LTE Downlink Frame Structure Reducing Blind Decoding Latency

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Solution Overview

Problem

Legacy LTE systems face inefficiencies in downlink frame structure and transmission methods, particularly in blind decoding of PDCCHs, leading to increased latency, power consumption, and reduced data communication rates due to UEs needing to search multiple regions for control information, which is inefficient and burdensome, especially for low-latency applications.

Innovation Solution

The proposed solution involves a data structure that divides the downlink channel into resource element blocks within a symbol, with a control region and a data region, where a downlink resource grant is located within the control region, allowing UEs to efficiently determine the position of the data region based on control information, thereby reducing the number of blind decodes required and improving latency and data communication rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If UEs perform blind decoding across multiple control regions to locate PDCCH, then control information can be found, but the number of blind decodes increases significantly (up to 44 or more per subframe)

Engineering Contradiction:
Improvecontrol information detectionVSAvoidblind decoding complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control region is segmented into multiple control element groups, where each group contains a subset of control elements. This segmentation allows UEs to perform blind decoding on a reduced scale within each group rather than across the entire control region, significantly reducing the number of blind decodes required while maintaining reliable control information detection

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension of organization by grouping control elements into control element groups with specific starting positions and lengths. This dimensional reorganization transforms the search space from a flat exhaustive search to a structured multi-dimensional search, reducing complexity while preserving detection capability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If UEs perform extensive blind decoding to locate PDCCH, then control information can be reliably detected, but power consumption at the UE increases excessively

Engineering Contradiction:
Improvecontrol information detectionVSAvoidUE power consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

By dividing the control region into control element groups, the patent reduces the search space for blind decoding. This segmentation enables UEs to perform fewer decoding operations while still reliably detecting control information, directly reducing power consumption associated with extensive blind decoding activities

Inventive Principle:
Principle #1Segmentation

3Reliability

If UEs perform many blind decodes to locate PDCCH, then control information can be found, but data communication rates decrease due to system burden

Engineering Contradiction:
Improvecontrol information detectionVSAvoiddata communication rate
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The segmentation of control elements into groups reduces the number of blind decodes required, thereby reducing the system burden. This efficiency improvement allows more resources to be allocated to data transmission, enhancing data communication rates while maintaining reliable control information detection

Inventive Principle:
Principle #1Segmentation

4Loss of time

If TTI is reduced to achieve lower latency, then latency is improved, but UEs cannot perform sufficient blind decodes within the reduced time interval

Engineering Contradiction:
Improvecommunication latencyVSAvoidblind decoding feasibility
Core Design Contradiction:
Loss of timeVSEase of operation

Solution Approach 1:

By segmenting the control region into control element groups, the patent reduces the number of blind decodes required per subframe. This reduction makes it feasible for UEs to complete the necessary blind decoding operations within shorter TTI intervals, enabling low-latency communication while maintaining operational feasibility

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary organization of control elements into groups with predetermined starting positions and lengths. This preliminary structuring enables UEs to efficiently locate and decode control information within reduced TTI intervals, making low-latency communication practical

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3198771B1Ultra-low latency LTE downlink frame structure
Publication Date: 2020.07.08 QUALCOMM INC
  • EP3198771B1 patent drawingFigure 1
  • EP3198771B1 patent drawingFigure 2
  • EP3198771B1 patent drawingFigure 3

AI summary

A data structure for managing user equipment communications in a wireless communication system is presented. In some examples, the data structure may include one or more resource element blocks into which a frequency bandwidth of a downlink channel is divided within a symbol that defines a transmission time interval in a downlink subframe. Furthermore, the data structure may include a control region and a data region within at least one resource element block of the one or more resource element blocks. Additionally, the data structure may include a downlink resource grant, located within the control region, for a user equipment served by the downlink channel. In an additional aspect, a network entity and method for generating the example data structure are provided.