PUCCH ACK/NACK Transmission Using Comb Structure for Short TTI
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Solution Overview
Problem
The reduction of Transmission Time Interval (TTI) in 5G wireless communication technologies poses challenges for the transmission structure of Physical Uplink Control Channel (PUCCH) ACK/NACK signals, leading to demodulation performance issues and resource shortages due to excessive overheads of Reference Symbols (RS), especially when TTI is shortened to 1-7 symbols.
Innovation Solution
A method that determines a predefined pattern for carrying ACK/NACK information using a predefined sequence or RS time-frequency structure, transmitted on a preset time-frequency domain resource, allowing simultaneous transmission of ACK/NACK and SRS within the same symbol by utilizing a comb structure in the frequency domain, eliminating the need for separate SRS transmission and optimizing resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the TTI length is reduced to 1-7 symbols to shorten transmission delay, then the transmission delay is reduced exponentially, but the PUCCH transmission structure cannot be directly used and demodulation performance deteriorates
Solution Approach 1:
The patent changes the TTI duration parameter from the conventional 1ms to shortened lengths of 1-7 symbols, and simultaneously adjusts the PUCCH transmission parameters including using cyclic shifted CAZAC sequences and comb-based frequency domain mapping to maintain demodulation performance under the new time constraint
Solution Approach 2:
The patent transitions from time-domain spreading to frequency-domain comb structure for PUCCH transmission, mapping ACK/NACK signals to specific subcarriers using a comb pattern (e.g., every other subcarrier), thereby achieving frequency domain diversity to compensate for the reduced time domain resources
2Productivity
If the TTI is shortened to 1-7 symbols, then the scheduling time is reduced, but frequency domain diversity is lost due to occupancy of only one PRB
Solution Approach 1:
The patent employs a comb-based frequency domain mapping structure where ACK/NACK signals are mapped to non-contiguous subcarriers (e.g., even or odd subcarriers) across multiple PRBs, thereby achieving frequency domain diversity without requiring extended TTI duration
3Loss of time
If the number of symbols within TTI is reduced, then the transmission delay is reduced, but available resources for transmitting valid data are reduced due to excessive overheads of Reference Symbols
Solution Approach 1:
The patent extracts and removes the dedicated reference symbol overhead from the PUCCH structure by implementing non-coherent detection using cyclic shifted CAZAC sequences, where the sequence shifts themselves carry the ACK/NACK information without requiring separate reference symbols for channel estimation
Solution Approach 2:
The cyclic shifted CAZAC sequences serve multiple functions simultaneously: they provide channel estimation, carry the ACK/NACK information through cyclic shift differentiation, and enable non-coherent detection, thereby eliminating the need for separate reference symbols
Data Source
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AI summary
A method and device for transmitting information, comprising: firstly, determining a predefined pattern for carrying information; wherein the predefined pattern comprises a predefined sequence, or the time-frequency structure of a predefined reference symbol (RS), and the information comprises an acknowledgment message (ACK) or a non-acknowledgment message (NACK); and then transmitting the predefined pattern carrying the information on a preset time-frequency domain resource.