How to buy wireless communications
By Tim Dees
The term "wireless communications" encompasses any information that doesn’t travel over a wire or optical cable or on a piece of paper.
The wireless system should be capable of supporting evolving open standards for wireless protocols providing for licensed and unlicensed radio frequency bands, security, quality of service, client access and wireless system radio management. The system should be easy to configure and manage for both indoor wireless LANs and outdoor Wireless mesh deployments allowing users to manage the wireless systems from a common, centralized user interface capable of managing the entire end to end system. The wireless system should support multiple radio channels, standards and frequencies and state of the art security and quality of service protocols for unlicensed and licensed radio bands and allow hybrid deployments using dual radios for uplink, access, bridging and mesh applications, as well as point-to-point configurations or point to multi-point.
Listed below are key points to consider when purchasing wireless communication equipment:
1. Establishing Bandwidth
One factor you need to consider early in this process is the amount and type of data you’ll be sending and receiving over your wireless network. All of it requires bandwidth, a term analogous to the diameter of a water pipe. A big pipe will carry a lot of water in a short time. A small pipe will carry the same amount of water, but it will require a lot longer to fill the container. Your data pipe is determined by its bandwidth.
Simple text requires the least bandwidth. Inquiries and replies to and from databases like your state’s motor vehicles bureau, the NCIC wanted persons and stolen property files, and digitized police reports will move pretty quickly over a low bandwidth connection. As long as the number of users trying to get data at the same time doesn’t bog things down too much, this is the cheapest and easiest type of communications channel to create and maintain.
Still photos require considerably more bandwidth. Streaming, real-time video is the biggest bandwidth hog. If you’re planning on sending or receiving video, get a real big data pipe.
4. Cell Phones
Since cell phones and other wireless devices have become so popular, radio spectrum is at a premium. You can either rent bandwidth from an existing provider, or put your traffic on channels already allocated for public use.
Cell phone carriers will sell you bandwidth—as much as you are likely to need. The upside is that they usually supply the hardware, and if something breaks, they fix it. Your network will work as long as you are within range of one of their towers, which are probably nationwide, and you can increase the bandwidth if your needs change. The downside of this plan is the recurring cost, and the inevitable price increase.
You can also set up a WLAN: Wide Local Area Network. This is a large-scale model of the Wi-Fi systems available in hotels and coffee shops, and what many people have in their homes. Instead of one access point/transceiver at the station, transceivers are mounted around town on utility poles and traffic signals. Data is encrypted to keep interlopers out. This works very well, especially in small communities.
An enhancement to either system is a mesh network, where the wireless transceivers in the patrol cars can act as access points for all the others. This allows for extending beyond the usual area of operation, and are "self-healing." If one access point goes down, the others will continue to work so long as they’re in range of one another.
Tim Dees is a retired police officer and the former editor of two major law enforcement websites who writes and consults on technology applications in criminal justice. He can be reached at firstname.lastname@example.org.
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