WiMedia Alliance
From Wikipedia, the free encyclopedia
The WiMedia Alliance is a not-for-profit open industry association that promotes and enables the rapid adoption, regulation, standardization and multi-vendor interoperability of ultra-wideband (UWB) worldwide.
WiMedia Alliance develop, maintain, enhance and reference technical specifications including:
- PHY and MAC
- Convergence architecture to provide coexistence and fairness including support for multiple applications (e.g., Wireless USB, Wireless 1394, bluetooth, IP, etc.)
- A protocol adaptation layer for the Internet Protocol
- IP-based application profiles
WiMedia Alliance and MultiBand OFDM Alliance Special Interest Group (MBOA-SIG) merged into a single organization in 2005. The merged group operate as the WiMedia Alliance.
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[edit] WiMedia Alliance
WiMedia UWB is the basis for the industry’s first UWB standards. The WiMedia Ultra-Wideband (UWB) Common Radio Platform incorporates media access control (MAC) layer and physical (PHY) layer specifications based on Multi-band Orthogonal Frequency Division Multiplexing (MB-OFDM). The solution enables shortrange multimedia file transfers at data rates of 480 Mbit/s and beyond with low power consumption, and operates in the 3.1 to 10.6 GHz UWB spectrum. WiMedia UWB is optimized for the personal computer (PC), consumer electronics (CE), mobile device and automotive market segments.
The UWB system provides a wireless PAN with data payload communication capabilities of 53.3, 55, 80, 106.67, 110, 160, 200, 320, and 480 Mb/s.
The WiMedia UWB platform is also optimized for complementary wireless personal area network (WPAN) technologies such as Bluetooth 3.0, Certified Wireless USB, the 1394 Trade Group’s “Wireless FireWire” Protocol Adaptation Layer (PAL) (Non-IP Peer to Peer architecture) and Wireless TCP/IP - UPnP (WiNet). Different wireless protocols can operate within the same wireless personal area network without interference. In addition to these, many other industry protocols can reside on top of the WiMedia UWB platform. Those include Ethernet, DVI and HDMI. Presently, the WiMedia PHY specification has an over-the-air uncoded capability of more than 480 Mbit/s; the specification is highly scalable and will ultimately support wireless DVI and HDMI, operating at Gbit/s data rates.
The WiMedia Network (WiNET) is a protocol adaptation layer (PAL) that builds on the WiMedia UWB common radio platform to augment the convergence platform with TCP/IP services.
Certified Wireless USB can operate in two way:
- Coexistence Wireless USB operates on top of Wimedia UWB PHY - Wimedia UWB MAC - Convergence Layer.
- Pure Wireless USB operates directly on top of Wimedia UWB PHY.
Bluetooth, Wireless 1394, IP (WiNet) operate on top of Wimedia UWB PHY - Wimedia UWB MAC - Convergence Layer like Coexistence Wireless USB.
Within the WiMedia MAC specification is the MAC Convergence Architecture (WiMCA) that allows applications to share UWB resources. WiMCA defines a number of policies, including channel-time utilization; secure association, authentication and data transfer; device and WPAN management; quality of service; discovery of services; and power management.
WiMedia plans to develop universal IP addressing protocols in alignment with organizations such as the UPnP Forum and the Digital Living Network Alliance (DLNA).
[edit] Standardisation
[edit] IEEE
IEEE_802.15.3a was an attempt to provide a higher speed UWB PHY enhancement amendment to IEEE 802.15.3 for applications which involve imaging and multimedia.
The attempt to create an IEEE ultrawideband standard failed because of several factors.
First, based on execution of the approved IEEE 802.15.3a Task Group down selection procedure, there were only two proposals remaining. Each of the remaining proposals contained mutually exclusive communication architectures. To say that more simply, neither proposer's radio could communicate with the others. One proposal was a merger of a novel OFDM architecture proposed by Texas Instruments with several technically inferior frequency and pulse based ultrawideband designs. This merged proposal became know as the MB-OFDM proposal and was sponsored by Texas Instruments as a member of the Multi Band OFDM Alliance, which is now part of WiMedia. The other proposal was a merger between an original direct sequence pulse based design (DS-UWB) contributed by Xtreme Spectrum that was modified to include features of several other pulse based proposals. Ironically, after the dust settled through several years of each proposer bashing the other's technical implementation, both remaining proposals achieved nearly identical performance in terms of data throughput, channel robustness, overall design DC power consumption, and device cost.
Second, there were numerous attempts by each proposer to achieve both victory in the down selection vote, and then reach the 75% approval rating required for task group confirmation of the selected technical proposal. Than never happened. In the first round of down selection, the MB-OFDM proposal was selected. Through several subsequent rounds of down selection, the selected proposal alternated between MB-OFDM and DS-UWB, with neither being able to achieve technical confirmation.
There was a significant attempt at creating a compromise that would have allowed the MB-OFDM and DS-UWB radios to communicate with each other. This common signaling mode (CSM) channel initially supported a lower data rate than the minimum mandatory 110 Mbit/s, for purposes of coordination and allowing other elements necessary for proper operation of a wireless personal area network. The common signaling mode (CSM) was proposed by John Santhoff of Pulse~LINK as a way forward for both proposals that would allow complete coexistence and at least minimal interoperability. However, MB-OFDM supporters insisted that a common signaling mode was not needed, and that their customer research supported a strict notion that only one physical layer (PHY) would be tolerated by the consumer market. Thus, even though the DS-UWB supporters embraced CSM as a bridge between the two proposals, the lack of flexibility and acceptance by MB-OFDM supporters killed what turned out to be the best solution to achieve a compromise between the proposers.
The contest became so contentious that the originally elected Task Group Chair, Bob Heile, who was also the 802.15 Working Group Chair, resigned his position. Bob Heile was replaced by Jim Lansford, CTO of Alereon, and Gregg Rasor, Director of Ultrawideband Research and Development in Motorola Labs, who co-chaired IEEE 802.15.3a until it's end. The idea of co-chairs was brought about in yet another attempt to forge a compromise that would generate an IEEE standard for ultrawideband.
Consequently, in the Spring of 2006, the IEEE 802.15.3a Task Group was officially disbanded by the IEEE Standards Association. On January 19, 2006, IEEE 802.15.3a task group (TG3a) members voted to recommend that the IEEE 802 Executive Committee ask NESCOM to withdraw the December 2002 project authorization request (PAR) which initiated the development of high data rate UWB standards.
The most commendable achievement of IEEE 802.15.3a was its consolidation of 23 UWB PHY specifications into two proposals using : Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) UWB, supported by the WiMedia Alliance, and Direct Sequence - UWB (DS-UWB), supported by the UWB Forum.
[edit] ECMA
On December 8, 2005 Ecma International released two international ISO-based specifications (ECMA-368 and ECMA-369) for UWB technology based on the WiMedia Ultra-Wideband (UWB) Common Radio Platform. Ecma will submit the standard to ISO/IEC JTC 1 for fast track approval.
