Uplink Signal Allocation in Short TTI Radio Systems

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Solution Overview

Problem

Existing LTE systems lack control mechanisms for the transmission of uplink data and demodulation reference signals when using short transmission time intervals (TTIs), leading to potential interference and inefficiencies in radio communication.

Innovation Solution

A user terminal is equipped with a transmission section and a control section that allocates uplink signals and demodulation reference signals to the same short TTI, except for the top TTI, to ensure proper control and reduce interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If uplink data and demodulation reference signals are transmitted in different short TTIs, then transmission flexibility is improved, but control complexity and interference increase

Engineering Contradiction:

Improvetransmission flexibilityVSAvoidcontrol complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-defining the association between uplink data and demodulation reference signals through RRC signaling or higher-layer parameters. The network configures which short TTI contains the demodulation reference signal before transmission occurs, allowing the user terminal to automatically determine the correct association without complex real-time control decisions.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If multiple demodulation reference signals are transmitted in different short TTIs, then demodulation accuracy is improved, but peak to average power ratio increases

Engineering Contradiction:

Improvedemodulation accuracyVSAvoidpeak to average power ratio

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent merges multiple demodulation reference signals into a single short TTI by configuring them to be transmitted together in the same time interval. This consolidation reduces the peak power requirements while maintaining demodulation accuracy through the combined reference signal resources.

Inventive Principle:

Principle #5Merging (Combining)

3Loss of time

If uplink transmission uses short TTIs, then latency is reduced, but control mechanisms become insufficient

Engineering Contradiction:

ImprovelatencyVSAvoidcontrol mechanism sufficiency

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent introduces higher-layer signaling (RRC signaling) as an intermediary mechanism to establish control rules for short TTI transmissions. This intermediary layer provides the necessary control framework without adding complexity to the physical layer timing structures, enabling reliable control while maintaining low latency.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11463225B2User terminal and radio communication method

Publication Date: 2022.10.04 NTT DOCOMO INC

AI summary

To control UL transmission properly even when uplink data and demodulation reference signals are transmitted using short TTIs, a user terminal according to one aspect of the present invention has a transmission section that transmits a UL signal and a reference signal for use for demodulating the UL signal, and a control section that controls the allocation of the UL signal and the reference signal, and, when UL signals are allocated to a plurality of contiguous predetermined time intervals (sTTIs), respectively, the control section allocates the UL signal and the reference signal for use for demodulating the UL signal to the same sTTI, at least in an sTTI apart from the top sTTI.