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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