For several years, police departments have used low-bandwidth wireless systems to check on suspect IDs and vehicle license plates. Cellular carriers are now promoting faster technologies, the so-called third-generation, or 3G, networks such as general packet radio service (GPRS) that offer modem-like speeds. But that\u2019s still not enough for transmitting photos or case records.That\u2019s why the police in Post Falls, Idaho, a town of 20,000, is using 802.11 wireless technology, popularly known as Wi-Fi, which offers much faster speeds. It\u2019s also much cheaper. "The cellular carriers were unable to provide an [unlimited-use] plan we could afford," says Lt. Scot Haug, who manages the department\u2019s IT group. The Wi-Fi deployment cost $208,000, about three years\u2019 worth of cellular charges, he says.The town has covered more than 50 square miles with 23 access points, providing 90 percent availability for roaming officers, Haug says. Using a combination of unidirectional and omnidirectional antennas and amplifiers, the access points have a 5-mile range, depending on the terrain, he notes. The system was completed in April.With an all-802.11 network, Haug has a lot of bandwidth to exploit, so he\u2019s implementing voice over IP, e-mail and remote-controlled video cameras over the network for use in 22 patrol cars. "This is the next frontier in wireless," says Mark Lowenstein, managing director of Mobile Ecosystem. "Presenting Wi-Fi as the last-mile access has been a very nichey thing, [but] it\u2019s the wave of the future," adds Kathryn Korostoff, president of Sage Research.For the Post Falls P.D., the biggest security concern is that others will tap into the network to access police and city systems, or simply to tap into a free citywide network, which could cause congestion that interferes with police access, Haug says. To keep out snoopers, the department enabled all the built-in encryption in its Wi-Fi network, including wired equivalency protocol (WEP), and is using 128-bit software encryption, dynamically rotating keys, proprietary compression and certificates-based encryption.Another need: By law, police must be able to audit communications to verify who accesses the system at all times. The standard approach of using dynamic IP addresses makes it impossible to track the user\u2019s changing IP addresses for use in such audit trails, says Mel Nottage, director of The Network Group, a consultancy in Coeur d\u2019Alene, Idaho, that implemented the Post Falls 802.11 network. To maintain a fixed IP address for roaming users, Nottage had to manipulate the network at the radio, network and presentation layers to handle the hand-offs, he says. The department uses Seattle-based NetMotion Wireless\u2019s Mobility management and security suite to handle the roaming between access points. NetMotion Mobility reauthenticates users as they switch access points and resumes any interrupted sessions.