Adaptive PUCCH Format Selection for Multi-Cell CSI Reporting

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Solution Overview

Problem

In wireless communication networks, particularly in LTE, the frequent dropping of periodic channel state information (CSI) due to collisions between multiple cells in a subframe leads to long reporting periodicity and delay, adversely impacting scheduling and downlink throughput.

Innovation Solution

A user equipment (UE) is configured with multiple control channel formats of different capacities to report CSI, allowing it to send CSI for multiple cells and ACK/NACK without frequent dropping, by selecting the appropriate PUCCH format based on collision conditions and payload size in each subframe.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single control channel format is used for CSI reporting, then the device complexity is reduced, but the CSI dropping frequency increases due to collision between multiple cells in a subframe

Engineering Contradiction:

Improvecontrol channel format configurationVSAvoidCSI reporting reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies dynamics by making the control channel format selectable and adaptive rather than fixed. The UE dynamically selects between different control channel formats (e.g., Format 1a, 1b, 2a, 2b, 2c, 3) based on the number of cells and collision conditions in each subframe, allowing the system to adapt to varying reporting requirements and avoid CSI dropping.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of control channel format capacity to match the reporting needs. By selecting different formats with different capacity characteristics (some support more cells, some support more CSI types), the system optimizes the balance between reliability and complexity for each specific reporting scenario.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multiple control channel formats are configured, then the CSI reporting reliability is improved, but the device complexity increases

Engineering Contradiction:

ImproveCSI reporting reliabilityVSAvoidcontrol channel format configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the control channel formats into different categories or types, each suited for specific scenarios (e.g., formats for single cell vs. multiple cells, formats for different CSI types). This segmentation allows the UE to divide and conquer the complex task of reporting across multiple cells by selecting appropriate segmented formats rather than handling all cases uniformly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The UE dynamically selects between different control channel formats based on the number of cells and collision conditions in each subframe, allowing the system to adapt to varying reporting requirements and avoid CSI dropping.

Inventive Principle:

Principle #15Dynamics

3Productivity

If CSI is reported for multiple cells in the same subframe, then the reporting efficiency is improved, but the collision between cells increases causing CSI dropping

Engineering Contradiction:

ImproveCSI reporting efficiencyVSAvoidCSI reporting reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Inventive Principle:

Principle #15Dynamics

4Reliability

If the reporting periodicity is increased to avoid collisions, then the CSI dropping frequency is reduced, but the scheduling delay increases

Engineering Contradiction:

ImproveCSI reporting reliabilityVSAvoidreporting delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The UE determines the appropriate control channel format in advance based on configured information about multiple cells and collision conditions, enabling it to prepare and send CSI reports efficiently without unnecessary delays while avoiding collisions through proactive format selection.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9912439B2Method and apparatus for sending channel state information using subframe-dependent control channel formats

Publication Date: 2018.03.06 QUALCOMM INC

AI summary

Techniques for reporting channel state information (CSI) for multiple cells (e.g., carriers) using multiple control channel formats are disclosed. A user equipment (UE) may be configured for operation on a plurality of cells. The UE may be configured to periodically report CSI for the plurality of cells and may also report CSI whenever requested. The UE may be configured with a plurality of control channel formats for sending CSI and possibly other control information in different subframes. The plurality of control channel formats may be associated with at least two different capacities. The UE may report CSI for the plurality of cells in the plurality of subframes based on the plurality of control channel formats.