Transmission Scheduling Based on HARQ Acknowledgement Delay
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Solution Overview
Problem
In wireless communication systems using time division duplex (TDD) channels, the Hybrid Automatic Repeat Request (HARQ) process introduces significant delays due to varying acknowledgement response times, which can exceed tolerable limits for delay-sensitive communications, especially when multiple re-transmissions are required.
Innovation Solution
Data transmission is scheduled in time intervals or subframes with lower associated HARQ delays, determined by the delay-sensitivity of the data and the acknowledgement delay of the selected subframe, to minimize overall communication delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is transmitted using HARQ re-transmission process in TDD channel, then data transmission reliability is improved, but communication delay increases
Solution Approach 1:
The patent pre-calculates and stores the acknowledgement delay for each subframe in advance, creating a lookup table that enables rapid selection of optimal subframes without real-time computation delays. This preliminary preparation resolves the contradiction by enabling fast decision-making that maintains reliability while minimizing delay.
Solution Approach 2:
The patent dynamically changes the transmission subframe parameter based on the calculated acknowledgement delay, selecting subframes with delays below a threshold for delay-sensitive data. This parameter adaptation allows the system to maintain high reliability through HARQ while reducing communication delay by avoiding high-latency subframes.
2Speed
If transmission subframe is selected based on lowest acknowledgement delay, then communication speed is improved, but data transmission reliability may deteriorate
Solution Approach 1:
The patent incorporates feedback mechanisms that monitor transmission outcomes and adjust subframe selection strategies. When low-delay subframes prove unreliable, the system receives feedback and adapts by selecting alternative subframes, thus maintaining both speed and reliability through continuous optimization based on actual transmission performance.
Solution Approach 2:
The patent implements dynamic subframe selection that adapts to changing channel conditions and data requirements. Rather than statically selecting the lowest delay subframe, the system dynamically adjusts selection based on real-time conditions, ensuring both high speed for delay-sensitive data and high reliability when channel conditions permit.
3Reliability
If multiple HARQ re-transmissions are allowed, then data transmission reliability is improved, but device complexity increases
Solution Approach 1:
The patent pre-determines the maximum number of HARQ re-transmissions and configures this parameter before actual data transmission begins. By establishing re-transmission limits in advance, the system maintains simplicity in the transmission process while ensuring sufficient re-transmission opportunities for high reliability when needed.
Data Source
AI summary
A method and system to help minimize communication latency. When data is to be transmitted from a transmitting entity to a receiving entity, the transmission will be scheduled to occur in a time interval that selected based on a consideration of the delay-sensitivity of the data and based on a HARQ delay associated with the selected time interval. For instance, if the data is particularly delay-sensitive, then the transmission could be scheduled to occur in a time interval that is selected based on the time interval having a relatively low associated HARQ delay, so as to help reduce the overall delay of the communication. Whereas, if the data is not particularly delay-sensitive, then the transmission could be scheduled to occur in a time interval that has a relatively high associated HARQ delay.