Skip to main content

Questions tagged [fading-channel]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
9 votes
1 answer
307 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 ...
Noor's user avatar
  • 337
7 votes
2 answers
2k 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 (...
AlexTP's user avatar
  • 6,605
6 votes
2 answers
1k 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 ...
user24907's user avatar
  • 313
5 votes
2 answers
134 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 ...
Marcel's user avatar
  • 189
5 votes
0 answers
138 views

Capacity of channels with pilots?

Question is about "channel capacity". I guess it is pretty elementary for experts, however I have not seen it discussed in e.g. Proakis book or Tse "Fundamentals of Wireless Com". ...
user avatar
4 votes
1 answer
997 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 ...
SKM's user avatar
  • 621
4 votes
1 answer
2k 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 ...
Ria George's user avatar
3 votes
2 answers
1k 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 ...
abdVef's user avatar
  • 41
3 votes
3 answers
894 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 ...
user36610's user avatar
3 votes
1 answer
278 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 ...
Bo LI's user avatar
  • 333
3 votes
1 answer
248 views

Derivation of Clarke's Doppler power spectral density

I am reading Wireless Communications by Andrea Goldsmith. I have some issues in the derivation of Clarke's Doppler power spectral density given there. 1)For beginning the autocorrelation of the in ...
UserHuffmann's user avatar
3 votes
1 answer
105 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 ...
jabak hamad's user avatar
3 votes
0 answers
249 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 ...
Coniferous's user avatar
3 votes
0 answers
40 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(\...
Robert L.'s user avatar
  • 2,222
2 votes
2 answers
1k 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 ...
Furkan Küçük's user avatar
2 votes
2 answers
235 views

Notes or books to quickly get started on the basics of signal processing or wireless communication

I'll soon start working in signal processing, specially wireless communication systems. Hence I'd like to get a quick understanding of MIMO and related systems, for example, the topics like: 1) where ...
Mathmath's user avatar
  • 161
2 votes
1 answer
78 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 ...
Gian's user avatar
  • 23
2 votes
1 answer
2k 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 ...
Mohamed Aly's user avatar
2 votes
1 answer
1k 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 ...
Noor's user avatar
  • 337
2 votes
1 answer
1k views

How to code Rician fading channel gains from k-factor?

I know that MATLAB provides some built-in functions but I am not interested in those. I want to know how can we code to obtain the Rician fading channel gains from normal or Gaussian distributions. ...
ZZ1's user avatar
  • 23
2 votes
4 answers
356 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?
Zaertiu's user avatar
  • 131
2 votes
0 answers
873 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: ...
Lizard_Paszczyk's user avatar
1 vote
2 answers
511 views

Why exponential decay power delay profiles are used to model fading?

I am trying to understand why exponential decay power delay profiles are used to model fading. In other words, why power of taps of channel impulse response decays exponentially and not, for instance, ...
Pawel's user avatar
  • 35
1 vote
1 answer
287 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 ...
Robert Fan's user avatar
1 vote
2 answers
3k 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"?
New_student's user avatar
1 vote
1 answer
51 views

frequency selective channel $\ne$ multi-tap channel?

A frequency selective wireless channel is necessarily a multi-tap channel, in the tap-delay line model, as the delay spread is significantly larger than the symbol duration. And a single-tap channel ...
syeh_106's user avatar
  • 223
1 vote
1 answer
8k views

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 ...
SJa's user avatar
  • 151
1 vote
2 answers
60 views

Understanding about correlation between random variables in context of Wireless Communication

I am trying to understand about correlation between random variables in context of wireless communication. In research papers related to 6G, I came across the following statements: Suppose there is a ...
Tushar Muratkar's user avatar
1 vote
2 answers
64 views

How to determine Transmission Rate for Task Offloading in edge computing?

I am new to communication systems and am working on a model for task offloading on edge computing. One key parameter I'm aiming to determine is the data transmission rate. While I am familiar with ...
user4594525's user avatar
1 vote
1 answer
58 views

Understanding Pathloss and latency

In my class on wireless communication, I came across the following sentence: The round trip path-loss can be defined to include aspects such as attenuation and/or latency etc Hence I am looking for ...
chaaru's user avatar
  • 37
1 vote
1 answer
934 views

Fast/Slow Fading: How are doppler shift and coherence time related?

