Simplifying Education (Multiplexing Methods)

Simplifying Education (Multiplexing Methods)

This evening, I was doing some research on multiplexing in communication networks and it evoked me a memory from my University,

In 2012, I was doing my Masters at the Middlesex University, London. We were having session about the different multiplexing methods like FDMA, TDMA, and CDMA.

My professor had explained the topics in a best theoretical way possible. While a few understood, but others were a bit puzzled.

Therefore, he decided to conduct a practical experiment. He asked everyone in the class to talk to the person sitting right next to them in non-native language (e.g English in our case). The whole class went berserk and started talking. Nobody could hear anything. My professor intervened and said he could fix this,

1. He selected 4 random people and asked them to occupy the adjacent rooms to continue their discussion however with a condition that only 2 people per room. They were given liberty to move anywhere in the room.

Discussion: ✅

Interference: No ❌, because of walls (guard bands)

Efficiency: 👎🏻 since the entire room was allocated causing resource (spectrum) wastage.

2. Now, he selected two groups (a group of 2) and asked them to occupy a particular place (cell) in the lecture hall to continue their discussion.

Discussion: ✅

Interference: No ❌, because of distance between two groups.

Efficiency: 👍🏻 since they were placed in the same room (frequency).

However, the catch is that he asked one of the groups (A) to move from their origin place to a place (e.g. cell) where the second group (B) is standing, but we had been told that these segregated places (cells) can’t hold more than two people at any given time, so the group A discussion had to be disconnected and would be resumed only when the Group B finish their discussion.

3. Now, to fix the above two issues, he requested us to repeat the very first exercise, but this time he asked us to talk to the person sitting next to us in a common language (native language/code). To everyone’s surprise, nobody had an issue hearing each other despite the entire class is talking because our communication is coded with native or common language

He concluded the session saying exercise 1 is FDMA, 2 is TDMA, and 3 is CDMA. He further added that marks will be given only if the explanation is similar to the one in the text book, and not if we write stories around these experiments 😆