Tuesday, August 31, 2010

Public Safety Advocate - Andrew Seybold
About now, many who are convinced that broadband is the only wireless technology we need going forward will be saying that broadband services will be able to handle all of the Public Safety voice communications described in the first two articles in this series. I respectfully disagree. In part 1, "Incident Communications," I described the need for local as well as wide-area voice communications and in part 2, "A Knowledge Gap," I discussed how Public Safety voice communications cannot be addressed using a broadband network. Here, in part 3, I will take a more in-depth look at the requirements for local, non-network voice communications services.
One of the difficulties in explaining these requirements is that there is a difference in the terminology used by the Public Safety community and the commercial wireless and IT worlds. Here I will be talking about the use of voice radio communications for one-to-many communications that do not rely on cell sites or radios mounted on towers. This type of communications is referred to in several ways including "simplex," "tactical," and"talk-around" communications. There are no terms to describe these capabilities in the world of commercial wireless since none of these are available over standard commercial networks. What's more, there probably never will be. Perhaps those of you who are more familiar with IT jargon will understand that this type of communications is peer-to-peer, or more precisely, peer-to-multi-peer.
Anyone who has used Citizens Band radio, or more recently the walkie-talkies for theFamily Radio band, can relate. You talk to another unit that is within direct range of your radio without the signal being received and relayed by a cell site or tower. The range is limited, sometimes to as little as one-quarter of a mile and sometimes over longer distances, depending on the type of radio, its power, and the frequency band it uses. This type of communications is essential for the Public Safety community as well as other land mobile radio (LMR) users.
This unique form of communications is not technically possible with a cellular handset since it does not use a cell site or tower to be able to communicate with other units on the same channel. It is important to Public Safety because it enables various groups of first responders to communicate at the scene of an incident without adding to congestion on the primary dispatch channel. We all know we must be in range of a cell site for our cell phone to work. If we are out of range and have no network coverage, or are inside a building, parking structure, or other place where there is no coverage, our cell phone is merely a paperweight. This cannot be tolerated in the world of Public Safety, thus the radios must be capable of simplex operation. ...

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