It looked as if home networks had finally taken their first step, but it actually only marked the start of the really big problems. The DLNA with which products currently comply only allows for networked equipment to play streaming data. So what happened to the concept of providing improved consumer convenience through networked equipment?
Based on past industry activity, the obvious approach would be to cover the idea with a new standard. That approach, though, would take quite a long time, and interoperability problems would crop up when specific products complied with different versions of the standard. Even if commercialized, the idea is already well known, and products would face competition, making it difficult to achieve competitive strength.
Standards: 2 Types
There are basically two types of home network standards: those for digital consumer electronics sharing multimedia data like photographs, audio and video; and those for white goods, home equipment and the like, allowing one piece of equipment to monitor, control or otherwise be linked to another. Representative examples of the first type of home network standards are DLNA and High-Definition Audio-Video Network Alliance (HANA), while an example of the second type is ECHONET (Table 1).
These standards define items like (1) physical networks to interconnect equipment, (2) network protocols for datacom between networked equipment, (3) procedures for detection functions, services, etc, provided by networked equipment, and (4) procedures allowing one piece of equipment to control another. Standards like DLNA and HANA, which are designed to handle multimedia data streams, also define items such as supported encoding schemes.
DLNA and HANA are much the same when it comes to how component equipment is interconnected, but the networks used are different. DLNA is fundamentally based on the Internet protocol (IP), primarily using Transmission Control Protocol/IP (TCP/IP), while HANA has a network running IEEE1394. ECHONET is designed for small equipment such as sensors and room lighting, and so supports not only IP networks, but also networks with low installation cost such as Bluetooth and infrared.
DLNA: What's Possible?
DLNA has defined device design guidelines, called the Networked Device Interoperability Guidelines. The UPnP Device Architecture is used as the method for sensing equipment, and the UPnP Audio-Visual (AV) is used for multimedia data functions like play. Version 1.0 of the guidelines, issued in June 2004, covered only systems with content servers streaming data to play clients.
Expanded guidelines were issued in March 2006, adding coverage of data handling between mobile equipment and servers (upload/download), printing still picture data from the server, and "push" streaming play, among others. A new standard called UPnP Printer was adopted to make printing possible. It became possible to use Bluetooth to link to mobile equipment, but IPv4 protocol is used on all physical networks for control messages, content and other data.
If a convenient and easy-to-use network product could be released ahead of the competition, consumers would buy it, and product competitiveness would rise. This is exactly the thought that led to the Viera Link from Matsushita Electric Industrial Co Ltd of Japan. It allows the user to program the recorder using information from the television's electronic program schedule, and it automatically switches television input if, for example, a digital videodisc (DVD) is played (Fig 1). The video interface is High-Definition Multimedia Interface (HDMI), to which Matsushita Electric Industrial added a proprietary expansion, to the optional control signal specification. By adding modest but unique functions to the network used to transmit video signals ahead of the competition, Matsushita Electric Industrial successfully made its own recorder vastly more marketable by tying it to an already popular TV.
Companies like Sharp Corp and Sony Corp, both of Japan, rapidly followed suit, adding their own functions for equipment interoperability to the HDMI interface. The resulting products have all been market hits.
Many Japanese household appliance manufacturers are strong in TV and digital household appliance sectors. The move to wire homes with IP networks is accelerating rapidly, accompanied by major growth in the number of products supporting network interoperability. The key to future competitiveness will be rapidly proposing new ways to use home networks that leverage the products the firm is strong in.
One product that stands out when it comes to rapid rollout is the Apple TV, which shipped from Apple Inc of the US in March 2007. It is designed to be used connected to the home IP network, and uses a proprietary standard for interconnect to the iTunes personal computer software used to manage audio, video and other data.
Spreading DLNA
Products with similar functions have been around for some time. Several companies have already released media players, TVs and other products compliant with the DLNA home network standard drawn up by companies from the PC, household appliance and other industries. As far as functions are concerned, the Apple TV is not much different from what DLNA can offer.
In September 2006, however, on the day that Apple revealed it was developing the Apple TV, engineers who had been working to spread DLNA feared the worst. The basic reason was the vast difference in the speed of implementation between a single company working alone, and standardization by the industry as a whole. The do-it-yourself approach proved very successful with the iPod, with its proprietary specs.
Consensus Problems
It always takes time for multiple companies to draw up a standard, but by investing that time the manufacturers can now provide customers with the assurance that DLNA-compliant products will connect reliably with equipment from other vendors. Despite the fact that DLNA has been working on the standard for quite a while, Apple was able to take the lead in solitaire.
This is exactly what those engineers were worried about. No doubt consumer perceptions of useful equipment will continue to evolve, and manufacturers in response will ship wholly new types of products to address them.
On the other hand, if a company forges ahead with a proprietary standard in an effort to get to market first, it cannot ensure compatibility with equipment from other vendors. Both approaches end up limiting the potential of the home network.
WWW: Low-Level Layers
One idea that a number of companies are suggesting to overcome this obstacle is to learn from the World Wide Web, which continues to develop with staggering speed. New services appear frequently for the Web, such as search services, online sales and video clip sharing, and they all add in new functions as needed. If the same approach can be use in home networks, it should be possible to add new types of household appliances, new services, or to make other modifications, without forcing a change in existing products. This would provide a whole new definition of interoperability.
The reason that so many new services and functions appear for the Web is that the standard only specifies that the client requests a uniform resource locator (URL) from the server, and the server sends it the hypertext markup language (HTML) file at that URL. The hypertext transfer protocol (HTTP) over TCP/IP is used to send a file written in HTML. It is significant that there are no application level standards, such as message formats or procedures for using online sales functions (Fig 3). Using HTTP as the transfer protocol and HTML as the format would seem to be one way of solving all the problems facing the home network.
Building on Prior Work
The results achieved by the DLNA until now remain significant, such as defining methods for networked equipment to automatically discover each other, and standard formats for video, still pictures and other files. This was the very essential first step in the implementation of a home network. As Haruhiko Handa, senior manager, Marketing, Ubiquitous Corp of
Japan explained, "Without DLNA, we would have had a jumble of different formats for video, stills and audio, and it would probably still be continuing today."
Perhaps the "killer app" for the home network hasn't been thought of yet. But rather than waiting for someone to find it, it is more important to keep working to provide an environment that facilitates trial-and-error so that it can be found eventually. The minimum standard, the lowest common denominator, has already been developed toward that end.
When the Web was first invented nobody predicted that Google Inc of the US would succeed to the extent it has. The time has come to build a new foundation for home networks, built on the work of the DLNA until now.
by Tomohisa Takei
Websites:
Apple: www.apple.com
Google: www.google.com
Matsushita Electric: panasonic.co.jp
Sharp: www.sharp-world.com
Sony: www.sony.com
Ubiquitous: www.ubiquitous.co.jp
UIEvolution: www.uievolution.com
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