In multiple-access networks, what term describes the event that occurs when two stations transmit over the medium at the same time?

Introduction / Context: Medium access control (MAC) protocols govern how multiple stations share a common medium. Understanding the terms for access methods and failure conditions is essential for analyzing throughput and reliability.

Given Data / Assumptions:

• Two stations transmit at the same time on a shared medium.
• The network uses a contention-based MAC (e.g., CSMA/CD/CA) or similar.
• We are naming the event that results.

Concept / Approach: A simultaneous transmission produces a signal overlap called a collision. Contention is the process of competing for the medium; collision is the unwanted outcome when competition fails to avoid overlap.

Step-by-Step Solution: Identify timing overlap of two transmissions.Recognize the MAC-layer term for this event: collision.Distinguish from contention (access method) and timing disciplines (synchronous/asynchronous).

Verification / Alternative check: Ethernet CSMA/CD explicitly detects and resolves collisions; Wi-Fi CSMA/CA aims to avoid them but they can still occur.

Why Other Options Are Wrong: Contention: Describes the access strategy, not the overlap event.

Synchronous/Asynchronous: Timing schemes, not the event of overlap.

Deterministic access: Token/time-slot methods designed to prevent collisions.

Common Pitfalls: Using “contention” and “collision” interchangeably; they are related but distinct.

Final Answer: Collision