## Forums Search for: OFDM

## 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?

## 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

## 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...

## 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...

## 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 ?

## Is low latency important in CFR of OFDM?

inHi, all: I am interested in CFR of OFDM. I find some relavant paper mentioned low latency feature in the crest factor reduction (CFR) topic of...

Hi, all: I am interested in CFR of OFDM. I find some relavant paper mentioned low latency feature in the crest factor reduction (CFR) topic of OFDM. I don't understand the reason. It seems to me that several hundreds of microseconds delay is not a big issue. I don't know the specification of WiMax of the latency. Anyone can tell me that? I appreciate to any feedback on this. Thanks.

## 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...

## 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...

## 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...

## 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

## OFDM model

inHi, i am learning about OFDM currently. And i am learning to implement the model in SIMULINK. Yet, i am stuck at the 'training symbols'. I...

Hi, i am learning about OFDM currently. And i am learning to implement the model in SIMULINK. Yet, i am stuck at the 'training symbols'. I dont really understand why training is needed in channel estimation and what forms those training symbols. Can recommend some nice books for OFDM or simulink? Thanks for ur patience.

## 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 ...

## ofdm in power line communication simulation

Hie all, I am now doing the OFDM Simulation for Power Line Communication. I have written a very simple code for OFDM and have the impulse response...

Hie all, I am now doing the OFDM Simulation for Power Line Communication. I have written a very simple code for OFDM and have the impulse response of the power line channel. I am facing the problem that the BER of my result are high and constant along the SNR. So I would like to know whether my simulation is correct or not, and hope that someone can give me an advice on the simulations. I am using...

## [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.

## OFDM Multipath Time-Varying Channel

inHi there. I have a question regarding the wireless channel model to be used on an OFDM system simulation. I have investigated for a while and...

Hi there. I have a question regarding the wireless channel model to be used on an OFDM system simulation. I have investigated for a while and most of the people use an ARMA Filter to simulate the time variations of the wireless channel, but this approach is for modeling a multipath channel. The thing is that I don't know if this model includes the distortion on the receiver do to the echoes. OFDM...

## Question regarding Concatenated Codes on OFDM

I am simulating an OFDM system and want to employ concatenated codes with different modulation schemes. I have a few queries about it. 1. RS code...

I am simulating an OFDM system and want to employ concatenated codes with different modulation schemes. I have a few queries about it. 1. RS code works on frame-by-frame basis like for a shortened code RS(32,24) on byte boundary. In this case, I need a minimum of 24*8 uncoded data bits. If i work on this boundary, the resulting symbols dont map completely to the OFDM symbol. How can i make it sat...

## simulation of carrier offset in OFDM

inHi i want to simulate small carrier offset in OFDM and see its effect on QAM constellations. How can is simulate...

Hi i want to simulate small carrier offset in OFDM and see its effect on QAM constellations. How can is simulate carrier offset in MATLAB for OFDM signal.. is iterpolation - decimation technique helpful?? i want to introduce this offset after passing the signal through channel filter. i want to simulate by noninteger factor say 0.5 i.e shift of tones by 0.5 ...

## 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!

## Modeling OFDM multipath channel in Matlab

Dear all, I have a basic question regarding modeling of a multipath channel for OFDM in Matlab and would appreciate your help. My intention...

Dear all, I have a basic question regarding modeling of a multipath channel for OFDM in Matlab and would appreciate your help. My intention is to simulate an 802.11a transmission which uses OFDM. From the 802.11a standard I know that: -Number of Subcarriers, Nsc = 64 -Sampling Rate at the receiver, fs = 20e6 samples/sec -BW = 20Mhz -Carrier Frequency, fc = 5.25 Ghz Now consider that I...

## ofdm signal (dab) decoding problem

hi, i am working on the development of an ofdm receiver (dab receiver). After frequency synchronisation, when i differentially decode the ofdm...

hi, i am working on the development of an ofdm receiver (dab receiver). After frequency synchronisation, when i differentially decode the ofdm symbols, i get 5th symbol corrupted i.e. the constellation of 5th symbol is not centerd on the multiples of pi/4. When i shift the fft window for 5th symbol 7 samples backward, the contellation improves, but it is still very noisy and not centerd at the mu...