Questions tagged [fading-channel]
The fading-channel tag has no usage guidance.
98
questions
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7 views
HF ionospheric Channel Model Example in matlab : Watterson model
In the example file in matlab HFIonosphericChannelModelExample.m, the watterson model is simulated. In this model the channel is represented as one tap (for the sake of simplification) delay channel.
...
0
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0answers
6 views
How to choose the algorithm for DFE filter adapatation, if the criterion is MMSE?
I hesitate between LMS and RLS ,
and for the feedforward filter and feedback filter, what must be the length of the filters as a function of the channel delay spread.
Any help will be really ...
0
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1answer
17 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?
1
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0answers
41 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 ...
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0answers
19 views
How to determine a number of taps in channel
I need to determine the number of taps of a channel. I have the channel simulated via channel simulator. My task is to try to estimate the channel by using pilots position. How the channel was ...
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0answers
39 views
Is MMSE equalizer necessary?
For observation $y$, channel coefficient $h$ and gaussian noise $w \sim \mathcal{CN}(0,\sigma^2)$,
$$y = hx + w \tag{1}$$
Note that for OFDM system, (1) is assumed channel input-ouput equation on ...
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0answers
13 views
Path delay influence in BER performance using Rayleigh channel
I am simulating a DSSS modulation in a Rayleigh channel to get the BER performance. For these purpose I am using the comm.RayleighChannel object.
My problem comes when I change the Paths delays of the ...
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0answers
16 views
Basic in frequency-selective channel: part with decoding
Here I have asked about the basic of the theory of frequency selective channel and the user @Florian explained to me how to compute precoding in such case using the effective channel.
I am just ...
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24 views
Wireless Channel Modelling - LOS
Let $T$ a transmitter and $R$ a receiver in a wireless scenario. The two entities are in an outside scenario with Line of Sight. The transmitter $T$ sets its maximum power transmission $P_{TX}$ and ...
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10 views
Relation between PDP (Power Delay Profile) and channel impulse response
I am traying to perform a simulation in Matlab and I faced up with some practical/theorical problems.
The channel I want to simulate is frequency selective fading. The packets are short compared with ...
0
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2answers
42 views
Meaning: channel unknown and known at the transmiiter
What does "channel unknown" and "known at the transmitter" mean?
In books about signal processing, it has always mentioned it if capacity or transmission (estimation) is discussed. I can't understand ...
0
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0answers
29 views
Time variant frecuency selective fading in matlab
I am traying to simulate a frequency selective fading channel in Matlab and I have faced with some issue/questions during the implementation.
It is a DSSS (BPSK) modulation and the code is organized ...
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0answers
14 views
How to estimate the channel in DS CDMA system
I am working with DS-CDMA system based on multi-path Rayleigh channel,My question, how can I estimate the channel from the received signal to cancel the effect of channel?
for example in OFDM system ...
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0answers
51 views
How to generate rayleigh fading coefficients in matlab
I want to calculate received SNR for each cellular user CUs, so i want the corresponding transmission power P of base station BS to each user, the noise, and the channel gain coefficient of the ...
0
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0answers
9 views
I don't know why the packet size is considered in this packet reception probability equation
https://www3.nd.edu/~mhaenggi/pubs/broadnets04.pdf
In 3 page of this paper, the packet reception probability without interference is $e^{-\theta N Ad^2/ P}$. $\theta$ is sinr threshold. $N$ is a ...
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0answers
35 views
Why are the following two packet reception probabilities different?
https://www3.nd.edu/~mhaenggi/pubs/broadnets04.pdf
In 3 page of this paper, the packet reception probability without interference is $e^{-\theta N Ad^2/ P}$. $\theta$ is sinr threshold. $N$ is a ...
0
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0answers
13 views
Smooth Cross-Fading [duplicate]
I want to cross-fade from one signal smoothly to another signal.
Example:
Signal1 = 5
Signal2 = 1
I already looked for algorithms/ procedures but could not find anything helpful. As I am not that ...
0
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0answers
23 views
why if I want to create a rayleigh fading channel with $E[|H_{i,j}|^2]$,I should multiply $\sqrt{\frac{1}{N_R \times N_T}}$?
I want to create a rayleigh fading channel,and my classmate told me that I can create an $N_R \times N_T $ channel $\mathbf H$ with $E[|H_{i,j}|^2]$,that is,$\sqrt{\frac{1}{N_R \times N_T}}\times CN(0,...
0
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1answer
19 views
Small Scale Fading time varying or position varying
I would like to ask how small scale fading can affect a transmission with time.
