Downlink Transmission Configuration Using Short TTIs
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Solution Overview
Problem
Current communication networks face challenges in reducing packet latency and improving radio resource efficiency due to fixed 1 ms subframe lengths for downlink control channels, which limits the ability to perform scheduling of uplink and downlink data in shorter time frames and increases signalling overhead and implementation complexity.
Innovation Solution
Implementing a method for configuring downlink transmission using short Transmission Time Intervals (sTTIs), where each sTTI can be shorter than a subframe, allowing for flexible configuration of sTTI lengths and patterns, and dynamic DMRS insertion to reduce overhead and improve resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fixed 1 ms subframe lengths are used for downlink control channels, then current communication protocols can be maintained, but packet latency cannot be reduced and scheduling flexibility is limited
Solution Approach 1:
The patent segments the 1 ms subframe into multiple shorter Transmission Time Intervals (TTIs), where each TTI can be independently scheduled. This segmentation allows the system to achieve lower latency by scheduling data in shorter time units while maintaining the overall subframe structure, thus resolving the contradiction between reducing packet latency and maintaining protocol compatibility.
Solution Approach 2:
The patent introduces dynamic TTI configuration where the length and number of TTIs within a subframe can be adjusted based on traffic conditions and service requirements. This dynamic adaptation enables the system to flexibly schedule uplink and downlink data transmissions in shorter time frames, improving both latency and scheduling versatility simultaneously.
2Productivity
If shorter TTIs are implemented for downlink transmission, then packet latency is reduced and scheduling flexibility improves, but signalling overhead and implementation complexity increase
Solution Approach 1:
The patent applies partial action by introducing sTTI configurations only where needed within the existing LTE framework, rather than completely overhauling the system. The sTTI feature can be selectively enabled for specific carriers or traffic types, allowing the system to gain scheduling efficiency benefits while limiting the scope of complexity increase to only the necessary components.
Solution Approach 2:
The patent changes the time domain parameter by introducing configurable TTI lengths (e.g., 2, 3, or 7 symbols) within the existing subframe structure. This parameter change allows shorter transmission intervals without fundamentally altering the protocol stack, thereby improving scheduling efficiency while keeping implementation complexity manageable through controlled parameter variation rather than structural redesign.
3Loss of energy
If dynamic DMRS insertion is used in sTTI, then radio resource efficiency improves and overhead is reduced, but processing complexity increases
Solution Approach 1:
The patent implements dynamic DMRS insertion where reference signals are placed only in the TTIs that actually carry data transmissions. This dynamic approach improves radio resource efficiency by eliminating unnecessary DMRS in empty TTIs, while the processing complexity is managed through clear conditional logic that determines DMRS placement based on scheduling decisions.
Data Source
AI summary
There is presented a method for providing configuration for downlink transmission to a wireless device. The method is performed by a network node and comprises transmitting a Downlink Control Information (DCI) message comprising configuration for downlink transmission in a short Transmission Time Interval (sTTI). Network nodes, wireless terminals, computer programs, and computer program products thereof are also presented.