Questions tagged [multipath]

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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 ...
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20 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 ...
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2answers
70 views

MU-MIMO Sensitivity to Line of Sight (LOS)

Why do researchers talk about MU-MIMO being "less sensitive to line of sight" / "LOS Okay"? For example in this video, time=[00:40,00:42] Similarly, "User separation based on spatial channel ...
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37 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 ...
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58 views

Where in the signal chain is Channel Equalization applied?

I am reading about channel equalization and I am somewhat confused on where in the signal chain channel equalization is normally applied and if it's before or after a correlator detector or matched ...
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33 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 ...
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2answers
89 views

Cross-correlation peaks in acoustic multi-path conditions

Consider a speaker and a microphone are placed in a multi-path environment and the audio signal to be transmitted is LFM(chirp) signal, the time of arrival of the audio signal is computed by cross-...
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2answers
304 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"?
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39 views

How do state of the art echo cancellation algorithms deal with variable propagation times of sound due to multiple speakers or reverberation?

I understand how echo cancellation works with a single speaker and no reverberation (using adaptive filtering and freezing the coefficients during double-talk). However, in cases with more than one ...
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1answer
97 views

Explanation of fractional sampling in OFDM [closed]

What is the concept fractional sampling? Is there a relationship between the fractional sampling and interpolation? And how does the fractional sampling help in convert the SIMO (Signal input multi-...
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1answer
177 views

Is Phase Locked Loop is essential for BPSK signal reception?

I'm noob in DSP studying BPSK communication between speaker and microphone using acoustic signal. I read article of this BPSK communication which says it needs Phase Locked Loop(PLL) sequence to match ...
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369 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 ...
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39 views

Random multipath power and delay generation

I'm trying to simulate an indoor environment that exhibits multipath propagation. However, I don't know how to generate random multipath variables like path power and path delay (power-delay profile)....
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126 views

OFDM in multipath channel simulation in it++

I am trying to simulate OFDM for an multi-path channel. I am using it++ for simulation. ...
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1answer
121 views

How to accurately model wideband RF reflections?

I would like to model a transmitter and received pair, both sampling at the same bandwidth (not clock synchronized), where there are a number of reflectors. The time delay due to the reflectors can be ...
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1answer
95 views

OFDM Times of Arrival of multipath

Assume i have received a known analog OFDM symbol (such the Short-Training-Field (STF) in WiFi systems), call it $s(t)$ with a known DFT per subcarrier, in the presence of multipath and absence of ...
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88 views

Multipath fading in wireless channel - parameter needed

I’m trying to implement in Matlab the magnitude of the channel taps of the wireless communication system that is described at page 23 (Section 2.1.4) in the classic book of D. Tse, Fundamentals of ...
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2answers
150 views

I want to know if there is a practical way to find out if multipath propagation is significant for audio in a given environment?

I am employing audio signals generated by a mechanical press for Blind Signal Separation. But, prior to algorithm application, I need to clarify if the signal strengths coming in multipath (except ...
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293 views

Multipath resistance of spread spectrum systems

I have been reading about various telecommunications technologies and one thing keeps being repeated many times without a clear explanation - that spread spectrum is not only resistant to multipath ...
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116 views

Problem using MMSE estimation of channel frequency response

I need to model the minimum mean square error (MMSE) performance in estimating channel frequency response. I have channel's power delay profile (PDP) as a table with tap delays and powers. The ...
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1answer
96 views

Sound reflections plot

I have sound files that contain recordings of an impulse signal in a room. I'd like to make such a plot from it. I basically want to compare early reflections. How do I go about it? Is just taking ...
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195 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?
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554 views

Effect of pathloss on signal power

Consider I have two transmitters $tx_1$ and $tx_2$ at say a distance of $d_1=5\text{ m}$ and $d_2 = 15\text{ m}$ respectively from a receiver. Now, if I consider the effect of path loss in such a ...
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1answer
282 views

