ARQpalautusmenetelmät

ARQpalautusmenetelmät, which translates to ARQ recovery methods or ARQ retransmission methods in English, refers to a set of techniques used in computer networking to ensure reliable data transmission. ARQ stands for Automatic Repeat reQuest. These methods are crucial for detecting and correcting errors that can occur during the transmission of data packets over unreliable communication channels.

The fundamental principle behind ARQ is that the receiver acknowledges the receipt of correctly received packets. If the sender does not receive an acknowledgment within a certain time frame, it assumes the packet was lost or corrupted and retransmits it. Different ARQ methods vary in how they manage acknowledgments and retransmissions.

Stop-and-wait ARQ is a simple method where the sender transmits one packet and then waits for an acknowledgment before sending the next. This is reliable but can be inefficient due to the waiting time. Go-back-N ARQ allows the sender to transmit multiple packets without waiting for individual acknowledgments. If an error is detected, the receiver requests the sender to retransmit all packets starting from the erroneous one. Selective repeat ARQ is a more efficient variation. It allows the sender to transmit multiple packets and the receiver acknowledges each correctly received packet individually. If an error occurs, only the erroneous packet is retransmitted.

These methods are essential components of many communication protocols, including TCP (Transmission Control Protocol), to guarantee the delivery of data in the correct order and without errors. The choice of ARQ method often depends on the desired balance between reliability, efficiency, and complexity for a given network environment.