Hello,

Please support providing a solution for the below-mentioned question for understanding the concepts.

23. (a) Describe, in one sentence, the function of a data link protocol. 2 marks (b) Describe the mechanisms (and their operation) used to delimit and confirm correct receipt of a frame in an asynchronous Backward Error Control (BEC) based data-link protocol. 5 marks (c) A Low Earth Orbit (LEO) satellite is in an orbit 2000km from the earth's surface. Communication between the satellite and the earth takes place over a variable bit-rate communication channel. (Assume a velocity of propagation to be 2108m/s.) Characteristics of the channel are listed in the table below. The system initially operates at the 512kb/s rate using a simple ARQ protocol based upon stop and wait principles. The system operates with default timer set to 25ms. i) Explain why such a timer is needed and confirm that the default value is appropriate. ii) Calculate the total time taken to transmit a single frame successfully and determine the overall link efficiency. 5 marks (d) In order to improve link efficiency and lower system delay, the link is reconfigured to work with as a sliding window ARQ protocol using selective retransmissions, making use of a 4-bit SEQ field within the frame header. i) Determine the appropriate fastest bit-rate that can be adopted to maximise overall link efficiency. ii) Determine, for this revised bit-rate, the new overall link efficiency. Comment upon the result. 5 marks (e) It is suggested that overall system performance can be