Philip Hunter /
04.08.2011 03:26 PM
HomeGrid Forum comes closer to universal domestic connectivity

The HomeGrid Forum claims to have made a breakthrough in its mission to provide a standard for universal connectivity between consumer electronics devices, TVs and other domestic systems by moving close to ratification of specifications for transmission over electric power cables.

The HomeGrid Forum announced April 6 that two recommendations within its overall G.hn standard were on schedule for final ratification by the ITU-T, the body that defines global telecommunications standards, later this year. The standards are G.9955 (PHY and system architecture) and G.9956 (DLL), which form the global G.hnem standard for low-frequency (9kHz-500kHz) power line communications for smart meters, energy management systems, electric vehicle communications, control and home automation.

Various improvements made in G.hnem include significant blocking of impulsive noise, improved cross-phase signal propagation and increased robustness under challenging power line conditions.

On the surface, these two standards don’t seem particularly relevant for TV, but they go some way to allaying concerns that data, and video, can be transmitted reliably over power networks. Although standards for communication over power lines have also been developed by a separate body, the HomePlug Powerline Alliance, there have been concerns that rather like WiFi, electricity cables can never be trusted absolutely to deliver broadcast-quality HD services. The new G.hnem standards indicate that power lines can be made fit for high-quality video distribution. And while video over power lines may not be widely deployed in the United States, where coaxial cable is so pervasive within homes, it is likely to figure more prominently in other parts of the world, including some European countries, where electrical wires are the only existing cables.

Perhaps more significantly, ratification of the HomeGrid power line standards will bring G.Hn a step closer to its promise of “one device, any wire,” which will reduce time and cost to market for TVs and consumer products designed to access future home networks. In some respects, a few members of the HomeGrid Forum are ahead of the game here, with media system semiconductor company Sigma Designs already demonstrating a chip set capable of connecting devices to all three of the main home wiring types: coax, telephony and power cables. This clears the way for manufacturers to produce consumer devices incorporating a single chip set that can connect to all three, avoiding the need for separate versions for each.

Meanwhile, TV operators, content owners and consumer electronics vendors alike have been looking for clarity to emerge within the home networking standards world, where there is a profusion of bodies, some of which have produced little more than vaporware so far. At least the HomeGrid Forum now has concrete recommendations that have been implemented in real silicon. As a rough guide, the home networking standards arena can be divided into three sectors relating to physical connectivity, interoperability and usability. The HomeGrid Forum sits at the top of the connectivity stack, aiming to unite each of the separate physical options — at least, that was the theory. But as always, there have been disputes among the different bodies, with the HomePlug Alliance, for example, resenting the HomeGrid Forum’s intrusion onto its territory and continuing to plough ahead with separate standards. However, the HomeGrid Forum does look like a good bet now to unify the physical options, given the clear desire on the part of vendors for this to happen.

Nevertheless, to date, each of the three wired media has its own dedicated standards body: MoCA (Multimedia over Coax Alliance) for cable, HomePlug for power line and the HomePNA Alliance (formerly the Home Phoneline Networking Alliance, also known as HPNA) for telephony wiring. But to confuse matters further, HomePNA now supports coaxial cable as well, in competition with MoCA. In fact, the HomePNA Alliance in March announced a new version of its standard for coax operating at up to 320Mb/s over single cables or 640Mb/s over four bonded pairs of cables, supporting up to 126 end points per network.

Furthermore, the HomeGrid Forum has spurned WiFi so far, supporting only wired options in the belief that wireless just will not cut it for broadcast TV in the next few years. Some cable TV specialist vendors would disagree, but either way, it is clear that home networking standards still have some way to go to reach a consensus at the physical level.

Fortunately, it is a different story at the level of device interoperability and automatic discovery, where the Digital Living Network Alliance (DLNA) reigns supreme. DLNA is widely acknowledged as the most important standards body for TV in the home, providing the glue that binds the other components together, with all the other principal standards groups therefore cooperating with it. The HomeGrid Forum has had a liaison agreement with DLNA since 2009.

DLNA should enable new devices to connect automatically to a home network without requiring any action by the user other than providing authentication details where required, and at one time was thought to provide the final standards layer serving the higher-level applications within a TV or multimedia service. But, it became clear that more was needed to ensure not just that all devices would connect and interoperate, but that they would also deliver the same user experience. This has led to UI standards, with U.S. satellite operator DirecTV filling the breach with its RVU standard, in the absence of any coherent proposal from the vendor side. The goal of RVU is “one service, many devices,” enabling operators to in effect download their UI, EPG and navigation system to any RVU-compliant client device.

As always, the need for devices to be compliant is the hurdle for the standard to overcome, because only Samsung TVs do comply at present. However, the presence of communications chip maker Broadcom among the RVU founding members, alongside DirecTV, Samsung and Sony, suggests that RVU has a fair chance of spreading beyond DirecTV’s subscribers.



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