Buffer Status Report Prioritization for URLLC Latency

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Solution Overview

Problem

Current 5G systems face challenges in prioritizing ultra-reliable low latency communication (URLLC) traffic, leading to latency issues due to the legacy medium access control (MAC) layer prioritization procedures, especially when mixed with enhanced mobile broadband (eMBB) traffic, which results in inadequate support for industrial IoT applications.

Innovation Solution

The introduction of multiple buffer status reports (BSRs) with different priorities allows for the temporary increase of MAC control element priorities, enabling timely transmission of critical traffic by prioritizing 'critical BSRs' over 'normal BSRs' and triggering scheduling requests when necessary, ensuring efficient resource allocation and reduced latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If legacy MAC layer prioritization procedures are used, then non-critical traffic (eMBB) is handled according to standard priority levels, but critical traffic (URLLC) cannot achieve sufficient latency performance

Engineering Contradiction:

Improvelatency performance of URLLC trafficVSAvoidMAC layer prioritization complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments buffer status reporting into multiple types (regular BSR and short BSR) with different priorities. The short BSR is specifically designed for critical URLLC traffic and can be transmitted with higher priority than regular BSR, allowing critical data to bypass the standard prioritization queue and achieve lower latency without fundamentally changing the MAC layer structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the priority parameter of buffer status reports based on the type of traffic being reported. By assigning different priority levels to different BSR types and allowing dynamic adjustment of these priorities, the system can elevate critical URLLC traffic above standard eMBB traffic in the transmission queue, directly addressing the latency performance issue

Inventive Principle:

Principle #35Parameter changes

2Reliability

If MAC PDU size is limited to accommodate only essential MAC CEs, then control information is transmitted reliably, but URLLC data transmission is delayed

Engineering Contradiction:

Improvecontrol information transmission reliabilityVSAvoidURLLC data transmission latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent introduces short BSR as an intermediary mechanism that provides essential buffer status information for critical traffic in a compact format. This intermediary report allows the MAC layer to make quick scheduling decisions for URLLC traffic without requiring full buffer status information, enabling faster transmission while maintaining control information reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies partial action by transmitting only the most critical buffer status information through short BSR rather than complete buffer status reports. This partial information transmission is sufficient for urgent URLLC scheduling decisions, reducing the time required for MAC PDU construction and transmission while maintaining reliability for critical data

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If dynamic priority assignment is implemented for URLLC LCH, then critical traffic priority can be increased above MAC CE BSR, but non-critical traffic may experience excessive delays

Engineering Contradiction:

Improvecritical traffic priority assuranceVSAvoidnon-critical traffic delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local quality by creating different priority treatment zones for different BSR types. Regular BSR maintains standard priority levels for non-critical traffic, while short BSR for critical traffic receives elevated priority treatment. This localized priority differentiation ensures critical traffic gets expedited handling without systematically delaying all non-critical traffic

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces dynamic priority adjustment where the priority of buffer status reports can be changed based on traffic conditions. The system can dynamically elevate the priority of short BSR when critical URLLC traffic is detected, while maintaining normal priority for regular BSR, creating a flexible prioritization system that adapts to real-time traffic needs rather than applying static priority rules

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11582775B2Methods of conveying buffer status with mixed critical and non-critical traffic

Publication Date: 2023.02.14 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method by a wireless device (110) includes determining that the wireless device has data to transmit on at least one logical channel of a priority N. The logical channel is associated with at least one logical channel group. The method further includes generating, by the wireless device, a buffer status report of type N, BSR N, for the at least one logical channel of the priority N and prioritizing a transmission of the BSR N for the at least one logical channel of priority N over a data transmission for at least one other logical channel that has a priority that is higher than the priority N.