Now the receiver's duty is to keep track of the sequence number of the next frame it expects to receive and sends the feedback after every data packet it receives.
It can be said that it's a special case of the general sliding window protocol where the transmitter or sender window size is N and the receiver's window size is 1, which means that it can transmit N frames to the receiving node before waiting for feedback. Go-Back-N ARQ (Go-Back-N automatic repeat request) is a flow control protocol( Read about Stop & Wait and Stop & Wait ARQ Flow Control Protocols) where the sender continues to send several frames specified by a window size even without receiving feedback from the receiver node.
