## Forums Search for: OFDM

## PSD in ZP-OFDM and CP-OFDM

inHi all.... I just simulated the Zero-Padding OFDM and Cyclic-Prefix OFDM system... I found some difference between their power spectrum...

Hi all.... I just simulated the Zero-Padding OFDM and Cyclic-Prefix OFDM system... I found some difference between their power spectrum density... In CP-OFDM, the in-band ripple is larger than ZP-OFDM... But in out-of-band, the ZP-OFDM is larger than CP-OFDM.... I just got the conclusion through simulation... How could i explain the phenomenon in physical or math. sense.... Anyone can tel...

## OFDM with Pilots

inHi I am new to OFDM and wideband communication in general. I went through the tutorial on OFDM at www.complextoreal.com. I have understood the...

Hi I am new to OFDM and wideband communication in general. I went through the tutorial on OFDM at www.complextoreal.com. I have understood the concept of orthogonality and how it works in OFDM, however I am not so clear about the use of pilots in OFDM. Can anyone guide me to some resources which explicitly explain what a OFDM pilot symbol is, with examples, and how it helps in frequency estimat...

## ofdm frame

inHi friends I have doubt in mind. I always read about OFDM frame where in each OFDM frame consist of 2 or 1000 or ...... OFDM symbols. Why...

Hi friends I have doubt in mind. I always read about OFDM frame where in each OFDM frame consist of 2 or 1000 or ...... OFDM symbols. Why OFDM signal is transmitted in frame format ? Why OFDM does not transmitted in each OFDM symbol ? Many thanks in advances. Regards, Wiwi

## OFDM Implementation (DVB_T)

inHello All I am looking to implement an OFDM system in VHDL on a DVB-T system. I have designed a 16-QAM block with outputs of a 3 bit binary bus...

Hello All I am looking to implement an OFDM system in VHDL on a DVB-T system. I have designed a 16-QAM block with outputs of a 3 bit binary bus for I and Q. I know want to build the OFDM block. I am looking as how to convert I and Q into a complex number I+jQ so I can buffer that up to push through the IFFT. This willl then output an OFDM value for I(OFDM) and Q(OFDM). Can anyone offer ...

## IFFT in OFDM

inDear sir / Madam, I am doing M.E in Communication system, i have gone through the concept and fundamentals of OFDM first time , but i could...

Dear sir / Madam, I am doing M.E in Communication system, i have gone through the concept and fundamentals of OFDM first time , but i could not understand the process of IFFT in OFDM modulation, why FFT is not taken at the first stage? if any kind personality explains the concepts behind the IIFT in OFDM, which will helpful for me to understand better. How can i get e-version of any OFDM text...

## Q) OFDM and BER verification

inHello. Could I have some help & discussion please? I built an OFDM simulator with IEEE 802.20 channel model. But, I'm not sure if my BER...

Hello. Could I have some help & discussion please? I built an OFDM simulator with IEEE 802.20 channel model. But, I'm not sure if my BER results are correct or not. Thus, I checked BER of OFDM in AWGN first. Then, I checked BER of OFDM in very very low bit rate. For example when a channel shows rms delay spread of 0.37usec, I tested with Rb = 1E4 bps. Then, I checked BER of OFDM with ...

## OFDM vs DMT

inHi, What is the difference between DMT and OFDM. Why isn't OFDM used in the xDSL technologies? If I have to guess the difference, I think...

Hi, What is the difference between DMT and OFDM. Why isn't OFDM used in the xDSL technologies? If I have to guess the difference, I think that OFDM has several carrier frequencies that are orthogonal. DMT I think uses carriers seperated by some space on the frequency spectrum. Kind Regards, Jaco

## Cylic prefix and postfix

inLet's say my transmittid frame is like this: || Preamble || GI1 | OFDM symbol 1 || GI2 | OFDM symbol 2 || Removing GI1 would remove any...

Let's say my transmittid frame is like this: || Preamble || GI1 | OFDM symbol 1 || GI2 | OFDM symbol 2 || Removing GI1 would remove any interference effects caused by the preamble. But what if the last few samples of OFDM symbol 1 is interfered by GI2? Wouldn't a structure like this: || Preamble || GI1 | OFDM symbol 1 | GI1' || GI2 | OFDM symbol 2 | GI2' || With GI1' and GI2' p...

## OFDM sychronization implementation?

inHi all, How to achieve synchronization(carrier phase timing) in ofdm? did ofdm need a pilot?

Hi all, How to achieve synchronization(carrier phase timing) in ofdm? did ofdm need a pilot?

## waterfilling for single user ofdm

inHi, i'm trying to simulate waterfilling for single user ofdm in matlab. i can't seem to find any reference on this topic as most papers deal...

Hi, i'm trying to simulate waterfilling for single user ofdm in matlab. i can't seem to find any reference on this topic as most papers deal with multiuser or multiple access ofdm system. Papers which mentioned watefilling for single user ofdm stopped short at providing simply the formula and not the implementation. im new to waterfilling and ofdm and thus need some help. I understand that f...

