Physical

Question 1

packetization

Answer 1

bits obtained by the source coding are divided into packets

Question 2

encapsulation

Answer 2

headers added to various layers of the network stack

Question 3

forward error correction

Answer 3

error control capabilities of a code depend on the redundancy introduced by the code(set of code words)

Question 4

hamming distance

Answer 4

number of bits in which two codewords differ

Question 5

distance of a code

Answer 5

minimun hamming distance between two codewords

Question 6

Hamming(7,4)

Answer 6

detects single but not double errors, d1-d4 are data bits, p1=d1+d2+d4, p2=d1+d3+d4, p3 = d2+d3+d4

Question 7

How good is FEC?

Answer 7

may not be able to correct or detect all layers, incurs overhead which reduces data rate

Question 8

Watt conversions

Answer 8

dBW = 10log10(W)
dBm = 10log10(W*10^3 or 1mW)

Question 9

what is the path loss

Answer 9

1/gain(R/T), so T/R, PL(db) = 10log10(PL)

Question 10

power budget

Answer 10

Pr = Pt + gains - losses, all in dBm/dB

Question 11

Signal to Noise Ratio

Answer 11

10log10(signal power/noise power), higher SNR means higher quality signal.

Question 12

free space propagation models

Answer 12

Pr = Pt-PL, PL(d) = PL(d0) + 20log(d/d0), (Pt/Pr) = (4pid^A)2/wlength2, Ldb = 20log(f)+20log(d)-147.56dB, Pr(d) = Pr(d0)(d0^A/d^A)

Question 13

additive white gaussian noise

Answer 13

Capacity = Wlog2(1+ Pr/(Inter+N0W))

Question 14

Energyperbit / N0

Answer 14

(S/bit rate) / No