Today's police officers increasingly rely on technology to carry out their duties, and their squad cars are data centers and communication hubs on wheels.
But law enforcement wireless networks suffer from growing demands and limited bandwidth. Police in Oakland, Calif., use technology called intelligent mobile routing that cures the problem while improving service and officer safety.
Most police data communications travel over private radio or private networks, offering citywide or countywide coverage at low bandwidth. Speeds range from 4.8 Kbps to 19.9 Kbps (kilobits per second), compared to a typical 56 Kbps dial-up connection.
Wireless local area networks (WLANs) that link office PCs using the 802.11b standard are much faster, typically up to 11 Mbps, and are capable of moving large blocks of data -- even streaming video. That type of connection, however, has a limited range of only several hundred feet.
The Oakland Police Department handles data traffic for its 55 square-mile service area with a primary low-speed Motorola wireless network serving 220 patrol cruisers, and a cellular data system for its 35 motorcycles. High-speed WLAN hubs are spotted at key points in the community for moving larger files.
The Best Connection
Intelligent mobile routing allows the department to combine radio, cellular and WLAN into an intelligent matrix providing both reach and throughput -- sending data based on the current connection and bandwidth. Padcom's Wireless Data Connectivity Suite routes network traffic, operating under Windows NT, 2000 or XP. It automatically detects the best connection and adjusts to the network, signal strength and carrier information. It allows the client to maintain a single IP address with all the networks -- even non-TCP/IP networks.
The Padcom suite contains four components:
- The TotalRoam client and server modules provide network routing and a connectivity gateway.
- TotalConnect acts as an interpreter, making any network in the matrix look like an IP environment to the client.
- TotalSecure enables end-to-end encrypted transmissions with support for AES, 3DES and ARC4 algorithms over any wireless network with no application modifications required.
- TotalControl is a rules-based administrative module that allows managers to control mobile user access. It also allows the creation of a mobile firewall on specific clients, automatically launches applications based on network conditions and can be customized using a Padcom application programming interface.
Switching between networks is automatic and transparent to officers, much like roaming with a cell phone. The software detects when patrol officers drive within a Wi-Fi transmitter's range, automatically switching the car's computers from the slower citywide radio to Wi-Fi.
"We have two WLAN links at the department gas pumps," said Oakland police officer Inez Ramirez. "When a cruiser comes in range, the unit switches to the WLAN. We have a software routine that automatically checks for files that need to be transferred and starts moving them."
The high-speed interface handles pictures, large reports (including booking summaries from the jail complete with mug shots), and software updates for the car's mobile data terminal (MDT). If the unit leaves the area before the download completes, the partial file is saved and downloading resumes next time the car comes in range. When the cruiser leaves the WLAN coverage, the low-speed connection takes over. Placing the nodes at the fuel center ensures each cruiser gets connected to the high-speed network on a regular basis.
Oakland incorporated XcelleNet's Afaria as a companion mobile management application, which provides more control over network operations. Working with TotalRoam, it allows the department's IT staff to distribute and track client software, manage the network servers and automate routine tasks. "We can use Afaria's push capability to make file operations invisible to the officer on the street, and keep full control of who has access or gets which