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Compare slotted Aloha and Pure aloha

written 7.8 years ago by teamques10 ★ 68k

modified 2.7 years ago by sagarkolekar ★ 11k

computer networks

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written 7.8 years ago by teamques10 ★ 68k

Slotted ALOHA	Pure ALOHA
1.Slotted ALOHA requires the global time synchronization.	1.Pure ALOHA do not required global time synchronization.
2.Slotted ALOHA was invented to improve the efficiency of pure ALOHA.	2.The original ALOHA protocol is called pure ALOHA.
3.In Slotted ALOHA, station cannot send data in continuous time manner. It divides the time in slot.	3.In Pure ALOHA, station can send data in continuous time manner.
4.Slotted ALOHA requires slot synchronization.	4.A simple version pure ALOHA, does not require Slots.
5.Force the station to send only at the beginning of the time slot.	5.The idea is that each station sends a frame whenever it has a frame to send.
6.If multiple nodes transmit, node detect collision Slotted.	6.However, since there is only one channel to share, there is the possibility of collision between frames from different stations.
7.It do not allow the user whenever they have data.	7.It allow the user whenever they have data.
8.Vulnerable time for Slotted ALOHA is T.	8.If multiple nodes transmit, node detect collision Slotted.
9.In slotted ALOHA we divide the time into slots of Tfr.	9.Pure ALOHA has a vulnerable time of 2 x Tfr This is so because there is no rule that defines when the station can send.
10.The throughput for slotted ALOHA is S =: G x e-G.	10.Throughput is reduced by one half i.e. S = (1/2e).
11.The max throughput is 0.368 when G= 1.	11.The max throughput is 0.184 when G=1/2.
12.Throughput Efficiency is Double as compared to Pure ALOHA.	12.Throughput Efficiency is Half as compared to Slotted ALOHA.

Comparison diagram of ALOHA & Slotted ALOHA:

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