Wi-Fi, UWB and WirelessHD battle for IEEE's 60GHz standards

The IEEE is already home to a standards initiative for 60GHz wireless personal area networks (PANs), called 802.15.3c. This is widely expected to favor a UWB-based approach, although a range of would-be standards are hoping to gain adoption, including the WirelessHD Alliance, which is supported by Sony, Panasonic, Samsung, Toshiba, NEC and LG Electronics. Now the wireless LAN portion of the IEEE, 802.11, which sets base standards for Wi-Fi, also aims to create a standard for 60GHz. The two groups will meet next week to try to avoid one of the inter-working group feuds that have sometimes delayed or even derailed IEEE processes.

The 802.11 study group is focusing on Very High Throughput (VHT) Wi-Fi but under IEEE rules, the newer group must demonstrate that it has technologies and applications that are sufficiently different from the ongoing work of 802.15.3c before it can be approved to proceed in drafting a standard. The danger to the industry, and the IEEE's already diminished influence, is that VHT will be rejected - since its objectives are likely to be very close to those of the older group - and will then seek a standards home elsewhere. The alternative, that the Wi-Fi community would voluntarily stay out of the 60GHz standards race, is almost inconceivable, especially as companies based on enhanced 802.11 platforms, such as Intel-backed Ozo, are starting to gain high profile in the nascent high definition digital home network. But a Wi-Fi initiative outside the auspices of the IEEE could create fragmentation of the silicon market, where the early years will anyway see challenges in the economics - the need for ultra-low cost chips to embed in every consumer device, combined with the complexities of implementing 60GHz devices in cost effective CMOS (a few chipmakers, such as Toshiba, have achieved this in small runs).

Industry insiders speculate that the VHT group will try to ensure acceptance by the IEEE by focusing on the need for interoperability with other Wi-Fi systems in other frequencies. This would support integrated Wi-Fi networks for a wider range of home applications - including PC LANs and even home monitoring - than 60GHz would enable on its own, and so would harness the legacy installed base. In particular, sources told EETimes, the group could define a standard that includes fast switching between Wi-Fi at 2.4GHz, 5GHz and 60GHz, plus the capability for devices to negotiate at the lower frequencies a move to the 60GHz links.

The greater challenge would be proving differentiation in targeted commercial applications, which is also mandated by the IEEE along with technical uniqueness. The 802.15.3c group is firmly focused on distribution of high definition video and other content, and on high speed synchronization of devices, which does not seem to leave much space for 60GHz Wi-Fi.

Even if both standards efforts go ahead, they will still face challenges from other high speed home networking efforts, such as WiMedia, Pulse~Link's C-Wave, WirelessHD and WHDI, and there will be pressure on 802.15.3c to incorporate at least one of those technologies in order to reduce fragmentation and industry feuds.

The VHT group wants to get approval at the IEEE meeting in mid-July on the definition and rationale for its suggested standard, so that it can officially begin work on it in the second half of the year. It could adopt one of two possible approaches - a modified Wi-Fi MAC that could achieve multi-gigabit speeds, something already addressed by some start-ups; or delivering the same data rates via aggregated throughput of multiple links. If it does not gain approval to devise a 60GHz standard, it could look to turn the latter approach to sub-6GHz frequencies, in order to achieve multi-gigabit networks in existing Wi-Fi bands, as an extension of the current 100Mbps-plus 802.11n.

The 802.15.3c group expects to finish defining its standard soon and to have an initial draft available early in 2009. Its work is divided into two modes for its two key applications - high speed video distribution and synchronization of devices. The former mode uses OFDM while the latter relies on a single carrier to support 1-2Gbps transmissions in a battery powered device. Terminals can support one or both modes. The draft also implements a 50Mbps Common Rate control channel so terminals can negotiate 60GHz channels to avoid interference with other networks - a technique also used in WirelessHD. Two Japanese organizations helped draft the 802.15.3c specifications as they currently stand, reflecting the power of the country's consumer electronics giants, which will certainly be looking for harmonization of Wireless HD, a UWB flavor and 15.3c. Key to the draft were the National Institute of Information and Communication Technology and the Consortium of Millimeter Wave Practical Applications, and the latter is developing prototype terminals that will go into field tests soon.

The 802.15.3c physical layer for the 60GHz band could be coupled with other standards' MAC layers to create converged standards that are compatible with existing and emerging networks. The application of a MAC such as those of WiMedia, WiMAX or Bluetooth to multiple physical layers could be a powerful way to create standards that are adaptable to changing spectrum allocations round the world, simplifying interoperability between systems in different bands and streamlining the development effort, avoiding the need to create an entire new standard for every frequency band. A logical extension of all this activity would be to use the UWB physical layer - whether WiMedia or another - in 60GHz too, leading to even greater harmonization and economies of scale. Two issues make this outcome uncertain - whether key regulators will extend the bands in which UWB is allowed to operate above 10GHz, and whether efficient chipsets could be designed.