## Forums Search for: OFDM

## Equalization: FDE or TDE? SC-FDE/OFDM?

inI have some questions.... Given the elegance of FDE, why has FDE lagged behind in use compared to TDE? Also, why is OFDM so popular when SC-FDE...

I have some questions.... Given the elegance of FDE, why has FDE lagged behind in use compared to TDE? Also, why is OFDM so popular when SC-FDE is so much better? (No ICI, no peak to average issues)

## Relationship (if any?) between OFDM receiver synchronisation and IF or baseband sampling rate

inHi, I'm trying to understand how synchronision might work in an OFDM receiver with respect to the consequences it has for how the baseband or...

Hi, I'm trying to understand how synchronision might work in an OFDM receiver with respect to the consequences it has for how the baseband or IF signal is sampled. I have tried to read widely, but the IEEE literature around OFDM synchronisation never seems to mention the sample rate or the hardwarey aspects. Below is brief background to try and illustrate where I am coming from, followed by ...

## CE-OFDM

inHi, I am new about constant envelope OFDM. Anyone knows what is good and/or bad about...

Hi, I am new about constant envelope OFDM. Anyone knows what is good and/or bad about this? Thanks -dvo _____________________________________ Do you know a company who employs DSP engineers? Is it already listed at http://dsprelated.com/employers.php ?

## OFDM

hi I really need some help to simulate an ofdm system. i need to show that graph of magnitude (amplitude) against frequency... Can somebody...

hi I really need some help to simulate an ofdm system. i need to show that graph of magnitude (amplitude) against frequency... Can somebody assist me in solving this problem. thanks all sheen

## [Enquiry] how to add OFDM subcarriers in simulink

inI am doing a project on OFDM equalization. So far, i have been doing equalization for one ofdm symbol. I wish to ask how could i add...

I am doing a project on OFDM equalization. So far, i have been doing equalization for one ofdm symbol. I wish to ask how could i add more subcarriers in by using Simulink? Is there any example that i can refer to? Thanks alot.

## MIMO-OFDM systems

inHi all, I've been looking at MIMO-OFDM based systems for about the last week (802.11n and 802.16) and have a couple of questions that I was...

Hi all, I've been looking at MIMO-OFDM based systems for about the last week (802.11n and 802.16) and have a couple of questions that I was hoping someone out there could answer. Here goes: 1) I want to look (in detail) at one of the more computationally demanding blocks of a typical MIMO-OFDM reciever. The main blocks that I have really been looking at have been a QR-based channel estim...

## What is difference between OFDM and GFDM?

inHi, I am trying to understand the difference(s) between OFDM and GFDM which are used as a multicarrier modulation techniques in wireless...

Hi, I am trying to understand the difference(s) between OFDM and GFDM which are used as a multicarrier modulation techniques in wireless communication. As far as I know the OFDM uses the orthogonal subcarriers and the GFDM is with the non-orthogonal subcarriers when designing a transmitter. Could anyone please explain further about their design and differences? What is the purpose of using...

## Using Filtfilt function for OFDM signals

Hello: I have a question regarding filtfilt function in Matlab. Due to forward and backward filtering, filtfilt function will have zero-phase...

Hello: I have a question regarding filtfilt function in Matlab. Due to forward and backward filtering, filtfilt function will have zero-phase response at any frequency. If I apply this filter to a time domain OFDM sequence, does that mean I can set the FFT start window the same as the transmitted IFFT starting point? In my test, I have an OFDM sequence of 5 symbols each with 80 samples at 20 M...

## Good intro books on OFDM?

inI'm a digital ASIC engineer looking for some *beginner* (not reference/advanced!) books on Orthogonal Frequency Division Multiplexing (OFDM.) ...

I'm a digital ASIC engineer looking for some *beginner* (not reference/advanced!) books on Orthogonal Frequency Division Multiplexing (OFDM.) Well, hopefully such a book exists? The book I already have "Multi-carrier Digital Communications: Theory and Applications of OFDM" (by Bahai, Saltzberg, and Ergen) seems a bit beyond me. It's a great reference for researchers, but as you've probab...

## LTE OFDM timing synchronization

inwe are working on the OFDM synchronization for 3GPP LTE, So far we have implemented the timing and fractional frequency synchronization using...

we are working on the OFDM synchronization for 3GPP LTE, So far we have implemented the timing and fractional frequency synchronization using the Maximum Likelihood method proposed in 'On Synchronization in OFDM Systems Using the Cyclic Pre?x'. The ML estimates of timing and frequency offset are then processed by the loop filter. It works pretty well. After the equalizer clearly I can tell

## SNR to EbNo in OFDM scheme

inhey all, I made an ofdm simulation in matlab, I want it to output Ber/EbNo plot, and I use the awgn function in order to add white noise in...

hey all, I made an ofdm simulation in matlab, I want it to output Ber/EbNo plot, and I use the awgn function in order to add white noise in the channel, and as u know the awgn function requires SNR as input, so I need to convert from Eb/No to SNR. I know this: Es/No(dB)=10log10(Tsymb*Fs)+SNR(dB) now I need to convert the Es/No of the ofdm signal to Eb/No: Es/No(dB)=Eb/No(dB)+10log10(...

