Base Station ACK/NACK Timing Adjustment
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Solution Overview
Problem
In mobile communication systems, the difference in subcarrier spacings between uplink and downlink leads to mismatched OFDM symbol lengths, requiring adjustments in transmission timings for data and ACK/NACK signals between base stations and terminal apparatuses.
Innovation Solution
A communication system is configured to allow varying symbol lengths between uplink and downlink, enabling appropriate timing adjustment for data and ACK/NACK transmissions by using different subcarrier spacings, allowing flexible adjustment of time slot lengths based on subcarrier spacing or OFDM symbol length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different subcarrier spacings are used for uplink and downlink to accommodate different use cases (eMBB, mMTC, uRLLC), then communication flexibility and adaptability are improved, but timing synchronization between data and ACK/NACK transmissions deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the reference timing for ACK/NACK transmission based on the subcarrier spacing configuration. When different subcarrier spacings are used for uplink and downlink, the system changes the timing reference parameter to maintain proper synchronization. Specifically, the transmission timing of ACK/NACK is adjusted according to the subcarrier spacing of the corresponding data transmission, ensuring that timing relationships are preserved despite parameter variations in different use cases.
2Productivity
If OFDM symbol length is adjusted by varying subcarrier spacings to meet different latency requirements, then communication performance for different use cases is improved, but transmission timing coordination between base station and terminal deteriorates
Solution Approach 1:
The patent applies dynamics by making the timing reference adaptable rather than fixed. The system dynamically selects which subcarrier spacing configuration serves as the reference for ACK/NACK timing based on the actual data transmission parameters. This dynamic adaptation allows the system to handle varying OFDM symbol lengths for different use cases (eMBB with longer symbols, uRLLC with shorter symbols) while maintaining coordinated timing through flexible reference selection, thereby managing timing coordination complexity effectively.
3Reliability
If subcarrier spacing is optimized for specific use cases (e.g., smaller spacing for eMBB, larger spacing for uRLLC), then quality of service for each use case is improved, but timing alignment between uplink and downlink transmissions deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-establishing timing adjustment rules and reference selection criteria before actual data transmission occurs. The system determines the appropriate timing reference and adjustment parameters in advance based on the configured subcarrier spacings for uplink and downlink. This preliminary configuration ensures that when data transmission occurs with optimized subcarrier spacing for specific use cases, the timing alignment is already prepared and can be applied immediately, thus preventing timing misalignment rather than correcting it after the fact.
Data Source
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AI summary
Included are a receiver configured to receive first downlink data mapped to the first component carrier and second downlink data mapped to the second component carrier; and a transmitter configured to transmit a signal for indicating delivery confirmation of the first downlink data and the second downlink data. A timing to transmit the signal for indicating the delivery confirmation is defined by a prescribed number of time slots, and a length of each of the time slots is configured based on a subcarrier spacing of the first component carrier and a subcarrier spacing of the second component carrier.