Gaussian, Rayleigh, and Exponential RVs

I am doing some simulations on the performance of OFDM systems in multi-path channels and I am confused about something. It is explained below: Assume that we have a multi-path channel with a number ...
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1answer
59 views

Modeling multipath distortion and shifting by fractions of a sample

I am working on modelling some FM transmitted signals, and I'm trying to figure out how to model the effects of multipath channels. The most obvious method is to delay the signal by some integral ...
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1answer
164 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 ...
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137 views

multipath propagation

i recorded a tone between two devices and applied cross correlation on the recorded and the sent signals. I want to know if there is a multipath effect on my result (on MATLAB). what can i use for ...
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1answer
137 views

Transmit diversity vs multi-path?

Are transmit diversity signal and the multi-path signal same? Multi-path contains LOS+delayed and attenuated/distorted versions of it and transmit diversity signal contains LOS1+delayed LOS2+ +delayed ...
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873 views

Ultrasonic signal detection

I have created a fairly simple TDOA system that uses ultrasonic signals emitted from two speakers to geolocate (relative to the speakers) mobile phones. The two signals are separated by frequency. ...
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1answer
762 views

Simulate a simple multipath channel for OFDM Modulation test. MATLAB [closed]

Hi I need to simulate a simple multipath channel in matlab through which I can send my OFDM transmission signal, I want to test my OFDM receiver design. So far I have: ...
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1answer
7k views

What does the one-tap equalizer used with OFDM accomplish?

I've read that OFDM normally uses a one-tap equalizer. It seems that a one-tap equalizer could only scale and delay a signal. Why is this useful? I thought multipath was handled through the cyclic-...
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2answers
149 views

what does “fixed multipath channel model” means?

I want to check the effect of this channel model on my signal transmitted with "impulse response-Ultra Wide Band" transmission (use very short pulses ~0.5 ns each), but i don't know where to find this ...
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1answer
171 views

Rician factor effect

The Rician factor is the ratio between the mean power of the LOS path to the mean power of all other (non-LOS) paths. Increasing/decreasing this factor means increasing/decreasing the mean power of ...
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2answers
1k views

how to simulate multipath fading?

I want to simulate a multipath fading channel, different amplitude and delay is given. I want to use delay in padding style. I read that the different values for delay like [0 .6 3.1 ...] represent ...
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2k views

Ricean Multipath channel model implementation

I'm trying to implement a multipath ricean channel model. I had found several resources but I'm kind of lost with too much information. What I have from now is the following step: ...
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1answer
181 views

simulating multipath via tap delays in FPGA

I have a Xilinx FPGA running at 200MHz with an ADC and DAC on board. I am taking a 2462MHz sine wave (pretending it is 802.11b chan 11), mixing it down to 40MHz putting it through my FPGA, mixing it ...
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1answer
533 views

Intersymbol Interference — Root raised cosine filter redundant if doing impulse response equalization?

I'm implementing DBPSK (differential binary phase-shift keying) over audio (44.1kHz sample-rate) using software. Eventually I'll use multiple audio frequencies at once, so I'm using FFTs and inverse ...
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1answer
127 views

Question about fading

Could you please help me to answer this question ? We have a Shannon formula for Capacity as \begin{align} C=B\log_2(1+\frac{h*P}{B*N_0}) \end{align} where h is a random variable which denotes the ...
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404 views

modelling wireless multi-path channel - is channel response sum of delta(t-path_delay) or “delta” should be smoothed somehow?

Consider the wireless channel. It is mult-path - means that signal is sum of sent signals with some delay and fadings. The standard models for "impulse response" for multi-path channel in wireless is: ...
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What effect does mutipath have on estimating optimal sampling time using the averaging method described therein

This question takes off from this question regarding syncronization of BPSK signals. For the sake of argument let us assume 10 samples make up 1 bit. One method currently suggested is break up the ...