MAC Header Overhead Reduction in LTE Transmitter
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Solution Overview
Problem
In high-speed packet communications like LTE, the variable size of MAC-SDUs leads to an increase in overhead due to the number of bits required for the Length Indicator (LI) in the header, which worsens as the number of multiplexed MAC-SDUs increases.
Innovation Solution
The transmitter apparatus generates MAC-PDUs with an optimized MAC header that includes 'LI' information only when necessary, reducing the number of 'LI' entries to match the number of multiplexed information elements, and uses 'C/T' and 'E' flags to identify the position and type of elements within the PDU, allowing for efficient size indication without unnecessary overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of multiplexed MAC-SDUs is increased to support more services, then the service capacity is improved, but the overhead in header information increases due to more LI bits being required
Solution Approach 1:
The patent extracts and removes unnecessary LI information from the MAC header. When a MAC-PDU contains only a single MAC-SDU, the LI field is completely removed from the header, eliminating the overhead of indicating the size of non-existent additional elements. This directly addresses the contradiction by reducing overhead while maintaining the ability to handle multiple services when needed.
Solution Approach 2:
The patent implements dynamic header formatting where the MAC header structure adapts based on the number of multiplexed MAC-SDUs. The header can contain 0, 1, or 2 LI fields depending on whether 1, 2, or 3 MAC-SDUs are multiplexed. This dynamic adjustment allows the system to optimize overhead for each specific case, resolving the contradiction between service capacity and overhead.
2Measurement precision
If LI information is included for all multiplexed MAC-SDUs to indicate their sizes, then the data transmission accuracy is improved, but the header overhead increases
Solution Approach 1:
The patent applies partial action by including LI information only when necessary. Instead of always including LI fields for all multiplexed elements, the system includes LI only when multiple MAC-SDUs are present. This partial inclusion of measurement information maintains accuracy where needed while avoiding excessive overhead in simpler cases.
Solution Approach 2:
The patent extracts and removes unnecessary LI information from the MAC header. When a MAC-PDU contains only a single MAC-SDU, the LI field is completely removed from the header, eliminating the overhead of indicating the size of non-existent additional elements. This directly addresses the contradiction by reducing overhead while maintaining the ability to handle multiple services when needed.
Data Source
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AI summary
A transmitter apparatus (10) includes: an MAC-PDU generator section (11) configured to generate an MAC-PDU by multiplexing one or more variable-length information elements each being any one of an MAC-SDU received from an RLC layer, control information, and padding information; and an MAC-PDU transmitter section (13) configured to transmit the generated MAC-PDU. The MAC-PDU generator section (13) is configured to add an MAC header including LI indicating sizes of a plurality of information elements, when the plurality of information elements is multiplexed into the MAC-PDU, and the number of pieces of the LI included in the MAC header is one number smaller than the number of the information elements being multiplexed.