From the Rx side, assume perfect operation
(1) is the position of time index start for DFT window process of N point (only useful data length) mean as find the first edge of each symbol or some point between channel length
Digital communication :: 12.04.2007 10:26 :: maomun :: Replies: 1 :: Views: 1102
hi udit .. my MS thesis was in channel estimation for ofdm transmission in fast fading doppler channels so that would be phy layer. righ now I am inclined towards getting to know WiMax so want to focus more on mac layer, though interesting ideas in phy are still welcome
Digital communication :: 01.05.2007 12:44 :: goosecool :: Replies: 8 :: Views: 2373
doppler has a devastating effect on ofdm signal due to ICI and loss of synchronizarion ,unless adequate compenasation techniques are applied
Digital communication :: 07.09.2007 05:05 :: sameerbabu :: Replies: 4 :: Views: 2594
Some one have code about ofdm Pilot based channel estiamtion in time domain?
Could you send the to me?I need them urgently. :cry:
My Email: email@example.com
Added after 5 hours 8 minutes:
help me！ how to add doppler shift to channel?
Digital communication :: 29.03.2008 03:14 :: zhouzhou1103 :: Replies: 2 :: Views: 783
Actually if you look at the frequency domain plot, the peak of one carrier is on the point where the the two carriers; one on its right and one on its left have their zero crossing. And you know at zero crossing they would contribute to zero energy to the center carrier, And this is how, even after 'overlapping' they dont mix.
In fact if you loo
Digital communication :: 10.03.2009 03:48 :: Communications_Engineer :: Replies: 6 :: Views: 3460
I am working on ofdm systems. I have come across a paper on channel estimation methods for ofdm systems . In this paper it was mentioned that , BPSK modulation doesn't require the traking even in a time varying channel .
would any one please explain the reason behind this ..
Thanks in advance .
Digital communication :: 30.06.2009 13:34 :: premkiran :: Replies: 1 :: Views: 1019
I want a sample source code in matlab for simple ofdm modulation that shows the doppler shift effect
I have some source codes for ofdm but none of them has the doppler effect
I'm wondering if anybody can help
Digital communication :: 22.03.2010 00:38 :: fallingrain_83 :: Replies: 0 :: Views: 2206
For what kind of application you use doppler signal? Sound, radar, WLAN?
Digital Signal Processing :: 15.07.2010 04:10 :: hakeen :: Replies: 3 :: Views: 1593
I'm performing ofdm equalizer for a pilot assisted system. The system parameters are:
Signal BW = 6 MHz
Carrier = 700 MHz
chip rate = 5.55 MHz
doppler shift corresponds to max 200 km/s receiver speed
Fading channel is a Rayleigh fading channel, the problem is that when I apply the channel to signal, the channel has a very ra
Digital communication :: 08.02.2011 11:32 :: Ahmed Alaa :: Replies: 0 :: Views: 518
frequency offsets are due to channel delay spread (coz of channel impairments ) and doppler spread ( movin vehicles)
suppose ur upconvertin RF frquency is @ 2 Ghz and IF :100 MHZ , ur transmitting frequency will be 2100 MHZ
so if ur channel delay spread is say 10 HZ
ur recieved signal at RX will be 2100. 000 010 hz , ur receiver d
Digital communication :: 17.03.2011 01:00 :: watsup :: Replies: 1 :: Views: 410
hi, i'm doing a comprfassion between ofdm and cdma.
doppler spread destroy the orthogonality between the sub carriers in ofdm and cause ICI.
but i cant figure if and how doppler spread effects CDMA (not MC CDMA but DS CDMA) i mean, every user spread its information with PN code on all the BW
can somone explein how and (...)
Digital communication :: 12.08.2011 11:56 :: sdahan112 :: Replies: 3 :: Views: 679
frequency offset (FO) occurred by the mismatch between the oscillators in the transmitter and receiver or doppler frequency and it can cause performance degradation or we can say it can increase BER
Digital communication :: 03.12.2011 04:59 :: cokibolong :: Replies: 3 :: Views: 558
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 of link whjat (...)
Digital communication :: 20.02.2012 01:46 :: Sherra :: Replies: 0 :: Views: 314
i have a bad problem with my code ....
