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54 Threads found on Fading And Multipath
I recall these terms are used different channel models for different fading types from self interference or multipath or Ricean or Raleigh, or block type low SNR channels, so that redundancy and forward error correction can be optimized for maximum code space distance of unexpected xy values are balanced or optimized with consecutive symbols (...)
Hi, In these two pages, Ts(t) and Tc(t) are the sums of sinusoidal waves with random phase, so the mean value in time ==0 Can you explain to me how the variance in time of Ts: =Eo/2 ? As I understand Ts(t) and Tc(t) are already the sums of random values so Ts(t) and (...)
The path loss equation is well known and there is a tradeoff with the Signal Bandwidth, SNR and BER. In case you forgot or are just learning, for 1Km distance the IDEAL path loss neglecting moisture loss and fading loss ( deadspots from multipath cancellation) f (MHz) 1km 100m Path (...)
Hi,I took 64 subcarriers outof which 52 are used.I find channel response.Now channel output is cconv of fading channel output and transmitted output.I stucked at this point.Here is my code.can any one please help me clc close all clear all nFFTSize = 64; % for each symbol bits a1 to a52 are assigned to subcarrier % index [-26 to -1 1
why there aren't multipath fading when rain? The multipath phenomena mostly occur for indoor or in-town propagation when signal power is relatively high and reflecting objects are close to signal propagation path. Rain causes a dispersion resulting in an additional loss and depolarization. (...)
For a given frequency, range to transmitter and velocity of the receiver how to determine the time interval at which the multipath environment may be assumed as constant, stable? I.e. when there are no even fast fading, when the number of paths and their delays and amplitudes dont change? Thanks. The time (...)
Could you pls answer the controversial concept of multipath fading usage in mimo and ofdm. They say that they need fading for mimo as high as possible for channel estimation. Whereas for ofdm they say that they use ofdm to mitigate multipath. What could it be???
There might be a multipath fading between transmitter and receiver.If there are some objects that reflect the signal with a time delay that is very difficult to observe with an oscilloscope, it may create a perturbation on received signal. Just an idea...
Hi, I am simulating the fading effect of multipath in wireless communications. I am using a contributed model in opnet the model ID- 418, Any one used this before can you please answer my questions 1.I am getting a very high spike for an instance for the nearest node why it is so? 2. how can see the SNR and BER curves, which i cannot see (...)
Hi friend, Its better to take a project on Optical CDMA. In a single channel, shared medium, wireless network the state depends on the channel conditions. The wireless medium is much noiser than the wired medium due to fading (slow and fast), multipath effects and frequency selective fading. In wireless (...)
Hi All, I would like to include Doppler shift to a 2x2 multipath MIMO-OFDM channel because i am considering fastfading channel instead of block fading channel. How do I implement this? Do I have to "cut" my OFDM symbol into several parts and at each part apply a different channel/? If so, those channels need some kind (...)
Dear All; I would appreciate your help. I have been reading one of publication entitled "A Matlab-based Object-Oriented Approach to multipath fading Channel Simulation" available to download from Mathwork website. This look at the theory behind Matlab Rayleigh and rice multipath fading simulator. (...)
Hi all, I entered a discussion with a colleague about the reason of fading, I always understood that the constructive and destructive interference of multipath components and moving along a spatial pattern of destructive and constructive interference will result in a time varying channel. Butmy colleague (...)
Why not? In practice matched filter is still applied, because in flat fading channels the fading effect will be multiplicative, i.e.: the received signal will be r=h.s+n. In (baseband) simulation you just multiply the received signal by h* and compare the result with 0, if it is >0 decide 1 and if it is <0 (...)
rayleigh channel is the basic channel model. The preferred ones are Ricean and Nakagami which offer more flexibility. Rayleigh has a single parameter, teh nakagami and rice have tow parameters and can more closely correlate to a fading channel. e.g. r(t)= a+b*e(-j2pift) has an attenuation component "a" and (...)
