Correcting RSRQ Measurements in LTE-A Networks
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Solution Overview
Problem
In LTE-A networks, the use of the almost blank subframe (ABS) mechanism by high and low power eNBs leads to inaccurate reference signal receiving quality (RSRQ) measurements, causing abnormal handover operations due to decreased received signal strength indicator (RSSI) and increased noise power, which existing solutions do not adequately address for LTE user equipment.
Innovation Solution
A method and apparatus that collect multiple measurement values from user equipment (UE) to calculate a variation degree value, correcting the RSRQ when it exceeds a threshold, using an abnormality detector and quality adjuster to generate a corrected RSRQ, thereby preventing erroneous handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ABS mechanism is used by eNBs to avoid co-channel interference, then interference between high power eNBs and low power eNBs is reduced, but the RSSI decreases and noise power increases, causing RSRQ measurement errors
Solution Approach 1:
The patent implements a feedback mechanism where the eNB monitors the RSRQ values reported by the UE and compares them against expected ranges. When the RSRQ exceeds a threshold indicating potential measurement error due to ABS, the eNB generates a correction indication signal sent back to the UE, which then adjusts its RSRQ reporting. This closed-loop feedback system resolves the measurement accuracy degradation caused by ABS without compromising the interference avoidance benefit.
Solution Approach 2:
The patent changes the parameter handling by introducing a correction factor or adjusted RSRQ value when ABS is detected. Instead of using the raw RSRQ measurement directly for handover decisions, the system applies parameter transformation to compensate for the measurement error introduced by ABS, thereby maintaining measurement precision while preserving the interference coordination benefit.
2Device complexity
If the UE reports RSRQ values without correction, then the handover decision process remains simple, but abnormal handovers occur due to inaccurate RSRQ measurements
Solution Approach 1:
The patent applies preliminary action by having the eNB pre-establish threshold values and correction mechanisms before handover decisions are made. The system proactively identifies potential measurement errors through threshold comparison and applies corrections in advance, preventing abnormal handovers before they occur. This approach maintains relatively simple handover logic while significantly improving reliability.
Solution Approach 2:
The patent introduces an intermediary correction mechanism between the UE's RSRQ measurement and the eNB's handover decision. The correction indication signal acts as a mediator that conveys information about ABS conditions to the UE, which then adjusts its reporting. This intermediary layer resolves the contradiction by adding minimal complexity to the decision process while preventing unreliable handovers.
3Measurement precision
If RSRQ values are corrected using multiple measurement values, then measurement accuracy improves, but the processing complexity increases
Solution Approach 1:
The patent applies partial action by collecting and processing only the necessary number of measurement values (typically three) to achieve reliable RSRQ correction, rather than processing all possible measurements. This selective approach provides sufficient accuracy improvement while keeping the processing complexity manageable. The system uses a predetermined number of samples that balances accuracy requirements with computational burden.
Data Source
AI summary
A method and an apparatus for correcting wireless signal quality are provided. The apparatus includes an abnormality detector and a quality adjuster. The abnormality detector collects multiple measurement values reported by a user equipment (UE), calculates a variation degree value according to the measurement values, and compares the variation degree value with a predetermined threshold value. The measurement values are generated by the UE when the UE measures the wireless signal quality of an evolved node B. The measurement values include a first reference signal receiving quality (RSRQ) of the evolved node B. When the variation degree value is larger than the predetermined threshold value, the quality adjuster corrects the first RSRQ based on the measurement values to generate a second RSRQ of the evolved node B.