First of all i write a matlab code for ofdm-CDMA system. the following picture shows the structure of the system :
but unfortunally the results for BER not stable .
for doppler frequency = 0.0001
Digital communication :: 06.03.2012 13:19 :: ammaralwazzan :: Replies: 5 :: Views: 1079
The following code gives higher BER than the theoretical.
Can anyone help me why? and give me the way to modify the code.
code of BPSK- ofdm
nFFT = 4; % fft size
nDSC = 4; % number of data subcarriers
nBitPerSym = 4; % number of bits per ofdm symbol (same as the number of subcarriers for BPSK)
Digital communication :: 15.04.2012 19:36 :: ReComm :: Replies: 6 :: Views: 620
i am working on MC-CDMA channel estimation
cdma + ofdm(802.11a)
i try two types of channel estimation : Block type and Comb type
i am using MATLAB built in function (rayleighchan) more specificlly (stdchan) as follow:
bitrate = 20000000; % Bit Rate
Digital communication :: 28.07.2012 03:07 :: ammaralwazzan :: Replies: 3 :: Views: 609
I used an matlab example " syncCarrierFreqMSKSignalRecovery" to construct my model
and apply it for QPSK system,it works . but when i applied it to ofdm-QPSK , it doesn't work. Kindly advice
nBitPerSym = 64; % number of bits per ofdm symbol
nSym = 10^3; % number of symbol
Digital communication :: 10.10.2012 20:17 :: ReComm :: Replies: 0 :: Views: 683
Please anyone help me for correcting the program given below. its very urgent.:cry:.....thanks in advance.
=SUI_fading(Power_dB,K_factor,doppler_shift_Hz, Fnorm_dB, N, M, Nfo
Digital communication :: 29.10.2012 11:19 :: MATHU :: Replies: 0 :: Views: 211
I am looking for a MATLAB code for ofdm that introduces doppler effect due to relative motion of Tx/Rx.
Thanks in advance
Digital communication :: 29.10.2012 17:26 :: David83 :: Replies: 0 :: Views: 307
I have simulated a certain wireless communication system in doppler fading channels. However the simulation results (BER vs. SNR) are different from the other books and papers, even the channel parameters and demodulation techniques are the same.
Is this a serious problem, or this kind of difference is popular when channel model( just model, no
Digital communication :: 30.03.2006 02:49 :: carpa :: Replies: 4 :: Views: 1118
I will want to study ofdm with time varying channel. I have a question.
As Rayleigh makes it possible to simulate time varying channel, why in the articles I find models defined by authors (pdf of doppler and delay spread)?. and how to use these functions in simulations?
that really blocks me;
Digital communication :: 19.08.2008 09:37 :: karene :: Replies: 0 :: Views: 639
Could someone help me on this, please
I am studying about the newly developed non-linear phase Generalized DFT proposed by Akansu.
(It's not that long, if you have time, please help)
The system is basica
Digital communication :: 06.02.2010 11:48 :: fgifriday :: Replies: 1 :: Views: 1229
I am working on the evaluation of the effects of interference on DVB-T using matlab/simulink, and need help on analyzing the effects. The only area i could reference to is the variation in the SNR using the AWGN and the doppler shift using rayleigh. I will appreciate anyone who can help in this area.
---------- Post added a
Digital communication :: 07.03.2012 17:04 :: engrleshawn :: Replies: 3 :: Views: 2593
I am using MATLAB's Rayleighchan function to simulate a fading channel. My ofdm system chip rate/Sampling rate = 5.55 MHz, but giving this rate to the function will cause an 'Out of Memory' error, so I enter a sampling rate of 4096 Hz and normalize path delays to this by multiplying path delays by 5.55 MHz / 4096 Hz.
My Question is:
Digital communication :: 08.05.2011 12:58 :: Ahmed Alaa :: Replies: 0 :: Views: 610
I do have problems implementing a 2x1D Wiener-Filter as channel estimator for an ofdm-System. I use the concept introduced in the following
Digital communication :: 02.04.2012 04:59 :: giny :: Replies: 0 :: Views: 472
I know this thread isn't very concern with digital communication, but my main goal is to simulate an ofdm system. So if anyone familiar with parallel computing this is my problem and. I think it is simple. In one of my functions I am using parfor loop and it working well ,improving by 50%.
I defined NumOfWorkers = 8
And launched "matl
Digital communication :: 21.04.2012 16:45 :: WUID :: Replies: 0 :: Views: 231