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14 Threads found on Doppler Ofdm
thanks for the reply. Lets say there's no multipath, strictly only doppler effect. I'm thinking that doppler is just compressing the signal in time, so if I speed up the "time" of the receiver, then doppler corrected. Any thoughts? additional question: suppose I have a satellite link sending an 20-MHz ofdm (64 pt) signal (...)
Hello, I am looking for a MATLAB code for ofdm that introduces doppler effect due to relative motion of Tx/Rx. Thanks in advance
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 of link whjat (...)
doppler shift is harmful for ofdm because you need data bins to be placed exactly on their proper subcarriers for proper demodulation, this is not the case for CDMA, or any other single carrier scheme.
hi , 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
Hi all, 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
Hi all 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 thanks :|
Hi , 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 . Regards Prem
hi all 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; Thank you.
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: Thanks. Added after 5 hours 8 minutes: help me! how to add doppler shift to channel?
doppler has a devastating effect on ofdm signal due to ICI and loss of synchronizarion ,unless adequate compenasation techniques are applied
Othogonality is preserved if the frequency of all subcarriers are matched. So only doppler shift, phase noise or inaccurate frequency estimates could distort the orthogonality of the subcarriers. The orthogonality is more important for ofdmA where different subscribers send interleaved subcarriers. So maintain in a system that all subscibers to
i have question if the mobile channel cause a frequency modulation of the subacarriers in an ofdm based syste? And i want to know what is the physical explanation of the doppler shift from the communications point of view?
in ofdm sytems carrier frequency offset can occur due to doppler shift and local oscillator mismatch. you have understood the first part. When the baseband signal is converted to RF signal at the Tx, there will be a oscillator used to generate the RF carrier wave. Now, at the Rx end, there will be a similar oscillator used, it may so happen that