Network Speed is defined as the rate of data transfer across the medium, typically measured in Mbps. The objective here is to determine the minimum packet size required to successfully detect a collision.
The time required to transmit a frame is calculated by dividing the Packet Size by the Network Speed. To identify interference, a node must actively transmit data—and simultaneously monitor the channel—for a duration equal to twice the signal's propagation delay (the round-trip time).
Consequently, successful collision detection is directly dependent on the packet being sufficiently large to span this duration.
For a more detailed explanation, please refer to the following link: https://www.youtube.com/watch?v=Zftv3U5_fwI&t=244s