Wireless Terminal Channel Access Inactivity Detection

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Solution Overview

Problem

In wireless communication systems using shared communication channels, especially in IoT and M2M applications, the probability of terminals waiting for the channel to be free increases with the number of terminals, leading to inefficient use due to the 'Listen Before Talk' constraint, where terminals spend significant time waiting and simultaneous transmissions are hindered by propagation delays.

Innovation Solution

A method where terminals listen continuously until they detect an absence of activity for a predetermined 'duration of inactivity' and then wait for an identical 'waiting time' before transmitting, allowing for simultaneous transmissions without interference by multiplexing in frequency or spreading codes, thus optimizing channel usage and reducing waiting times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If terminals listen continuously until detecting an absence of activity for a predetermined duration before transmitting, then channel access reliability is improved, but transmission delay increases

Engineering Contradiction:

Improvechannel access reliabilityVSAvoidtransmission delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The terminal performs preliminary actions by detecting the end of channel activity and starting to count the inactivity duration ΔTin before the actual transmission is needed. This preliminary counting process allows the terminal to be ready to transmit immediately when the inactivity period is satisfied, reducing the overall transmission delay while maintaining reliable channel access.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If a large number of terminals share the same communication channel, then system capacity is improved, but channel access difficulty increases

Engineering Contradiction:

Improvenumber of terminalsVSAvoidchannel access difficulty

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

All terminals apply the same channel access rules: they listen for activity, detect its end, and count the same predetermined inactivity duration ΔTin before transmitting. This equipotential approach ensures that regardless of the number of terminals, each terminal has an equal opportunity to access the channel based on the same criteria, preventing any single terminal from having unfair advantage or disadvantage.

Inventive Principle:

Principle #12Equipotentiality

Solution Approach 2:

Each terminal independently monitors the channel activity and autonomously determines when to transmit based on the detected inactivity period. The terminals self-regulate their transmission timing without requiring complex coordination or arbitration mechanisms, allowing a large number of terminals to share the channel efficiently while maintaining ease of access for each individual terminal.

Inventive Principle:

Principle #25Self-service

3Use of energy by moving object

If terminals interrupt listening when activity is detected and retry later, then energy consumption is reduced, but channel utilization efficiency decreases

Engineering Contradiction:

Improveterminal energy consumptionVSAvoidchannel utilization efficiency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The terminal maintains continuous listening action until the inactivity duration ΔTin is detected, rather than interrupting and retrying later. This continuous monitoring ensures that the terminal captures the exact moment when the channel becomes available, maximizing channel utilization efficiency. The energy consumption is optimized by only requiring continuous listening up to the point of channel availability detection.

Inventive Principle:

Principle #20Continuity of useful action

4Speed

If terminals transmit immediately after detecting inactivity, then transmission speed is improved, but interference from propagation delays increases

Engineering Contradiction:

Improvetransmission speedVSAvoidinterference from propagation delays

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system applies preliminary anti-action by introducing a waiting period equal to the maximum propagation delay time after detecting the inactivity duration ΔTin. This waiting period prevents transmission interference caused by propagation delays, as all terminals wait long enough for their transmissions to propagate through the network before actually transmitting, thereby eliminating conflicts while maintaining efficient channel utilization.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentEP3398394B1Method of sending a message after listening to a communication channel shared by terminals

Publication Date: 2020.02.19 SIGFOX

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Figure 5a~5g

AI summary

The present invention relates to a method (50) of sending, by a terminal (20) of a wireless communication system (10), a message on a communication channel shared with other terminals (20), said method (50) comprising: - before sending said message: a step (51) of listening without interruption to the communication channel by said terminal (20) until it detects an absence of activity on the communication channel for a predetermined time, termed the "inactivity time ∆Tin", - when no activity is detected on said communication channel for the inactivity time ∆Tin: a step (54) of waiting, for a predetermined time which is identical for all the terminals (20) of the wireless communication system (10), termed the "waiting time ∆Tat", - a step (52) of sending said message on the communication channel.