Simulation of ALOHA, S-ALOHA, and CSMA Protocols

This document presents MATLAB simulations for ALOHA, Slotted-ALOHA (S-ALOHA), and Carrier Sense Multiple Access (CSMA) protocols. These fundamental multiple access protocols are widely used in wireless communication systems for both Local Area Networks (LANs) and Wide Area Networks (WANs). The ALOHA protocol represents a basic random access method originally developed for the University of Hawaii's computer network system. In MATLAB implementation, this typically involves modeling packet transmission attempts with Poisson arrival processes and calculating collision probabilities when multiple nodes transmit simultaneously. Slotted-ALOHA (S-ALOHA) is an enhanced variant that reduces packet collisions by requiring transmissions to begin only at predefined time slots. The MATLAB simulation would implement discrete time slots and synchronize transmission attempts across all nodes, significantly improving throughput compared to pure ALOHA. CSMA protocols employ a "listen-before-talk" strategy where nodes check channel availability before transmitting. The MATLAB code would typically incorporate carrier sensing mechanisms, backoff algorithms for collision avoidance, and different persistence methods (like 1-persistent or non-persistent CSMA). MATLAB serves as an excellent platform for these simulations due to its powerful mathematical computing capabilities and visualization tools. Through MATLAB-based protocol simulations, researchers can analyze key performance metrics such as throughput efficiency, delay characteristics, and collision rates under various traffic conditions. This provides valuable insights for protocol optimization and forms the foundation for developing improved network communication strategies.