Question 3-86N5

ARQ (Automatic Repeat reQuest) systems inherently require two-way communication. The receiving station sends acknowledgments for correctly received data and requests retransmission of corrupted data packets. This feedback loop necessitates a return path, making it a two-way process. FEC (Forward Error Correction) adds redundant information to the transmitted data, allowing the receiving station to detect and correct errors without needing a return channel to request retransmissions. This makes FEC ideal for one-way communications, especially to all stations (broadcasts), as no individual acknowledgment is expected or required for error correction from multiple receivers. SFEC (Selective Forward Error Correction) is a specific application of FEC designed for targeted or selective calling. While still a one-way error correction method (the receiver doesn't send retransmission requests), it's typically employed when transmitting data *to a single designated station* or a specific group, rather than a general broadcast. This selective nature makes it suitable for one-way communications directed to a specific station.