Question

***Please type the answers to the following questions in typing, not handwriting.

1- Comparing pure ALOHA and slotted ALOHA, which one can lead to a shorter delay when the traffic load is very small? Why?

4- The simple bit-map protocol is a contention Alec MAC protocol. Based on the simple bit-map protocol, you are asked to design s limited contention protocol. (Just explain the main idea. At least show that scheduling still exists based on the bit-map protocol, and collision also exists).

6- Assume the minimum data transmitted in an 802.11 frame is 1 byte (it can be 0 bytes in practice), and the maximum data is 2312 bye, calculate the overhead of an 802.11 frame (the ratio of useless data to the upper layer).

Answer 1

Solution:

Note: The first question is done as per Chegg guidelines, please repost others.

1)

The difference between pure ALOHA and slotted ALOHA is given below:

Pure ALOHA	Slotted ALOHA
The user can transmit the data whenever the user wants	The data can be transmitted by the user whenever the slot is started until then the user has to wait.
The time is continuous here.	The time is discrete here.
The probability of successful transmission of the data frame is: S= G* e^-2G	The probability of successful transmission of the data frame is: S= G*e^-G
Maximum throughput here is 18%	Here maximum throughput is 37%

When the traffic load is very small, pure ALOHA will offer shorter delay, because of the less traffic there will be fewer collisions and pure ALOHA doesn't wait to transmit the data which eventually will turning in shorter delay.

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