UE RSTD Timing Adjustment for EC Mode Delay
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Solution Overview
Problem
In Enhanced Coverage (EC) mode, the significant number of message repetitions in wireless communication systems lead to increased communication delays, causing Reference Signal Time Difference (RSTD) measurement reports to be received late at Position Determination Entities, thereby affecting the accuracy and continuity of User Equipment (UE) location determination.
Innovation Solution
The UE determines an expected communication delay (TCE-X) based on parameters such as message repetitions and uplink subframes during a coverage mode transition to EC mode, and initiates the RSTD measurement report transmission at a time that ensures it is received before the specified measurement timeout, using a method that includes transitioning to EC mode and maintaining a Normal Coverage mode bandwidth for measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE operates in Enhanced Coverage (EC) mode with message repetitions to maintain communication reliability in poor signal quality regions, then the communication reliability is improved, but the communication delay increases causing RSTD measurement reports to be received late at the Position Determination Entity
Solution Approach 1:
The UE determines the expected communication delay (TCE-X) in advance based on the EC mode configuration parameters before transmitting the RSTD measurement report. This preliminary calculation allows the UE to proactively adjust the transmission timing to compensate for the anticipated delay, ensuring the report arrives before the positioning measurement session timeout period.
2Device complexity
If the UE uses a fixed transmission timing for RSTD measurement reports without accounting for EC mode delays, then the positioning measurement session timing is simple to manage, but the RSTD measurement reports may be received after the timeout period causing location determination failure
Solution Approach 1:
The UE dynamically adjusts the RSTD measurement report transmission timing based on the detected coverage mode. When in EC mode, the UE calculates the expected communication delay using the formula TCE-X = (N-1) × 10ms where N is the number of message repetitions, and transmits the report at time t2 = t1 + TCE-X. This dynamic adaptation ensures reliable location determination while maintaining manageable complexity through mode-based rules.
3Stability of the object's composition
If the UE transitions to EC mode to maintain communication in poor signal regions, then the communication continuity is improved, but the positioning accuracy deteriorates due to increased measurement and transmission delays
Solution Approach 1:
The UE performs preliminary calculation of the expected communication delay (TCE-X) based on EC mode parameters before transmitting the RSTD measurement report. By determining TCE-X in advance using the formula TCE-X = (N-1) × 10ms and adjusting the transmission timing accordingly, the UE ensures that positioning measurements remain accurate and timely even during EC mode operation, thus maintaining positioning accuracy while ensuring communication continuity.
Data Source
AI summary
A User Equipment (UE) may receive a coverage mode transition request at a first time and upon determining that the coverage mode transition request includes a request to transition to an Enhanced Coverage (EC) mode, the UE may determine, based on parameters in the coverage mode transition request, an expected communication delay for transmission of a Reference Signal Time Difference (RSTD) measurement report. The UE may initiate transmission of the RSTD measurement report for the positioning measurement session at a second time not exceeding a specified RSTD measurement time. The second time may precede an RSTD measurement timeout time for the positioning measurement session by at least the expected communication delay. Disclosed embodiments also pertain to communication of the expected communication delay between a Location Server (e.g. Evolved Serving Mobile Location Center) and a Base Station (e.g. evolved NodeB) using Long Term Evolution Positioning Protocol Annex (LPPa) messages.