Downlink Control Channel Segmentation for User Terminal Power Reduction

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Solution Overview

Problem

In next-generation radio communication systems, the capacity of the downlink control channel is expected to be insufficient due to an increased number of users, leading to potential inefficiencies in MU-MIMO transmission and increased power consumption in user terminals when conventional radio resource allocation methods are used.

Innovation Solution

A radio communication system that allocates downlink control information in a first control region and a second control region, frequency-divided with a data region, and includes decoding control information to manage the decoding process for user terminals, allowing selective decoding and reducing unnecessary power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the downlink control channel is extended to accommodate increased number of users, then the control channel capacity is improved, but the user terminal power consumption increases due to additional decoding processes

Engineering Contradiction:
Improvecontrol channel capacityVSAvoiduser terminal power consumption
Core Design Contradiction:
Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The control channel is divided into two separate control regions: a first control region that is always decoded by the user terminal, and a second control region that is selectively decoded based on the presence of a specific identifier. This segmentation allows the terminal to process only necessary control information, reducing power consumption while maintaining adequate control channel capacity for multiple users.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The user terminal performs partial decoding by only processing the first control region unless its specific identifier is detected in the second control region. This partial action approach prevents excessive decoding of all control regions, thereby reducing power consumption while still enabling the system to support increased user capacity when needed.

Inventive Principle:
Principle #16Partial or excessive action

2Ease of manufacture

If conventional radio resource allocation methods are used, then the implementation is simple, but MU-MIMO transmission efficiency deteriorates due to insufficient control channel capacity

Engineering Contradiction:
Improveimplementation simplicityVSAvoidMU-MIMO transmission efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The control channel structure is segmented into two regions with different decoding requirements, enabling efficient MU-MIMO transmission by providing dedicated control information for multiple users while maintaining a simple base implementation where terminals only decode the first control region by default.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically changes the control channel allocation parameters by activating the second control region only when MU-MIMO transmission is required. This parameter change allows the system to maintain simplicity for single-user operations while achieving high efficiency for multi-user scenarios.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2734000B1User terminal, wireless base station device, wireless communication system, and wireless communication method
Publication Date: 2019.04.17 NTT DOCOMO INC
  • EP2734000B1 patent drawingFigure 1
  • EP2734000B1 patent drawingFigure 2
  • EP2734000B1 patent drawingFigure 3A~3B

AI summary

The present invention is designed to minimize the increase of user terminal power consumption even when downlink control channels are extended. A radio base station apparatus having: an allocation section that allocates downlink control information in a first control region from a top of a radio frame to a predetermined OFDM symbol and in a second control region that is frequency-divided with a data region in a region that is time-divided with the first control region, and also allocates decoding control information that indicates a user terminal to perform a decoding process for the second control region, in the first control region; and a transmission section that transmits the downlink control information and the decoding control information; and a user terminal having: a receiving section that receives the downlink control information and the decoding control information from the radio base station apparatus; and a decoding section that controls the decoding process for the second control region based on the decoding control information received, are provided.