Questions tagged [fading-channel]

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7
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1answer
177 views

Practicality of the assumption of i.i.d. for Rayleigh channels

I would like to understand how far the assumption of having i.i.d. is accurate/valid (from the practical point of view) when an OFDM system is working in Rayleigh channels. Is this means the channel ...
5
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2answers
400 views

Intersymbol interference due to limited channel bandwidth

What is the difference between limited-bandwidth induced intersymbol interference (ISI) and ISI due to multipath propagation. I noticed that the delay spread in indoor environment is in the range of ...
4
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2answers
665 views

Flat fading criterion of OFDM subcarrier spacing

I have always thought that the OFDM subcarrier spacing $\Delta f$ is chosen such that not too small because Doppler spread can destroy subcarrier orthogonality not too large to avoid Cyclic Prefix (...
3
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1answer
441 views

Educational purpose - What is the correct way to simulate a multipath fading channel which has ISI

I am following the codes for rayleigh fading channel given in the webpage: http://www.raymaps.com/index.php/m-qam-bit-error-rate-in-rayleigh-fading/ I am confused and need help in clarifying some ...
3
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1answer
1k views

Matlab: Difference between flat fading and Rayleigh multipath fading, terminologies and concept

The information that I put down are from the site http://www.gaussianwaves.com/2011/05/ebn0-vs-ber-for-bpsk-over-rayleigh-channel-and-awgn-channel-2/ . My QUestions are due to some misconception and ...
3
votes
1answer
192 views

Channel capacity with additive Gaussian noise with changing variance

As we all know the capacity for a AWGN channel with constant noise variance is just given by $$\frac{1}{2}\log(1+SNR)$$ What if the variance of the noise changes with the type (assuming the variance ...
3
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0answers
52 views

Actual measurements of the influence of fading and multipath on HF radio communication

I'm looking for papers or books that contain actual measurements of the influence one has to expect in HF radio communication. I'm interested in this, because i've simulated the influence of a ...
2
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1answer
55 views

Transmitting over Unknown Fading Channel

I have a system with no diversity and the channel's coefficients change every $T = 10\text{ bits}$ transmitted. The channel estimation system has a flaw and detects the channel's coefficients equal to ...
2
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0answers
24 views

Is it safe to call this WSSUS channel a Gaussian process?

BACKGROUND: Equation (3.6) of Wireless Communications by Goldsmith gives the baseband impulse response of a time-varying channel as: $$ c(\tau,t) = \sum_{n=0}^{N(t)}\alpha_n(t)e^{-j\phi_n(t)}\delta(\...
2
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0answers
431 views

PortAudio: sound fade in/out by scaling sample data

I've done already some fade in or fade out effect in portaudio, but that is not working properly. My callback function: ...
1
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1answer
167 views

OFDM intra-block multipath interference

We know that OFDM eliminates the inter-block intereference. But there are still multipath interference in a single OFDM block(symbol). How does LTE handle this intra-block interference induced by ...
1
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2answers
805 views

Correct way to simulate Rayleigh fading for indoor environments

I am trying to simulate indoor communications with all components included. But something disturbs me when it comes to Rayleigh fading part. I am adding my rayleigh fading to the transmitted signal ...
1
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2answers
327 views

Why do we express complex noise as Gaussian distributed while the channel is Rayleigh distributed?

I have a confusion regarding the distribution of noise and channel fading. As we know channel fading is usually modeled with Rayleigh fading since it has Gaussian distributed real and imaginary ...
1
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1answer
703 views

Question about path loss exponent estimation from measurment

I have a simple question that confuses me. Assume that we have the following results of a measurement campaign, distance (km) and the corresponding path loss $L_{e}$ (dB). I want to estimate the ...
1
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3answers
59 views

Explanation a flat fading channel in case MIMO OFDM

I am trying to understand flat fading and frequency selective channels. As I understood, in the case of flat fading channels MIMO channel elements, $h_{i,j}$, are random variables. Which assumption ...
1
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1answer
38 views

Questions about reproducing results of a paper on Communication Systems and Wireless Communication

I'm trying to reproduce the results of a paper on Device-to-Device Communication, channel assignment and mode selection (G. Yu, L. Xu, D. Feng, R. Yin, G. Y. Li and Y. Jiang, "Joint Mode Selection and ...
1
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1answer
135 views

