MAC Subheader Field Omission for 5G NR Overhead Reduction
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Solution Overview
Problem
Current 5G New Radio (NR) communications face challenges in reducing layer 2 overhead for ultra-reliable low-latency communications, particularly in the Random Access procedure, which affects latency and reliability.
Innovation Solution
The proposed solution involves optimizing the Medium Access Control (MAC) PDU structure by omitting certain fields such as the logical channel identifier and length field from the MAC subheader under specific conditions, ensuring efficient multiplexing and grant size alignment for Msg3 in the RA procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MAC subheader includes complete fields (logical channel identifier and length field) for all logical channels, then the overhead is higher but the reliability and latency are improved through complete information signaling
Solution Approach 1:
The patent extracts and removes redundant fields from the MAC subheader structure. Specifically, it omits the logical channel identifier field when only one logical channel is present, and omits the length field when the data size can be determined from other information (such as grant size). This extraction of unnecessary elements directly reduces overhead while maintaining sufficient information for reliable transmission.
Solution Approach 2:
The patent introduces dynamic field omission based on transmission conditions. The MAC subheader structure adapts its complexity according to the number of logical channels and available grant size. When conditions permit (single logical channel or sufficient grant size), fields are dynamically omitted to reduce overhead; when conditions require completeness, full fields are included to ensure reliability.
2Quantity of substance
If the MAC subheader omits certain fields to reduce overhead, then the overhead is reduced but the complexity of parsing and interpreting the remaining fields increases
Solution Approach 1:
The patent changes the parameters of the MAC subheader based on transmission conditions. By dynamically adjusting which fields are present (omitting logical channel identifier when N=1, omitting length field when grant size suffices), the subheader structure adapts to minimize overhead. The receiving end uses corresponding rules to parse the variable structure, maintaining manageable complexity through standardized omission criteria.
3Loss of time
If the MAC PDU structure is optimized by omitting fields, then the latency is reduced through faster processing but the reliability may be compromised through information loss
Solution Approach 1:
The patent performs preliminary determination of which fields to omit before constructing the MAC PDU. By pre-evaluating conditions (number of logical channels, grant size sufficiency), the system decides in advance which fields can be safely omitted. This preliminary action ensures that no critical information is lost while maximizing overhead reduction, thereby improving latency without compromising reliability.
Solution Approach 2:
The patent implements feedback mechanisms where the receiving end verifies received data against expected parameters (such as checking if received data size matches grant size when length field is omitted). This feedback ensures that field omission does not lead to information loss, maintaining reliability while benefiting from reduced overhead and latency.
Data Source
AI summary
In accordance with an example embodiment of the apparatus there is at least a method and apparatus to perform determining a grant for data to be communicated, comprising identifying logical channels to be multiplexed into a medium access control protocol data unit for the data to be communicated, wherein at least one of a logical channel identifier for at least one logical channel of the multiplexed logical channels and length of at least one logical channel service data unit is configured to be omitted from the medium access control protocol data unit. Further in accordance with an example embodiment of the apparatus there is at least a method and apparatus to perform receiving a grant for the data to be communicated, comprising logical channels multiplexed into a medium access control protocol data unit for the data to be communicated, wherein at least one of a logical channel identifier for at least one logical channel of the multiplexed logical channels and length of at least one logical channel service data unit is configured to be omitted from the medium access control protocol data unit.