TDD Subframe Segmentation for Unpaired Spectrum Latency

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Solution Overview

Problem

Current wireless communication systems using Time Division Duplexing (TDD) face challenges in latency due to the complexity of HARQ procedures when operating in unpaired spectra, where the number of downlink and uplink subframes differ, leading to increased latency and inefficiency in message transmission.

Innovation Solution

A method and apparatus that divide a radio frame into downlink, uplink, and guard periods, with a downlink control channel providing timing information for ACK/NACK feedback, allowing for flexible allocation of packet durations and timing advances, enabling efficient data transmission even in unpaired spectrum conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If TDD scheme is used with unpaired spectrum, then spectrum allocation flexibility is improved, but HARQ procedure complexity increases

Engineering Contradiction:

Improvespectrum allocation flexibilityVSAvoidHARQ procedure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The subframe is segmented into distinct downlink time duration and uplink time duration with a guard period in between. This segmentation allows independent configuration of downlink and uplink packet durations, simplifying the HARQ procedure by providing clear temporal separation between downlink and uplink transmissions in unpaired spectrum TDD systems.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If many-to-one correspondence relationship is defined for downlink and uplink subframes, then TDD operation in unpaired spectrum is enabled, but latency increases

Engineering Contradiction:

ImproveTDD operation capabilityVSAvoidcommunication latency

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The system dynamically configures the downlink control channel to include timing information that adapts to different unpaired spectrum TDD configurations. The timing information dynamically indicates when ACK/NACK feedback should be transmitted, allowing the system to optimize latency for each specific configuration rather than using fixed many-to-one correspondence relationships.

Inventive Principle:

Principle #15Dynamics

3Reliability

If base station waits for specific uplink subframe for HARQ ACK, then transmission reliability is improved, but transmission speed decreases

Engineering Contradiction:

Improvetransmission reliabilityVSAvoidtransmission speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The downlink control channel includes preliminary timing information that indicates in advance when the ACK/NACK feedback will be transmitted. This allows the base station and terminal to prepare for the feedback transmission at the indicated time, ensuring reliability through proper timing synchronization while minimizing waiting time by not requiring the base station to wait passively for a predetermined subframe.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10966199B2Method and apparatus for receiving or transmitting data

Publication Date: 2021.03.30 ELECTRONICS & TELECOMM RES INST

AI summary

A base station divides a subframe into a downlink time duration for downlink, an uplink time duration for uplink, and a guard period between the downlink time duration and the uplink time duration. The base station transmits a downlink control channel including information on a downlink packet duration allocated for downlink transmission of a terminal and information on an uplink packet duration allocated for uplink transmission of the terminal to the terminal in the downlink time duration.