The Channel Allocation problem refers to the challenge of efficiently allocating a shared communication channel, such as a radio frequency or a time slot, among multiple users or devices to minimize interference and maximize the utilization of the channel. This problem is common in wireless communication systems and networks.
Pure ALOHA and Slotted ALOHA are two early multiple access protocols used to address the Channel Allocation problem:
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Pure ALOHA:
- In Pure ALOHA, devices transmit data frames whenever they have data to send, without any regard for the timing of other devices.
- Collisions can occur when two or more devices transmit simultaneously, leading to data frame corruption.
- Collided frames are typically detected through acknowledgments or by checking for collisions after transmission.
- After a collision, devices use random backoff times before attempting to retransmit their data.
- Pure ALOHA is inefficient because of its high collision rate, resulting in low channel utilization.
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Slotted ALOHA:
- Slotted ALOHA divides time into discrete slots, and devices are required to transmit data only at the beginning of a time slot.
- This synchronization reduces the chance of collisions because devices are less likely to overlap in their transmissions.
- Like Pure ALOHA, Slotted ALOHA also handles collisions by detecting them and initiating retransmissions.
- Slotted ALOHA is more efficient than Pure ALOHA in terms of channel utilization, but it still suffers from some inefficiencies, especially as the number of devices or the traffic load increases.
