Shortened TTI Control Channel Design for Wireless Latency Reduction
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Solution Overview
Problem
Current LTE and 5G systems face challenges in supporting transmission time intervals (TTIs) shorter than 1 ms, which is essential for reducing latency and power consumption, particularly in latency-sensitive services like VoLTE and mission-critical IoT applications.
Innovation Solution
The implementation of a method and apparatus that enable shortened TTIs by modifying the communication operations between base stations and user equipment, including frequency hopping patterns and control channel configurations, to facilitate efficient transmission and reception of control information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the transmission time interval (TTI) is reduced to shorten latency, then the latency-sensitive service performance is improved, but the system complexity and implementation difficulty increase
Solution Approach 1:
The patent divides the 1 ms subframe into multiple shorter TTIs (e.g., 2-symbol or 3-symbol TTIs), creating segmented transmission intervals within the original subframe structure. This segmentation enables shorter latency while maintaining compatibility with the existing LTE subframe framework, reducing implementation complexity compared to completely redesigning the TTI structure.
Solution Approach 2:
The patent nests multiple short TTIs within a single 1 ms subframe, where each short TTI contains its own control and data regions. This nested structure allows the system to support both traditional 1 ms TTI operations and shortened TTI operations simultaneously, enabling gradual deployment and reducing system complexity.
2Loss of time
If the TTI is shortened to improve responsiveness, then the packet data latency is reduced, but the power consumption increases due to more frequent processing
Solution Approach 1:
The patent implements dynamic TTI length adaptation, where the system can switch between different TTI lengths (1 ms, 2-symbol, 3-symbol) based on service requirements and channel conditions. This dynamic approach allows the terminal to use shorter TTIs only when necessary for latency-sensitive services, reducing power consumption compared to continuously using short TTIs.
Solution Approach 2:
The patent changes the TTI duration parameter based on service type and channel conditions, allowing the system to optimize between latency and power consumption. For non-latency-sensitive services, the system uses longer 1 ms TTIs to reduce processing frequency and power consumption, while switching to shorter TTIs only when low latency is required.
3Productivity
If the control channel configuration is optimized for short TTI, then the transmission efficiency is improved, but the compatibility with legacy systems deteriorates
Solution Approach 1:
The patent designs the control channel structure to serve multiple functions: it can operate with traditional 1 ms TTIs for legacy compatibility, and simultaneously support shortened TTIs for improved efficiency. The control channel format is designed to be flexible, accommodating both operation modes without requiring separate dedicated structures, thus maintaining universality.
Solution Approach 2:
The patent introduces indication information in advance to notify terminals about the TTI length and control channel configuration to be used. This preliminary notification allows terminals to properly configure themselves for the upcoming transmission, ensuring both short TTI efficiency and smooth operation with legacy terminals that expect traditional configurations.
4Productivity
If the frequency hopping pattern is modified for short TTI operation, then the resource utilization is improved, but the interference management becomes more difficult
Solution Approach 1:
The patent segments the frequency hopping pattern into smaller intervals corresponding to the short TTI durations. Instead of hopping frequencies once per 1 ms subframe, the system performs frequency hopping at the boundaries of each short TTI (2-symbol or 3-symbol). This segmented approach improves resource utilization by enabling more granular frequency diversity while maintaining manageable interference patterns through the regular hopping structure.
Data Source
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AI summary
A communication method and system for converging a 5th-generation (5G) communication system for supporting higher data rates beyond a 4th-generation (4G) system with a technology for Internet of things (IoT) are provided. The disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security, and safety services. A shortened transmission time interval (TTI)-based downlink (DL) and uplink (UL) transmission method and apparatus for use in a wireless communication system.