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 250 frames per second?

(a) 38 frames

(b) 48 frames

(c) 96 frames

(d) 126 frames

This question was addressed to me in examination.

My doubt stems from Layers in chapter Cryptography Overview, TCP/IP and Communication Networks of Cryptograph & Network Security

Answer 1

Correct choice is (a) 38 frames

For explanation I would say: If the system creates 250 frames per second, or 1/4 frames per millisecond, then G = ¼.

S = G  × e−2G = 0.152 (15.2 percent).

This means that

Throughput = 250 × 0.152 = 38.

Only 38 frames out of 250 will probably survive.