TDD Subframe Grouping for 1 ms Latency in Wireless Systems
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Solution Overview
Problem
Current wireless communication systems, such as 3GPP LTE, face challenges in achieving low latency due to the fixed structure of transmission time intervals (TTIs), which is not suitable for next-generation wireless communication systems requiring user-plane latency of 1 ms.
Innovation Solution
The proposed method involves subdividing the conventional TTI into shorter subframes, specifically a short TTI (sTTI), with configurations that include downlink and uplink symbols separated by guard periods, allowing for dynamic allocation of resources and interference minimization between cells, using a TDD-based structure that adjusts uplink and downlink resources based on traffic demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the conventional TTI structure with fixed length is used, then the system maintains simple scheduling and resource allocation, but the user-plane latency cannot be reduced to 1 ms
Solution Approach 1:
The patent divides the conventional 1 ms TTI into multiple shorter sub-TTIs (e.g., 2 or 3 sub-TTIs per TTI). Each sub-TTI can be independently scheduled and allocated resources, enabling finer-grained time division multiple access (TDMA) and reducing the latency for user-plane data transmission to meet the 1 ms requirement while maintaining manageable scheduling complexity through hierarchical resource allocation.
2Adaptability or versatility
If TDD configurations are changed frequently to adapt to traffic demand, then resource allocation flexibility is improved, but interference between adjacent cells increases
Solution Approach 1:
The patent introduces periodic TDD configuration patterns where adjacent cells follow coordinated uplink-downlink switching cycles. By synchronizing the periodicity of TDD configurations across cells and using the sub-TTI granularity to align switching points, the system achieves flexible resource allocation adapted to traffic demand while minimizing inter-cell interference through predictable, periodic behavior that allows interference coordination.
3Speed
If sub-TTI length is reduced to achieve 1 ms latency, then the transmission speed increases, but the number of scheduling decisions and control signaling overhead increases
Solution Approach 1:
The patent implements dynamic sub-TTI scheduling where the length and number of sub-TTIs can be adjusted based on channel conditions, traffic type, and QoS requirements. This dynamic adaptation allows the system to use shorter sub-TTIs (e.g., 2-symbol sub-TTIs) when low latency is critical while using longer sub-TTIs (e.g., 4-symbol sub-TTIs) when traffic patterns allow, thereby optimizing transmission speed while controlling scheduling complexity through condition-based adaptation rather than uniform short scheduling.
Data Source
AI summary
Provided are a method and device for performing communication using a plurality of subframes in a time division duplex (TDD) based wireless communication system. Specifically, groups are set by grouping a first configuration and a second configuration which arrange at least one downlink symbol and at least one uplink symbol in a subframe unit. The first configuration and the second configuration are configured in a manner that the downlink symbol and the uplink symbol do not overlap with each other in a particular symbol interval. Information indicative of a group is transmitted to a terminal for at least one subframe from among the plurality of subframes. Information indicative of a configuration to be used in the terminal of the first configuration and the second configuration in a group with respect to at least one subframe is transmitted to the terminal.