1
GATE ECE 2016 Set 1
Numerical
+2
-0
A digital communication system uses a repetition code for channel encoding/decoding. During transmission, each bit is repeated three times (0 is transmitted as 000, and 1 is transmitted as 111). It is assumed that the source puts out symbols independently and with equal probability. The decoder operates as follows: In a block of three received bits, if the number of zeros exceeds the number of ones, the decoder decides in favor of a 0, and if the number of ones exceeds the number of zeros, the decoder decides in favor of a 1, Assuming a binary symmetric channel with crossover probability p = 0.1, the average probability of error is _______
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2
GATE ECE 2016 Set 1
MCQ (Single Correct Answer)
+2
-0.6
An analog pulse s(t) is transmitted over an additive white Gaussian noise (AWGN) channel. The received signal is r(t) = s(t) + n(t), where n(t) is additive white Gaussian noise with power spectral density $${{{N_0}} \over 2}$$. The received signal is passed through a filter with impulse response h(t). Let $${E_s}$$ and $${E_n}$$ denote the energies of the pulse s(t) and the filter h(t), respectively. When the signal-to-noise ratio (SNR) is maximized at the output of the filter $$\left( {SN{R_{\max }}} \right)$$, which of the following holds?
A
$${E_s} = \,{E_h};\,\,SN{R_{\max }} = \,{{2{E_s}} \over {{N_0}}}$$
B
$${E_s} = \,{E_h};\,\,SN{R_{\max }} = \,{{{E_s}} \over {2{N_0}}}$$
C
$${E_s} > \,\,{E_h};\,\,SN{R_{\max }} > \,\,{{2{E_s}} \over {{N_0}}}$$
D
$${E_s} < \,\,{E_h};\,\,SN{R_{\max }} = \,\,{{2{E_h}} \over {{N_0}}}$$
3
GATE ECE 2015 Set 2
MCQ (Single Correct Answer)
+2
-0.6
Consider a binary, digital communication system which uses pulses g (t) and − g (t)for transmitting bits over an AWGN channel. If the receiver uses a matched filter, which one of the following pulses will give the minimum probability of bit error?
A
GATE ECE 2015 Set 2 Communications - Noise In Digital Communication Question 11 English Option 1
B
GATE ECE 2015 Set 2 Communications - Noise In Digital Communication Question 11 English Option 2
C
GATE ECE 2015 Set 2 Communications - Noise In Digital Communication Question 11 English Option 3
D
GATE ECE 2015 Set 2 Communications - Noise In Digital Communication Question 11 English Option 4
4
GATE ECE 2015 Set 1
Numerical
+2
-0
The input X to the Binary Symmetric Channel (BSC) shown in the figure is ‘1’ with probability 0.8. The cross-over probability is 1/7. If the received bit Y = 0, the conditional probability that ‘1’ was transmitted is _______. GATE ECE 2015 Set 1 Communications - Noise In Digital Communication Question 13 English
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