ARQ Consider a simple ARQ scheme through a single transmission link of data rate R.

The ARQ scheme works as follows. The sender transmits a data packet across the link. Once the receiver receives the whole packet, it checks whether data have been corrupted. If there is no error, a packet is sent to the sender to acknowledge the correct receipt of the data packet. If there is an error, an ARQ is sent for a retransmission. The sender resends the packet immediately after it receives the ARQ packet. Assume the lengths of data and ARQ packets are L and LARQ respectively, and the propagation delay along the link is given as td. Neglect the turn-around time at the sender and the receiver. Suppose that the probability that the data packet is corrupted during transmission is Pe and ARQ packets are always correctly received.

(a) Determine the average number of transmissions required for a packet to be correctly received.

(b) Find the average delay that a packet experiences. The delay is defined as the time interval between the start of the first packet transmission and the end of the correct packet reception. Note it does not include the transmission of the last acknowledgement packet.