MAC Sub-header LCID Extension for Logical Channel Identification
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Solution Overview
Problem
The Logical Channel Identifier (LCID) field in LTE MAC protocol headers is limited, leading to a shortage of available LCID values, particularly with only 13 remaining for downlink and 9 for uplink, which restricts the number of logical channels and MAC control elements that can be identified, necessitating an extension to accommodate future functionalities.
Innovation Solution
The proposed solution involves extending the LCID field by using reserved bits in the MAC sub-header to indicate the presence of additional octets containing part or all of the LCID value, allowing for a combination of LCID fields to signal extended LCID values, thereby expanding the LCID value space without altering the existing header structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the LCID field is extended to accommodate more logical channels and MAC control elements, then the number of available LCID values increases, but the header size and complexity increase
Solution Approach 1:
The LCID field is segmented into a base LCID field (5 bits) and an optional extension field. The base field provides the standard 32 LCID values, while the extension field can be added when additional LCID values are needed. This segmentation allows the system to maintain the original simple header structure for common cases while providing an extension mechanism for future needs without altering the existing header structure.
Solution Approach 2:
The patent introduces an extension dimension to the LCID field by adding an extension indicator and optional extension field. This allows the LCID space to expand from 5 bits (32 values) to potentially 10 bits (1024 values) when the extension is activated, effectively doubling the available LCID values as stated in the technical effect.
2Adaptability or versatility
If reserved bits in the MAC sub-header are used to indicate extended LCID values, then no new reserved bits need to be allocated, but the existing header structure must be interpreted differently
Solution Approach 1:
The patent makes the header structure dynamic by introducing an extension indicator that can be set to different values. When the indicator is clear, the standard 5-bit LCID field is used. When the indicator is set, the extended LCID field is activated. This dynamic approach allows the same header structure to adapt to different LCID value requirements without requiring multiple fixed header formats.
Solution Approach 2:
The extension indicator and extension field serve multiple functions: they can indicate the presence of extended LCID values, they can signal the format of subsequent fields, and they can be used to maintain backward compatibility with existing LTE MAC protocol implementations. This multi-functionality reduces the need for separate dedicated structures for different scenarios.
Data Source
AI summary
Systems and methods for generating and decoding messages including header extensions are provided. It can be determined that a header extension is required for signaling a LCID value. A MAC sub-header including an indicator that the LCID value is extended can be generated and transmitted. A received message including a header extension can be decoded appropriately.