An earth station transmits to a satellite 1000-bit information-carrying frames at speed of 1 Mbps through the uplink channel. The satellite transmits back to earth station on the downlink channel acknowledgement frames. The satellite acknowledges every frame it receives. The propagation delay of each channel (uplink, downlink) is 270msec. The size of acknowledgement frames is small, and you can assume transmission time of acknowledgement frames is zero. Processing time of received information frames by satellite and acknowledgement frames from earth station is assumed zero. Assume that all information frames and all acknowledgement frames arrive undamaged (no loss or damage occurs).

What is the maximum utilization for:

1. Stop-and-wait flow control?
2. Sliding-window flow control with window size of 127?
3. Sliding-window flow control with window size of 255?
4. Sliding-window flow control with window size of 1023?