Mixed TTI Scheduling for Uplink Latency Reduction
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently scheduling user equipment (UEs) with mixed transmission time interval (TTI) lengths, leading to network congestion and increased latency, which can negatively impact TCP performance and user perceived throughput.
Innovation Solution
The implementation of a mixed TTI length scheduling mechanism, where UEs can dynamically adjust TTI lengths and operate different TTIs simultaneously by dividing PRB zones and using specific rules for downlink control information management, allowing for efficient scheduling and reduced latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If multiple TTI lengths are used to reduce latency, then UL latency is reduced, but scheduling complexity and system overhead increase
Solution Approach 1:
The system segments the TTI structure into different length types (short TTI and long TTI) and assigns them to different subframe configurations. This allows the system to reduce latency for time-sensitive traffic using short TTIs while maintaining compatibility with legacy systems using long TTIs, thereby managing scheduling complexity through structured segmentation
Solution Approach 2:
The system dynamically adjusts TTI length based on traffic conditions and requirements. The eNodeB can flexibly switch between short and long TTI configurations for different UEs or different subframes, enabling adaptive latency reduction without permanently increasing system complexity
2Productivity
If multiple TTI lengths are used to improve scheduling flexibility, then scheduling efficiency is improved, but TCP performance deteriorates due to increased latency variability
Solution Approach 1:
The system applies different TTI lengths to different local contexts or traffic flows based on their specific requirements. Short TTIs are applied locally to latency-sensitive traffic while long TTIs are used for other traffic, ensuring that TCP performance is maintained for non-time-critical flows while achieving latency reduction for sensitive flows
Solution Approach 2:
The system changes the TTI length parameter dynamically based on traffic conditions, UE capabilities, and network state. This parameter adaptation allows the system to optimize scheduling efficiency for mixed traffic while maintaining TCP performance by adjusting TTI length rather than using a fixed configuration
3Loss of time
If short TTI is used to reduce latency, then UL latency is reduced, but control overhead increases
Solution Approach 1:
The system merges control information for multiple short TTIs into consolidated control messages where possible. By combining scheduling decisions and control elements across multiple short TTI instances, the system reduces the per-TTI control overhead while maintaining the low-latency benefits of short TTI structure
Data Source
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AI summary
In accordance with an example embodiment of the present invention, a method, comprising determining, by a user equipment, whether the user equipment is scheduled in one or more time frequency resources of a first transmission time interval or in one or more time frequency resources of a second transmission time interval, where the second transmission time interval is shorter than the first transmission time interval; and based on the determining, adjusting the monitoring of scheduling opportunities within a duration of the first transmission time interval, is disclosed.