RACH Uplink Grant Skipping When No UE Data Is Available
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Solution Overview
Problem
Existing wireless communication systems force UEs to perform unnecessary uplink transmissions, such as PUSCH, even when no data is available, leading to power consumption and interference, especially on unlicensed carriers like NR-U, due to the need for Clear Channel Assessment and Listen-Before-Talk procedures.
Innovation Solution
The system allows UEs to selectively skip uplink transmissions allocated by the RACH procedure when no data is available, using indications in the RAR message to avoid generating transport blocks with padding or BSR MAC CE, and instead perform short transmissions like SRS or HARQ ACK.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the terminal performs uplink transmission in the second time window after random access procedure completion, then the uplink data can be transmitted promptly, but it causes unnecessary power consumption and potential interference when no uplink data is available
Solution Approach 1:
The terminal dynamically changes the transmission parameter by skipping the uplink transmission in the second time window when determining that no uplink data is available, adapting the transmission behavior based on data availability status to avoid unnecessary power consumption
Solution Approach 2:
The terminal autonomously determines whether uplink data is available and decides whether to perform transmission or skip it, using its own data buffer status information to make the decision without requiring external control, thereby avoiding unnecessary power consumption
2Loss of energy
If the terminal skips uplink transmission when no data is available, then power consumption is reduced, but the random access procedure time is extended due to additional skipping determination steps
Solution Approach 1:
The terminal performs preliminary determination of uplink data availability during the random access procedure, specifically in the second time window before actual transmission would occur, to avoid unnecessary transmissions and reduce overall power consumption while minimizing time impact
3Loss of energy
If the terminal determines uplink data availability in the second time window, then unnecessary transmissions are avoided, but the device complexity increases due to additional determination mechanisms
Solution Approach 1:
The terminal uses its existing data buffer status information to autonomously determine whether uplink data is available, leveraging already-available internal state information rather than requiring complex external determination mechanisms, thus avoiding unnecessary transmissions without significantly increasing device complexity
Data Source
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AI summary
Apparatuses, methods, and systems are disclosed for skipping an uplink transmission allocated by a RACH procedure. One apparatus includes a transceiver 825 of a remote unit 800 that receives a random access response message 230 ("RAR") including an RAR grant 420 having an uplink resource allocation 515, 520 during a random access procedure 725 ("RACH procedure"), a processor 805 of the remote unit 800 determines an indication that skipping of an uplink transmission is configured for the RACH procedure 725 and that no uplink data is available; and the processor 805 controls the transceiver 825 to skip the PUSCH transmission of a transmission block without logical channel ("LCH") data on the uplink resource allocation 515, 520 in response to the indication that skipping is configured for the RACH procedure 725 and that no uplink data is available. A method 900 or system 100 may perform functions of the apparatus.