In the literature I've read that fast fading happens if the bit duration is larger than the coherence time of the channel. The coherence time of a channel is proportional to $\frac{1}{f_{Doppler}}$. ...
scopusd's user avatar
  • 11
1 vote
1 answer
243 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 ...
vishal vudayagiri's user avatar
1 vote
1 answer
232 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 ...
Ria George's user avatar
1 vote
1 answer
27 views

Transmit/receive signal of two-path propagation model

In wireless communication, when the transmitted signal is $x$ and the received signal is $y$. Please tell me why the formula below holds true. \begin{align} y(t) &= \left( e^{-\jmath 2\pi f_c\...
Ryo Onishi's user avatar
1 vote
3 answers
84 views

which type of diversity is used by rake receivers?

My question is: Which type of diversity technique is used by the rake receivers? In Bahai, et. al. "Multi-Carrier Digital Communications Theory and Applications of OFDM," Second Edition, ...
Ali's user avatar
  • 95
1 vote
1 answer
65 views

On-Off keying for wireless communication channel estimation

Let us assume I have $k$ (a fixed number) sensors in a wireless sensor network with unknown channel statistics $\{h_1,h_2 \ldots, h_k\}$. In my system model, each of these $k$ sensors has an ...
wanderer's user avatar
  • 151
1 vote
1 answer
47 views

Is time varying channels same as circulary symmetric complex gaussian?

From the literature i understood that if the channel is non time varying then we can consider it as circularly symmetric complex gaussian distributed. So can we consider the same if the channel is ...
charu's user avatar
  • 47
1 vote
1 answer
87 views

Hf ionospheric channel model for large bandwidth

I know some models like the Watterson model for HF ionospheric channels but those are limited to narrow band frequencies. Are there some models to bandwidth like 12kHz up to 24 kHz?
user avatar
1 vote
1 answer
1k 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 ...
tuner's user avatar
  • 635
1 vote
1 answer
180 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: $$\...
AlexTP's user avatar
  • 6,605
1 vote
1 answer
415 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 ...
Mike's user avatar
  • 211
1 vote
2 answers
87 views

Channel impulse response (CIR) and OFDM relationship

In Chapter 3 of the [Goldsmith book] (https://faee.sut.ac.ir/Downloads/AcademicStaff/1/Courses/7/Andrea%20Goldsmith-Wireless%20Communications-Cambridge%20University%20Press%20(2005).pdf) we can see ...
rick87's user avatar
  • 11
1 vote
0 answers
83 views

Channel equalization in uplink

I have a multiuser uplink signal $$ Y=h_1x_1+h_2x_2$$ where, $h_1$ and $h_2$ are channels for user 1 and user2 respectively. At the receiver how can I equalize the signal $Y$, assuming known $h_1$and $...
Digi1's user avatar
  • 171
1 vote
0 answers
53 views

fractionally spaced channel equalizer code [closed]

I want to write a program in matlab for an adaptive fractionally spaced equalizer with lms algorithm.consider each packet with 150 bits that 25 first bits are pilot and used to train weights of the ...
Mahtab's user avatar
  • 11
1 vote
0 answers
50 views

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)\...
UserHuffmann's user avatar
1 vote
2 answers
541 views

Rayleigh Fading

I am calculating the capacity of $K$ channels between a transmitter and $N$ receivers in a cellular scenario. I use the following equation: $$C_n^k = B\log_2\left(1 + \frac{Ph_n^k}{N_0B + I_n^k}\right)...
Kasparov92's user avatar
1 vote
1 answer
318 views

Related to channel power gain

I am having a doubt that why channel power gain is denoted by $|h|^2$. For example, if the signal received is $$y(n) = hx(n)+w(n)$$ where $x(n)$ is transmitted signal with power $P$ , $w(n)$ is AWGN ...
paru's user avatar
  • 17
1 vote
0 answers
87 views

Compressive sensing based sparse vector estimation

I am newbie in compressive sensing (CS), I read about compressive sensing and its use for sparse vector estimation. As I understood CS can be used either in time or frequency domain. For me, The part ...
Fatima_Ali's user avatar
1 vote
0 answers
391 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 ...
Kinka-Byo's user avatar
  • 324
1 vote
0 answers
59 views

Detect orthogonal sequence with fading

For a set of $N$ orthogonal sequences $\textbf{A}^i = \{a_1^i,a_2^i,...,a_M^i\}, i =1 ..N$, the detection of these sequences can be done by calculating the inner product (dot product) of receive ...
Rokai's user avatar
  • 63