Trunking Base Station Isolation Handling via Preliminary Control Packets
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Solution Overview
Problem
In trunked radio systems, when control channel base stations become isolated from the control infrastructure, it can lead to widespread service interruptions due to unmanaged registration requests from subscriber radios, as existing systems lack effective methods to handle such isolation events promptly and robustly.
Innovation Solution
Implementing methods and apparatus that allow control channel base stations to continue transmitting subscriber control packets based on predetermined schedules and inform subscriber radios of a non-zero registration hold off timer, delaying their abandonment of the current trunking site and reducing the likelihood of overwhelming neighboring sites with registration requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control channel base stations stop transmitting subscriber control packets when isolated from control infrastructure, then destructive interference is avoided in simulcast systems, but subscriber radios abandon the current trunking site and cause widespread service interruptions
Solution Approach 1:
The control channel base station transmits a predetermined subscriber control packet when isolated from the control infrastructure to preemptively inform subscriber radios of the isolation condition. This preliminary action prevents subscriber radios from abandoning the current trunking site, thereby avoiding the harmful effect of widespread service interruptions while maintaining system reliability.
2Ease of operation
If control channel base stations continue normal operation without informing subscriber radios of isolation, then system operation is simple, but neighboring trunking sites are overwhelmed by flood of registration requests
Solution Approach 1:
The base station transmits a predetermined subscriber control packet containing information about a non-zero registration hold off timer before subscriber radios can generate registration requests. This preliminary notification prevents the flood of registration requests from overwhelming neighboring sites, while requiring minimal operational changes to the base station.
3Reliability
If subscriber radios immediately register with neighboring trunking sites upon detecting control packet loss, then service continuity is maintained, but neighboring sites experience overwhelming registration loads
Solution Approach 1:
The predetermined subscriber control packet is transmitted to subscriber radios in advance, informing them of the isolation condition and the non-zero registration hold off timer. This preliminary information causes subscriber radios to delay their registration attempts with neighboring sites, reducing the registration request volume while maintaining service continuity.
4Object-generated harmful factors
If control infrastructure manages registration hold off timers for all base stations, then registration floods are prevented, but system complexity increases and responsiveness to isolation events decreases
Solution Approach 1:
The control channel base station autonomously transmits the predetermined subscriber control packet when it detects isolation from the control infrastructure. This self-service approach enables the base station to independently prevent registration floods without requiring complex control infrastructure management, thereby reducing system complexity while improving responsiveness to isolation events.
Data Source
AI summary
Embodiments include a trunking site base station receiving a first base station control packet over a network and, in response, transmitting a first subscriber control packet over a subscriber control channel at a first transmission time that is determined based on a transmission schedule. The first subscriber control packet includes a frame sync, a network ID, and a payload. Responsive to determining that a second base station control packet has not been received before a first timeout (or based on another trigger), the base station transmits a second subscriber control packet at a second transmission time that is determined based on the transmission schedule. The second subscriber control packet includes the frame sync and the network ID. The second subscriber control packet also may include a payload indicating a delay period for a subscriber radio to wait before making an attempt to register with a different trunking site.