Flexible TDD Subframe Structure for Latency Reduction
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Solution Overview
Problem
Wireless communication systems, particularly in LTE, face challenges in reducing latency due to insufficient control signaling for low latency communications, leading to communication delays and disruptions.
Innovation Solution
The implementation of a flexible time division duplexing (TDD) subframe structure that includes multiple regions within a subframe, such as uplink, downlink, and guard regions, where transmissions are coordinated based on a timing relationship between these regions to support low latency communications through hybrid automated repeat request (HARQ) feedback and scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional TDD subframe structure is used with separate uplink and downlink subframes, then system simplicity is maintained, but communication latency increases due to insufficient control signaling for low latency communications
Solution Approach 1:
The patent segments a single subframe into multiple regions including a first downlink region, a first uplink region, a second downlink region, and a second uplink region. This segmentation allows different parts of the same subframe to serve different communication directions and latency requirements, enabling low latency communications through intra-subframe HARQ feedback while maintaining overall subframe structure
Solution Approach 2:
The patent implements dynamic subframe configuration where the base station can flexibly configure the timing relationships between different regions. The second downlink region and second uplink region are configured with different timing relationships compared to the first regions, allowing adaptive adjustment for different communication scenarios and latency requirements within the same subframe
2Productivity
If control signaling is enhanced for low latency communications, then communication efficiency improves, but system complexity increases
Solution Approach 1:
The patent merges control signaling for multiple communication directions into the same subframe structure. The base station transmits downlink control information in the first downlink region that schedules both the first uplink region and the second uplink region, consolidating control functions and reducing the need for separate control signaling mechanisms for different latency requirements
Solution Approach 2:
The base station transmits downlink control information in advance during the first downlink region before the uplink regions occur. This preliminary scheduling action includes configuring timing relationships for both first and second uplink regions, allowing UEs to prepare for low latency HARQ feedback transmissions without requiring complex real-time control signaling
Data Source
AI summary
Methods, systems, and devices for wireless communication are described. A wireless device may identify multiple regions within a subframe, such as one or more uplink regions, one or more downlink regions, and a guard region. The wireless device may identify and communicate during each region based on a timing relationship between the downlink region and the uplink region. For example, the device may expect hybrid automated repeat request (HARQ) feedback for one downlink region in the same subframe based on the proximity to the next uplink region. Another downlink region may not have HARQ feedback in the same subframe. Similarly, uplink regions may or may not be scheduled within the same subframe.