Reference Signal Mapping for Shortened TTI Latency

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Solution Overview

Problem

Current wireless communication technologies face challenges in reducing latency, particularly with the shortening of transmission time intervals (TTIs) from 14 OFDM symbols to 7 or less, while maintaining compatibility with legacy systems and ensuring effective reference signal design to avoid performance degradation.

Innovation Solution

The proposed solution involves mapping reference signals (RSs) onto OFDM symbols outside of shortened TTIs, allowing for efficient transmission and demodulation of physical channels within these intervals, thereby reducing latency and overhead while ensuring compatibility with legacy systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If TTI length is shortened from 14 OFDM symbols to 7 or less to reduce latency, then latency is reduced, but reference signal design becomes more challenging and may cause performance degradation

Engineering Contradiction:

ImprovelatencyVSAvoiddemodulation performance

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent segments the reference signal transmission by mapping CRS and DMRS to different OFDM symbols within the shortened TTI structure. This segmentation allows proper demodulation resources to be allocated without compromising performance despite the reduced TTI length.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary mapping of reference signals to specific OFDM symbols before the actual data transmission in shortened TTIs. This preliminary arrangement ensures that demodulation resources are prepared in advance, enabling reliable demodulation even with the compressed time interval.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If reference signals are mapped within shortened TTIs, then demodulation is enabled, but signaling overhead increases

Engineering Contradiction:

Improvedemodulation capabilityVSAvoidsignaling overhead

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The patent applies local quality by selectively mapping different types of reference signals (CRS and DMRS) to different OFDM symbols based on their specific demodulation needs. This localized allocation optimizes the use of reference signal resources and reduces overall signaling overhead.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If reference signals are mapped to OFDM symbols outside shortened TTIs, then signaling overhead is reduced, but compatibility with legacy systems must be maintained

Engineering Contradiction:

Improvesignaling overheadVSAvoidlegacy system compatibility

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent achieves universality by designing a reference signal mapping scheme that serves both legacy systems and shortened TTI transmissions. The same mapping framework accommodates different TTI lengths and maintains compatibility with existing demodulation procedures while enabling reduced overhead.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12184461B2Wireless communication device and wireless communication method for mapping reference signals to shortened transmission time intervals

Publication Date: 2024.12.31 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

Provided are wireless communication devices and methods. A wireless communication device can comprise: circuitry operative to map at least a first type of reference signals (RSs) onto orthogonal frequency division multiplexing (OFDM) symbol(s) other than the OFDM symbols onto which shortened transmission time intervals (TTIs) are mapped in a subframe, each of the shortened TTIs comprising 1-7 OFDM symbols; and a transmitter operative to transmit a physical channel in one of the shortened TTIs and transmit at least the first type of RSs.