Retransmission Feedback Resource Mapping in 5G NR

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Solution Overview

Problem

In wireless communication systems, particularly in 5G New Radio (NR), the existing retransmission feedback mechanisms using ARQ and HARQ schemes face challenges in reducing latency and avoiding collisions of retransmission feedback on UL resources, leading to increased transmission latency and buffer overload.

Innovation Solution

The method involves determining the UL time-frequency resource for retransmission feedback based on the DL time-frequency resource used for data transmission, allowing for flexible allocation of UL resources and reducing collisions by ensuring that the UL resources for feedback are derived from the corresponding DL resources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If retransmission feedback is sent immediately after each downlink slot to reduce latency, then transmission latency is reduced, but uplink-downlink switching overhead increases

Engineering Contradiction:

Improvetransmission latencyVSAvoidswitching overhead

Core Design Contradiction:

Loss of timeVSLoss of energy

Solution Approach 1:

The patent combines multiple retransmission feedback transmissions into a single uplink slot. Instead of sending feedback after each downlink slot, the UE accumulates feedback for multiple downlink slots and transmits them together in one uplink slot, thereby reducing the frequency of uplink-downlink switching while maintaining timely feedback delivery.

Inventive Principle:

Principle #5Merging (Combining)

2Loss of energy

If retransmission feedback is transmitted at a later point in time to reduce uplink-downlink switching overhead, then switching overhead is reduced, but collisions of retransmission feedback on UL resources occur

Engineering Contradiction:

Improveswitching overheadVSAvoidfeedback collision

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent segments the feedback resources by associating each downlink slot with a specific uplink feedback slot. This segmentation ensures that feedback from different downlink slots is transmitted in different uplink slots, preventing collisions while allowing later feedback transmission that reduces switching overhead.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent dynamically determines the mapping between downlink slots and uplink feedback slots based on system conditions and scheduling decisions. This dynamic allocation allows the system to optimize the balance between latency, switching overhead, and collision avoidance adaptively.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If UL resources for feedback are fixed to reduce complexity, then device complexity is reduced, but flexibility in resource allocation is limited

Engineering Contradiction:

Improveresource allocation complexityVSAvoidresource allocation flexibility

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent changes the parameters used to determine UL feedback resources from fixed values to values that depend on DL resource characteristics. Specifically, the UL slot is determined based on the DL slot index and configuration, allowing the system to maintain relatively simple device complexity while achieving significant flexibility in resource allocation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10999824B2Methods and apparatuses for handling of retransmission feedback

Publication Date: 2021.05.04 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

There is disclosed a method of operating a User equipment, UE, in a cellular communications network. The method comprises receiving a data on a Downlink, DL, time-frequency resource, and transmitting on an Uplink, UL, time-frequency resource, a retransmission feedback to indicate whether a data packet, comprised in the data, was received properly, wherein the UL time-frequency resource is determined based on the DL time-frequency resource. The disclosure also pertains to related methods and devices.