LTE RRM Measurement Accuracy with Interference Rejection Combining
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Solution Overview
Problem
Existing LTE UE RRM measurements, such as RSRP, RSSI, and RSRQ, can be inaccurate when interference rejection combining (IRC) is applied, leading to a mismatch between actual SINR conditions and measurements, which affects mobility decisions and radio link quality in heterogeneous networks.
Innovation Solution
Modifying RRM measurements to account for IRC receiver performance by using the N rx -th strongest interfering RSRP, neglecting interference from N rx -1 strongest cells in RSSI, and calculating RSRQ based on IRC values, ensuring accurate signal quality and power assessments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional RRM measurements (RSRP, RSSI, RSRQ) are used in LTE UE, then measurement simplicity and compatibility are maintained, but measurement accuracy deteriorates when IRC is applied due to mismatch between actual SINR condition and measurements
Solution Approach 1:
The patent modifies the measurement parameters by introducing IRC-specific adjustments: using N rx -th strongest interfering RSRP instead of traditional RSRP, neglecting interference from N rx -1 strongest cells in RSSI calculation, and calculating RSRQ based on IRC values. These parameter changes enable accurate measurements that reflect the actual SINR condition when IRC is applied.
Solution Approach 2:
The patent introduces an intermediary measurement approach that accounts for IRC receiver performance. By using the N rx -th strongest interfering RSRP and adjusting RSSI/RSRQ calculations to reflect IRC interference suppression capabilities, the measurement system acts as an intermediary that bridges the gap between traditional measurements and actual IRC-enhanced SINR conditions.
2Reliability
If IRC is applied at the receiver side to suppress interference, then SINR quality and user throughput are improved, but mismatch between actual SINR condition and RSRP/RSSI/RSRQ measurements occurs
Solution Approach 1:
The patent applies parameter changes by modifying how RSRP, RSSI, and RSRQ are measured and calculated when IRC is applied. Specifically, it uses the N rx -th strongest interfering RSRP, adjusts RSSI to neglect interference from N rx -1 strongest cells, and calculates RSRQ based on IRC values, ensuring measurements accurately reflect the improved SINR condition achieved through IRC.
Solution Approach 2:
The patent implements a feedback mechanism where the measurement system adapts to the actual IRC receiver performance. By continuously adjusting measurements based on IRC values and interference suppression effects, the system provides accurate feedback about the true SINR condition, enabling proper mobility decisions that reflect the actual link quality enhancement from IRC.
3Productivity
If mobility decisions are made based on traditional RRM measurements, then decision simplicity is maintained, but mobility performance deteriorates due to inaccurate measurements in IRC scenarios
Solution Approach 1:
The patent modifies mobility decision parameters by using IRC-adjusted RSRP, RSSI, and RSRQ values. Instead of relying on traditional measurements that don't account for IRC effects, the system uses transformed parameters that accurately reflect the SINR condition with IRC, leading to more accurate mobility decisions despite increased processing complexity.
Data Source
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Figure 3
AI summary
An apparatus and a method are described, in which a plurality of signals is received via plurality of receiver units of a receiver, signal quality and/or power related measurements are performed, and a signal quality and/or power related measurement result is generated based on a combination of signals received by the receiver units.