MAC PDU Header Overhead Reduction in LTE Systems
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Solution Overview
Problem
In LTE mobile communication systems, the existing MAC PDU header structure is inefficient due to the inclusion of unnecessary size information for RLC PDUs, which increases overhead and reduces transmission efficiency, especially in high-speed communication scenarios where precise size indication is required for various QoS requirements.
Innovation Solution
The proposed solution involves omitting the LEN field in the MAC PDU header under specific conditions, such as when only one RLC PDU is accommodated and the last byte of the RLC PDU corresponds to the MAC PDU, or when general padding does not exist, allowing for byte-aligning padding to deduce the RLC PDU size, thereby reducing header overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the LEN field is included in the MAC PDU header to indicate the size of each RLC PDU, then the receiving side can accurately identify packet boundaries and perform demultiplexing, but the header overhead increases and transmission efficiency decreases
Solution Approach 1:
The patent extracts and removes the LEN field from the MAC PDU header structure when certain conditions are met (single RLC PDU per MAC PDU, or when RLC PDU size can be inferred from MAC PDU size and padding information). This eliminates unnecessary information transmission while preserving the ability to accurately identify packet boundaries through alternative means such as padding indicators and MAC PDU size information.
Solution Approach 2:
The receiving side uses self-service by calculating the RLC PDU size from the MAC PDU size and padding information already available in the received packet, rather than relying on explicitly transmitted LEN fields. The MAC layer utilizes its own size information and padding indicators to derive the upper layer packet size, making the system self-sufficient and reducing dependency on additional header fields.
2Ease of operation
If the MAC PDU header includes size information for all RLC PDUs, then demultiplexing accuracy is improved, but the header size increases and transmission efficiency decreases
Solution Approach 1:
The patent removes unnecessary LEN fields from the MAC PDU header when the receiving side can infer RLC PDU sizes from MAC PDU size and padding information. This extraction eliminates redundant data while maintaining demultiplexing accuracy through alternative calculation methods that use available MAC layer information.
Solution Approach 2:
Instead of explicitly indicating RLC PDU sizes in the header, the patent inverts the approach by using the absence of LEN fields combined with MAC PDU size and padding indicators to implicitly convey size information. The receiving side actively calculates sizes rather than passively receiving them, reversing the traditional information flow direction.
3Productivity
If the LEN field is omitted to reduce overhead, then transmission efficiency improves, but the receiving side loses ability to precisely determine RLC PDU size
Solution Approach 1:
The patent introduces padding indicators and MAC PDU size information as intermediary elements that mediate between the omitted LEN field and the receiving side's size determination needs. These intermediaries carry implicit size information that allows the receiving side to calculate accurate RLC PDU sizes without requiring explicit LEN fields in the header.
Solution Approach 2:
The receiving side performs self-service by calculating RLC PDU sizes from MAC PDU size and padding information rather than relying on transmitted LEN fields. This self-determination mechanism maintains measurement precision while enabling overhead reduction, as the receiving side uses its own processing capabilities to derive necessary information.
4Device complexity
If the MAC PDU header structure is simplified by removing LEN fields, then device complexity decreases, but the protocol's ability to handle variable QoS requirements is reduced
Solution Approach 1:
The patent applies dynamics by making the MAC PDU header structure flexible and adaptive rather than static. The presence or absence of LEN fields, and the method of size indication, dynamically adjusts based on transmission conditions, RLC entity configurations, and QoS requirements. This dynamic approach allows the simplified header structure to maintain versatility in handling variable QoS scenarios.
Solution Approach 2:
The patent changes parameters such as the use of padding indicators, MAC PDU size information, and conditional LEN field inclusion to adapt to different QoS requirements. By varying these parameters based on traffic characteristics and service requirements, the system maintains adaptability and versatility despite the overall simplification of the header structure.
Data Source
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AI summary
Disclosed is a method and apparatus for transmitting/receiving a packet in a mobile communication system. When upper layer packets are multiplexed into a packet whose overall size is informed via a separate path, the size of the upper layer packet is not signaled if it can be calculated from the overall size of the packet, so that the size a packet transmitted/received over a radio channel can be reduced.