Aloha
and Network Stability
It is known through theoretical
analysis of the Slotted ALOHA
protocol that the maximum achievable
throughput is or about 0.368
for a Poisson distributed network
with uniform traffic. However,
it has been shown in numerous
papers that excess capacity
exists in a slotted ALOHA network
when there is one large user
and several small users.
Figure 1 shows that the network
achieves stability at a channel
speed of 900 Mb/sec (in fact
it is something less than 900
Mb/sec for burst=1) which equates
to a utilization greater than
.40. This is excess capacity
due to the disparity in station
traffic (i.e. three large users
and three small users). The
results above are for a burst
factor of 1. Higher burst factors
require slightly higher channel
speeds for stability so we will
begin our simulation execution
at 1000 Mb/sec.
Figure 1 looks at the network
as a whole rather than individual
stations because of the contentive
nature of the protocol which
gives all stations equal access
to the channel and thus equal
service potential.
Figure 1: Slotted ALOHA stability
minimum. Service meets generation
at 900 Mb/sec f burst=1.
Figure 2 shows that the network
achieves stability at a channel
speed of 400 Mb/sec.
Figure 2: Reservation ALOHA
stability minimum. Service meets
generation at 400 Mb/sec.
Slotted
Aloha
Pure Aloha
Aloha
and Network Stability
Aloha
Simulation & Reservation
Aloha Protocol
Slotted
ALOHA Simulation Parameters
ALOHA
PROTOCOL IN C - LANGUAGE
