5G Unlicensed Band Channel Access via Base Station Coordination
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently providing multiple services, such as eMBB, mMTC, and URLLC, over unlicensed bands due to limitations in channel access procedures, which can result in failed signal transmissions when the unlicensed band is not idle.
Innovation Solution
A method and apparatus that allow a terminal to receive information from a base station indicating the time to transmit an uplink signal, determine a slot for transmitting a response to downlink data, and send a message with the response, enabling efficient channel access and signal transmission even when the unlicensed band is not initially idle, by using a frame-based channel access procedure and slot format indicators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a terminal uses conventional channel access procedures to transmit uplink signals in unlicensed bands, then the system can operate with simple protocols, but signal transmission fails when the unlicensed band is not idle
Solution Approach 1:
The base station performs channel access procedures and determines channel occupancy time before the terminal transmits uplink signals. The base station sends downlink data and receives HARQ-ACK feedback within the predetermined channel occupancy time, ensuring the channel is ready for transmission before the terminal attempts to access it.
Solution Approach 2:
The base station acts as an intermediary that manages channel access on behalf of the terminal. It performs LBT, determines channel occupancy time, and coordinates downlink and uplink transmissions within this time window, eliminating the need for the terminal to independently perform complex channel access procedures.
2Productivity
If the base station transmits downlink data without coordinating channel access, then the base station can operate independently, but the terminal cannot transmit uplink signals when the channel is occupied
Solution Approach 1:
The terminal sends HARQ-ACK feedback to the base station within the channel occupancy time. The base station configures the terminal to transmit this feedback in specific uplink slots within the occupancy period, ensuring reliable acknowledgment of downlink data reception even in unlicensed bands.
Solution Approach 2:
The system dynamically adapts to channel conditions by using slot format indicators to define flexible uplink and downlink slot configurations within the channel occupancy time. This allows the system to optimize resource allocation based on real-time channel availability and service requirements.
Data Source
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.