Sub-channel Carrier Sensing for Low-power Wireless Transmission

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Solution Overview

Problem

Existing communication networks face inefficiencies in utilizing multiple sub-channels, as they either require scheduled access, blind transmission, or the ability to monitor all sub-channels simultaneously, which is not suitable for low-power devices that need to transmit unpredictably and conserve energy.

Innovation Solution

A method where a communications device performs carrier sensing on assigned sub-channels to determine vacancy, transmitting on available sub-channels and entering an inactive mode when none are available, reducing power consumption and enabling decentralized operation without coordination among devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a communication device monitors all sub-channels simultaneously to ensure efficient utilization, then the channel access efficiency is improved, but the power consumption increases and device complexity increases

Engineering Contradiction:

Improvechannel access efficiencyVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent divides the total bandwidth into multiple sub-channels and assigns each sub-channel a specific state (unknown, vacant, or occupied). Instead of monitoring all sub-channels simultaneously, the device only monitors sub-channels with unknown states, segmenting the monitoring task to reduce power consumption while maintaining efficient channel access.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic state transitions for sub-channels based on carrier sensing results. When a sub-channel is sensed as vacant, the device transitions from unknown to vacant state and begins transmission. When occupied, it transitions to occupied state and selects another sub-channel. This dynamic adaptation allows efficient channel utilization without continuous monitoring of all sub-channels.

Inventive Principle:

Principle #15Dynamics

2Reliability

If scheduled access is implemented for sub-channel utilization, then collision avoidance is improved, but the device complexity and coordination requirements increase

Engineering Contradiction:

Improvecollision avoidanceVSAvoidcoordination requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent enables each communication device to autonomously perform carrier sensing on sub-channels and make independent decisions about which sub-channel to use for transmission. Devices self-manage their channel access without requiring centralized scheduling or coordination with other devices, reducing system complexity while maintaining collision avoidance through the carrier sensing mechanism.

Inventive Principle:

Principle #25Self-service

3Use of energy by moving object

If carrier sensing is performed on multiple sub-channels sequentially, then the power consumption is reduced, but the channel access time increases

Engineering Contradiction:

Improvepower consumptionVSAvoidchannel access time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent performs preliminary carrier sensing on sub-channels in sequential order before committing to transmission. The device checks sub-channels one by one, and as soon as a vacant sub-channel is found, it immediately begins transmission. This preliminary sequential checking reduces power consumption compared to simultaneous monitoring, while the immediate transmission upon finding a vacant channel minimizes access time delay.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for efficient use of all available sub-channels without requiring simultaneous monitoring, reducing power consumption and enabling extended operation time for low-power devices, while ensuring fair radio resource usage and faster access to the communication medium.

Implementation Method 1

The first communications device performs carrier sensing on a first sub-channel assigned an unknown occupancy state to determine whether the first sub-channel is vacant or occupied

Methodology Applied

Scientific EffectCarrier sensing: Electromagnetic Induction

Data Source

PatentUS10440748B2First communications device and methods therein for transmitting data to a second communications device

Publication Date: 2019.10.08 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A first communications device 102 and a method therein for transmitting data to a second communications device 104 on a sub-channel. The first device performs carrier sensing on a first sub-channel assigned an unknown occupancy state. When the first sub-channel is determined as being vacant, the first device transmits, to the second device, the data on the first sub-channel. When the first sub-channel is determined as being occupied, the first device assigns the first sub-channel an occupied state, starts a first time period associated with the first sub-channel, and performs carrier sensing on a second sub-channel assigned with the unknown occupancy state. When the second sub-channel is determined as being vacant, the first device transmits, to the second device, the data on the second sub-channel. In absence of the second sub-channel assigned an unknown occupancy state, the first device enters an inactive mode until the first time period has expired.