Wireless Terminal Control Signal Detection in Latency Reduction Mode
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Solution Overview
Problem
In FDD or TDD LTE systems, reducing signal processing time from 3 ms to 1 ms or 2 ms to minimize latency requires efficient detection of downlink control signals, which is challenging due to different DCI formats and timing settings, especially in latency reduction modes.
Innovation Solution
A method and apparatus for the terminal to efficiently decode control signals in latency reduction mode operations by utilizing different DCI formats and search spaces, allowing for earlier transmission timing of ACK/NACK signals, such as at subframe n+3 or n+2, instead of the conventional subframe n+4, to reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the signal processing time is reduced from 3 ms to 1 ms or 2 ms, then the latency is reduced, but the control signal detection becomes more complex due to different DCI formats and timing settings
Solution Approach 1:
The patent segments the control signal detection process into distinct search spaces: a first search space for latency reduction mode DCI formats and a second search space for fallback DCI formats. This segmentation allows the terminal to efficiently detect control signals by knowing which search space to monitor based on the configured mode, reducing detection complexity despite the reduced processing time
Solution Approach 2:
The patent implements dynamic switching between different DCI formats and search spaces based on whether latency reduction mode is configured. The terminal adapts its detection behavior dynamically - using first DCI formats with earlier timing (n+1 or n+2) when latency reduction is enabled, and falling back to conventional formats and timing when not enabled, thus managing complexity through adaptive behavior
2Productivity
If different DCI formats are used for latency reduction mode, then the transmission timing can be optimized, but the detection process becomes more challenging
Solution Approach 1:
The patent divides DCI formats into two distinct groups: first DCI formats optimized for latency reduction mode with earlier transmission timing, and second DCI formats for fallback operation. Correspondingly, two search spaces are defined - the terminal monitors the first search space for first DCI formats when latency reduction is configured, and the second search space for second DCI formats otherwise. This clear segmentation simplifies detection by providing explicit rules for which format to expect in which search space
Solution Approach 2:
The patent changes key parameters of the control signal detection based on the operational mode: when latency reduction mode is configured, the terminal uses first DCI formats with modified timing parameters (transmission at n+1 or n+2 instead of n+4) and monitors a first search space. This parameter change approach allows optimized performance while maintaining detectability through systematic variation of format and timing parameters
Data Source
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AI summary
The present invention relates to a communication technique, which is a convergence of IoT technology and 5G communication system for supporting higher data transmission rate beyond 4G system, and a system for same. The present invention can be applied to smart services (e.g. smart homes, smart buildings, smart cities, smart cars or connected cars, health care, digital education, retail businesses, security- and safety-related services and the like) on the basis of 5G communication technology and IoT-related technology. The present invention provides a method for detecting a downlink control signal when a delay time reduction mode terminal is set to a delay reduction mode.