PHICH Transmit Power Control in LTE Base Stations

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Solution Overview

Problem

In LTE systems, achieving optimal transmit power control for control channels like PHICH is challenging due to limited resources, leading to either increased error rates or reduced system efficiency.

Innovation Solution

Determine the transmit power of the PHICH based on downlink radio quality information (CQI), the contents of ACK/NACK signals, and whether an UL scheduling grant is transmitted, allowing for appropriate power allocation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transmit power is increased for control channels (PDCCH, PCFICH, PHICH), then error rate decreases and communication stability improves, but system efficiency and resource utilization deteriorate

Engineering Contradiction:
Improvecommunication stabilityVSAvoidsystem efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies dynamics by making the transmit power of PHICH adjustable rather than fixed. The base station dynamically determines the PHICH transmit power based on real-time channel conditions, CQI information, and ACK/NACK contents, allowing the system to adapt power allocation to actual communication needs and resolve the contradiction between reliability and efficiency

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the power parameter of PHICH by introducing power control mechanisms that adjust transmit power based on multiple factors including downlink radio quality information (CQI), ACK/NACK contents, and scheduling grant transmission status. This parameter adjustment allows optimal power allocation that balances error rate reduction with system efficiency

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If transmit power is allocated to PHICH based on fixed rules, then implementation is simple, but error rate and resource utilization cannot be optimized

Engineering Contradiction:
Improveimplementation simplicityVSAvoiderror rate
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent implements power control by changing the power parameter of PHICH based on measurable parameters such as downlink radio quality information (CQI), ACK/NACK contents, and scheduling grant transmission status. This allows the system to move from fixed power allocation to adaptive power allocation that optimizes error rate while maintaining manageable implementation complexity through standardized measurement and control procedures

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2268088B1Base station device and communication control method
Publication Date: 2016.07.27 NTT DOCOMO INC
  • EP2268088B1 patent drawingFigure 1
  • EP2268088B1 patent drawingFigure 2
  • EP2268088B1 patent drawingFigure 3A

AI summary

A base station apparatus communicates to a user apparatus in an uplink shared channel and controls transmit power for a PHICH (Physical HARQ Indicator Channel) on the shared channel. The transmit power for the PHICH is controlled based on downlink radio quality information (CQI) reported from the user apparatus, information (ACK/NACK) mapped into the PHICH and the presence of transmission of an uplink scheduling grant for indicating transmission of the shared channel.