Speeding Communication; Fremont, Calif., PD Migrates to New Cellular Network Technology
Fremont, Calif., PD Migrates to New Cellular Network Technology
American City & County
The Fremont, Calif., Police Department has phased out the use of its Cellular Digital Packet Data (CDPD) network in favor of a new wireless network that transmits data to and from laptop computers in patrol cars more quickly. The transition from the old network was practically invisible to its users, but officers are noticing big improvements in service as a result of the change.
Public safety agencies have relied on CDPD networks since the early 1990s to allow officers in the field to use laptops to access information without calling dispatchers for assistance. Unfortunately, cellular phone carriers are discontinuing the analog CDPD networks because they are not as profitable as expected. After five years of relying on its CDPD network, the Fremont, Calif., Police Department learned in 2002 that AT&T Wireless, its cellular phone carrier, would discontinue CDPD service as early as June 2004.
The city began investigating other options for wireless communication and discovered that replacing CDPD with a new network, such as General Packet Radio Service (GPRS), would not be easy. Fremont found that its main obstacle would be losing static Internet protocol (IP) addressing. New networks, such as GPRS, assign dynamic IP addresses to clients, so every time clients log on to GPRS networks, they are assigned new IP addresses.
Switching to dynamic IP addressing would force Fremont to retire its current software and switch to dynamic IP-friendly applications on officers' laptops. Federal, state and local databases also require a static IP address for identification purposes. In addition, Fremont would lose the ability to “push” communications from dispatchers to patrol cars because dispatchers need static IP addresses to “find” individual users. The city's field officers would be forced to use unfamiliar software and find new ways to accomplish everyday tasks.
In May 2003, to prepare officers' computers for a transition to a GPRS network, Fremont decided to upgrade the virtual private network (VPN) and network roaming software already in use on officer laptops. The software, TotalRoam by Bethlehem, Pa.-based Padcom, provided the needed static IP addressing to help ease the transition to a new network.
Shortly thereafter, Fremont elected to completely replace its CDPD network with AT&T Wireless' GPRS network. “We decided to implement a new network ahead of the CDPD sunset date,” explains Pam Lutzinger, information systems manager for the Fremont Police Department. “That way we could take advantage of faster data transmission and get our fleet ready for the absence of CDPD.”
Fremont further enhanced its mobile data capabilities by integrating 802.11b, or wireless local area networks (WiFi hotspots), into its network. The city has installed 26 WiFi hotspots that offer fast data transmission rates, at 11 megabits per second.
Fremont IT administrators equipped the first cruiser with the upgraded TotalRoam software on June 11, 2003. By September, Fremont's 80 remaining cruisers were equipped with the technology, integrating their databases and current applications with the GPRS network. The software allows officers to invisibly switch between WiFi and the GPRS network. Officers can take advantage of the faster WiFi throughput when it is available for high-bandwidth applications, such as software updates and uploading mug shots. When an officer roams out of WiFi coverage, the software automatically switches the officer to the GPRS network without any user intervention.
Today, the Fremont Police Department enjoys the faster throughput of the new GPRS network, which transmits data at 115 kilobits per second, or almost six times the speed of CDPD. Field officers are able to continue using familiar applications and receiving information in accustomed ways — just at much faster transfer rates than before.