Intra-Cluster D2D Retransmission Link Adaptation

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Solution Overview

Problem

Current cellular networks face inefficiencies in resource usage and battery life due to the lack of effective intra-cluster device-to-device (D2D) retransmission methods, particularly in scenarios where some devices in a cluster cannot decode data correctly, leading to suboptimal link adaptation and resource wastage.

Innovation Solution

The implementation of a method that calculates and selects between two retransmission modes based on link parameters, allowing ACK devices to adaptively determine whether to retransmit data to NACK devices using either a conservative or aggressive mode, optimizing resource usage by selecting the least resource-intensive approach.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional cellular downlink multicast/broadcast is used, then network coverage is provided, but resource usage efficiency is low and battery life is reduced due to lack of effective intra-cluster D2D retransmission

Engineering Contradiction:

Improveresource usage efficiencyVSAvoidbattery life

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

ACK devices within the cluster autonomously perform retransmission to NACK devices without requiring network node intervention. The system enables devices to serve themselves by selecting local ACK devices as retransmitters based on channel conditions, eliminating the need for continuous network control and reducing overall energy consumption.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

ACK devices act as intermediaries between the network node and NACK devices. Instead of the network node directly retransmitting to all NACK devices, ACK devices relay the data within the cluster, reducing the burden on network resources and improving overall efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If D2D direct communications are enabled, then resource usage efficiency and battery life are improved, but link adaptation complexity increases due to varying channel conditions

Engineering Contradiction:

Improveresource usage efficiencyVSAvoidlink adaptation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system dynamically adapts the number of retransmitters and their selection based on instantaneous channel conditions. ACK devices calculate parameters such as spectrum efficiency for different retransmission modes and feed back this information, allowing the network node to select the optimal retransmission strategy in real-time according to current link quality.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes key parameters including the number of retransmitters, modulation and coding schemes (MCS), and resource allocation based on feedback parameters from ACK devices. These parameter adjustments are made dynamically to match channel conditions, optimizing performance while managing complexity through structured parameter selection.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If adaptive retransmission modes are implemented, then resource costs are reduced, but system complexity increases due to mode selection and parameter calculation

Engineering Contradiction:

Improveresource costsVSAvoidsystem complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The retransmission process is segmented into distinct modes (first retransmission mode and second retransmission mode) with different characteristics. Each mode has specific parameter calculations and selection criteria, allowing the system to choose the most appropriate mode based on channel conditions rather than using a single complex adaptive mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

ACK devices calculate and feed back parameters related to different retransmission modes to the network node. This feedback mechanism enables the network node to make informed decisions about mode selection and retransmitter assignment, distributing the computational complexity across multiple devices rather than concentrating it in one location.

Inventive Principle:

Principle #23Feedback

4Productivity

If instantaneous link adaptation is used, then data delivery efficiency is improved, but overhead increases due to parameter calculation and reporting

Engineering Contradiction:

Improvedata delivery efficiencyVSAvoidoverhead

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

Not all ACK devices need to perform full parameter calculations and reporting. The system allows selective participation where only certain ACK devices with favorable channel conditions or specific roles in the cluster perform detailed link adaptation, while others can use simplified procedures or rely on decisions made by designated retransmitters.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS9717069B2Intra-cluster D2D retransmission with instantaneous link adaptation and adaptive number of re-transmitter

Publication Date: 2017.07.25 NOKIA TECHNOLOGIES OY

AI summary

A method for intra-cluster D2D retransmission comprises: calculating parameters of a first and a second retransmission modes for an acknowledgement device in a cluster at which data from a network node is decoded correctly; reporting the parameters to the network node; and determining whether or not to retransmit the data to at least one non-acknowledgement device in the cluster at which the data from the network node is decoded incorrectly, in response to a selection between the first and the second retransmission modes from the network node based at least in part on the parameters according to a pre-determined criterion.