Power Control Method for Soft Handover in Cellular Systems

Solution Overview

Problem

In cellular radio systems, mobile stations in soft handover experience inefficiencies in power control due to multiple base stations transmitting power control commands, leading to uncertain command follow-up and increased SINR oscillations, which existing methods struggle to address effectively.

Innovation Solution

Communicating the power control status of a mobile station to base stations allows for optimized power control command generation, enabling the selection of appropriate power control methods based on the status, either through a central node, base station-centric, or mobile station-centric approaches, ensuring that only one base station controls the mobile station during soft handover.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple base stations transmit power control commands to a mobile station in soft handover, then the mobile station can be power controlled by any connected base station, but the base stations cannot know whether their power control commands are followed, leading to uncertain command follow-up and increased SINR oscillations

Engineering Contradiction:

Improvepower control flexibilityVSAvoidpower control command reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces feedback mechanisms where the mobile station reports its power control status to the base station. This feedback loop allows the base station to determine whether its power control commands are being followed by the mobile station, enabling adaptive adjustment of power control strategies based on actual command follow-up behavior.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent implements dynamic power control adaptation where the base station changes its power control behavior based on the mobile station's status. When the mobile station is in soft handover with multiple base stations, the system dynamically adjusts which base station's power control commands are prioritized and how they are combined, optimizing the control process for varying network conditions.

Inventive Principle:

Principle #15Dynamics

2Loss of time

If the base station uses measures like RSCP to improve power control convergence in soft handover, then it can compensate for generating delay, but it cannot compensate for transmitting delay and suffers from estimation errors

Engineering Contradiction:

Improvepower control delay compensationVSAvoidRSCP estimation accuracy

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary mechanism where the mobile station acts as a mediator between the base station and the power control command execution. The mobile station reports its actual power control status, providing accurate information about command follow-up without relying on potentially erroneous RSCP measurements. This intermediary feedback mechanism eliminates the need for delay compensation techniques that introduce estimation errors.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the system disables the utilization of already generated power control commands at base stations during soft handover, then it avoids uncertain command follow-up, but mobile stations cannot compensate for time delay and have larger SINR oscillations

Engineering Contradiction:

Improvepower control command reliabilityVSAvoidSINR stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent implements dynamic power control adaptation where the base station changes its power control behavior based on the mobile station's status. When the mobile station is in soft handover with multiple base stations, the system dynamically adjusts which base station's power control commands are prioritized and how they are combined, optimizing the control process for varying network conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces feedback mechanisms where the mobile station reports its power control status to the base station. This feedback loop allows the base station to determine whether its power control commands are being followed by the mobile station, enabling adaptive adjustment of power control strategies based on actual command follow-up behavior.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP2420097B1A method of power control

Publication Date: 2016.01.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

In a cellular radio system the power control status of a mobile station is used in the base stations to generate power control commands. Hereby a radio base station can select a power control method that is optimal for the situation at hand. This is obtained by communicating power control status to base stations or deriving power control status in a radio base station. The radio base station is adapted to select power control method based on the power control status. Thus, a base station can select the most suitable power control improvement method, even during soft handover, thereby making make use of the advantages of different types of power control improvement methods.