Recent questions in Communications

Consider a discrete memoryless source with an alphabet of four source symbols. $s(t)$ is a multi-level $(-1,0,+1,+2)$ signal representing a long sequence of random symbol...

Which option(s) represents/ represent the dielectric loss tangent of a substrate?Ratio of the real to imaginary parts of the total displacement current$\left(\omega \epsi...

A wireless digital transmission scheme is using $16$-QAM over an additive white Gaussian noise channel and a maximum-likelihood receiver. Consider the information bit rat...

A QPSK modulated signal from an additive white Gaussian noise (AWGN) channel is received with an $E_{b} / N_{o}=8.4 \mathrm{~dB}$ at the input of a coherent QPSK demodula...

Let the relevant bandwidth $(B)$ of a digital communication system be $1 ~\text{MHz}$ and $k T=-174 \mathrm{~dBm} / \mathrm{Hz}$, where $k$ is Boltzmann's constant and '$...

Consider a real, narrowband signal $x(t)=A(t) \cos \left[2 \pi f_{c} t+\theta(t)\right]$ where the maximum frequency components of $A(t)$ and $\theta(t)$ are $f_{M}$ and ...

The average bit error rate at the input of a $(7,4,1)$ Hamming decoder is $0.10$. The probability that the decoder will fail to decode a received word correctly is $\_\_\...

Consider a frequency-modulated (FM) signal$$f(t)=A_{c} \cos \left(2 \pi f_{c} t+3 \sin \left(2 \pi f_{1} t\right)+4 \sin \left(6 \pi f_{1} t\right)\right)$$where $A_{c}$ ...

Consider a real-valued random process$$f(t)=\sum_{n=1}^{N} a_{n} \: p(t-n T),$$where $T>0$ and $N$ is a positive integer. Here, $p(t)=1$ for $t \in[0,0.5 T]$ and $0$ othe...

A digital communication system transmits through a noiseless bandlimited channel $[-W W]$. The received signal $z(t)$ at the output of the receiving filter is given by $z...

​​​​A white Gaussian noise $w(t)$ with zero mean and power spectral density $\frac{N_{0}}{2}$, when applied to a first-order RC low pass filter produces an output $n(t)$....

A source transmits symbols from an alphabet of size $16$. The value of maximum achievable entropy (in bits) is $\_\_\_\_\_\_$.

​​​​​A source transmits a symbol $s$, taken from $\{-4,0,4\}$ with equal probability, over an additive white Gaussian noise channel. The received noisy symbol $r$ is give...

​​​​​The information bit sequence $\{111010101\}$ is to be transmitted by encoding with Cyclic Redundancy Check $4$ (CRC-$4$) code, for which the generator polynomial is ...

Let $X(t)=A \cos \left(2 \pi f_{0} t+\theta\right)$ be a random process, where amplitude $A$ and phase $\theta$ are independent of each other, and are uniformly distribut...