Radio Base Station PDCCH Quality Estimation via Usage Rate
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Solution Overview
Problem
In LTE systems, the radio base station faces challenges in estimating the quality of the control channel (PDCCH) received by the radio terminal, as the terminal only reports the quality of the user data channel (PDSCH), necessitating an indirect estimation method to ensure the PDCCH quality meets required levels, especially due to interference from nearby cells using the same frequency.
Innovation Solution
The radio base station employs a first acquisition unit to measure the user data channel quality, a second acquisition unit to determine the control channel usage rate from adjacent cells, and an estimation unit to calculate the PDCCH quality by multiplying the user data channel quality by the reciprocal of the control channel usage rate, or by adding an offset value based on historical data, to accurately estimate the PDCCH quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the radio base station uses the same frequency for nearby cells or sectors to increase capacity and speed, then the frequency utilization efficiency is improved, but interference from other cells or sectors increases
Solution Approach 1:
The patent changes the parameter of frequency allocation by allowing the same frequency to be used in nearby cells or sectors (frequency reuse), which improves frequency utilization efficiency. To counteract the resulting interference, the system adjusts other parameters such as power control and resource allocation strategies to maintain acceptable signal quality.
2Reliability
If the radio base station controls downlink communication to ensure PDCCH quality meets required levels, then the control channel reception quality is improved, but the complexity of communication control increases
Solution Approach 1:
The patent introduces an intermediary estimation mechanism where the base station estimates PDCCH reception quality at the radio terminal by using the reported PDSCH reception quality as a proxy. This intermediary approach avoids the need for direct PDCCH quality reporting from the terminal, simplifying the control mechanism while maintaining reliability.
Solution Approach 2:
The patent uses the PDSCH reception quality as a copy or proxy indicator for PDCCH reception quality. Since the terminal reports CQI (Channel Quality Indicator) for PDSCH, the base station uses this copied information to infer PDCCH quality, avoiding the need for separate PDCCH quality measurement and reporting mechanisms.
3Quantity of substance
If the radio terminal transmits only PDSCH reception quality information to the radio base station, then the uplink signaling overhead is reduced, but the accuracy of PDCCH quality estimation deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the terminal reports PDSCH reception quality (CQI) to the base station, and the base station uses this feedback to estimate PDCCH quality. The system continuously adjusts downlink transmission parameters based on this feedback loop, improving estimation accuracy over time while maintaining low signaling overhead.
Data Source
AI summary
A control unit (102) in a radio base station (1A) receives a measurement W-CQI message from a radio terminal (2A) and acquires the usage rate of the PDCCH corresponding to the serving sector. Further, the control unit (102) in the radio base station (1A) multiplies the measurement W-CQI corresponding to the serving sector by the reciprocal of the usage rate of the PDCCH corresponding to the radio base station (1A), and thereby estimates the SINR of the PDCCH corresponding to the serving sector at the radio terminal (2A).