Overlapping Priority Contention Windows Power Line Communications

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Solution Overview

Problem

In G3-PLC networks, the existing mechanism results in wasted network resources due to the High Priority Contention Window (HPCW) being maintained even when there are no high priority frames, leading to reduced throughput as normal priority frames must wait for the entire HPCW before transmitting, and collision avoidance is not effective with hidden nodes.

Innovation Solution

Introducing an overlapping Normal Priority Contention Window (NPCW) that can extend beyond the HPCW, allowing normal priority frames to access the channel sooner and increasing the window size for collision avoidance, thereby improving network throughput without compromising priority access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the High Priority Contention Window (HPCW) is maintained to ensure priority access for high priority frames, then high priority frames can access the channel preferentially, but normal priority frames must wait for the entire HPCW window, reducing network throughput

Engineering Contradiction:

Improvepriority access guaranteeVSAvoidnetwork throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The contention window is segmented into two distinct windows: HPCW for high priority frames and NPCW for normal priority frames. These windows operate independently and can overlap in time, allowing high priority frames to access the channel during HPCW while normal priority frames can access during NPCW without being blocked by HPCW waiting periods

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts the operation of contention windows based on traffic conditions. When there are no high priority frames, the NPCW can overlap with the HPCW time period, allowing normal priority traffic to utilize the channel without waiting. This dynamic behavior optimizes throughput while maintaining priority access when needed

Inventive Principle:

Principle #15Dynamics

2Reliability

If the HPCW window size is increased to provide more contention opportunities for high priority frames, then high priority frames have better access probability, but normal priority frames experience longer waiting times and reduced channel utilization

Engineering Contradiction:

Improvehigh priority frame access probabilityVSAvoidwaiting time for normal priority frames

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

By segmenting the contention mechanism into separate HPCW and NPCW windows, the system allows high priority frames to contend during HPCW while normal priority frames can contend during NPCW. This segmentation eliminates the forced waiting time for normal priority frames while maintaining adequate contention opportunities for high priority frames within their dedicated window

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The NPCW acts as an intermediary mechanism that mediates between high priority and normal priority traffic requirements. By introducing this separate contention window for normal priority frames, the system provides a dedicated access path that does not require waiting for HPCW to complete, thereby reducing waiting time while high priority frames maintain their access probability through HPCW

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the contention window size is reduced to decrease waiting time for normal priority frames, then network throughput improves, but collision avoidance capability is reduced especially with hidden nodes

Engineering Contradiction:

Improvenetwork throughputVSAvoidcollision avoidance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system segments collision avoidance into two separate mechanisms operating in parallel: HPCW for high priority frames and NPCW for normal priority frames. Each window can be optimized independently - NPCW can be sized to reduce waiting time and improve throughput, while HPCW maintains appropriate size for collision avoidance with high priority traffic

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the parameter of contention window size differently for different priority levels. NPCW size can be configured smaller to reduce waiting time and improve throughput for normal priority frames, while HPCW size can be configured larger to maintain collision avoidance capability for high priority frames. This parameter differentiation resolves the contradiction between throughput and collision avoidance

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9319238B2Overlapping priority contention windows power line communications networks

Publication Date: 2016.04.19 TEXAS INSTRUMENTS INC

AI summary

Embodiments of a power line communication (PLC) transmitter device for overlapping priority contention windows are presented. A processor is configured to perform a physical channel sense operation to detect an idle channel on a PLC network. A transmitter transmits a normal priority data packet on the channel during a high priority contention window. In another embodiment, a Normal Priority Contention Window (NPCW) is allowed to overlap with a High Priority Contention Window (HPCW). The minimum contention window for the normal priority frames (i.e., NPCW) is equal to or longer than the contention window for high priority frames (i.e., HPCW). By making the NPCW longer than the HPCW, the high priority frames will have a better chance than normal priority frames to get access to the channel on transmission reattempts.