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.
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.
Invisible Operations
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 files," Ramirez said.
Push technology originally was developed to enable Internet applications to send data without a client request. That level of integration requires programming. The department develops custom scripts and tunes delivery to specific groups or classes of users with Visual Basic.
"We can send selected files to shift supervisors and route software updates at set times, and the system will track who got what and when," Ramirez said. The system uses Windows' application, system, performance and security logs to keep tabs on the network, and identifies usage patterns and potential bottlenecks. It also ensures the client system is free of corrupt files and tracks hardware changes.
"If a client system is missing RAM or has some similar modification, the administrator is notified with an alter message," Ramirez noted. That level of detail makes it easier to keep MDTs in operation and make sure they have the latest updates.
TotalRoam can be deployed as a software solution loaded directly on individual MDTs, or as an embedded Windows appliance mounted in the trunk and connected to the unit's MDT via Ethernet. Oakland uses the software solution on its laptops, along with Cisco Aironet 350 network cards.
Ramirez said it took about two months to get the Padcom and XcelleNet software online. "There were several vendors involved that had to coordinate actions, adapting the different networks, and there was sending out the RFP and the bidding process to deal with. The final cost worked out to about $500 a unit.
"One concern we had going in was making sure the entire process was transparent to the end-user," Ramirez added. Law enforcement officers are often too busy to deal with computer problems, and have widely different levels of computer expertise. Also, training time is expensive and better spent by police agencies on topics of more tactical value.
Both TotalRoam and Afaria operate without any client intervention and load before the user logs into Windows. The applications automatically handle network identification and transfer files in the background. Their only visible indicators on the client side are monitor icons on the Windows taskbar. Officers don't have to log on, launch client software or even know what network is currently operating on their MDT.
Eye on the Future
The department now is considering ways to maximize its investment. The agency is adding its CDPD network to the matrix, allowing motorcycle officers full access to the system. It may add other advanced features as well.
"We are considering placing TV cameras in selected places, like schools, and tying them into a WLAN that can feed images to a patrol unit as it arrives," Ramirez said. Oakland Police could even begin piping video from helicopters to nearby patrol units during surveillance or pursuits.
Improved bandwidth and wide-area networking offer other potential benefits. Many law enforcement agencies currently have limited mutual aid communications. Linking networks could make it easier to share data and pass critical information about an immediate event. Push technology could be used to broadcast alerts, weather advisories, or past activity or arrest summaries to an officer en route to a call.
Intelligent mobile routing isn't just for law enforcement. Fire and emergency medical departments have similar needs, and could be linked into a global area network, sharing appropriate resources.
Given the wide mix of data communications hardware and networking solutions in the public-sector marketplace, an open solution like the one adopted in Oakland offers a cost-effective way to increase access and gather and distribute information.
