MANHASSET, N.Y. — With wireless technologies seemingly multiplying faster than microbes in a petri dish, the consumer electronics industry is desperate for a viable approach that will help it meet time-to-market deadlines for the expected launch of wireless delivery of audio and video content to the home by next Christmas. But designers face a kaleidoscope of options-from Wi-Fi and IEEE 802.15.3 to ultrawideband, 802.11n and others-for the wireless distribution mechanism.
In an effort to streamline the decision process, the Consumer Electronics Association (CEA) has initiated a two-phase project that, in its first phase, is developing a comparative listing of all wireless technologies. "These will be based on accumulated data [that has been] pushed as claims but not verified," said Virginia Williams, director of engineering at the Technology and Standards group of the CEA's Home Networking division. "Phase two will be the generation of methods to evaluate the technologies through quantitative measurements, where we will start saying how measurements will be made, so that vendors are comparing apples to apples."
Phase one has already begun, and those results will be presented in late March at the Communications Design Conference (www.commdesignconference.com). Williams didn't know exactly when phase two would begin but said she expects the project to be completed by year's end.
Companies offering various distribution alternatives are all jockeying for position in a wirelessly networked environment where multiple channels of streaming high-definition TV, delivered at rates of up to 20 Mbits/second, will converge and compete for bandwidth with lower-rate voice telephony, MP3 audio and data access. They will each battle possible interference from such items as cordless phones, Bluetooth devices and microwave ovens, while avoiding mutual interference.
Complicating matters for engineers with a black-and-white mentality is the propensity among the approaches' proponents to continually morph the capabilities and descriptions of their respective technologies to encompass an ever-widening range of applications-a process that blurs the very differentiators consumers rely on to make a choice. The accelerating traction of wired distribution mechanisms such as the HomePlug Powerline Alliance's approach, which will reach 170 Mbits/s, adds to the indecision, as do advances in compression schemes that are rapidly reducing bandwidth and performance requirements.
Factor in obfuscation and wireless vendors' oft-exaggerated claims of performance, cost, interoperability and predicted availability, and synaptic paralysis looms for designers. Hence the need for standard evaluation methods of the type in the works at the CEA.
Bird in hand
Ever-present time-to-market pressures make currently available IEEE 802.11 options attractive. Of the three defined physical layers (PHYs), only 802.11g and .11a are serious contenders, because of their support for 54-Mbit/s data rates, compared with .11b's 11 Mbits/s. The .11g variant operates in the 2.45-GHz band and so may have greater range than .11a for a given output power and data rate. But .11a's 5-GHz band is cleaner and has 24 available 20-MHz channels, for a 480-MHz total, while .11g has only three 20-MHz channels.
