🛰️ CDMA Protocol Visualizer

A dynamic, interactive web application that demonstrates Code Division Multiple Access (CDMA) communication protocol using Walsh-Hadamard codes. This educational tool helps visualize how multiple stations can simultaneously transmit data over the same frequency band.

🌟 Features

• Dynamic Station Management: Add/remove stations dynamically
• Real-time Visualization: See encoding, combining, and decoding processes
• Interactive UI: Modern, responsive design with animations
• Educational Focus: Clear visualization of CDMA concepts
• Walsh Code Generation: Automatic generation of orthogonal Walsh-Hadamard codes
• Error Handling: Input validation and error reporting

🚀 Getting Started

Prerequisites

• Node.js (v14 or higher)
• npm (Node Package Manager)

Installation

1. Clone or create the project structure:

mkdir cdma-simulation
cd cdma-simulation

2. Set up the file structure:

cdma-simulation/
│
├── public/
│   └── index.html         ← Frontend UI
│
├── cdma.js                ← CDMA logic implementation
├── server.js              ← Express server
├── package.json           ← Dependencies
└── README.md              ← This file

3. Install dependencies:

npm install

4. Start the server:

npm start

5. Open your browser and navigate to:

http://localhost:3000

🎯 How to Use

1. Add Stations: Click "➕ Add Station" to add communication stations
2. Enter Data: Input binary data (0s and 1s) for each station
3. Simulate: Click "▶️ Simulate CDMA" to run the simulation
4. Observe Results: Watch the encoding, combining, and decoding process

Example Input

• Station 1: 1010
• Station 2: 1100
• Station 3: 0011

🔬 CDMA Process Explained

1. Encoding Phase

• Each station's data bits are spread using unique Walsh codes
• Binary 0 becomes -1, binary 1 remains 1 (BPSK modulation)
• Each bit is multiplied by the station's Walsh code sequence

2. Channel Combining

• All encoded signals are added together
• Simulates multiple stations transmitting simultaneously
• Creates interference that needs to be resolved

3. Decoding Phase

• Combined signal is correlated with each station's Walsh code
• Positive correlation indicates bit 1, negative indicates bit 0
• Orthogonal codes allow perfect separation (in ideal conditions)

🧮 Walsh-Hadamard Codes

Walsh codes are orthogonal binary sequences that enable multiple access:

Example 4x4 Walsh Matrix:

Code 1: [ 1,  1,  1,  1]
Code 2: [ 1, -1,  1, -1]
Code 3: [ 1,  1, -1, -1]
Code 4: [ 1, -1, -1,  1]