Physical Downlink Control Channel Start Time Determination

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Solution Overview

Problem

In LTE systems, Machine Type Communication (MTC) devices located in areas with high penetration loss, such as basements, face challenges in determining the start time of the physical downlink control channel, which affects coverage and reliability.

Innovation Solution

A method where a base station sends a configurable parameter set to user equipment, including repetition level, sub-frame offset information, and gap value to determine the start time of the physical downlink control channel, enabling accurate placement and decoding of repetitive control channels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If MTC devices perform blind decoding to determine PDCCH start time, then coverage is improved, but power consumption increases

Engineering Contradiction:

ImprovecoverageVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The UE autonomously determines the PDCCH start time offset using pre-configured parameters and formulas, without requiring network assistance or blind decoding. The device serves itself by calculating the offset based on its own identity (CIF) and configured parameters, eliminating power-consuming blind decoding operations while maintaining reliable coverage.

Inventive Principle:

Principle #25Self-service

2Reliability

If repetitive PDCCH transmission is used, then reliability is improved, but device complexity increases

Engineering Contradiction:

ImprovereliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses parameter-based determination of PDCCH start time offsets, where different UEs are assigned different offset values based on their CIF. This parameter-driven approach enables repetitive transmissions to be systematically managed across multiple subframes without increasing device complexity, as each UE independently calculates its reception timing based on configured parameters.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If blind decoding is performed for PDCCH detection, then downlink control channel reliability is improved, but processing time increases

Engineering Contradiction:

Improvedownlink control channel reliabilityVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The network pre-configures parameters (including CIF and offset formulas) to the UE before PDCCH transmission. The UE uses these pre-configured parameters to directly calculate the PDCCH start time offset, eliminating the need for time-consuming blind decoding operations. This preliminary configuration enables immediate and accurate PDCCH detection.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3050386B1Method for determining start time of a physical downlink control channel

Publication Date: 2022.02.16 ALCATEL LUCENT SA

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AI summary

A method is provided for a UE to determine the start time of the downlink control channel for M2M communication in LTE systems. The method comprises a UE receiving a parameter set to determine the start time of the (E)PDCCH from the eNB; calculating the start time based on the received parameter set from the eNB; combining/decoding the repetitive (E)PDCCHs; and sending the feedback information to confirm/reject the reception of the (E)PDCCH.