Uplink Access Indication for Group Call Channel Availability
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Solution Overview
Problem
In radio trunking communication systems, listeners are unable to initiate uplink access requests on the group call channel uplink when the talker is present, and there is a lack of clear indication for listeners to determine whether they can use the group call channel uplink for access requests, especially when the talker is in a different cell.
Innovation Solution
The system sends an indication message via downlink channels to inform subscribers which uplink channel is available for sending an uplink access request, allowing listeners to select either the group call channel uplink or the RACH based on the availability indicated, and to determine the cell where the talker is located to avoid unnecessary RACH usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the talker occupies the group call channel uplink, then the talker can maintain continuous communication, but listeners are unable to initiate uplink access requests on the group call channel uplink
Solution Approach 1:
The patent introduces a downlink indication message as an intermediary signal that mediates between the talker's occupation of the uplink channel and the listener's need to access the channel. The base station sends availability indication messages on the downlink to inform listeners whether the group call channel uplink is currently available, enabling listeners to make informed decisions about channel access without directly interfering with the talker's continuous communication
Solution Approach 2:
The system performs preliminary action by sending availability indication messages to listeners before they attempt to access the uplink channel. This advance notification allows listeners to prepare their access requests appropriately, selecting either the group call channel uplink or alternative channels based on the current channel availability status, thereby avoiding failed access attempts and reducing access delay
2Reliability
If listeners use RACH to send uplink access requests, then they can access the channel when group call channel uplink is unavailable, but access delay increases and channel utilization decreases
Solution Approach 1:
The patent implements dynamic channel selection by enabling listeners to adaptively choose between the group call channel uplink and alternative channels (such as RACH) based on real-time channel availability information received from the base station. This dynamic approach allows listeners to exploit the faster group call channel uplink when available, while falling back to RACH only when necessary, thereby reducing overall access delay and improving channel utilization efficiency
Solution Approach 2:
The system establishes a feedback mechanism where the base station continuously monitors uplink channel availability and sends indication messages to listeners via the downlink. This feedback loop provides listeners with real-time information about channel status, enabling them to make optimal access decisions and avoid unnecessary delays associated with blind RACH access attempts when the group call channel uplink is actually available
3Productivity
If listeners cannot determine talker cell location, then they cannot avoid unnecessary RACH usage, but providing cell information increases system complexity
Solution Approach 1:
The patent makes the downlink indication message serve multiple functions: it not only informs listeners about the availability of the group call channel uplink but also conveys the cell location information of the talker. By embedding cell identification information within the existing indication message structure, the system enables listeners to determine whether the talker is in the same cell and make intelligent decisions about channel access without requiring separate signaling mechanisms, thus improving access efficiency while minimizing additional system complexity
Data Source
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AI summary
A method for indicating a channel for sending an uplink access request, includes: ending an indication message indicating whether a group call channel uplink is available in a cell of a group call area; receiving an uplink access request via the group call channel uplink from a listener if the group call channel uplink is available according to the indication message; and receiving the uplink access request via an uplink channel from the listener if the group call channel uplink is unavailable according to the indication message. The solution of the present invention enables listeners to send uplink access requests when a talker is talking on the group call channel uplink.