Enhanced PDCCH Search Space Configuration for LTE-A

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Solution Overview

Problem

In future radio communication systems like LTE-A, the shortage of capacity in downlink control channels hinders the optimization of MU-MIMO transmission, particularly due to insufficient radio resource regions for transmitting downlink control information, which limits the expansion of search space candidates for blind decoding.

Innovation Solution

The expansion of radio resource regions for downlink control channels is achieved by employing enhanced PDCCH, which is frequency-division-multiplexed with the PDSCH, allowing for localized and distributed mapping of DCI across multiple PRB pairs, and configuring multiple enhanced PDCCH sets for each user terminal to optimize search space candidates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the radio resource regions for downlink control channels are expanded to transmit more downlink control information, then the capacity of downlink control channels is improved, but the configuration complexity of search space candidates increases

Engineering Contradiction:
Improvecapacity of downlink control channelsVSAvoidconfiguration complexity of search space candidates
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The downlink control channel is divided into multiple enhanced PDCCH sets, each with its own search space candidates. This segmentation allows the system to expand control channel capacity by adding more sets while managing complexity through modular organization of search spaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension by configuring multiple enhanced PDCCH sets beyond the traditional single search space structure. This dimensional expansion enables increased control channel capacity while maintaining manageable complexity through structured configuration of multiple sets with different parameters.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If multiple enhanced PDCCH sets are configured for each user terminal to expand search space candidates, then the frequency scheduling gain is improved, but the device complexity increases

Engineering Contradiction:
Improvefrequency scheduling gainVSAvoiddevice complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

Different enhanced PDCCH sets are configured with different local qualities (distinct parameter sets including search space candidates, resource block assignments, and aggregation levels). This allows the system to optimize frequency scheduling gain by tailoring each set's characteristics to specific scheduling requirements while managing overall complexity through structured configuration.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2903371B1Radio base station, user terminal, radio communication system, and radio communication method
Publication Date: 2018.02.14 NTT DOCOMO INC
  • EP2903371B1 patent drawingFigure 1
  • EP2903371B1 patent drawingFigure 2
  • EP2903371B1 patent drawingFigure 3A~3B

AI summary

The present invention is designed to make it possible to adequately form the search space candidates to be used in the blind decoding of downlink control information when the radio resource region for downlink control channels is expanded. The radio base station of the present invention is a radio base station that transmits downlink control information for a user terminal by using an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, and has a configuring section that configures, for the user terminal, a plurality of resource sets that are each formed by including a plurality of resource blocks allocated to the enhanced downlink control channel, and a determining section that determines enhanced control channel elements to constitute a plurality of search space candidates such that the plurality of search space candidates of each resource set are all placed in different resource blocks.