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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Simple Pathloss Model Question

If I have the path loss model below, $$128+37\log_{10}(d)$$ Why it is equivalent to $$\frac{P_r}{P_t} = \frac{10^{-12.8}}{d^{3.7}}$$
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What is meant by channel knowledge? Difference between partial and full?

Keep coming across the term channel knowledge (specifically in the transmitter) in a reading for class but can't really grasp the idea and don't see a clear cut definition. From what I understand it ...
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Binary-Input AWGN Channel Capacity

I am trying to reproduce graph 1.7 from the book Channel Codes: Classical and Modern. The graph contains the capacity plots for both soft-decision and hard-decision decoding plus the Shannon limit. I ...
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How to resolve some inconsistencies in the mathematical model for the narrowband fading channel?

I am reading Wireless Communications by Andrea Goldsmith. There the author mentions that for narrow band channel the received signal can be given as: $$r(t)=\text{Re} \left\{u(t)\text{exp}(j2\pi f_ct)\...
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Why is there fear of interference between 5G and airline altimeter C-band?

The C-band frequency range to be used for the 5G-advanced rollout is the US is in the 3.7-3.98 GHz range. Whereas altimeters operate in the 4.2-4.4 GHz range. Is there any genuine reason to worry ...
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Simulating Es/N0 by adding noise to analog signal

I believe I am familiar with simulating $E_s/N_0$ by adding noise to the output of the matched filter, but what would be the correct way to simulate $E_s/N_0$ starting with the analog signal at the ...
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I am trying to estimate the Channel Impulse Response(time domain) for a 5G-NR signal using the DMRS-PBCH pilots only , any suggestions

I want to obtain the $h(t)$, the channel impulse response for my NR signal using the DMRS PBCH pilots only.
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Pilot Signal Overhead

I have a doubt regarding Pilot signals such as CSI-RS in NR. Using a large number of CSI-RS affects Datarate significantly? or it is negligible? Because I wonder it is meaningful that optimize the ...
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What does $\mathcal{ E}(|h|^2)$, where $|h|^2$ is power of the channel gain $h$ represent?

I came across this notation of $\mathcal{E}(|h|^2)$ in a research article. $h$ is the channel gain of a wireless communication channel. In particular, a Rayleigh fading channel. I know that $|h|^2$ ...
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What are TDL and CDL channel models in principle, and which variation can be used for indoor and outdoor environment, respectively?

I am making a simulation using 5G-toolbox in Matlab. IN 5Gtoolbox we have two kind of channels, CDLChannel and TDLChannel. Now, CDL means Clusteresd Delay Line, and TDL means Tapped Delay Lines. But ...
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Channel Parameters

I'm a newbie in wireless communication. I found one channel model and have some questions regarding its parameters In this channel model below.. $\alpha_m,$$e^{j\varphi(k,n)}$, $\tau_m$, $\theta_m$, $...
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Delta dirac function in the Channel model

I have a question about the channel model below. theta, phi denotes AoA(Angle of Arrival), AoD(Angle of Departure) from receiver and transmitter. I know that channel impulse response is the sum of ...
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Can a cosine modulated complex valued baseband signal be transmitted over physical channels?

I am reading Digital Communication by Lee and Messerschmitt. In Chapter 6 on modulation, the authors say: "Modulating a complex-valued baseband signal with a cosine wave yields complex-valued ...
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Multiple Transmitter Localization - Channel Modelling

I read in this paper about to localize multiple transmitter in a wireless scenario. I know from other source that this hypothesis is completely false. What do you think? Is there in the literature ...
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How to estimate optimal channel length for multichannel blind system identification?

Let P1 and P2 two distinct output signals that are generated by a common input signal S. If you want to estimate S using multichannel blind system identification algorithms, you have to specify the ...
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Averaging two channels with Python

I am trying to convert a stereo audio into a mono one by averaging both channels with Python. My audio is stored in sound and I calculate the average using ...
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How does higher received signal power enable higher data rates?

On page 30, of the book Fundamentals of LTE by Arunabha Ghosh et al. it is written: This allows broadcast signals from different cells to combine over the air to significantly enhance the received ...
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Generating a 2D delay-Doppler channel matrix

I was wondering if anyone here has any idea on 2D delay-Doppler channel and how to generate the channel matrix? Even a hint or a resource would be helpful. I just want to understand and visualize the ...
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Understanding MMSE equalizer equation

I have read many online materials and journal paper where the equation for MMSE equalizer is given as: $G_{MMSE}$ = $H^H(HH^H+\nu^2I )$ where $H$ is the channel, $H^H$ is its hermitian. $\nu^2$ is ...
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Can Oversampling help to mitigate the effect of additive white gaussian noise?

Oversampling the signal at the receiver's ADC is a common technique to improve the ADC's resolution, dynamic range and to improve the signal to noise ratio (SNR) due to ADC quantizaiton noise, thermal ...
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Optimal FEC option for extremely low SNR situation

I am new to this site, which I joined with the aim of finding someone to help me with a little doubt. I am trying to design a system that must be able to work at extremely low (the lower, the better, ...
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Centre channel derivation using correlation

I would like to know the algorithm for how centre channel is derived from rejecting left and right channel in audio upmixing process. Can someone explain intuitively rather than hard hitting ...
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Unstable Phase in Channel Impulse Response

I'm using DW1000 UWB radio transceiver and extract its channel impulse response (CIR). The CIR output by the transceiver is the complex baseband CIR. In a static environment, the CIR is a LTI filter ...
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Channel estimation using bit reversed order of FFT matrix

Is it possible to use the bit-reverse order of FFT instead of FFT to estimate the channel? Based on my reading, I found that bit reversed order of FFT matrix can diagonalize the channel, but ...
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OFDM use a pulse shaping filter or not?

I've heard in various literature that band limited channels use pulse shaping filters. By the way, In OFDM it use a cyclic prefix to overcome ISI, so I wonder if OFDM does not use pulse shaping filter....
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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 ...
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