Capacity loss of fast fading regarding AWGN

The theoric capacity of fast fading channel is: $$ C_{\rm fading}=E\left\{\log\left(1+\lvert h \rvert^2\textrm{SNR}\right)\right\}, \quad\text{with $E$ is expectance operator.}$$ At high SNR: $$\...
1
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1answer
234 views

FWGN model implementation vs explaination (textbook pages attached)

I came across the FWGN model for multipath channel simulation in the book: "MIMO-OFDM Wireless Comuunications with MATLAB" Here is an explanation about Clarke/Gans model: Some code to generate a ...
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0answers
37 views

CDF of product of two *translated* exponential variables

It is known that the CDF of the product of two exponential random variables is given by this answer If $X$ and $Y$ have rate parameters $\mu$ and $\lambda$, so their pdf's are $f_X(x) = \mu e^{-\...
1
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0answers
94 views

How to model fading channels in MATLAB?

I am asked to write a MATLAB program for the simulation of the end-to-end transmission of a JPG file through a fading channel by using OFDM technique for one of my courses' term project. I wrote my ...
1
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0answers
90 views

Ideal channel in OFDM simulation

I am trying to simulate an OFDM based system in MATLAB where the estimated channel in the reciever is fed back to transmitter. As a proof of concept I wanted to return the ideal channel. I used the ...
1
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1answer
1k views

AWGN and Rayleigh fading in slow flat fading channels in MATLAB

I wanted to add Additive White Gaussian Noise (AWGN) and involve effect of slow flat fading on my transmitted signal in Matlab. I created noise with zero mean and variance of one by ...
1
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3answers
204 views

Channel impulse reponse multipaths

I find this image : Does it mean that at 0ns there is one path, 10ns second path, ... and approximately at 130 ns, there is a power path?
0
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2answers
427 views

what does mean quasi-static channel [closed]

When I read papers about channels, I usually see something Quasi-static Channel, Does "Quasi-static Channel" mean "time-variant channel" or "time-invariant channel"?
0
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1answer
605 views

Rayleigh Fading Simulation

I have a question about simulating Rayleigh Fading channel. I know theory behind the Rayleigh channel and it is sum of two Gaussian random variable where the amplitude is Rayleigh distributed and the ...
0
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1answer
311 views

How can I generate time-variant Rayleigh channel in MATLAB

One of known models for channel simulation is called Rayleigh Fading channel, it's usually used to simulate wireless channel in time variant/invariant. As I know, Rayleigh fading channel can be ...
0
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1answer
46 views

Is the Channel shortening similar to Time domain Equalizer (TEQ)

I used to read about Time domain equalizer (TEQ) in many lectures, i.e here , But in many other papers, that's called Channel shortening i.e here . However, in the a two above links, the cost ...
0
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2answers
32 views

Which channel coding technique is suitable for wireless SPIHT compressed image: Reed-Solomon or convolutional code?

I want to transmit a SPIHT-based (Set Partitioning In Hierarchical Trees) image compressed image over a wireless fading channel, which will be suitable as channel coding technique: Reed-Solomon or ...
0
votes
1answer
179 views

why did convolution coding achieve BER less than Reed-Solomon?

I tried convolutional coding and Reed-Solomon (RS) (block coding technique) for wireless channel where the input data is bitstream. Convolutional coding achieved lower BER comparing with RS. If the ...
0
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1answer
149 views

MIMO System Model in Matlab

I have this lame doubt which has ended up confusing me which is probably trivial. I am modelling a MU-MIMO system with a Rayleigh fading channel. I have created a wanted signal as an OFDM signal, and ...
0
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2answers
7k views

Matlab: Correct method of generating Rayleigh fading channel

A Rayleigh flat fading channel has 1 tap and so there will be no intersymbol interference. if N= 1000; Then, h=(1/sqrt(2))*(randn(N,1)+1i*randn(N,1)); will ...
0
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1answer
31 views

Assessing relative wireless channel quality using Capacity and Condition Number CDFs

I have Channel capacity analysis figures for two wireless channels show below: My question: While ergodic capacity in the first subplots are very clear in conveying the channel capacity, How to make ...
0
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2answers
127 views

BER of QPSK modulation in Rayleigh fading channel model

i am having trouble deriving a BER analytical expression for QPSK modulation system operating in a Rayleigh Fading channel model. Could anyone direct me to a reference that would help in this matter. ...
0
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1answer
105 views