"permute" is right... its a model...but a bit of correction here: channel is convolved in both the cases of BPSK and OFDM!! fading comes from multipath phenomena. i.e multiple copies of the same signal arriving from different paths. constructive/destructive addition on the reciever leads to amplitude fluctuations which we call (...)
Hi all. I am trying to simulate a fading multipath Rayleigh channel and I need the channel gains for channel tracking of the OFDM system... I was referring to this thread: I tried this simulation. All parameters have been defined, fftleng is
can anyone tell me how to create rayleigh fading effect for cellular channel from rayleigh pdf. Both tx and rx are stationary, still there will be attenuation and phase change due to multipath signal. these changes are model by rayleigh fading. so can anyone help me out to understand how i (...)
Hi, I need some profiles for the path gains and path delays that are common for Rayleigh and Rician fading mobile channels. Thanks.
Hello, I am implementing OFDM in frequency domain and run it under multipath fading, and to mitigate the effect of multipath I have done channel correction by multiplying the received signal by the phase of channel response (h). But that not enough to reduce the MP effect I need 1-tap equalizer: I read (...)
Hi Everbody, I need your help I am not good at matlab/simulink, My Problem is about multipath Rayleigh Channel BER Calculation in Simulin/matlab. BER Results are for the below cases; Generating Data:Bernoulli Binary Generator Modulation:QPSK Modulator Channel:Rayleigh fading and AWGN Equalizer:LMS Based Equalizer Demodulation:QPSK (...)
I am trying to build 16QAM Transmitter/Receiver in multipath fading channel, First I need to transmit Packet of 1500 bytes (12000 bits) through the channel and plot the BER. Then I need to transmit the same Packet of bytes + 20 additional bytes (12160 bits) and plot the BER. The problem is that I need to transmit both (...)
hi, I am new to matlab and i need to simulate, Matlab program to simulate a two path Rayleigh fading channel (using Rayleigh random variable generator of Matlab) with 2 micros time delay and the second path has 3dB lower power than the first path. Without using commands from communication (...)
hi i want matlab file or good paper in the following area: "multipath rayleigh fading channel modelling"
i read that in UWB-IR communicatiions MODULATION RESOLUTIONS LEADS to elimination of significant multipath fading. Can any1 help me to understand what is modulation resolution means and how wil it help to remove multipath fading. .... help me to understand the basics (...)
There are a lot of factors influencing a wireless transmission and here are some of them: propagation, fading and multipath, receiver desense by multiple factors (internal or external), nearby frequency interferers (as adjacent, alternate, blocking, etc), frequency stability, modulation distortions (as phase error, EVM, etc).
Hello~! I'm studying priciple of OFDM. OFDM is crucial in multipath fading environment because it has ability to resolve selective fading channel into flat fading by one-tap equalizer. Then, in AWGN environments, is it no benefit using ofdm? Does it mean that both non-ofdm and ofdm system has (...)
Hello, In a multipath fading channel, we know that the transmitted signal travels over different paths subjected to different attenuation and delay factors. The receiver combine all these signals together as a superposition. The question is: why the receiver has to wait until all replicas are recieved, or wait a specific amount of time (...)
I want to study the impact of diverse multipath fading over communication channels and how Tubo codes can help to decrease its effects. Can anyone send me or give me the link where can I find a model of PCCC turbo encoder/ decoder for QPSK in simulink or matlab function? Thank you!
Hi, I would like to know if it is possible to simulate a multipath rayleigh fading channel without simulink, in matlab and, also, can any one please give me an example of simulation of multipath rayleigh fading channel in Simulink, with a OOK Sine wave passing through the channel? Thanks
Hi, I am designing an RF repeater at 5.8 GHz for point to point link. Can anybody tell me about how to select the transmit and receive frequency of the RF repeater? should they be same or different? How to mitigate multipath effects and fading? Do anybody has any circuit diagram for that? what kind of configurations (...)
The Matlab simulink model is attached below. After add the AWGN and multipath fading, the constellation is messy. and then i add the MLSE equalizer, the constellation seems ok, but the rx data rate seems half below the tx data rate. Please help to find the reason, 3x. B. R. Eric
Receiver Static Sensitivity is the sensitivity without multipath (fading and reflections), and Dynimic Sensitivity is the RX sensitivity using a multipath environment (when the mobile is moving).
