Slotted Aloha: Another probability question

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In summary, Slotted Aloha is a random access protocol in computer networks that divides a single channel into discrete time slots for multiple users to share. Each user is assigned a time slot to transmit data and if there is a collision, the data is lost and must be retransmitted. The main advantage of Slotted Aloha is a reduced chance of collisions, leading to a more efficient use of the communication channel. However, it is not commonly used in modern networks due to its simplicity and lack of adaptability to varying network conditions. It is also not suitable for high traffic networks and does not prioritize certain types of data.
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zak100
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Homework Statement
Suppose four active nodes – nodes A, B, C and D – are competing for access to a channel using slotted ALOHA. Assume each node ha an infinite number of packets to send. Each node attempts to transmit in each slot with probability p. The first slot is numbered slot 1, the second slot is numbered slot 2, and so. What is the probability that node A succeeds for the first time in slot 5?
What is the probability that some node (either A, B, C or D) succeeds in slot 3?
Relevant Equations
Probability equation of failure
Hi,
probability that one node succeeds = p
probability that one node does not succeed = (1-p)
probability that 3 nodes do not succeed = (1-p) ^3
Total probability = probability that one node succeeds * probability that 3 nodes do not succeed

Total probability = p(1-p)^3

Is it correct?

Zulfi.
 
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  • #2
Hi,
p(A succeeds in slot 3) = p(1-p) ^3
p(B succeeds in slot 3) = p(1-p) ^3
p(C succeeds in slot 3) = p(1-p) ^3
p(D succeeds in slot 3) = p(1-p) ^3
= 4p(1-p)^3

Same answer for slot 4?

Please tell me which answer is correct, this one or the previous one?
What about 4 sots?
Zulfi.
 

FAQ: Slotted Aloha: Another probability question

What is Slotted Aloha?

Slotted Aloha is a random access protocol used in computer networks to control the flow of data between multiple users sharing a single communication channel. It was one of the first protocols developed for early Ethernet networks.

How does Slotted Aloha work?

In Slotted Aloha, the communication channel is divided into discrete time slots. Each user waits for an empty slot to transmit data. If two users attempt to transmit data in the same slot, a collision occurs and the data is lost. The users then wait for a random time period before attempting to transmit again.

What is the advantage of using Slotted Aloha?

The main advantage of Slotted Aloha is its simplicity and efficiency in sharing a communication channel among multiple users. It also allows for a high throughput of data transmission, especially when the channel is not heavily loaded.

What is the probability of successful transmission in Slotted Aloha?

The probability of successful transmission in Slotted Aloha is approximately 36.8%. This means that only about 1 out of 3 attempted transmissions will be successful, assuming a large number of users and a random distribution of data transmission attempts.

How is Slotted Aloha different from Pure Aloha?

Slotted Aloha differs from Pure Aloha in that it divides the communication channel into discrete time slots, whereas Pure Aloha allows for continuous transmission. This makes Slotted Aloha more efficient and reduces the likelihood of collisions, resulting in a higher probability of successful transmission.

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