What is interference?

Interference is a phenomenon in which signals interfere with one another, which distorts the information being transmitted.

Put simply: interference is noise that happens when one signal "overlaps" another.

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#How interference occurs

Interference arises when:

• several signals are transmitted over one medium
• there are sources of interference nearby
• the signals have similar frequencies

As a result:

• a 0 may be received as a 1
• a 1 may be received as a 0
• the signal becomes "noisy"

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#Examples of interference

#In wired networks

• neighboring cables affect one another
• poor shielding
• a long cable: the signal weakens and gets distorted

Example:

an Ethernet cable runs next to a power cable

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#In wireless networks

• several Wi-Fi networks on the same frequency
• a microwave oven, Bluetooth, radio devices
• signal reflections from walls and objects

Example:

in an apartment with 10 Wi-Fi networks, speed drops

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#Why interference is a problem

Because of interference:

• the number of errors increases
• transmission speed drops
• connection drops are possible

The physical layer deals with interference directly, because it works with the real signal.

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#How it is countered (briefly)

At the physical layer:

• shielding cables
• twisting the twisted pair
• choosing a different frequency
• amplifying and filtering the signal

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#Simple analogy

A conversation in a noisy room:

• what you say is the useful signal
• the noise around you is the interference
• the other person hears worse and asks you to repeat

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#Briefly, for the interview

Interference is the mutual effect of signals or noise on one another, which distorts the transmitted signal and causes errors during data transmission.