Team targets 802.15.3 for wireless video networks

Potentially much faster than 802.11

The latest attempt to get 1394 Firewire operating across a wireless network kicked off last week with the foundation of a working group seeking to tie the connectivity standard to 802.15.3 Personal Area Networks (PANs).

The group's work could lead to 100Mbps 10m wireless links capable of maintaining multiple high-quality MPEG-2 streams. The group expects to have its specification done and dust in 12 months' time, EE Times reports.

To date, wireless 1394 -'Firewireless' - efforts have centred on hooking the 1394 protocols up to 802.11 and before that proprietary transports. The 1394.1 spec. details how to bridge 1394 to 802.11a. The 1394 Trade Association's 1394-to-802.11 protocol adaptation layer (PAL) build on that spec. to deliver 1394 across an 802.11a network. The PAL supports the 5C (aka Digital Transmission Content Protection) DRM scheme designed to stop anyone sneakily copying commercial content while it's being transmitted over a wired 1394 link.

An 802.11a network provides a working data throughput of 25-30Mbps. The addition of the PAL overhead reduces this even further from the WLAN standard's raw data rate of 54Mbps. 802.11a also lacks the quality of service (QoS) provision seen as essential for the transmission of commercial-quality video over a wireless link.

Enter 802.15.3, a specification being groomed for IEEE standard status that provides ad hoc wireless PANs - short range (1-50m) and ad hoc, in other words. 802.15.3 builds on the 802.15 standard by adding QoS specifically to allow the PAN to carry digital imaging and multimedia data. It also builds in data security, implementing privacy and authentication services. 802.15.3 operates in the 2.4GHz band at 11, 22, 33, 44, and 55Mbps.

Unlike 802.11 connections, 802.15.3 is designed for peer-to-peer operation rather than routing data through an access point, whether that's a base-station or a client machine configured as one. Access points can become network bottlenecks.

The final spec. is expected to be submitted for IEEE approval in June. In the meantime, an alternative spec., 802.15.3a, is under development to create a higher data PHY to replace the 55Mbps 2.4GHz PHY in 802.15.3. It's increasingly likely that 802.15.3a will be based on ultra-wideband (UWB) technology, but it has to get through selection procedures this month and in July first. However, it has the potential to reach data rates of 100Mbps and ultimately the 400Mbps (at 5m) offered by standard 1394 wired links.

The group developing the PAL for 802.15.3/3a expects to have a completed spec. in a year's time. Products using 802.15.3 are anticipated to be available during Q4, according to the WiMedia Alliance, a Wi-Fi Alliance-style organisation formed to promote consumer multimedia PAN-based wireless networking. It was set up last September by Eastman Kodak, HP, Motorola, Philips, Samsung, Sharp Labs of America, Time Domain and XtremeSpectrum. Many of them are members of the 1394 PAL-defining working group.

Interoperability with 1394 is key to ensuring compatibility with wired devices and supporting consumer electronics interconnection schemes based on 1394, such as the Home AV Interoperability (HAVi) standard. It also provides, through 5C, the level of DRM that commercial content creators are insisting upon and the consumer electronics industry will undoubtedly demand too. It's what takes 802.15.3 beyond being just another network.

If the WiMedia Alliance has its way, Wi-Fi will continue to be the standard for wirelessly networking computer systems, and WiMedia will become the standard for wirelessly networking home entertainment systems. Wi-Fi may have a considerable lead in mindshare, but it's popularity is based on computing applications - it doesn't have anything like the same profile in the consumer electronics space.

If the working group's timetable is met, 802.15.3-based wireless consumer electronics devices are likely to appear before their 802.11-based equivalents, and will offer better performance in any case. However, with PC companies pursuing home entertainment-oriented 'digital hub' strategies, some clash between the standards is inevitable, particularly given the way 802.11 has been adopted by companies offering remote players that link your hi-fi to your PC-based MP3 collection, as demonstrated by products like Turtle Beach's Audiotron and others.

More likely, Wi-Fi will emerge as a consumer electronics network standard too, co-existing with WiMedia as a cable-replacement technology, just as today Wi-Fi sits alongside Bluetooth, as network and cable replacements, respectively.

Either way, there's no doubt the consumer electronics industry is looking to home networking, particularly wireless, as a way of tempting buyers with a whole new generation of products. ®

Related Link

EE Times: Group hopes to leapfrog 802.11 for wireless video

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