BLE Advertiser Randomized Listening for Collision Avoidance

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Solution Overview

Problem

Bluetooth Low Energy (BLE) communication systems face challenges in managing multiple devices communicating with a single advertiser, leading to message collisions and vulnerability to denial-of-service attacks due to the lack of collision avoidance mechanisms and immediate response processing.

Innovation Solution

Implementing a randomized listening time period for response messages, allowing advertisers to buffer multiple requests and reducing the risk of collisions, while also making it difficult for malicious nodes to disrupt communication by introducing a random offset in response timing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If multiple active scanners send scan requests immediately after receiving an advertisement, then communication speed is improved, but message collisions increase and reliability deteriorates

Engineering Contradiction:

Improvecommunication speedVSAvoidmessage transmission reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies preliminary action by having the advertising device prepare a randomization factor before receiving scan requests. This pre-computed randomization is then used to stagger the transmission timing of multiple scan requests, preventing collisions while maintaining efficient communication. The advertising device buffers requests and transmits them at calculated intervals based on the randomization factor.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by making the scan request transmission timing adaptive rather than fixed. The randomization factor dynamically adjusts the transmission intervals based on current network conditions and device identifiers. This dynamic timing mechanism allows the system to optimize between communication speed and collision avoidance in real-time.

Inventive Principle:

Principle #15Dynamics

2Loss of time

If the advertising device processes scan requests immediately, then response time is reduced, but vulnerability to denial-of-service attacks increases

Engineering Contradiction:

Improveresponse timeVSAvoiddenial-of-service attack vulnerability

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-computing a randomization factor based on the advertising device's identifier before processing scan requests. This pre-prepared randomization mechanism then systematically spaces out request processing and response transmissions, preventing malicious devices from overwhelming the advertising device with simultaneous requests while maintaining acceptable response times.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by using the randomization factor to dynamically adjust response timing based on the sequence and source of incoming scan requests. The system monitors request patterns and uses feedback from the randomization mechanism to modulate response timing, thereby detecting and mitigating denial-of-service attack patterns while maintaining legitimate communication.

Inventive Principle:

Principle #23Feedback

3Device complexity

If scan requests are transmitted at fixed intervals, then device complexity is reduced, but collision avoidance capability deteriorates

Engineering Contradiction:

Improvetiming control complexityVSAvoidcollision avoidance capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies parameter changes by transforming the fixed interval timing parameter into a variable timing parameter based on a randomization factor. This factor changes the transmission intervals dynamically based on device identifiers and request sequences. The system maintains manageable complexity by using a simple randomization algorithm rather than complex adaptive scheduling, yet achieves superior collision avoidance.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10779149B2Methods and arrangements for communication between advertising and advertisement responding wireless devices

Publication Date: 2020.09.15 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

An advertising wireless device (110) broadcasts (202; 802) an advertising message over a wireless communication link (115). The advertising wireless device receives (203a; 803), from an advertisement responding device (120-1), a request message that was sent by the advertisement responding device (120-1) at a certain point in time in response to the broadcasted advertising message. Said certain point in time being randomized within a listening time period during which the advertising wireless device (110) listens for a response to the broadcasted advertising message and is able to receive the request message.