HARQ-ACK Feedback Timing Optimization in 5G Unlicensed Bands
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for efficient service provision in 5G communication systems, particularly in unlicensed bands, where existing channel access procedures may fail due to busy states, leading to incomplete or failed signal transmissions.
Innovation Solution
A method and apparatus that utilize a frame-based channel access procedure, where a terminal or base station determines channel occupancy time and slot structure through a slot format indicator, allowing for efficient transmission and reception of signals in unlicensed bands by optimizing channel access and HARQ-ACK feedback timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a base station performs channel access procedure in unlicensed band, then the base station can transmit downlink signals, but the channel may be in busy state causing transmission failure
Solution Approach 1:
The base station performs channel access procedure before transmitting downlink signals to check if the channel is idle. This preliminary action allows the system to detect busy channel states in advance and adjust transmission timing accordingly, preventing transmission failures.
Solution Approach 2:
The channel occupancy time is dynamically determined based on the channel access result. When the channel is busy, the base station adjusts the channel occupancy time and retransmits the downlink signal at a different timing, making the transmission adaptive to channel conditions.
2Device complexity
If HARQ-ACK feedback timing is fixed, then the feedback process is simple, but the feedback may be lost when channel access fails
Solution Approach 1:
The HARQ-ACK feedback timing is dynamically adjusted based on the actual channel access result and downlink signal transmission timing. When channel access fails or timing needs adjustment, the feedback timing indicator is modified to ensure the terminal can successfully transmit feedback within the channel occupancy time.
Solution Approach 2:
The base station receives HARQ-ACK feedback from the terminal and uses this feedback information to adjust subsequent transmissions. The feedback mechanism ensures reliable communication by allowing the base station to retransmit data if acknowledgment is not received or is negative.
3Loss of time
If the base station transmits downlink signal immediately after channel access, then transmission latency is reduced, but the terminal may not have enough time to process and feedback
Solution Approach 1:
The timing between downlink signal transmission and HARQ-ACK feedback is dynamically determined based on the channel access result and terminal processing capabilities. The base station adjusts the channel occupancy time and feedback timing indicator to ensure sufficient processing time while minimizing overall latency.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The disclosure relates to 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). 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. The disclosure relates to a method and an apparatus for transmitting/receiving a feedback by a receiving end in a wireless communication system.