HARQ-ACK Codebook Selection for Wireless Multi-Connectivity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In wireless communication networks, especially in multi-connectivity scenarios with carrier aggregation, there is a challenge in efficiently selecting the appropriate HARQ-ACK codebook type for Hybrid Automatic Repeat reQuest (HARQ) feedback due to delays and differences in radio access node locations, leading to issues like delayed feedback, HARQ process exhaustion, and varying requirements for HARQ feedback offset.

Innovation Solution

A method is introduced where a network node evaluates the delay associated with transferring HARQ-ACK feedback from a User Equipment (UE) to a processing entity responsible for downlink transmission control in a secondary cell, and based on this evaluation, selects a particular HARQ-ACK codebook type from defined types, such as semi-static or dynamic, to optimize feedback efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If HARQ-ACK feedback is transferred through backhaul or sidehaul connections to geographically-separated radio access nodes, then carrier aggregation and multi-connectivity can be supported, but feedback delay increases

Engineering Contradiction:

Improvecarrier aggregation supportVSAvoidfeedback delay

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent dynamically selects between semi-static and dynamic HARQ-ACK codebook types based on the actual delay conditions of the backhaul/sidehaul connection. The codebook type is not fixed but adapts to network conditions, allowing the system to optimize feedback timing flexibility according to real-time delay characteristics of geographically-separated nodes.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of codebook type selection (semi-static vs. dynamic) in response to delay evaluation. By monitoring and evaluating the delay associated with feedback transfer, the system adjusts the HARQ-ACK codebook configuration to match actual network conditions, thereby managing the feedback delay issue while maintaining carrier aggregation functionality.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If dynamic HARQ-ACK codebook type is used to accommodate varying feedback timing requirements, then adaptability to different network conditions improves, but HARQ process exhaustion risk increases

Engineering Contradiction:

Improvefeedback timing flexibilityVSAvoidHARQ process exhaustion

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the network node continuously monitors the delay characteristics of feedback transfer and uses this information to adjust the HARQ-ACK codebook type selection. This closed-loop feedback allows the system to adapt to changing network conditions while avoiding HARQ process exhaustion by selecting the appropriate codebook type based on actual delay experience.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically switches between semi-static and dynamic codebook types based on real-time delay evaluation. This dynamic adaptation allows the system to maintain flexibility when needed while avoiding the pitfalls of persistent dynamic codebook usage that could lead to HARQ process exhaustion, thereby improving reliability.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If semi-static HARQ-ACK codebook type is used to simplify feedback processing, then processing complexity reduces, but ability to handle varying network conditions deteriorates

Engineering Contradiction:

Improvefeedback processing complexityVSAvoidnetwork condition adaptation

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent employs dynamic codebook type selection, allowing the system to switch between semi-static and dynamic modes based on network conditions. This dynamic approach maintains the simplicity of semi-static codebooks when network conditions are stable while enabling adaptability to varying conditions when needed, thus balancing complexity and versatility.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the codebook configuration parameter (semi-static vs. dynamic) based on delay evaluation results. This parameter change allows the system to leverage the simplicity of semi-static codebooks when appropriate while transitioning to dynamic codebooks when network conditions require greater adaptability, effectively resolving the contradiction between complexity and versatility.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20240356712A1Apparatus and method for control of HARQ-ACK codebook selection for wireless communication

Publication Date: 2024.10.24 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Disclosed techniques provide for selection of the codebook type used by a User Equipment (UE) (12), for Hybrid Automatic Repeat reQuest (HARQ) feedback to a wireless communication network (10) in multi-connectivity scenarios. The particular HARQ-ACK codebook type selected for use by the UE (12) depends on a delay associated with transferring HARQ feedback received from the UE (12) for a secondary cell (34) to the processing entity (42) that is responsible for downlink transmission control in the secondary cell (34). For example, the HARQ feedback is received via a first or primary cell (34) and then transferred from there to a radio network node or other geographically-remote circuitry that performs the downlink transmission control for the secondary cell (34).