Question

A pure ALOHA network transmits 200-bit frames on a shared channel of 200 kbps. What is the throughput if the system (all stations together) produces 500 frames per second?

(a) 146 frames

(b) 92 frames

(c) 38 frames

(d) 156 frames

The question was posed to me in an internship interview.

Query is from Layers in portion Cryptography Overview, TCP/IP and Communication Networks of Cryptograph & Network Security

Answer 1

Correct option is (b) 92 frames

The explanation: If the system creates 500 frames per second, or 1/2 frames per millisecond.

Then G = 1/2.

S = G × e−2G  = 0.184 (18.4 percent)

This means that

Throughput = 500 × 0.184 = 92

Only 92 frames out of 500 will probably survive

This is the maximum throughput case, percentage-wise.