## OFDM Simulation & understanding

inHi, I would like to understand more and more about OFDM and its applications for my work. I need to simulate it with Matlab. If possible,...

Hi, I would like to understand more and more about OFDM and its applications for my work. I need to simulate it with Matlab. If possible, could you supply me matlab code which will be enable me to simulate OFDM ( that will be very helpful for understanding OFDM and its concept). Thx in advans, Karthik Balaguru

## Channel tracking in an OFDM system

inHello, I am trying to design an adaptive equalizer for an OFDM system which has an extremely low symbol rate. I have a question regarding...

Hello, I am trying to design an adaptive equalizer for an OFDM system which has an extremely low symbol rate. I have a question regarding this. The transmitter and the receiver are moving wrt each other. For what amount of relative motion between them in one OFDM symbol period (as a fraction of the carrier wavelength) can I assume that the channel is reasonably correlated across OFDM symbols...

## OFDM/DFT/Sampling question.

inHello, I am pretty confused with some DFT/Sampling techniques and how these apply to OFDM. Fundamentally, if a (baseband) signal has a...

Hello, I am pretty confused with some DFT/Sampling techniques and how these apply to OFDM. Fundamentally, if a (baseband) signal has a highest frequency component of f Hz, that signal needs to be sampled at 2f Hz for aliasing-free data reconstruction. My confusion begins with OFDM, which does the process in reverse. That is IDFT is performed first. So, in OFDM, the output of the IDFT blo...

## some good papers on OFDM/MIMO-OFDM

Hi All Can anyone please suggest me some good papers/books on OFDM and MIMO-OFDM. Of course, I did google it but the problem is that so...

Hi All Can anyone please suggest me some good papers/books on OFDM and MIMO-OFDM. Of course, I did google it but the problem is that so much of stuff is out there that it is difficult to pick the right one. Thanks. Chintan

## Measuring PAPR of OFDM signals

inHi there! I am working on PAPR measurement of OFDM signals connected to a RF amplifier.I created the OFDM signal from a signal studio. Then the...

Hi there! I am working on PAPR measurement of OFDM signals connected to a RF amplifier.I created the OFDM signal from a signal studio. Then the signal is connected to RF amplifier and with the spectrum generators to see the input OFDM spectrum and output OFDM spectrum. The generated OFDM Spectrum from the Spectrum generator is stationary or it is changing for a particular input power of RF ...

## OFDM system

inHi, It is clear that OFDM systems may have different SNR values for each subcarrier due to frequency selectivity of the channel. If an OFDM...

Hi, It is clear that OFDM systems may have different SNR values for each subcarrier due to frequency selectivity of the channel. If an OFDM packet consists of n number of FEC blocks and in case of adaptive modulation and coding systems, a single FEC block may have different modulation scheme. However, is it possible for OFDM (e.g.IEEE 802.11a/n) systems that the block error probability of FEC b...

## DAC Output Level in OFDM Signal

inHi All, I'm having trouble making an analog conversion of OFDM signal using DAC 904E from Burr Brown. The DAC works fine, I have set up a...

Hi All, I'm having trouble making an analog conversion of OFDM signal using DAC 904E from Burr Brown. The DAC works fine, I have set up a digital sine signal and when I looked at the osciloscope and spectrum analyzer it has 600mVpp and 0dBm power with good spurious performance in the baseband bandwidth that I want to use for OFDM (0-4MHz -- OFDM bandwith is 7MHz) with adequate sampling rate in ...

## MB-OFDM-UWB

inI want to simulate a MB-OFDM-UWB system in Matlab. I did pure OFDM system before which consist of convolution code block, modulation block,...

I want to simulate a MB-OFDM-UWB system in Matlab. I did pure OFDM system before which consist of convolution code block, modulation block, FFT block, Cyclic Prefix block, multipath block and corresponding receiver blocks. However, how to modify them to a MB-OFDM-UWB system, what kind of block I need to add into? thank!

## IFFT & DAC in IFFT

inHi, I am doing project in OFDM .I have doubts regarding the functionality of IFFT & DAC in OFDM TX. In OFDM block Where the carrier comes...

Hi, I am doing project in OFDM .I have doubts regarding the functionality of IFFT & DAC in OFDM TX. In OFDM block Where the carrier comes into picture?. After IFFT what is exactly done in DAC block?. There we are using any carrier suppliers?. IF possible anybody can explain the flow of data in OFDM Tx. can anybody help me out regarding the above queries. Thanks & Regards Lakku Raji...

## Trouble in generate SER in OFDM

inhi all , Recently , I have generated a OFDM signal , but meanwhile I have noticed that my Analytical & Computer Simulation of my SER are...

hi all , Recently , I have generated a OFDM signal , but meanwhile I have noticed that my Analytical & Computer Simulation of my SER are totally difference, Moreover , the Numbers of Errors in my signal also quite large, therefore i am wondering whether there are some Errors in my signal detection or the progress of generate OFDM signal. Actually I should generate channel estimation of OFDM sig...