totallex.blogg.se - Download pure aloha program in c

Probability of successful transmission of data packet Vulnerable time in which collision may occur The time is discrete and globally synchronized. The time is continuous and not globally synchronized. The maximum efficiency of Slotted Aloha is high due to less number of collisions.ĭifference Between Pure Aloha And Slotted Aloha-Īny station can transmit the data at any time.Īny station can transmit the data at the beginning of any time slot. Maximum Efficiency of Slotted Aloha (η) = 36.8%

Substituting G = 1 in the above expression, we get.

Where G = Number of stations willing to transmit data at the beginning of the same time slot

A collision may occur if two or more stations try to transmit data at the beginning of the same time slot.Įfficiency of Slotted Aloha (η) = G x e -G.

If the beginning of the slot is missed, then station has to wait until the beginning of the next time slot.

The only condition is that station must start its transmission from the beginning of the time slot.

Any station can transmit its data in any time slot.

Slotted Aloha divides the time of shared channel into discrete intervals called as time slots.

The maximum efficiency of Pure Aloha is very less due to large number of collisions. Maximum Efficiency of Pure Aloha (η) = 18.4%

Substituting G = 1/2 in the above expression, we get.

Where G = Number of stations willing to transmit data

It keeps trying until the back off limit is reached after which it aborts the transmission.

After back off time, it transmits the data packet again.

Transmitting station uses a Back Off Strategy and waits for some random amount of time.

In this case, transmitting station assumes that the transmission is unsuccessful.

Transmitting station does not receive any acknowledgement within specified time from the receiving station.

In this case, transmitting station assumes that the transmission is successful.

Transmitting station receives an acknowledgement from the receiving station.

After transmitting the data packet, station waits for some time.

It allows the stations to transmit data at any time whenever they want.

There are two different versions of Aloha.