Channel model: LOS Component and Rician K-factor

I am asking about Rician K- Factor in this model: I know that if $K=0$ then it is a pure Rayleigh fading, if $K= \infty$, then non fading Channel. What is it, if $0<K<\infty$ ? If i represet ...
0
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2answers
583 views

How to compute the channel gain from the path loss model of a wireless channel

I did my research but I did not get a satisfying answer. We have a transmitter and a receiver over a wireless communication channel. The channel's path loss is modeled as $ 128 + 37 \log_{10} (d)$, ...
0
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1answer
36 views

Need information about following channel model

The following research paper is for blind channel equalization and the author has modeled the channel as 7 tap weights https://ieeexplore.ieee.org/document/1096877 On page 3 it has shown the ...
0
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1answer
74 views

What's the difference between SISO and SIMO in using matched Filters

Suppose we are transmitting a signal $x$ in $OFDM$ with $N$ subcarriers, After performing Parallel/Serial conversion and then N-points FFT, we suppose to have signal $s = IFFT^Hx$, Then adding the ...
0
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1answer
58 views

When to use Rician fading vs Gain for Directional Antenna

This is a pretty simple question. [The answer might not be simple :( ] If I am using a directional antenna, can I used Antenna gain $G_T=1$ as I am considering Rician Fading between transmitter and ...
0
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1answer
519 views

Rayleigh fading with frequency selective fading channel

I Read in one reference that, the Rayleigh distribution is commonly used to describe the statistical time varying nature of the received envelope of a flat fading signal, or the envelope of an ...
0
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1answer
167 views

How to get a Rician fading channel matrix from a Rayleigh fading channel matrix?

I have a Rayleigh fading channel matrix H. Let's say the dimension is 2000*128. Is there any way to convert this matrix into a Rician fading channel matrix for example κ = 5, 10, 15, etc.? Is there a ...
0
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2answers
121 views

Demodulation in Rayleigh Flat Fading Channels

A core part of demodulation in Flat-Fading channels is (assuming) the channel as a(random) constant complex number multiplied with your signal. This is done in order to de-rotate the symbol for ...
0
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1answer
409 views

What is the suitable mathematical form of the multipath channel impulse response?

I am trying to understand the nature of a wireless multipath channel impulse response but I am a bit confused while interpreting the time domain multipath impulse response. There are different ...
0
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1answer
452 views

Zigbee Transceiver Using OQPSK Modulation under Fading Channels

I am working on transmitting ECG signal over wireless body area networks. According to IEEE802.15.4 standards , I am using ZigBee transceiver at 2.4 GHZ . Complex baseband equivalent channel model is ...
0
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1answer
110 views

Brief introduction to wireless communication and communication terminologies [closed]

In the Question Design of equalizer for wireless communication the diagram of a basic communication system is presented with informative points and discussions. My Questions are: Considering the ...
0
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1answer
121 views

Help in analytical expression of BER for M-QAM [duplicate]

I am new in learning deriving BER expression. I am familiar for the case of BPSK in AWGN but cannot understand how the BER expression in Eq(12) in this paper, An Enhanced Spectral Efficiency Chaos-...
0
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1answer
215 views

Conceptual Question on equalization technique in rayleigh fading channel based on a paper

Question Link http://www.raymaps.com/index.php/theoretical-ber-of-m-qam-in-rayleigh-fading/ gives theoretical expressions for BER in Rayleigh fading channel. Can I use the expression for 64-QAM in ...
0
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1answer
550 views

Matlab: Help in applying equalizer and proper calculation of symbol error rate for QAM modulation in Rayleigh channel

I am unable to understand why the Constant Modulus ALgorithm is not functioning properly for QAM modulation in Rayleigh multipath fading. The same code worked for BPSK in AWGN (previous Question ...
0
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1answer
27 views

channel gain calculation

I want to calculate the SINR term in an up-link of wireless communication system but there is different models for simulation. I want to know what is the exact meaning of |h|^2 in this formula: SINR = ...
0
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1answer
22 views

Detecting multi-path propagation when one acoustic signal is dominant

I am sending an acoustic signal from a source to a receiver where there are limited number of paths the signal can travel. I want to detect if there has been multipath propagation or not when one path ...
0
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0answers
35 views

SNR and Correlation

Signal to Noise ratio is essentially the ratio of the signal power to the average noise power. Correlation is the similarity of two signals. Assuming a signal travels through a channel or medium, and ...