## Computing per stream SNR in a full CSI MIMO-OFDM system for fast link adaptation

inDear all, I have a MIMO-OFDM system, like 802.11n. I assume full CSI in both TX and RX and my goal is to obtain in the receiver a per spatial...

Dear all, I have a MIMO-OFDM system, like 802.11n. I assume full CSI in both TX and RX and my goal is to obtain in the receiver a per spatial stream and per OFDM subcarrier SNR estimation in order to perform a fast link adaptation algorithm, i.e. I want to compute SNR[i][k] where i=1..Nss (Nss: number of spatial streams) and j=1..Nsc (Nsc: number of OFDM subcarriers). Since I assume ful...

## OFDM modulator

inHi, I have problem concerning process of generating OFDM signal. From what I know, the real part of IFFT is sampled OFDM signal. So why after...

Hi, I have problem concerning process of generating OFDM signal. From what I know, the real part of IFFT is sampled OFDM signal. So why after IFFT block is IQ modulator that uses real and imaginalis part of IFFT? Why we do not take the real part of IFFT and then convert it to analog signal and then upconvert to the IF frequency? And what about real part of OFDM signal at the output of IQ modula...

## MIMO-OFDM

inI want to modify my OFDM program into a MIMO-OFDM one. But I dont know where I should modify? channel matrix? Can anybody share a simple...

I want to modify my OFDM program into a MIMO-OFDM one. But I dont know where I should modify? channel matrix? Can anybody share a simple MIMO matlab program and tell me how I can do it?

## HiperMAN Standard/OFDM

inI recently started simulating a HiperMAN/WiMAX PHY on MATLAB. However, in the standard available in the ETSI website, there is mention of a...

I recently started simulating a HiperMAN/WiMAX PHY on MATLAB. However, in the standard available in the ETSI website, there is mention of a "sampling frequency" and a term "bandwidth over sampling frequency". I haven't a clue as to what these terms mean and where they're used in the OFDM process. Could somebody shed some light on what these terms mean in the context of OFDM? Thanks Neelabh...

## MIMO OFDM FFT Symbol timing estimation

inHello As part of a semester long project, I am performing the hardware implementation of a 2 x 1 MIMO OFDM link. I am formulating a...

Hello As part of a semester long project, I am performing the hardware implementation of a 2 x 1 MIMO OFDM link. I am formulating a packet transmission scheme as well as the receiver implementation as part of this project.. I ran into the following issue, and wondering if anyone could offer some advice/references. If you have Q transmit antennas and 1 receive antenna in a MIMO-OFDM syst...

## OFDM demodulation question

inHere's my question: In doing the OFDM (like DVB-T) demodulation, why do people just talk about carrier frequency sync and carrier phase noise...

Here's my question: In doing the OFDM (like DVB-T) demodulation, why do people just talk about carrier frequency sync and carrier phase noise but not carrier phase itself? Does that mean OFDM is not coherently demodulated? Thank you for your help! -- Harry

## Effect of guardbands ofdm preamble on crosscorrelation

Hello, I m currently simulating a channel estimation based preamble in OFDM system. The ofdm signal is convolved with the channel taps which...

Hello, I m currently simulating a channel estimation based preamble in OFDM system. The ofdm signal is convolved with the channel taps which is in this case 3 taps. The technique is to correlate the received preamble with its local copy in time domain before FFT. This kind of correlation should give an impulse as the result and in this matter, these impulses should be the channel taps. But th...

## OFDM subcarrier overlapping......

inHi all members of DSP! I am getting familiar to OFDM because of you guys! Thanks a lot! in frequency domain subcarriers may overlap each...

Hi all members of DSP! I am getting familiar to OFDM because of you guys! Thanks a lot! in frequency domain subcarriers may overlap each other, however transmitting information doesn't mix. What is the reason? could somebody explains me, I appreciate a feedback! thanks again!

## Help with OFDM transmitted over multipath channel

inHi I want to simulate the transmission of a set of OFDM symbols over a multipath channel. The steps I intend to implement are 1) Generate a...

Hi I want to simulate the transmission of a set of OFDM symbols over a multipath channel. The steps I intend to implement are 1) Generate a 64 subcarrier OFDM system as follows. Take binary data and modulate it using a standard modulation scheme, say 64 QAM. Pass these modulated symbols through a 64 IFFT block. Before passing it through the IFFT block insert 16 pilots at 16 subcarriers. The ...