Wireless Mirror Device Mitigating Multipath Interference in IIoT Networks
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Solution Overview
Problem
IEEE 802.11 based wireless networks in Industrial Internet of Things (IIoT) deployments face reliability issues due to multipath interference, which cancels out line-of-sight signals and renders transmissions undetectable, especially in resource-constrained devices with limited transmit power and receiver gain.
Innovation Solution
Deployment of wireless mirror devices that detect link layer transmissions between access points and client devices on a first frequency channel and retransmit them on a second allocated frequency channel, providing time diversity, frequency diversity, and spatial diversity to mitigate multipath interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If IEEE 802.11 based wireless networks are deployed in IIoT environments, then wireless coverage cost and service provider independence are improved, but transmission reliability deteriorates due to multipath interference
Solution Approach 1:
A wireless mirror device is introduced as an intermediary component that receives transmissions from the access point and retransmits them to client devices. This mirror device acts as a mediator to provide alternative signal paths, thereby mitigating multipath interference while maintaining the benefits of IEEE 802.11 wireless networks.
Solution Approach 2:
The patent introduces frequency diversity by having the wireless mirror device transmit on a different frequency channel than the original access point. This adds a frequency dimension to the transmission, allowing receivers to select signals from multiple frequency paths and avoid multipath interference on any single frequency.
2Use of energy by moving object
If resource-constrained IIoT devices are used, then device cost and power consumption are reduced, but transmission detectability deteriorates due to limited transmit power and receiver gain
Solution Approach 1:
The wireless mirror device combines signals from multiple transmit sources (access point and mirror device) to provide composite signal coverage. This merging of transmission paths increases signal detectability for resource-constrained devices without requiring them to increase their own transmit power.
Solution Approach 2:
The mirror device creates a copy of the original transmission and retransmits it on a different frequency channel. This copied signal provides an alternative detection path for receivers, improving transmission detectability without requiring the original resource-constrained devices to transmit at higher powers.
3Device complexity
If single-frequency transmission is used, then device complexity is reduced, but transmission reliability deteriorates due to multipath interference on the same frequency
Solution Approach 1:
The patent introduces frequency diversity by allocating different frequency channels to the access point and wireless mirror device. This adds a frequency dimension to the transmission system, allowing receivers to exploit frequency selectivity to avoid multipath interference while keeping individual device complexities low.
Data Source
AI summary
In one embodiment, a method comprises: detecting, by a wireless mirror device in a wireless data network, link layer transmission of a wireless data unit between a wireless access point (AP) device and a wireless client device on a first allocated frequency channel at a first transmission interval; and transmitting, by the wireless mirror device based on detecting the link layer transmission, the wireless data unit at a second transmission interval on a second allocated frequency channel that is allocated to the wireless mirror device for a mirror transmission between the wireless AP device and the wireless client device at the second transmission interval.