Electronics engineers have long dreamed of ubiquitous connectivity—wireless data delivery for everyone and everything, everywhere, all the time. And they have made significant strides toward their goal: more than two billion people today have cell phones, and hundreds of millions send and receive messages and files via laptops, handhelds and other digital devices using Wi-Fi, the radio-frequency-based wireless local-area network (“hot spot”) technology.

In addition, more and more Wi-Fi users enjoy the convenience of employing wireless mobile devices anywhere indoors. At the same time, manufacturers are installing wireless communications capabilities in traditionally stationary electronic devices and appliances to enable consumers to communicate with them remotely. Increasingly, these users also want to access broadband services without the fixed wire links they typically must have to receive them. But because of the limited availability of radio bandwidth in desired frequency ranges, Wi-Fi suffers from insufficient transmission speed and channel capacity, which slows the wireless access of Web-based multimedia services such as Internet browsing and video conferencing, as well as television and movies on demand. And even the new higher-speed, wide-area radio systems, such as WiMAX, are not well suited to wireless broadband communications inside structures because they can handle only a few users in a confined space and, more important, cannot provide secure communications.