-centric approach. In Europe the proposed use of existing power lines within the house, enabling second generation data transfer at rates between 30 and 40 megabytes, or HP & A employing the existing telephone lines is a much more attractive consumer-centric solution. But none is as attractive as wireless, whether the high bit rate afforded by wireless local area networks (WLAN, up to 50Mb/s), or the lower bit rates of Bluetooth, which can replace infrared.
  WLAN is particularly attractive because it incorporates a secure software stack that provides network and content protection. This is an essential facility in the eyes of the content providers who will want to ensure that their revenue streams are secure before supporting the adoption of a given transmission standard.
  As there is still no industry consensus, there is a chance for a leading company to set a de facto wireless standard. Right now it is not clear which format will dominate. HiperLAN 2 is well thought out from the physical layer through to the logical layer that already has data management and content security in place, but 802.11 may win due to earlier availability of products. It could well be the Betamax versus VHS story all over again.
  In the long term there is no argument that wireless solutions will become the winning option for the European NDH. Not just because of retro fitting — European houses tend after all to be more robust in their construction compared to those in the US — but because of its portability and flexibility. Consumer devices such as flat panel televisions employing wireless connectivity point the way towards some of the attractions of the NDH.
5 Holding the keys to the Networked Digital Home. Conceptually, the NDH is not so far away. Armed with a £1000 budget, an early adopter with the right knowledge would be able to build a simple NDH gateway. However, the growth of this sector will only start to take off when fully merchandised gateway systems are on the market. The questions then will be: is there a compelling reason for individuals to invest in such a device? Or, which service provider will subsidise them?
  Ultimately, as with all consumer equipment, widespread adoption of a gateway box depends upon providing the functionality whilst meeting the consumer price point, whether or not the box is subsidised by a service/content provider. It falls therefore to the equipment manufacturers to attain an economic price for the product. Although software is critical and accounts for a significant proportion of development investment, it is semiconductors that enable these systems to increase functionality whilst reducing real costs year on year.
  The semiconductor manufacturer's role therefore is to incorporate more and more functions on a given piece of silicon, replacing multiple chips that decode satellite and terrestrial feeds, control hard disk drives, transcode video formats and drive communication devices. This ability to develop and incorporate more functionality onto silicon means that semiconductor manufacturers really do hold the keys to the Networked Digital Home.
  David Baillie and Kenroy Francis will be presenting LSI Logic Europe Ltd. at Mediacast from 21 to 23 May 2002 at the ExCeL, London. For free tickets call +44(0) 870 429 4422. Photography: Authors and NDH Collage
  2002 © Soundscapes