Question 1) Differentiate between LAN, MAN and WAN along with neat diagrams.
b) Briefly describe the following:
(i) Spectrum of a signal.
(ii) Digital transmission
(iii) Codec
(iv) Intermodulation noise.
Question 2)a) What is attenuation? How does it affect signal transmission through a communication medium? How can you make sure good signal quality when there is attenuation?
b) Given a channel with an intended capacity of 200 Mbps, the bandwidth of the channel is 30MHz. Suppose white thermal noise, what signal to noise ratio is required to achieve this capacity.
c) Describe satellite transmission.
Question 3)a) For the bit stream 1010011010(10 bits) sketch the waveforms for the following codes. Make suitable assumptions where ever necessary.
i) NRZL
ii) NRZ-I
iii) Bipolar-AMI
iv) Manchester
v) Differential Manchester.
b) With a neat diagram and appropriate equations explain quadrature amplitude modulation.
Question 4)a) An asynchronous transmission scheme uses 8 data bits, an even parity bit and a stop element of length 2 bits. Duration of one bit is 100 microseconds. If the receiver clock is 6% faster than the transmitter clock illustrate the sampling instants for all the bits. Are all the bits received correctly? Suppose that the bit samples are taken at the middle of the clock period. Also assume that at the beginning of the start bit, the clock and incoming bits are in phase.
b) For P=101011 and M=1110010110(10 bits) find CRC by using polynomial notation.
c) Describe the problem associated with maximum window size in Go-back-N ARQ.
Question 5)a) Along with neat diagrams explain Frequency Division Multiplexing. What are its disadvantages?
b) A large population of ALOHA users manage to generate 50 requests/sec including both originals and retransmissions. Time is slotted in units of 40 msec.
(i) What is the chance of success on the first attempt?
(ii) What is the probability of exactly k collisions and then a success?
(iii) What is the expected number of transmission attempts needed?
Question 6)a) What are the properties of a routing algorithm?
b) Describe link state routing with an example.
c) Describe load shedding.