Quiz 4 Flashcards
(40 cards)
What is the purpose of multiple access protocols?
To coordinate transmissions in shared media and avoid collisions.
What is multiplexing in networking?
Sharing a communication link among multiple users.
What does TDM stand for?
Time Division Multiplexing.
How does TDM work?
Divides time into slots, assigns each to a user.
What are pros of TDM?
Guaranteed bandwidth, no collisions, predictable performance.
What are cons of TDM?
Inefficient with unused slots, requires time synchronization.
What does FDM stand for?
Frequency Division Multiplexing.
How does FDM work?
Divides frequency band into channels assigned to users.
What are pros of FDM?
Continuous access, no timing sync, simple implementation.
What are cons of FDM?
Guard bands needed, inefficient with unused allocation.
How are TDM and FDM similar?
Both are static allocation schemes.
How are TDM and FDM different?
TDM slices time, FDM slices frequency.
What are the two types of access control?
Centralized and distributed.
What is centralized access control?
A scheduler picks who transmits and when.
What are pros of centralized control?
Fair, efficient, no collisions.
What are cons of centralized control?
Setup needed, single point of failure, overhead.
What is distributed access control?
Devices manage access themselves.
What are pros of distributed control?
Simple setup, no central failure point, good under low load.
What are cons of distributed control?
Scaling is hard, collisions can happen, bad under high load.
How does ALOHA work?
Transmit immediately; retry after collision with random delay.
What’s the difference between Pure and Slotted ALOHA?
Pure sends anytime, Slotted sends at time slot starts.
What’s the max efficiency of Pure ALOHA?
0.18
What’s the max efficiency of Slotted ALOHA?
0.37
What is CSMA?
Carrier Sense Multiple Access — listen before you send.
