The focus in home networking these days has shifted from Internet access to video. With big screen HDTVs becoming more popular and more consumers trying to hook up digital video recorders (DVRs), DVD players and all sorts of other video devices, there is a real need for a good networking technology that can handle video. This is especially true for uncompressed video, which is what all the big displays use.

Since wireless networks dominate in the home networking space today, consumers are already addicted to the freedom and convenience that wireless delivers. We are all wishing for the wireless technology that will let us do with our video what we have done with our PCs and laptops. But there is some doubt that current wireless technologies can win this battle. Video is tough.

Wireless Options On Tap

Since virtually all home wireless networks use Wi-Fi, this technology is the prime candidate for wireless video. It has been shown that an 802.11a/g system can easily deliver a compressed video stream reliably. But Wi-Fi also has some downsides. Its data rate very quickly drops off from its peak of 54 Mbits/s to less than half that the instant the two communicating nodes get out of range or other problems like walls, ceilings, and reflecting objects get in the way. That kills the video capability really fast. And don't forget: compression degrades the video. The real purpose of HDTV is to preserve the fine detail. Compression reduces it.

The new pre-n or draft-n 802.11n systems now available use MIMO to boost range and reliability as well as increasing the data rate to over 100 Mbits/s. It definitely has a better chance to deliver video with real QoS in the home. The final 802.11n standard is not expected to be ratified until early 2008, but in the meantime, the Wi-Fi Alliance is certifying pre-n products just to get the technology to market. These products really do extend range and data rate as well as boost reliability in the home environment, but they still have to prove themselves with video. New 11n products certainly have the potential for video in the home, and we are all pulling for it to work.

Ultra wideband (UWB) has always been a contender for the home video marketplace. It is fast enough (480 Mbits/s max), but its range is typically limited to less than 10 meters. Lots of companies are working to extend that range so that room to room video will work reliably. An example is Tzero, who adds MIMO to UWB. UWB is certainly the winner of the short range cable replacement wireless video connection, but can it really hack the longer ranges demanded of uncompressed HD signals?

Another up-and-coming choice is WirelessHD, a new standard under development by major semiconductor and consumer electronic companies. It uses the 60 GHz band where lots of bandwidth is available, and can potentially deliver a data rate over 2 Gbits/s. It remains to be seen what the range will be and how these millimeter wave signals propagate in the home. Line of sight is the usual operational characteristic of light-like 60 GHz signals, but maybe with special antennas that problem can be overcome. In any case, the standard is not fully developed and it appears that it could be 2008 or beyond before any practical products are available.

Most HD video delivered to the home is in a compressed form using a version of MPEG. Once the video gets into the home it is decompressed and sent to the display and other devices. The most common way to connect uncompressed video to other devices is by way of an HDMI or DVI cable. Sending the video data wirelessly causes it to be recompressed, then again decompressed at the receiving end (thereby further reducing its definition). Not good. Yet that is what 802.11a/g/n, UWB or any other wireless technology does.