Suppose that a server sends four packets of audio data, in 15 seconds each. The first is sent by the server exactly at noon (12:00:00), while each of the three successive packets is sent immediately after the completion of its predecessor. The client, on the other hand, receives the four packets beginning at 12:00:03, 12:00:20, 12:00:41, 12:00:59 respectively. What is the smallest delayed wait time (buffer) in seconds that would ensure the client had seamless playback (i. e. each packet plays immediately after the previous one ends)?

Consider a slotted aloha system, where the time slot equals the fixed duration of each packet. assume that there are 4 stations a, b,c, d sharing the medium. (a) stations a, b,c, d receive one packet each from higher layers at times 1.3, 1.5, 2.6,5.7 respectively. show which transmissions take place when, according to the slottedaloha protocol; describe all transmissions until all four packets have been successful. when needed, each station has access to the following sequence of random number, provided by a random number generator and drawn uniformly between 0 and 1: (1) station a draws numbers: 0.31, 0.27, 0.78, 0.9, 0.9, 0.11, 0. (2) station b draws numbers: 0.45, 0.28, 0.11, 0.83, 0.37, 0.22, 0. (3)station c draws numbers: 0.1, 0.2, 0.3, 0.4, 0. (4) station d draws numbers: 0.36, 0.77, 0.9, 0.1, 0.1, 0.1, 0.1, 0. (b) in slotted aloha, a station transmits in each time slot with a given probability. what probabilities would you assign to each of the four stations so as to: (i) maximize the efficiency of the protocol? (ii) maximize fairness among the four stations? (c) will the efficiency increase or decrease if we modify slotted aloha as follows: (i) get rid of slots and allow stations to transmit immediately? (ii) implement carrier sensing? (iii) implement collision detection? (iv) implement collision avoidance?

Match the items with their respective descriptions.

Two students are discussing the flow of electricity. student a says that voltage is a measure of the amount of electron flow in a circuit. student b says that power is the product of voltage and current. which of the following statements is correct? a. only student a is correct b. only student b is correct c. both of the two students are correct d. neither of the two students is correct