## Forums Search for: OFDM

## OFDM Transceiver code

inThis code was used for making the practical measurements in section 2.3 of my thesis. This Matlab code allows an OFDM signal to be...

This code was used for making the practical measurements in section 2.3 of my thesis. This Matlab code allows an OFDM signal to be generated based on an input data file. The data can be random data, a grey scale image, a wave file, or any type of file. The generated OFDM signal is stored as a windows wave file, allowing it to be viewed, listened to and manipulated in other programs. The modif...

## EVM in OFDM

inMeasuring the RMS EVM of the underlying modulation in an OFDM signal is straight forward. However the accuracy of the EVM appears to be...

Measuring the RMS EVM of the underlying modulation in an OFDM signal is straight forward. However the accuracy of the EVM appears to be affected by the number of null tones present in the OFDM FFT. In other words if there are no null tones, then the EVM measurement is as expected and as the number of null tones increases the EVM measurement diverges from expected. Does anybody know of any lit...

## Two questions about OFDM

inSome articles say that an OFDM system will reduce the symbol rate through parallel data transmission. Is this really true? Let's say suppose...

Some articles say that an OFDM system will reduce the symbol rate through parallel data transmission. Is this really true? Let's say suppose there are 100 subcarriers in an OFDM system and the data rate before the IDFT is 100 symbols per second. It seems to me that, after IDFT, each subcarrier only transmits one of the 100 symbols in 1/100 second like this: 1st subcarrier: 1/100 idle ...

## Do we have to use null tones in OFDM modulation?

inHi there, I have a question on OFDM. As we know, most OFDM systems nowadays do not use all the available tones (subcarriers) for data...

Hi there, I have a question on OFDM. As we know, most OFDM systems nowadays do not use all the available tones (subcarriers) for data modulation. Let us say we have 64 tones in total and we might end up with 48 data tones, 4 pilot tones, 3 DC tones and 9 null tones, which is kind of an typical setup. My question is regarding the null tones, which are usually placed on the two boundaries...

## MATLAB OFDM Simulation

inDoes anyone know if there is a OFDM simulation in matlab is possible? If anyone has it, can you please share it with me. I have a final sem...

Does anyone know if there is a OFDM simulation in matlab is possible? If anyone has it, can you please share it with me. I have a final sem project that's due next week and am going crazy over this coding. SOS! Thanks.

## book for OFDM

inplease i need your advice 1_what the best book that explain the idea of OFDM 2_ what is the best book for matlab for digital com

please i need your advice 1_what the best book that explain the idea of OFDM 2_ what is the best book for matlab for digital com

## WLAN modeling and OFDM

inHi guys I've got my OFDM system up and running in MATLAB. Now I want to parameterize it in terms of BW and T_s etc. I want to use the WLAN...

Hi guys I've got my OFDM system up and running in MATLAB. Now I want to parameterize it in terms of BW and T_s etc. I want to use the WLAN channel model but I don't know how many tabs the channel length should be and what the gains are. Can anyone help on this? thanks

## OFDM or SC-FDMA

inHi All, 1) I want to implement MODEM with 128Kbps at 100Khz with high doppler shift channel. Which modulation technique would be suitable...

Hi All, 1) I want to implement MODEM with 128Kbps at 100Khz with high doppler shift channel. Which modulation technique would be suitable . Whether I can go with OFDM or SC-FDMA? Any suggestions 2) Is it possible to simulate 128Kbps with Matlab Thanks & Regards, Ammankumar.S

## SINR estimation in OFDM systems

inHI, here People usually estimate the SINR in the OFDM systems in the following way. 1. Estimate over each specific pilot subcarrier of...

HI, here People usually estimate the SINR in the OFDM systems in the following way. 1. Estimate over each specific pilot subcarrier of different OFDM symbols. (i.e. CINR estimation) 2. Then average over all pilot subcarriers (i.e. average CINR) to approximate the SINR. The problem is, most CINR estimation algorithms are based on a simpliied channel model assumption. That is, "y = h*a +...

## OFDM transmission under rayleigh fading

Hi all, I would like to find theoretical 802.11g BER performances in the case of a transmission under rayleigh channel. I found theoretical...

Hi all, I would like to find theoretical 802.11g BER performances in the case of a transmission under rayleigh channel. I found theoretical M-QAM curves, but I don't know how to compute BER curves for OFDM transmission due to the use of several sub-carriers... Is the OFDM BER something like that: BER = (1/N)*SUM(BER_i, i=1..N) where N is the number of sub-carriers and BER_i the BER on e...

