CDMA

Hampton Moore - 2024-02-22 - an interactive example of CDMA modulation

CDMA Interactive Demo

Senders: 2
First the desired sender count must be chosen so that sender codes can be calculated.

Walsh Table

A Walsh matrix is used to generate orthogonal codes

Per Sender Code

Each sender's orthogonal is taken from the relevant row on the Walsh table

Encoded Message

Each sender can send one trit (-1, 0, 1) at a time. The first input corresponds to sender 0's data point, the second one is sender 1, etc

Per Sender Transmission

The sender's data (input i) multiplied by the senders code

Received Transmission

This is the sum of the transmissions, as the waves from each sender constructively and destructively collide

Decoded Transmission

By multiplying the received transmission by the sender's code, the original data can be recovered

Why

Recently, in my wireless networking class we were covering CDMA, and I found it difficult to understand how the encoding and decoding process worked. I made this interactive example to help me understand it better. I felt that having something interactive could have better helped me understand the concept, and I hope it helps you too.

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