A Long-Term View of Short-Range Wireless

T ake a moment to look around, whether you're reading this article in an office, airport, hotel, convention center, restaurant, shopping mall, library, dorm, or even your own home. A casual glance will reveal walls and ceilings fes-tooned with lighting fixtures, phone jacks, power outlets, ventilation ports, fire sprinklers, motion detectors, temperature sensors, and other infrastructure artifacts now so common we usually overlook them. You may also see a LAN access jack, which signals the presence of a wired connection to the Internet, arguably the fastest-growing global infrastructure in history. All these infrastructures will soon be joined by another that provides high-speed, low-cost, low-power, wireless access to the Internet over very short range. Next-generation cellular systems have been designed to bring fast, wireless data connections to users. However, currently planned systems limit data speeds to 2 megabits per second or less because, at the distances they must cover to remain economical, these technologies encounter constraints imposed by physical laws that govern channel bandwidth, power, and available spectrum. Short-range wireless is a complementary class of emerging technologies meant primarily for indoor use over very short distances. SRW links will offer peak speeds of tens or even hundreds of megabits per sec-ond—at very low cost and with very low power—to many closely spaced users. In its base set of applications , SRW technologies will provide cableless connections among the portable devices people wear and carry daily, including cell phones, headsets, PDAs, lap-top computers, digital cameras, audio and video players , and health monitoring devices. SRW will also give these users wireless access to a host of new services provided by in-building LANs and their wired Internet connections, as well as services offered via more traditional voice and data connections. Were wireless an ideal medium, we could use it to send a lot of data, very far, very fast, for many separate uses, all at once. Unfortunately, physical laws make it impossible to implement all five of these attributes simultaneously—we must compromise on one or more if we wish to do well on the others. In the early days of wireless, users found the ability to send data " very far " the most important attribute. Marconi willingly compromised on the other four attributes when he sent the world's first transatlantic radio transmissions in December 1901. The past 100 years of wireless, however, show a clear trend toward improving the other four attributes …