Q. What’s Wireless HDMI and Is It Available?
Steve Venuti, VP of the HDMI Licensing Group, says Wireless HDMI doesn't technically exist. But you do have some options.
Feb. 25, 2008 — by Steve Venuti
Q. What’s Wireless HDMI and is it available? - Frank, Las Vegas, NV
A. Technically speaking, there is no such thing as “Wireless HDMI,” since the HDMI specification makes no mention of wireless technologies. That being said, there are a number of companies tackling the challenge of sending an HDMI signal wirelessly. Typically, these systems are designed to serve as a bridge between two wired HDMI connections, using proprietary technology to convert, transmit, and reconvert the signal across a wireless gap. From the viewpoint of HDMI Licensing, these systems are somewhat akin to Cat 5/6 and fiber solutions, which perform a similar bridging function in long-run wired applications: as long as they comply with the HDMI standard on both ends of the bridge, we impose no additional requirements, and we play no favorites.
There are a number of competing technical approaches, each with its own unique set of advantages and challenges. Generally speaking, there are lower-bandwidth solutions that are available in the short term, based on mature technology, but with a trade-off: they require signal compression, and that can compromise audio-visual quality. Higher-bandwidth solutions, on the other hand, have the potential to transmit a signal with little or no compression, but these technologies are less market-ready, and are likely to cost more when they do arrive.
There are three major contenders for your wireless HD dollar, each with its own industry group to back it up: WiMedia, based on the familiar 802.11n protocol; WirelessHD, which uses the 60 Ghz band, and WHDI, an ultra wideband (UWB) solution using the unlicensed frequencies around 5 Ghz.
WiMedia, backed by an alliance that includes Sony, Samsung, Intel, HP, and others, has the first-to-market advantage. Radiospire’s AirHook and Pulse~LINK’s CWave products are examples of WiMedia technology. Based on the same 802.11n protocol that’s already employed in many WiFi devices, it’s a cheap, stable, and mature solution, but its narrow bandwidth means that signals have to be compressed, resulting in less-than-ideal signal quality. Moreover, the ubiquitous nature of 802.11 devices means that there may be possible spectrum-contention problems in this increasingly popular frequency band.
WirelessHD is based on the 802.15.3c protocol, and is backed by an industry group that includes the previously mentioned Sony and Samsung as well as LG, Matsushita, NEC, and Toshiba. SiBeam’s OmniLink60 chipsets will be among the first to leverage this technology, which uses the 60 Ghz band to transmit up to 5 Gbps of data. While that’s plenty of bandwidth for uncompressed 1080p video, there are some technical points that still need to be proven. 60 Ghz technology is directional, sensitive to obstacles, and generally prone to atmospheric loss, meaning it may be suitable for in-room use only rather than for whole-house applications. The RF and modem technologies employed are also relatively immature, so it may be a while before we see this solution deployed in the marketplace.
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