ARQVarianten

ARQVarianten is a term used to describe different versions or implementations of the Automatic Repeat reQuest (ARQ) error-control protocol. ARQ is a fundamental technique in digital communication networks for ensuring reliable data transmission over unreliable channels. It works by detecting corrupted or lost packets and requesting retransmission of those packets until they are received correctly.

The basic principle of ARQ involves a sender transmitting data blocks and a receiver acknowledging their successful reception. If the sender does not receive an acknowledgment within a certain time frame, it assumes the packet was lost or corrupted and retransmits it. There are several well-known variants of ARQ, each with its own strategies for managing acknowledgments, timeouts, and retransmissions, aiming to optimize throughput and efficiency.

Common ARQ variants include Stop-and-Wait ARQ, where the sender stops and waits for an acknowledgment after each packet transmission. This is simple but inefficient as it requires a separate transmission for every acknowledgment. Go-Back-N ARQ allows the sender to transmit multiple packets without waiting for individual acknowledgments. If an error is detected, the receiver discards all subsequent packets until the erroneous one is retransmitted, and the sender then retransmits from the point of the error. Selective Repeat ARQ is another variant where the receiver acknowledges correctly received packets individually, even if they are out of order. If an error occurs, only the erroneous packet needs to be retransmitted, making it more efficient than Go-Back-N in scenarios with high error rates.

The choice of ARQ variant often depends on factors such as the expected error rate of the communication channel, the required throughput, and the available buffer space at the sender and receiver. These variations allow protocols to adapt to different network conditions and application requirements for reliable data transfer.