 a single high-speed Internet connection such as a cable modem into a US$10 to US$175 WAP and share it with scores of people in a WLANs building, park, or small neighborhood. Anyone can snap a US$50 antenna into a laptop and tap into many of these unsecured mini-networks for free, without per- mission. Those with clever entrepreneurial tendencies might charge their neigh- bors anywhere from US$5 to US$75 per month and become the neighborhood high-speed data access provider, and it's all legal (at least at the moment and in the United States). Wi-Fi is popping up at thousands of hotspots, in locations including hotels, air- ports, shopping centers, restaurants/cafes, and educational environments; basically, wherever people congregate, there is an application for a hotspot. Hotspots are much less expensive to build than 3G systems, and they offer similar data capabili- ties, although voice service is not yet a reliable application on WLANs. Therefore, WLANs and cellular are uniting to provide road warriors with a complete toolkit. Wi-Fi is a trade term promulgated by the Wi-Fi Alliance (www.wirelessethernet. org). Products that the Wi-Fi Alliance certifies are interoperable with each other, even if they are from different manufacturers. A user with a Wi-Fi product can use any brand of WAP with any other brand of client hardware built to the Wi-Fi standard. Even though Wi-Fi is extremely cost-effective to deploy and is extremely pop- ular today, some issues need to be recognized: Limited range of service-Today's Wi-Fi implementations are limited to coverage areas of 150 to 300 feet (50 to 100 m). Whenever there is a prob- lem to be addressed, clever minds find a solution, and in the case of limited range, techniques such as mesh networking can extend the coverage area substantially; in fact, individual hotspots can be interconnected to blanket a large area, such as an entire metropolitan area. Lack of QoS-Wi-Fi is not inherently suitable for voice and video because it lacks the ability to control bandwidth allocatio