Uplink LBT Subframe Allocation for LTE Unlicensed Band Efficiency
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Solution Overview
Problem
In LTE communication systems, especially in unlicensed bands, uplink transmission efficiency is hindered due to interference from other communication systems, and existing methods like LBT do not effectively manage channel availability for efficient data transmission.
Innovation Solution
A terminal apparatus and base station apparatus are designed to perform Listen-Before-Talk (LBT) procedures, where a channel measurement unit in the terminal apparatus and a radio resource control unit in the base station apparatus allocate and manage subframes for uplink transmission based on random access response grants, ensuring efficient PUSCH transmission even when the channel is busy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT procedure is used for uplink transmission in unlicensed band, then channel access can be achieved, but transmission efficiency deteriorates due to channel busy conditions
Solution Approach 1:
The base station performs downlink LBT before transmitting the random access response, and the terminal performs uplink LBT before transmitting message 3. These preliminary channel access actions ensure that transmissions only occur when the channel is clear, resolving the contradiction between reliable channel access and transmission efficiency by preventing collisions and retransmissions
Solution Approach 2:
The patent dynamically adapts the LBT procedure type based on the random access response grant received from the base station. The terminal can switch between different LBT types (Type 1 with random backoff, Type 2 without random backoff) depending on channel conditions and base station instructions, optimizing the balance between reliability and efficiency in real-time
2Reliability
If multiple subframes are allocated for message 3 transmission, then transmission reliability improves, but time consumption increases due to LBT procedures in each subframe
Solution Approach 1:
The base station performs downlink LBT in advance before allocating uplink resources for message 3. This preliminary action ensures that the channel is clear before the terminal needs to transmit, reducing the time loss associated with uplink LBT procedures while maintaining transmission reliability across multiple subframes
Solution Approach 2:
The patent enables continuous uplink transmission across multiple subframes by performing LBT procedures efficiently. Once the channel is accessed successfully in one subframe, the transmission can continue in subsequent subframes without repeated LBT, maintaining continuous useful action and reducing overall time loss while ensuring reliability
Data Source
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AI summary
Provided is a terminal apparatus that performs an uplink LBT procedure, wherein one or more than one subframes are allocated for transmission of a message 3 in an LAA cell, and an LBT procedure for transmission of a random access preamble is initiated in a case where it is determined that a channel is busy in all of the one or more than one subframes.