Mobile Terminal Power Control Using RSCP Statistics
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Solution Overview
Problem
Conventional downlink power control techniques in mobile communication systems face inefficiencies during the convergence phase of block error rate determination, leading to increased interference and reduced system capacity due to excessive power consumption.
Innovation Solution
The method involves determining the received signal code power (RSCP) of common pilot channel (CPICH) signals to adjust the target signal-to-interference ratio (SIR) and perform downlink outer loop power control independently, using time-averaged RSCP values and thresholds to optimize power control until the block error rate (BLER) converges, thereby reducing interference and improving system capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional downlink outer loop power control is performed using BLER determination, then the target SIR can be maintained, but the convergence process is slow and causes excessive power consumption and interference
Solution Approach 1:
The patent applies preliminary action by performing initial power control adjustments based on RSCP measurements before the BLER determination converges. The system calculates an initial target SIR using RSCP statistics and applies power control commands to the base station in advance, so that power optimization begins immediately after connection setup rather than waiting for slow BLER convergence. This preliminary power control based on RSCP reduces the convergence time while maintaining reliable target SIR control.
2Reliability
If the base station transmits with higher power during BLER convergence, then coverage is ensured, but interference to other terminals increases and system capacity decreases
Solution Approach 1:
The patent applies dynamics by making the power control strategy adaptive based on the convergence state. The system dynamically switches between two modes: during the convergence phase, it uses RSCP-based power control with time-averaged values to reduce power gradually; after convergence, it transitions to standard BLER-based power control. This dynamic adaptation allows the system to reduce interference during the critical convergence period while maintaining coverage, and then optimizes for capacity after convergence is achieved.
3Productivity
If RSCP-based power control is applied during convergence, then convergence speed improves, but measurement precision requirements increase
Solution Approach 1:
The patent applies beforehand cushioning by using time-averaging of RSCP measurements over multiple measurement intervals. Instead of relying on single instantaneous RSCP values, the system accumulates measurements over time and uses averaged values for power control decisions. This cushioning approach smooths out measurement variations and provides more stable, reliable input for power control during the convergence phase, reducing the impact of measurement noise while maintaining fast convergence.
Data Source
AI summary
A power control method performed by a mobile communication terminal comprises determining a received signal code power of common pilot channel signals received from a base station on a common pilot channel in at least one time interval. A block error rate determination is performed to determine a block error rate for transmissions received from the base station. A downlink outer loop power control is performed in dependence on the determined received signal code power of the common pilot channel signals until the block error rate determination fulfills a convergence criterion.