Logical Channel Prioritization for Delay-Critical Uplink Data
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Solution Overview
Problem
The priority-based token bucket algorithm in 5G NR LCP procedures fails to ensure timely transmission of delay-critical data, as it does not allocate resources if a logical channel lacks positive tokens, despite higher priority, affecting low-latency applications like XR and telesurgery.
Innovation Solution
Enhance LCP by allocating resources to logical channels with delay-critical data even if they have zero tokens, and selectively exempt or reduce token decrement for such channels, ensuring they always have positive tokens for allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the priority-based token bucket algorithm is used for UL resource allocation in LCP procedure, then PBR-based fairness is achieved, but delay-critical data in logical channels without positive tokens cannot be transmitted in time
Solution Approach 1:
The patent changes the allocation parameter logic by introducing a new condition: logical channels carrying delay-critical data are allocated resources regardless of their token bucket status. This parameter change allows the system to bypass the traditional token-based restriction and allocate resources based on delay requirements, thereby resolving the contradiction between maintaining PBR fairness and ensuring timely transmission of delay-critical data
Solution Approach 2:
The patent performs preliminary classification of logical channels to identify those carrying delay-critical data before the resource allocation process. By pre-identifying these channels and their delay requirements, the system can prioritize them in the allocation process even when tokens are insufficient, preventing time loss before the allocation decision is made
2Quantity of substance
If resources are allocated strictly according to token availability in the priority-based token bucket algorithm, then PBR requirements are met, but low-latency applications such as XR and telesurgery are adversely affected
Solution Approach 1:
The patent introduces a dual-mode allocation parameter system: for logical channels without delay-critical data, allocation follows the traditional token-based PBR mechanism; for channels with delay-critical data, allocation switches to a delay-based mechanism that ignores token constraints. This parameter change enables the system to meet both PBR requirements and latency requirements simultaneously
Solution Approach 2:
The patent segments the resource allocation process into two distinct paths: one for normal data following PBR rules and another for delay-critical data following delay-based rules. This segmentation allows the system to maintain PBR fairness for general traffic while providing dedicated low-latency paths for time-sensitive applications, resolving the contradiction between resource quantity control and latency reduction
Data Source
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AI summary
Various solutions for logical channel prioritization (LCP) enhancements in mobile communications are described. An apparatus may select a plurality of logical channels for an uplink (UL) grant. The apparatus may allocate resources of the UL grant to one or more of the plurality of logical channels in a decreasing priority order. Each of the one or more of the plurality of logical channels carries delay-critical data or is associated with a positive number of tokens. Then, the apparatus may decrement the positive number of tokens for each of the one or more of the plurality of logical channels by a total size of medium access control (MAC) service data units (SDUs) served to a corresponding logical channel of the one or more of the plurality of logical channels. After that, the apparatus may multiplex the MAC SDUs in a MAC protocol data unit (PDU) for transmission on the UL grant to a network node.