TTI Integration for LTE and NR sTTI Coexistence

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Solution Overview

Problem

Existing wireless communication systems face challenges in efficiently supporting coexistence between radio access technologies (RATs) with different transmission time intervals (TTIs), particularly when one RAT uses shortened TTIs (sTTIs), leading to issues such as collisions and resource conflicts.

Innovation Solution

The system employs techniques like indicating layouts for both RATs, multiplexing subslots and slots, rate-matching for the second RAT based on sTTI resources, dropping TTIs or sTTIs based on collisions, enabling single uplink operations, and configuring power control settings to facilitate coexistence between LTE and NR RATs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple RATs with different TTI durations are supported simultaneously, then communication flexibility and adaptability are improved, but resource conflicts and collisions occur between RATs

Engineering Contradiction:
Improvecommunication flexibilityVSAvoidresource conflict
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the TTI structure by introducing subslot boundaries within slots, allowing different RATs to be allocated different portions of the TTI. This segmentation enables LTE to use subslot-based sTTI while NR uses slot-based TTI, resolving the contradiction by dividing the time resource into manageable segments that can be independently allocated to different technologies

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic TTI configuration where the base station can flexibly allocate resources between LTE and NR based on real-time traffic conditions. The ability to dynamically adjust which RAT gets which time resources allows the system to adapt to changing communication needs while avoiding fixed resource conflicts

Inventive Principle:
Principle #15Dynamics

2Speed

If shortened TTIs (sTTI) are used for low latency communication, then transmission speed is improved, but processing collisions occur with standard TTI RATs

Engineering Contradiction:
Improvetransmission speedVSAvoidprocessing collision
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

By segmenting the TTI into subslots, the patent allows sTTI to be implemented as a portion of the larger TTI structure. This segmentation enables fast sTTI transmissions for low-latency communication while the overall TTI structure provides a framework that prevents processing collisions with standard TTI operations through structured time division

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs preliminary actions by configuring sTTI resources in advance within the TTI structure before actual transmission occurs. This pre-configuration allows the system to prepare for fast transmissions while avoiding collisions with other TTI-based operations through predetermined resource allocation

Inventive Principle:
Principle #10Preliminary action

3Productivity

If TTI integration techniques are implemented for multiple RATs, then resource utilization is improved, but system complexity increases

Engineering Contradiction:
Improveresource utilizationVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent creates a universal TTI structure that serves multiple functions: it can accommodate both LTE sTTI and NR slot-based TTI within the same framework. This multi-functional design improves resource utilization by allowing one structure to handle multiple RAT requirements, though it does increase the complexity of the base station's scheduling and control mechanisms

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3791653B9Transmission time interval integration for multiple radio access technologies
Publication Date: 2025.09.10 QUALCOMM INC
  • EP3791653B9 patent drawingFigure 1
  • EP3791653B9 patent drawingFigure 2
  • EP3791653B9 patent drawingFigure 3A~3B

AI summary

Methods, systems, and devices for wireless communications are described. A base station and a user equipment (UE) may support coexistence of more than one radio access technology (RAT), where one of the RATs supports shortened transmission time intervals (sTTIs). Efficient techniques are described for enabling a coexistence between sTTIs associated with a first RAT and TTIs associated with a second RAT. The techniques may include indicating a layout that can accommodate the RATs, multiplexing subslots and slots for the RATs, rate-matching for the second RAT based on signaling around sTTI resources, dropping sTTIs for the first RAT or TTIs for the second RAT based on a collision of processing the TTIs or sTTIs, a single uplink operation for the UE, transmitting uplink control information for one RAT with an uplink channel for the other RAT, configuring power control settings for the first and second RAT, or a combination thereof.