Sidelink MAC-CE Routing and Relaying for Low-Latency UE Communication

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Solution Overview

Problem

Existing wireless communication technologies, particularly in NR and LTE, face challenges in improving mobile broadband access and latency, especially in sidelink communications, which are not adequately addressed by current MAC-CE designs.

Innovation Solution

The development of advanced sidelink MAC-CE designs that include relaying and routing information, allowing for efficient communication between UEs without network assistance, and supporting various use cases such as V2X and IoT applications, with enhanced reliability through hybrid automatic repeat request (HARQ) and reduced latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing MAC-CE designs are used for sidelink communications, then basic communication functionality is maintained, but communication reliability and latency performance are insufficient

Engineering Contradiction:
Improvesidelink communication reliabilityVSAvoidMAC-CE structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The MAC-CE is divided into multiple sub-CEs (first sub-CE, second sub-CE, third sub-CE) with distinct functions. The first sub-CE contains routing information, the second sub-CE contains relaying information, and the third sub-CE contains other control information. This segmentation allows each component to be optimized independently for its specific function, improving overall reliability without creating a monolithic complex structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a scheduling entity as an intermediary that generates and manages the MAC-CE structure. The scheduling entity determines which sub-CEs need to be included based on communication requirements, and manages the timing and transmission of these sub-CEs. This intermediary coordination ensures reliable communication while managing complexity through centralized control.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If network-assisted communication is used, then communication reliability is improved, but latency increases and network interference occurs

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidcommunication latency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent enables sidelink communications where UEs can directly exchange data without requiring continuous network assistance. The MAC-CE structure includes specific fields for routing and relaying information that enable autonomous decision-making by receiving UEs about how to forward messages. This self-service capability reduces dependency on the network, thereby reducing latency while maintaining reliability through direct peer-to-peer communication.

Inventive Principle:
Principle #25Self-service

3Productivity

If MAC-CE includes comprehensive relaying and routing information, then communication efficiency is improved, but message processing complexity increases

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidmessage processing complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The MAC-CE is segmented into specialized sub-CEs where routing information, relaying information, and other control information are separated into distinct sections. This segmentation allows receiving UEs to process only the relevant sub-CEs based on their specific needs and communication scenario, rather than processing the entire message, thereby improving efficiency without proportionally increasing processing complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent allows flexible inclusion of sub-CEs based on actual communication requirements. Not all sub-CEs need to be present in every MAC-CE message - only the necessary ones are included. This partial action approach optimizes the balance between providing comprehensive routing/relaying information for efficiency and avoiding unnecessary processing complexity when full information is not required.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4055889B1Sidelink medium access control (MAC) control element (CE) designs
Publication Date: 2025.08.13 QUALCOMM INC
  • EP4055889B1 patent drawingFigure 1
  • EP4055889B1 patent drawingFigure 2
  • EP4055889B1 patent drawingFigure 3

AI summary

Certain aspects of the present disclosure provide techniques for conveying information via medium access control (MAC) control element (CEs). In some cases, the MAC-CEs may relate to sidelink communications between two user equipments (UEs). A first wireless node may send the first MAC-CE on at least one of a sidelink or a cellular link and provide providing routing information for the first MAC-CE. The routing information may indicate, for example, a source node, a destination node, or a transit route through one or more nodes. The routing information may also indicate whether traffic sent with the first MAC-CE is relayed traffic or traffic originating at the first node.