Adaptive Transmit Power and Rate Control for Vehicular Networks

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Solution Overview

Problem

Vehicular ad hoc networks (VANETs) face challenges such as time-varying network topology, difficulty in connecting vehicles due to obstacles, limited power and rate resources, and channel congestion from periodic beacon messages, which affect communication efficiency and safety applications.

Innovation Solution

Each moving object independently adjusts its transmit power level and rate to achieve a target cooperative awareness ratio and maintain a channel load within a predefined interval, using adaptive power and rate control mechanisms that account for environment and application-specific requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If periodic beacon messages are transmitted to provide vehicle awareness, then cooperative awareness is improved, but channel congestion increases

Engineering Contradiction:

Improvecooperative awarenessVSAvoidchannel utilization

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The beacon transmission rate is made dynamic rather than fixed, allowing each vehicle to adapt its transmission frequency based on current channel conditions and awareness requirements. This resolves the contradiction by enabling the system to maintain necessary cooperative awareness while reducing channel congestion when conditions permit.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the transmission parameters (beacon rate, transmit power) based on channel load conditions. When channel utilization is high, beacon rates are reduced; when channel conditions are good, higher rates are permitted. This dynamic parameter adjustment resolves the trade-off between awareness and congestion.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If transmit power is increased to extend communication range, then vehicle connectivity is improved, but energy consumption increases

Engineering Contradiction:

Improvevehicle connectivityVSAvoidtransmit power

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Transmit power is adjusted dynamically based on channel conditions, vehicle density, and connectivity requirements. The system transitions from fixed high power to adaptive power levels, maintaining connectivity when needed while reducing energy consumption in favorable conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The power control mechanism uses feedback from channel quality indicators and connectivity status to adjust transmit power levels. This closed-loop control ensures connectivity is maintained only at the minimum necessary power level, resolving the contradiction between range and energy use.

Inventive Principle:

Principle #23Feedback

3Reliability

If beacon rate is increased to improve awareness, then cooperative awareness is improved, but channel load increases

Engineering Contradiction:

Improvecooperative awarenessVSAvoidchannel load

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The beacon rate transitions from a fixed periodic transmission to a dynamic rate that adapts to channel conditions and awareness needs. This allows the system to achieve necessary awareness levels while minimizing channel load through intelligent rate adjustment.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system transmits beacons at the minimum necessary rate to achieve target awareness levels rather than using excessive periodic transmissions. This partial action approach maintains safety requirements while reducing overall channel load.

Inventive Principle:

Principle #16Partial or excessive action

4Productivity

If centralized control is implemented to manage channel load, then channel utilization is improved, but system complexity increases

Engineering Contradiction:

Improvechannel utilizationVSAvoidcontrol infrastructure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Each vehicle independently controls its own transmission parameters based on locally observed channel conditions and awareness requirements. This distributed self-service approach eliminates the need for centralized control infrastructure while achieving efficient channel utilization through autonomous adaptation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The centralized control function is segmented and distributed to individual vehicles. Each vehicle performs local decision-making about its transmission behavior, transforming the system from centralized to distributed control and reducing infrastructure complexity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10440666B2Managing communication between a plurality of moving objects through control of transmit power and/or transmit rate

Publication Date: 2019.10.08 NEC CORP

AI summary

A method for managing communication between a plurality of moving objects, wherein one or more communication channels are used for the communication, wherein each moving object is operable to adjust a transmit power level for transmitting information via the one or more communication channels, and wherein each moving object is operable to adjust a transmit rate for sending information via the one or more communication channels, includes performing, for each of the plurality of moving objects: a) adjusting the transmit power level of each moving object independently of other moving objects such that a target cooperative awareness ratio is achieved, and b) adapting the transmit rate at each moving object independently such that a channel load of a respective communication channel is within a predefined load interval.