The particular system is an antenna transmitting an ASK modulated signal at 915MHz and with bandwidth between 200KHz to ...
1
vote
1answer
36 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 ...
0
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0answers
43 views
Two different models of Rician fading
The amplitude of the signal in Rician fading case is characterized by the Rician distribution (let's call this model 1). However, the received power in Rician fading is sometimes modelled as (model 2)...
0
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1answer
357 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:
$\...
0
votes
1answer
28 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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1answer
33 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 ...
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0answers
115 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 ...
0
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0answers
22 views
Channel information from power spectra
Linked below is a previous post regarding a multipath channel.
Equalisation of FFT spectra
I am reusing the images here:
The first image is that of the power spectra when there is no multipath and ...
0
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1answer
72 views
Validating Jakes model in Rayleigh Fading channels
I am trying to validate the Jakes model by comparing the autocorrelation function given by $ \rho(\Delta t ) = J_{0}(2 \pi f_{d} \Delta t)$, where $ f_{d} $ is the maximum Doppler shift, $ J_{0} $ is ...
0
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0answers
34 views
Automotive Radar Simulation
I am looking to simulate a radar channel and a waveform to test some ideas from other signal processing domains on automotive radar.
However, I have no experience with the typical automotive radar ...
-1
votes
1answer
36 views
What's the effect of spread spectrum on frequency- selective channel
In brief, we consider the channel as frequency-selective channel if the frequency of the signal is larger than then frequency of channel.
So, does using the spreading spectrum change the frequency-...
2
votes
3answers
111 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 ...
0
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0answers
61 views
Frequency selective channel modeling using rayleighchan object in matlab
I intend to model a frequency selective channel using matlab "comm.RayleighChannel" object. Consider the following command, which sets the parameters of Rayleigh channel :
...
0
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2answers
313 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.
...
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0answers
25 views
Channel models for wireless body area networks
To transmit a signal over wireless body area network, the signal is transmitted over a fading channel with additive white Gaussian noise. The channel model can be obtained from the IEEE standards. My ...
0
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1answer
288 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
votes
1answer
55 views
Channel estimation
In single-carrier systems, at the receiver, when we need to do channel estimation and equalization? Do we need to do before timing synchronization and CFO correction or before it? And, please let me ...
0
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1answer
45 views
Designing Rayleigh Fading Wireless Channel with particular properties [closed]
I have some information on particular wireless channel between an Access Point(AP) and K users as described in the picture below:
How i can create this channel in Matlab?
0
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2answers
193 views
How to find the instantanous SNR over Fading channel
I would like to prove that the instantnous SNR of flat fading channel
$$y=hx+n$$
is
$$\gamma=\frac{|h|^2}{N_0}P$$
where $E\{z\}$ is the expectation of $z$ and
$$
E\{x\}=P
$$
$$
E\{n\}=0
$$
$$
E\{...
0
votes
1answer
68 views
Error detection and correction algorithms for Wireless Body Area Networks
I am working on transmitting ECG signals over wireless body area network based on IEEE 802.15.4 standard. To reduce the BER and increase the signal reconstruction quality, I think that I need to ...
0
votes
1answer
70 views
channel estimation for cdma
I am looking for a method to make a multi-user channel estimation with CDMA.
Here is my question:
Is there a way to estimate multi-user channels with their spreading codes? If yes, what is the ...
-2
votes
2answers
105 views
Digital communication BER performance
I've searched for the theoretical equations of bit error rate over Rayleigh flat fading channel basically for binary phase shift key and 16-Quadrature modulation but i didn't find them, could any one ...
1
vote
1answer
42 views
Questions about reproducing results of a paper on Communication Systems and Wireless Communication
I'm trying to reproduce the results of a paper on Device-to-Device Communication, channel assignment and mode selection (G. Yu, L. Xu, D. Feng, R. Yin, G. Y. Li and Y. Jiang, "Joint Mode Selection and ...
2
votes
0answers
30 views
Is it safe to call this WSSUS channel a Gaussian process?
BACKGROUND:
Equation (3.6) of Wireless Communications by Goldsmith gives the baseband impulse response of a time-varying channel as:
$$
c(\tau,t) = \sum_{n=0}^{N(t)}\alpha_n(t)e^{-j\phi_n(t)}\delta(\...
1
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0answers
44 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^{-\...
0
votes
2answers
886 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
votes
1answer
484 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
votes
1answer
43 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
95 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
votes
1answer
66 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
votes
1answer
65 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
votes
1answer
780 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 ...
