HARQ Buffer Retention for Uplink Data Integrity
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Solution Overview
Problem
In wireless communication systems using HARQ, data loss occurs due to errors in ACK/NACK signals, particularly NACK-TO-ACK errors, where the transmitter mistakenly receives an ACK signal despite the receiver not receiving the data, leading to data being transmitted again instead of being retransmitted.
Innovation Solution
A method is implemented where uplink data is kept in a HARQ buffer if an ACK/NACK signal is an ACK, and retransmission is suspended until uplink scheduling information is received, while retransmitting data if the signal is a NACK, ensuring data integrity by promptly detecting transmission errors and managing retransmissions based on accurate feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transmitter transmits new data upon receiving an ACK signal, then transmission efficiency is improved, but data loss occurs due to NACK-TO-ACK errors
Solution Approach 1:
The transmitter keeps the previous data in the HARQ buffer after receiving an ACK signal, preparing for possible retransmission before actually needing to retransmit. This preliminary action prevents data loss when NACK-TO-ACK errors occur, as the data is still available for retransmission if needed.
Solution Approach 2:
The system uses uplink scheduling information as an additional feedback mechanism to determine whether to retransmit data. By monitoring whether uplink scheduling information is received within a predetermined time after transmitting an ACK, the transmitter can detect NACK-TO-ACK errors and take appropriate corrective action.
2Reliability
If the transmitter retransmits data upon receiving a NACK signal, then data reliability is improved, but transmission resources are wasted due to ACK-TO-NACK errors
Solution Approach 1:
The system uses the presence or absence of uplink scheduling information as feedback to verify NACK signals. When a NACK is received, the transmitter checks whether uplink scheduling information is received within the predetermined time. If no scheduling information is received, it confirms the NACK is valid and proceeds with retransmission, avoiding retransmission for ACK-TO-NACK errors.
Solution Approach 2:
The system uses its own existing scheduling mechanism (uplink scheduling information) to detect and correct feedback errors, rather than requiring additional separate error detection mechanisms. This self-service approach efficiently identifies ACK-TO-NACK errors and prevents unnecessary retransmissions.
3Reliability
If data is kept in the HARQ buffer after receiving an ACK signal, then data loss is prevented, but buffer memory is occupied unnecessarily
Solution Approach 1:
The buffer retention policy is dynamic rather than static. Data is kept in the HARQ buffer temporarily after receiving an ACK signal, but only for a limited predetermined time period. If no uplink scheduling information is received during this period, the data is safely discarded. This dynamic approach balances data loss prevention with efficient memory usage.
Solution Approach 2:
The system retains data in the buffer as a preliminary measure before confirming whether retransmission is needed. This temporary retention prepares the system for possible retransmission without permanently occupying buffer space, as the data will be discarded if not needed within the predetermined time.
Data Source
AI summary
A method of data transmission using HARQ is provided. The method includes transmitting an uplink data, receiving an ACK/NACK signal for the uplink data, keeping the uplink data in a HARQ buffer when the ACK/NACK signal is an ACK signal, and retransmitting the uplink data when an uplink scheduling information for retransmission of the uplink data is received. In the present invention, a transmission error in an ACK/NACK signal is promptly detected, and thus data can be transmitted at a high speed.