Questions tagged [channel]

A channel for communication between transmitter and receiver. Sometimes a channel is multi-input/multi-output, allowing for multiple transmitters and multiple receivers.

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31 views

How is the Tx/Rx Gain calculated in USRP?

I know that USRPs are uncalibrated devices. In many exampls you can set the so called Tx or Rx gain (as in the picture below). Now, I know that this does not correspond to the real power of the ...
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32 views

What is impulse response in simple AWGN channel?

Assume a sender and receiver communicate through an AWGN channel. Let $x(t)$ be a transmitted signal and $y(t)$ be a received signal and $z(t)$ be the Gaussian noise. It is known that $y(t) = kx(t-\...
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31 views

BER and distance relation

I have a system using 16-QAM, with 2.4 GHz, working up to 2 km at different bit rates, e.g. 1Mbit/s. My task is to provide graph, which will show relation between BER and distance for different bit ...
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Uplink Pilot Design in TDD based OFDM system

In a paper “Design of Orthogonal Uplink Pilot Sequences for TDD Massive MIMO under Pilot Contamination”,it was mentioned that, In the uplink channel estimation, if each user occupy all available ...
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52 views

White noise generation for different bandwidth signals in MATLAB

I'm working on simulating an uplink scenario in satellite communication. The goal is to send a preamble + data to the satellite from ground station. Data symbols have a bandwidth of $15\ \rm kHz$ and ...
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57 views

Shannon formula for channel capacity

Shannon formula for channel capacity states that $$C=\log\left(1+\frac{S}{N}\right)$$ If this formula applied for baseband transmission only? Is it applied with passband transmission? Are there any ...
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90 views

Difference between sampling rate and baud rate and their relation to channel capacity

The sampling rate says that one Hz can carry at least 2 samples, and the bit rate is obtained by multiplying the sampling rate by the number of bits per sample. Thus, many samples and many bits can ...
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58 views

How to remove the modulation before doing frequency offset estimation?

To use DFT/FFT (or maximum likelihood) method to estimate the frequency offset introduced by the channel, we need to remove the modulation on the received data samples in the front. If the unknown ...
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41 views

About discrete time model for wireless channel

I am trying to understand Section 2.2.3 of the book "Fundamentals of wireless communication" by Tse and Viswanath. In this section the authors explain how to go from the continuous time ...
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What is meant by Beamspace domain and antenna domain for channel matrix?

I am not from Engineering background that's why asking these overly simplistic question. Anyone who can answer. These are basic research questions. Thanks
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41 views

awgn function in MATLAB

I'm using 'awgn(input_signal,snr_db,'measured')' function in MATLAB to add white noise to the input signal. Here is the simplified script. Does zero padding the input signal affect the behavior of ...
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15 views

In a communications system does the order of channels is in a cascaded channel affect the overall capacity?

I'm currently looking at capacity for cascaded channels as part of my Communications Systems module and we're looking at a question in which we have four identical channels represented by the ...
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117 views

Why is the relationship between Es/N0 and SNR different for complex and real signals?

I try to use the AWGN Channel model of MATLAB to build my simulation model, but the explanation of the relationship between Es/N0 and SNR in the official manual of MATLAB makes me confused. It says ...
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34 views

Why SRS signalling is used in 5g?

Since DMRS is also being used as a reference signal in PUCCH and PUSCH channel, so why an extra SRS signalling is required.
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Correlated fading channel: transmit and receive antenna correlation matrices

I am trying to create a non-i.i.d channel: correlated Rayleigh fading channel. $$ H= R_H \cdot H_o,$$ where $H_o$ is i.i.d. channel ( uncorrelated) and $ R_H$ is a channel correlation matrix, is ...
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57 views

Degrees of freedom in coding (for a communication channel)

I was reading on my lecture slides about how to achieve diversity (i.e. transmit more copies of the same message in order to avoid its corruption; this technique may be realized by repeating the ...
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43 views

how to determine a length of a channel? ( given path, delay)

Given a channel matrices for each subcarrier of a frequency selective channel (OFDM): i.i.d.. channel =(randn(ntx,nrx, N)+1i*randn(ntx,nrx, N))/sqrt(2); simulated ...
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How to send two packets in a point-to-point transmission with NOMA? [duplicate]

If a transmitter T1 has two packets M1 and M2 to send to a receiver R1, can T1 send M1 and M2 at the same time and using the same frequency based on Non-orthogonal multiple access (NOMA)? If T1 sends ...
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67 views

How does subcarrier correlation affect the BER of OFDM?

I am studying the OFDM system and would like to examine it under different subcarrier correlation scenarios. I have calculated BER for the uncorrelated scenario and now I have rewritten it for the ...
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50 views

Why does altering path length in radio transmission alter the phase of the received signal?

I do have a very naive yet bothering question: Assume I send a sinusoid signal \begin{equation} A*cos(2\pi ft+ \phi_0) \end{equation} over a radio channel. Assume there is only a LOS-path for each ...
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35 views

Gain and average gain of two-path channel

For two-path channel with no loss or phase shift in the reflection, Why the gain of the channel at radio frequency less than average gain of the channel?
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88 views

Relationship between Nyquist and Shannon channel capacity

Nyquist channel capacity(Cn) used for theoretical noiseless channel $C_n=2B\log_2(M)$ Shannon channel capacity(Cs) for noisy channel $C_s=B\log_2(1+\text{SNR})$ So is there a relationship between ...
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139 views

Why multi-path channel has linear phase within the coherence bandwidth?

I read some sentence that said "It is usually assumed that the multi-path channel has a constant gain and linear phase within the coherence bandwidth". I can't understand what it mean " linear phase "....
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What is the physical meaning of coherence bandwidth in mmWave massive MIMO channel?

I am doing some research about millimeter wave massive MIMO channel now. We first take account about static MIMO channel, cause we only have SISO measurement system now. We use scanner to move our ...
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29 views

Interference Distribution Assumption in NOMA IoT Scenario

I am assuming a NOMA IoT Uplink scenario, which is interference marred. I have to ascertain the SINR at the Access Point (AP) for the NOMA users. A sub-channel is allocated to various users and ...
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59 views

Least square error channel estimation in the presence of AWGN noise

I want to implement Least Square (LS) channel estimation method in the presense of AWGN noise in MATLAB. $y(n) = x(n) * h(n)$ $Y(k) = X(k)H(K)$ Y(k) is the received signal in frequency ...