Publishing Venue
Motorola
Related People
Authors:
Darin Minter
•
Anatoly Belkin
Abstract
When a subscriber is on a non-emergency traffic channel, it will receive an Error-481 if an Emergency Dispatch Call contends for and is assigned to that same traffic channel resource. For the non-emergency user, there are no details at the subscriber level to indicate what has actually happened. As designed, the channel is ruthlessly preempted from the non-emergency user and given to the emergency requestor by the Access Controller Gateway (ACG).
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M-LA Technical Developments
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EMERGENCY TCH PRE-EMPTION INDICATION
by Darin Minter and Anatoly Belkin
BACKGROUND
When a subscriber is on a non-emergency traffic channel, it will receive an Error-481 if an Emergency Dispatch Call contends for and is assigned to that same traffic channel resource. For the non-emergency user, there are no details at the subscriber level to indicate what has actually happened. As designed, the channel is ruthlessly preempted from the non-emergency user and given to the emergency requestor by the Access Controller Gateway (ACG).
OPPOFtTUNITY
The Error-481 (also known as a Loss of Transmission or LOT) occurs due to a failure or loss of synchronization with the Fixed Network Equipment (FNE) from the Subscriber's perspec- tive. In the case of the emergency call, this occurs because the Access Controller Gateway has, in effect, "ripped" out the channel from a nonemer- gency call to process the emergency call request. To the subscriber, there is simply a loss of synchro- nization with the FNE, thereby resulting in an immediate Unassigned Channel assignment with no means of receiving any indication why.
In general, however, the Error-481 represents the presence of some undesirable condition or system behavior (i.e., system instability), and not a normal condition with normal results (i.e., emer- gency call preempts channel of non-emergency call -normal call processing). This can be confusing to the radio user who is operating the subscriber with...
