Access Terminal Handoff Error Recovery via Confirmation Signals
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Solution Overview
Problem
Wireless communication systems face errors due to false detection of handoff completion signals, leading to loss of connectivity and interference, as access terminals incorrectly assume handoff is complete before confirmation from the target base station.
Innovation Solution
Implementing a method where access terminals send a specific request signal to the target base station, detecting a completion signal, and confirming successful handoff or re-entry by receiving a forward link confirmation signal before a timer expires, which includes more CRC bits than the completion signal for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the access terminal listens for a handoff completion signal from the target base station, then the handoff process can be completed, but false detection of the completion signal can occur due to fading errors and physical channel errors
Solution Approach 1:
The access terminal performs preliminary actions by sending a handoff request signal to the target base station before actually completing the handoff. This preliminary request establishes an expected handoff sequence, allowing the terminal to later verify whether the completion signal was truly received or if it was a false detection based on fading errors or channel interference.
Solution Approach 2:
The system implements feedback mechanisms where the access terminal sends a handoff request signal and then expects a corresponding completion signal in response. This feedback loop allows the terminal to verify the actual handoff status by comparing the request with the completion signal, enabling detection and correction of false completions through the feedback discrepancy.
2Speed
If the access terminal assumes handoff is complete upon detecting the completion signal, then handoff speed is improved, but connectivity loss and interference occur due to false positive detection
Solution Approach 1:
The access terminal sends a handoff request signal as a preliminary action before completing the handoff procedure. This preliminary request creates an expected sequence that can be verified later, allowing the terminal to maintain speed by quickly detecting completion signals while preventing false positives by having the preliminary request establish the expected handoff state.
Solution Approach 2:
The feedback mechanism through handoff request and completion signal pairs allows the access terminal to verify actual handoff completion status. The feedback loop enables the terminal to distinguish between true completion signals and false detections by checking whether the completion signal appropriately responds to the preliminary request, thus maintaining both speed and reliability.
3Device complexity
If the access terminal uses conventional handoff completion detection, then the handoff process is simple, but false detection leads to random power control and loss of service
Solution Approach 1:
The access terminal performs a preliminary handoff request action before the actual handoff completion. This preliminary action adds a verification step to the detection process, increasing complexity slightly but significantly improving reliability by establishing an expected handoff sequence that can be verified to prevent false detections causing random power control and service loss.
Solution Approach 2:
The feedback mechanism through request-completion signal pairing provides verification of actual handoff status. This feedback loop increases detection complexity by requiring verification of the completion signal against the preliminary request, but it significantly improves service continuity reliability by preventing false positives from causing power control errors and service loss.
Data Source
AI summary
Systems and methodologies are described that facilitate recovering from error due to false detection of completion signals at an access terminal. An access terminal specific request signal can be sent to a target base station to initiate handoff or semi-connected state exit. A completion signal can be transferred in response to the access terminal specific request signal. To mitigate errors stemming from false detection of the completion signal at the access terminal, forward link and reverse link confirmation signals can be transferred to confirm successful handoff or connected state re-entry completion. For example, the access terminal can determine handoff or re-entry to be successful when a forward link confirmation signal is detected prior to expiration of a timer. Moreover, the forward link and reverse link confirmation signals can each include more CRC bits as compared to a number of CRC bits included in the completion signal.