## OFDM & Simulink

inHi to everybody, I'm a new user of this forum; I'm trying to realize a model in simulink with I can simulate an ofdm trasmitter and receiver. I...

Hi to everybody, I'm a new user of this forum; I'm trying to realize a model in simulink with I can simulate an ofdm trasmitter and receiver. I have seen the model proposed from mathwork and I want to insert the effect of a channel and not only the noise; Has anybody any information about this task? Thanks, AlexGiul

## Digiatal Sampling correction Interpolation/Decimation for application in flexible OFDM Modem.

inHi all, My project is Digiatal Sampling correction Interpolation/Decimation for application in flexible OFDM Modem. I'm implementing in Matlab...

Hi all, My project is Digiatal Sampling correction Interpolation/Decimation for application in flexible OFDM Modem. I'm implementing in Matlab the 5_taps optimized interpolator which will improve the performance for long data OFDM bursts. I used control parameters basepoint index (m(k)) and fractional interval (mu(k)) (reference to FM Gardners article "Interpolation In Digital Modems---PART...

## 802.11a PLCP training sequence question

inI have a question that why in 802.11a IEEE standard, the PLCP long training sequence takes the GI2(Guard interval 2) as the prefix of two OFDM...

I have a question that why in 802.11a IEEE standard, the PLCP long training sequence takes the GI2(Guard interval 2) as the prefix of two OFDM symbols, not one GI before one OFDM and the other GI before the second OFDM symbol? What is the advantage of that?? The following includes the IEEE 802.11a 1999 version: http://standards.ieee.org/getieee802/802.11.html Thanks.

## Conv. coding with ofdm in flat rayleigh

inHi all, I tried to simulate the bit error rate performance using bpsk with convolutional code: R=1/2, K=7, generator polynomials (133,171) in...

Hi all, I tried to simulate the bit error rate performance using bpsk with convolutional code: R=1/2, K=7, generator polynomials (133,171) in AWGN and the performance using bpsk ofdm with the code in AWGN. I got the same ber curve for both cases, which showed some advantage or gain after using the coding However, when I simulated the bpsk ofdm system using the conv. code in flat rayleigh, I ...

## ofdm:cdma

Hello i need a matlab code about combinaition of OFDM/CDMA

Hello i need a matlab code about combinaition of OFDM/CDMA

## OFDM Modulator

inhi everyone Im devloping an OFDM modulator using DSP techniques, with the following specifications: Bit rate = 16Kbs/s 16...

hi everyone Im devloping an OFDM modulator using DSP techniques, with the following specifications: Bit rate = 16Kbs/s 16 sub-carriers QPSK 8 Bit Resultion DAC can anyone help regarding how to start the matlab program for this project.. thnx best regards Omar

## Oversampling in OFDM

inHi, I have a question related with the OFDM transmitter. What is the commonly method to increase the sampling rate ? - Increasing the IFFT...

Hi, I have a question related with the OFDM transmitter. What is the commonly method to increase the sampling rate ? - Increasing the IFFT size and insert zero in the inpput ? or - Insert zero in the IFFT output and followed by interpolation filter ? What is the trade-off ? anyone can help ? Thanks. Buzz

## OFDM simulation

inhi all I hope that you can help me. I actually have to simulate an ofdm system to show the graph of magnitude against frequency. I am...

hi all I hope that you can help me. I actually have to simulate an ofdm system to show the graph of magnitude against frequency. I am however stuck... part my initial codes are as follows: % generating 400 symbols (block 20 x 20)-> transmitted signal qpsk= exp(j*[pi/4 3*pi/4 5*pi/4 7*pi/4]'); s=qpsk(randint(20,20,4)+1); %convert to time dom

## Sparse Channel Estimation in OFDM Systems

inHi, I am actually new in sparse signal processing and first trying to get the basics of the sparse signals. In OFDM systems the sparse channel...

Hi, I am actually new in sparse signal processing and first trying to get the basics of the sparse signals. In OFDM systems the sparse channel is estimated by using some sparse signal processing algorithms such as compressive sensing. Could anyone please explain me how to model the sparse channel/sparse signal in OFDM systems? What is the logic behind the sparse representation? Thanks i...

## Does OFDM based system use PLL or DLL for synchronization?

inI have been wondering if OFDM based system use PLL or DLL as in single carrier system e.g. GSM to do synchronization at all? Currently, a lot of...

I have been wondering if OFDM based system use PLL or DLL as in single carrier system e.g. GSM to do synchronization at all? Currently, a lot of ofdm based systems talk about implementing the frequency offset and time offset compensation in the digital domain. Do they also implement the time and frequency synchronization in hardware?