Dynamic Contention-Window OFDMA for IoT Access

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Solution Overview

Problem

Current IEEE 802.11ax contention mechanisms do not exploit the regular transmission behavior of low-power devices, leading to inefficient power usage and increased collision probabilities in wireless communications networks, particularly with the introduction of Internet-of-Things (IoT) devices, and the Restricted Access Window (RAW) mechanism is limited to time-domain allocations.

Innovation Solution

Implementing a method where communications devices randomly select a counter value from a smaller Contention-Window OFDMA (CWO) range when initiating access attempts within designated 'reward windows' and a larger range outside these intervals, allowing for optimized access to Resource Units (RUs) and reducing collisions by incentivizing timely access attempts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If devices use a fixed large Contention-Window OFDMA (CWO) range for all access attempts, then collision probability is reduced for random access, but power efficiency deteriorates for devices with regular transmission patterns

Engineering Contradiction:

Improvecollision probabilityVSAvoidpower efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The CWO range is made dynamic rather than fixed. The system adapts the CWO range based on the timing of access attempts relative to reward windows. Devices use a smaller first CWO range when accessing within reward windows and a larger second CWO range when accessing outside these windows, optimizing both collision probability and power efficiency for different transmission patterns.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameter CWO range based on the timing condition of the access attempt. By switching between a first CWO range (smaller) for reward window accesses and a second CWO range (larger) for other accesses, the system optimizes performance for devices with regular transmission patterns while maintaining reliability for random access.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If devices transmit at regular intervals to exploit predictable behavior, then power efficiency is improved, but collision probability increases during peak transmission times

Engineering Contradiction:

Improvepower efficiencyVSAvoidcollision probability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

Different CWO ranges are applied to different time periods. Reward windows have a smaller first CWO range to favor regular transmissions, while other periods have a larger second CWO range to accommodate random access. This local differentiation resolves the contradiction by providing optimized parameters for each time context.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system introduces periodic reward windows at regular intervals where devices with predictable transmission patterns can access the medium with advantageous parameters (smaller first CWO range). This periodic structure allows power-efficient regular transmissions to thrive during reward windows while maintaining overall network stability through the larger second CWO range during other periods.

Inventive Principle:

Principle #19Periodic action

3Productivity

If the Restricted Access Window (RAW) mechanism is used for time-domain allocations, then access efficiency is improved, but versatility deteriorates as it is limited to time-domain only

Engineering Contradiction:

Improveaccess efficiencyVSAvoidaccess allocation flexibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The reward window mechanism serves multiple functions: it provides time-domain allocation like RAW for improved access efficiency, but also introduces frequency-domain differentiation through distinct first and second CWO ranges. This multi-functionality allows the system to handle both regular and random transmission patterns effectively, enhancing versatility beyond traditional RAW.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system adds a new dimension to access allocation by introducing CWO range selection as an additional degree of freedom. Instead of only time-domain allocation (RAW), the system now has time-domain (reward windows vs. other periods) and parameter-domain (first CWO range vs. second CWO range) dimensions, creating a more versatile access control mechanism.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11039484B2Communications device, an access point and methods therein for accessing a resource unit

Publication Date: 2021.06.15 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A communications device and a method therein for accessing a Resource Unit (RU) are provided. The communications device and an Access Point (AP) are operating in a wireless communications network. When wanting to start an access attempt within a time interval, the communications device selects a counter value from a first range given by zero and a first Contention-Window OFDMA (CWO) value CWO1. Further, when wanting to start an access attempt outside the time interval, the communications device selects the counter value from a second range given by zero and a second CWO value CWO2, wherein the second CWO value CWO2 is larger than the first CWO value CWO1. The communications device performs a contention procedure using the selected counter value, wherein a Resource Unit (RU) is accessed in dependence of the performed contention procedure.