Empty MAC PDU Transmission Management in 5G NR
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Solution Overview
Problem
In 3GPP NR, UE performs autonomous retransmissions of empty MAC PDUs, leading to unnecessary power consumption and interference, as these PDUs are treated similarly to those containing uplink data despite being solely for UCI multiplexing and having outdated information.
Innovation Solution
Preventing autonomous retransmissions of empty MAC PDUs without MAC SDUs and flushing the HARQ buffer after initial transmission, ignoring DCI scheduling for retransmissions, and not starting configured or retransmission timers when the PDU contains only padding or BSR for UCI multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs autonomous retransmissions of empty MAC PDUs, then the reliability of UCI transmission is improved, but the power consumption increases and unnecessary interference is caused
Solution Approach 1:
The patent changes the parameter of NDI (New Data Indicator) from toggled to non-toggled for empty MAC PDUs, which prevents the HARQ entity from initiating autonomous retransmissions. This parameter change resolves the contradiction by maintaining UCI transmission reliability through the initial transmission while avoiding unnecessary retransmissions that would increase power consumption.
Solution Approach 2:
The patent extracts the harmful retransmission behavior from the normal HARQ process by introducing a specific condition (empty MAC PDU with non-toggled NDI) that excludes retransmission. This separation allows the system to maintain reliable initial UCI transmission while removing the unnecessary energy-consuming retransmission cycle.
2Reliability
If the UE performs autonomous retransmissions of empty MAC PDUs, then the transmission reliability is improved, but unnecessary interference is caused
Solution Approach 1:
By changing the NDI parameter to non-toggled for empty MAC PDUs, the patent prevents autonomous retransmissions that would cause unnecessary interference. This parameter modification maintains transmission reliability for the initial UCI delivery while eliminating the harmful interference from repeated empty transmissions.
Solution Approach 2:
The patent converts the potentially harmful autonomous retransmission behavior into a beneficial single transmission by using the non-toggled NDI condition. This transforms what would be a harmful retransmission cycle into a beneficial once-only transmission that maintains reliability without causing interference.
3Adaptability or versatility
If the UE transmits empty MAC PDUs for UCI multiplexing, then the UCI transmission capability is maintained, but resource utilization deteriorates
Solution Approach 1:
The patent extracts the UCI multiplexing function from the data transmission function by allowing empty MAC PDUs to be transmitted only when necessary (when UCI needs multiplexing). This separation maintains UCI capability while preventing unnecessary data transmission resources from being wasted on empty PDUs that would cause poor resource utilization.
Solution Approach 2:
The patent applies partial action by transmitting empty MAC PDUs only when UCI multiplexing is required, rather than continuously. This partial transmission approach maintains the necessary UCI capability while avoiding excessive transmissions that would waste resources on empty PDUs without data payload.
Data Source
AI summary
Apparatuses, methods, and systems are disclosed for managing MAC PDU transmissions. An apparatus (300) includes a processor (305) that generates an empty MAC PDU according to an UL CG, the empty MAC PDU free of any MAC SDUs. The apparatus (300) includes a transceiver (325) that instructs the physical layer to transmit, to a network, the empty MAC PDU on a HARQ process associated with the UL CG. The processor (305) prevents autonomous retransmission of the empty MAC PDU to the network.