MAC CE Uplink Configuration for LAA Reliability
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Solution Overview
Problem
In the LTE-A CA system, the current transmission method in LAA systems does not differentiate between serving cells, leading to unreliable and delayed transmission of MAC control elements, particularly in unlicensed bands, resulting in high latency and transmission failures.
Innovation Solution
The UE determines whether an uplink grant exists in the licensed band when an MAC control element is triggered and allocates it for transmission if capable, prioritizing the licensed band for MAC control elements to ensure reliable and timely transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current transmission method is followed in LAA systems where cells are not differentiated, then the system can operate with simple cell selection, but the reliability of MAC control element transmission deteriorates and latency increases
Solution Approach 1:
The patent applies local quality by differentiating between licensed band cells and unlicensed band cells, assigning different transmission priorities to different cell types. Specifically, the UE is configured to preferentially select licensed band cells for transmitting MAC control elements, while unlicensed band cells are used for other data transmissions. This localized differentiation of cell quality and transmission priority resolves the contradiction by improving MAC CE reliability without requiring complete system-level complexity
2Productivity
If MAC control elements are transmitted through unlicensed band cells, then more cells can be utilized for transmission, but transmission failures and latency increase
Solution Approach 1:
The patent implements preliminary action by pre-configuring the UE with cell differentiation rules and transmission priorities before actual MAC control element transmission occurs. The UE is pre-instructed to identify licensed band cells and prioritize them for MAC CE transmissions, ensuring that when MAC CEs need to be sent, the appropriate reliable cells are already selected and ready, thereby reducing transmission latency while maintaining high cell utilization
3Reliability
If all serving cells are treated equally without differentiation, then the system operation is simple, but MAC control elements may be transmitted with high latency and failures
Solution Approach 1:
The patent applies parameter changes by modifying the cell selection criteria from a uniform approach to a differentiated approach based on band type. The key parameter change is the introduction of transmission priority levels: licensed band cells are assigned higher priority for MAC CE transmission, while unlicensed band cells have lower priority. This parameter-based differentiation improves reliability while maintaining operational simplicity through clear, rule-based cell selection
Data Source
AI summary
An MAC control element (CE) uplink configuration method and device, and communications system, the method includes: when an MAC CE is activated, determining, by user equipment (UE), whether an uplink grant of a serving cell in an authorization frequency band exists; and when the uplink grant of the serving cell in the authorization frequency band exists and can accommodate the MAC CE, allocating, by the UE and for the MAC CE, the uplink grant of the serving cell in the authorization frequency band. An embodiment of the present disclosure improves reliability for transmitting the MAC CE, in an LAA system, and reduces unnecessary latency or failure.