Radio Transceiver Power Control Using Predicted Interference Cancellation

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Solution Overview

Problem

In cellular radio communications, achieving accurate and fast power control is challenging, especially when interference cancellation is used, as it affects the capacity of CDMA systems and can lead to unnecessary power level adjustments, causing instability and reduced system performance.

Innovation Solution

The technology determines signal power combined with predicted interference to generate transmit power control commands, using a predicted signal-to-interference indicator that accounts for interference cancellation efficiency, allowing for timely and accurate power adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If transmit power control does not take into account interference cancellation, then power control is simpler to implement, but mobile transmit power levels are set higher than necessary, reducing system capacity

Engineering Contradiction:

Improvepower control implementation complexityVSAvoidsystem capacity

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The system performs preliminary interference cancellation processing on received signals before power control decisions are made. By pre-processing the interference components and providing cleaned signal measurements to the power control algorithm, the system achieves accurate power control that recognizes interference cancellation benefits, thereby maximizing system capacity without excessive complexity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where interference cancellation results are fed back into the power control loop. The power control algorithm uses information about interference cancellation effectiveness to adjust mobile transmit power levels appropriately, ensuring power is set based on actual received signal quality rather than raw interference-containing measurements

Inventive Principle:

Principle #23Feedback

2Reliability

If interference cancellation is used to improve signal quality, then receiver performance is improved, but power control accuracy deteriorates without proper coordination

Engineering Contradiction:

Improvereceiver signal qualityVSAvoidpower control measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system segments the power control measurement process into distinct phases: interference cancellation processing and power control measurement. By separating these functions and ensuring measurements are taken from interference-cancelled signals rather than raw signals, the system maintains both high receiver performance and accurate power control measurements

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system introduces an intermediary processing stage where interference cancellation is performed on received signals before they are used for power control measurements. This intermediary step acts as a bridge that improves signal quality for subsequent measurements without compromising measurement accuracy, as the power control algorithm operates on the cleaned signal data

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If mobile stations transmit at higher power levels due to inaccurate power control, then signal reception is more reliable, but system capacity and energy efficiency are reduced

Engineering Contradiction:

Improvesignal reception reliabilityVSAvoidmobile station energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system uses feedback from interference cancellation performance to dynamically adjust mobile transmit power levels. When interference cancellation effectively removes interfering signals, the power control algorithm receives feedback indicating improved signal quality and reduces mobile transmit power accordingly, maintaining reliable reception while reducing energy consumption

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically changes the transmit power parameter based on interference cancellation effectiveness. By monitoring the quality of interference-cancelled signals and adjusting mobile power levels in response, the system maintains signal reception reliability while optimizing energy efficiency through parameter adaptation

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7856243B2Power control for a radio transceiver that uses interference cancellation

Publication Date: 2010.12.21 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A signal power associated with a signal received in a current time period is determined. The determined signal power is combined with a predicted effective interference to form a predicted signal-to-interference indicator. The predicted signal-to-interference indicator is compared to a target signal-to-interference indicator. One or more transmit power control commands are generated based on the comparison. In one example embodiment, the predicted effective interference is based on an effective interference estimated for a previous time period. In another example embodiment, the predicted effective interference is based on interference contributions estimated in a current time period and a predicted interference cancellation efficiency. The predicted interference cancellation efficiency is based on the estimated interference cancellation efficiency for a previous time period. The technology is particularly useful in receivers that use interference cancellation and achieves excellent transmit power control performance both in terms of accuracy and speed.