The setting sun is a pleasant sight while driving home. I’m listening to satellite radio and a call comes in. At my verbal request, the car’s media system switches off the music and answers the phone. I continue the conversation as I pull into the garage and switch the call to my home line as I exit the car. Continuing to chat, I move into a room with an HDTV and switch to video conferencing. The call ends and the radio program resumes from the point of interruption. Finally, I use a graphic control panel to turn off the audio, open the shades, and check my e-mail.
This sci-fi scenario isn’t too farfetched. But while the industry moves in this direction, the coordination and standards necessary for such a level of support are lacking. We currently have a Tower of Babel when it comes to device communication within the home and car. Pockets of devices can communicate with each other, but they tend to be isolated islands, such as security systems or multimedia rooms.
The problem arises because of the many issues involved, such as bandwidth requirements, quality of service (QoS), digital rights management, security, authentication, and authorization. Groups and standards are growing and emerging, but there’s still a long way to go before a truly seamless multimedia communications network becomes reality, especially when it involves multiple vendors.
Established standards have set the groundwork for much of the standardization. TCP/IP and Ethernet are critical parts of the equation, though consumers typically are isolated from these details. For example, Ethernet ports are common on Blu-ray players, but IEEE-1394b links are found on HDTV set-top boxes. Both support TCP/IP protocols.
HDTVs such as Samsung’s large-screen HL-T5687 DLP model use HDMI (High-Definition Multimedia Interface) connections (Figure 1 and Figure 2). This high-speed serial interconnect can be found in all electronic entertainment stores, but most consumers don’t know that highspeed switching is occurring in devices such as HDMI audio amplifier/receivers.
Interestingly enough, HDTVs like Sony’s Bravia tie together the high-speed communication via HDMI and low-speed control with an 802.15.4 remote-control protocol based on Freescale’s 802.15.4 entertainment control platform (ECP) (see “Remote Controls Go From IR To IF” at www.electronicdesign.com, ED Online 16523).
The advantage we have today is that the acceptable limits have been reached. For example, HDMI and HDTV standards set an acceptable limit for most devices that will enter the market over the next 10 years. They aren’t the absolute limit, though, because HDMI and HDTV are defined past the 1080p standard commonly accepted as the high end for consumer video.
NETWORKING HARDWARE
Much of the standardization work has centered around the hardware, usually pushing performance to the limits. Wi-Fi, Ethernet, and HDMI are joined by phoneline links from the 320-Mbit/s HomePNA Alliance to the 200-Mbit/s Homeplug Powerline Alliance. The Multimedia over Coax Alliance (MoCA) targets existing in-home cable networks with 175-Mbit/s throughput.
These high-speed links can deliver highquality video and often HD video in uncompressed form. The primary limitations occur when they’re dealing with multiple streams of HD video, but they usually utilize compression to handle those streams.
The new HomeGrid Forum was formed to unify this fragmented hardware market with a common physical-layer/media-accesscontrol (PHY/MAC) approach. It supports the work of the International Telecommunication Union (ITU-T) G.hn committee. Concentrating on the hardware and low-end software levels is useful and can simplify the job significantly, but it doesn’t force interoperability at the application level. Of course, resolving currently inconsistent networking platforms and protocols will be a challenge.
Essentially, the homemultimedia data plane doesn’t address the control or management plane. This is where infrared control units such as Logitech’s Harmony 1000 attempt to control multiple devices, albeit at a very local and limited level (see “Logitech Harmony 1000,” ED Online 17953). The result is quite useful, but it’s a far cry from an integrated system.
Likewise, the standardization of profiles in the ZigBee Alliance is enabling interoperability among control and status devices in a range of environments, such as lighting control. As with many other networks, interoperability among devices within the homogeneous network is possible and sometimes automatic. However, transitioning this control and information to or through other networks generally isn’t possible.
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