What is: Polarization, Direction of Propagation, Line-of-Sight, Fresnel Zone, Space Loss, Absorption, Ducting, Scattering, Reflection, Refraction, Diffraction, multipath, fading, etc.
hi I want to add multipath fading(frequency selective) in my signal. can any body help me for doing this using tap. bari
Hello, What is the difference between fading and multipath, and what is the relation between them? Thanks in advance
MIMO it self is a good technique to achieve diversity gain at receiver, which basically increase the reliability of system as well SNR margin. Addition to the above comments, OFDM also has a good flexibility over the multipath fading channels. It uses frequency very efficiently (think about FDM) and require no hardware wise filtering but (...)
I'm a begineer in Microwave link planning. Can somebody give me some nice books or tutorials covering all aspects of microwave planning specially link planning issues like multipath fading, frequency planning and interference. Also if somebody can share tutorials about how to use path loss.
Can any one help me to understand the difference between the following terms in wireless communication: 1- Inter Symbol Interference(ISI). 2- fading. 3- Doppler Shift. Thanks in advance
Hi, Could you please help me how to use the Maximum Ratio combination in multipath Rayleigh fading channel, using Matlab comands, and have a look for the program bellow you will see the error that I have, and could you tell me the problem, and how to solve it. clear all whos (...)
Rake receiver: A rake receiver is a radio receiver designed to counter the effects of multipath fading. It does this by using several "sub-receivers" each delayed slightly in order to tune in to the individual multipath components. Each component is decoded independently, but at a later stage combined i
Hello!! I'm trying to implement a DVB-T simulation based on the avaiable demo of simulink but with the addition of mobile channel before AWGN: multipath Rayleigh fading Channel. In the beginning I used the complex gain path port from the multipath rayleigh block to perform my channel estimation and then equalize. But I'm (...)
Hi, Could you recommend a good book on the topic of RF propagation. Specifically on topics such as fading, and multipath effects. If the book is available as an ebook it will be great. Thanks in advance Slayerza
hi, can any one ps send me the follwoing springer document PERFORMANCE ANALYSIS OF CHANNEL ESTIMATION FOR LDPC-CODED OFDM SYSTEM IN multipath fading CHANNEL" By Zhu Qi , Li Hao and Feng Guangzeng Journal of electronics, Volume 23, Number 6 / November, 2006 ISSN: 0217-9822 (Print) 1993-0615 (Online) DOI: (...)
hi freind. when signals arrive from different way and different direction to receiver, the phase of signals from different way will becom different , so if sum of these phases are constructive, the amplitiude of signal will high. and if sum of these phases are deconstructive, the amplitiude of signal will low. this phenomena is variable with tim
MATLAB Release: R14 Required Products: Communications Blockset,RF Blockset,Signal Processing Blockset,Simulink Description: This Simulink model simulates the entire transmission and reception of voice data of a traffic channel for GSM (TCH/FS)over a multipath fading channel, and it calculates the BER of the received (...)
The book "Wireless Communication: Principles and Practice" deals with Mobile Radio Propagation: Large Scale Path Loss and Small Scale fading and multipath. This deals in some detail about propagation models used for wireless mobile technology. Refer that book. M
I'd like to ask for your advice. You see, I simulated BPSK passband signal, then I created flat Rayleigh fading and created multipath signal with no delay of the 4 paths so that the fading would be flat. But something's wrong with it though I based by simulation on theory. Because when I use coherent (...)
They are not the same but the consequences are almost the same if the transmission uses a narrow bandwidth. Narrowband Interference usually is a continuous wave (CW) near the center frequency of the receiver when Frequency Selective fading represents dips or fades of the signal due to multipath reflections. Both can be (...)
dear friends, i'm currently implementing a simulation of a MIMO correlated fading channel, and it's based on a paper by "ben letaief" in IEEE which basically separates the transmitter correlation and receiver correlation respectively and puts into account the effects of multipath and a (...)