D2D Channel Access Counters for Priority-Based Collision Control

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Distributed channel access mechanisms in device-to-device (D2D) communications lead to unavoidable collisions and high resource overhead, particularly in high channel load environments, affecting the efficiency and reliability of wireless communication.

Innovation Solution

Implementing a channel access counter (CAC) mechanism that determines channel access priority based on packet priority and window size, adjusting the CAC value to reduce collision probability while minimizing resource overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If distributed channel access mechanisms are used in D2D communications, then devices can autonomously access channels without centralized control, but collision probability increases and resource overhead becomes high

Engineering Contradiction:
Improveautonomous channel accessVSAvoidcollision probability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the parameter of channel access by introducing a counter mechanism that tracks access attempts and modifies transmission behavior based on collision detection. The counter value is adjusted dynamically - incremented on collision, decremented on successful transmission - thereby adapting the access strategy to current channel conditions and reducing overall collision probability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by having devices monitor channel access outcomes (successful transmission or collision) and use this information to adjust their future access behavior through the counter mechanism. When a collision is detected, the counter is incremented, which triggers a backoff period before the next access attempt, thereby reducing future collision probability based on past experience.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If distributed channel access mechanisms are used in D2D communications, then devices can autonomously access channels without centralized control, but resource overhead becomes high

Engineering Contradiction:
Improveautonomous channel accessVSAvoidresource overhead
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The patent applies partial action by having devices perform channel access only when necessary, using the counter to limit the number of retry attempts. Instead of continuously attempting access, devices pause for backoff periods determined by the counter value, thereby reducing overall resource consumption while maintaining autonomous access capability.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent introduces periodic action through the backoff mechanism, where devices alternate between transmission attempts and waiting periods. The counter controls the duration of these periodic intervals, creating a rhythm of access attempts separated by calculated wait times, which reduces resource overhead compared to continuous access attempts.

Inventive Principle:
Principle #19Periodic action

3Reliability

If channel access counter mechanism is implemented to reduce collision probability, then transmission reliability improves, but device complexity increases

Engineering Contradiction:
Improvetransmission reliabilityVSAvoidchannel access control complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the channel access control into distinct functional components: a counter for tracking access attempts, a collision detection mechanism, and a backoff control logic. This segmentation allows each component to perform its specific function independently, making the overall system more manageable and easier to implement despite the increased complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies self-service by having the device automatically manage its own channel access through the counter mechanism without requiring external control. The device independently detects collisions, adjusts the counter value, and determines backoff periods, thereby improving transmission reliability while the complexity is contained within a self-managing autonomous system rather than requiring complex external coordination.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3874889B1Congestion control and priority handling in device-to-device (D2D) communications
Publication Date: 2025.07.30 QUALCOMM INC
  • EP3874889B1 patent drawingFigure 1
  • EP3874889B1 patent drawingFigure 2
  • EP3874889B1 patent drawingFigure 3

AI summary

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first wireless communication device may iterate a value of a channel access counter (CAC) to a trigger value based at least in part on configuring the value of the CAC. In some aspects, the first wireless communication device may utilize a channel access mechanism to select a set of time-frequency resources for a transmission of a packet based at least in part on iterating the value of the CAC to the trigger value. In some aspects, the first wireless communication device may transmit the packet to a second wireless communication device via the set of time-frequency resources based at least in part on utilizing the channel access mechanism to select the set of time-frequency resources for the transmission. Numerous other aspects are provided.