Tech – AVOIDING COLLISIONS

ADDING DETERMINISM TO A NETWORK

07 May 2020

Authors
Xavier Bush
Jesper Lindström
Prof. James Gross
Dr. Mathias Bohge

5 minute read

In our previous post, we dug into wireless propagation effects like shadowing and fading, the challenge they pose to industrial wireless networks and how EchoRing delivers an effective solution. That said, another challenge remains, one that’s inherent to numerous devices being present within a single wireless network: collisions. In this post, we’ll explain what collisions are, how they affect wireless communications and finally present an effective countermeasure that preserves real-time wireless performance.

A worker (transmitter), an assembly robot (receiver) and a passing autonomous forklift (collider)

Collisions – The Effect of Simultaneous Transmissions

The easiest analogy to understand collisions is to imagine an interruption during a conversation. Whenever more than one person speaks at the same time, the listener often has trouble understanding what’s being said. In wireless communications the same principle applies; whenever two nodes in a network transmit at once, collisions (i.e. signals on the same frequency interrupting each other) often occur. In these cases, the receiving antenna experiences an entirely different signal than intended – a mashup of the two or more signals that were sent.

The Receiving node experiences a mixed signal from the Transmitting node and the Colliding node

By this point another important term in wireless communications may have come to mind: interference. The effect a receiving node experiences during a collision is identical in function to interference, therefore collisions can be defined as type of self-interference. However, interference is distinct enough that it will be covered on its own in a later post. This is because a) unlike collisions, interference is caused by nodes in other networks, or even by non-wireless technologies on the same frequency band, and b) different techniques employed to counter interference.

To learn about the impact of collisions and why standard wireless solutions are insufficient for an industrial setup, please download the free PDF.

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