Another key design decision for ATM is the size of the data field for fixed-size cells.

Let us consider this decision from the point of view of efficiency and delay.

a. Assume that an extended transmission takes place, so that all cells are completely filled. Derive an expression for the efficiency N as a function of H and L.

b. Packetization delay is the delay introduced into a transmission stream by the need to buffer bits until an entire packet is filled before transmission. Derive an expression for this delay as a function of L and the data rate R of the source.

c. Common data rates for voice coding are 32 kbps and 64 kbps. Plot packetization delay as a function of L for these two data rates; use a left-hand y-axis with a maximum value of 2 ms. On the same graph, plot transmission efficiency as a function of L; use a right-hand y axis with a maximum value of 100%. Comment on the results.