LTE Downlink Grant Acknowledgement for TTI Bundle Transmission

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Solution Overview

Problem

Current TTI bundling methods in LTE systems are inefficient as they do not account for lost or corrupted downlink grant messages, leading to unnecessary spectral resource consumption when User Equipment (UE) fails to decode, causing the Evolved Node B (eNB) to transmit entire TTI bundles without confirmation of receipt.

Innovation Solution

Implementing a method where the UE explicitly acknowledges receipt of a downlink grant message, and the eNB aborts TTI bundle transmission if no acknowledgement is received within an expected time interval, thereby preventing unnecessary resource usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If TTI bundling is used to improve coverage, then coverage is improved, but spectral resources are wasted when the UE fails to decode the downlink grant message

Engineering Contradiction:

ImprovecoverageVSAvoidspectral resource wastage

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements a feedback mechanism where the UE sends an acknowledgement message to the eNB after successfully decoding the downlink grant message. The eNB uses this feedback to confirm whether the UE is ready to receive the TTI bundle, thereby avoiding transmission of the bundle when the UE has not properly received the grant instructions, and preventing spectral resource wastage.

Inventive Principle:

Principle #23Feedback

2Reliability

If the eNB transmits TTI bundles without confirmation of UE receipt, then coverage is improved, but processing time and latency increase

Engineering Contradiction:

ImprovecoverageVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by having the UE send an acknowledgement message before the eNB transmits the TTI bundle. This ensures the UE is ready to receive the bundle, and the eNB can proceed with transmission only after confirmation, reducing unnecessary delays and processing time while maintaining coverage improvements.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If TTI bundling is implemented without acknowledgement confirmation, then data transmission is simplified, but spectral resources are consumed unnecessarily

Engineering Contradiction:

Improvedata transmission simplicityVSAvoidspectral resource consumption

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent introduces a lightweight feedback mechanism where the UE sends a brief acknowledgement message to confirm receipt of the downlink grant. This simple feedback loop enables the eNB to make informed decisions about whether to transmit the TTI bundle, preventing unnecessary spectral resource consumption while maintaining operational simplicity.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9769787B2Method and system for facilitating transmission of TTI bundles via a LTE downlink channel

Publication Date: 2017.09.19 ROLLING WIRELESS SARL

AI summary

A method and system for facilitating communication between an Evolved Node B (eNB) and a user equipment (UE) in a Long Term Evolution (LTE) network. In particular the technology addresses downlink transmission via potentially large TTI bundles. The eNB transmits a downlink grant message to the UE, indicating a pending TTI bundle for downlink transmission. The UE transmits an acknowledgement message to the eNB if the DL grant message is successfully received and decoded. The eNB aborts transmission of the TTI bundle if it fails to timely receive the acknowledgement and may reassign the network resources scheduled for use in the transmission. In some embodiments, the eNB may introduce a delay between the downlink grant message and the TTI bundle.