I was having a discussion regarding working of a new technology called li-fi with a friend. He told me that he will use a software defined...

I was having a discussion regarding working of a new technology called li-fi with a friend. He told me that he will use a software defined radio and generate a ofdm modulated signal. Then instead of using an antenna he will use a light source which switches on and off with respect to voltage of the signal. Then at the receiver he uses a photodiode that detects the changes in light transitions at ...

Hi all. I have been asked to design a high speed wireless link and being rather new, I have some questions and I hope you guys and gals out...

Hi all. I have been asked to design a high speed wireless link and being rather new, I have some questions and I hope you guys and gals out there can help me out. 1) I am looking in particular at OFDM as a way to deliver the high data rates. Before that ISI would certainly pose a threat to the system so channel estimation must be done. With particular emphasis of implementation on FPGAs, w...

Hi, Hi in trying to really understand the difficulty in controlling the PAR in multi-carrier modulations for example OFDM, I was trying...

Hi, Hi in trying to really understand the difficulty in controlling the PAR in multi-carrier modulations for example OFDM, I was trying to solve these two problems. I have the following two cases where I would like to control the peak to average ratio for the generation of a picket-fence of sinewaves. Case 1: Assumptions: Sample Rate (Fs) = fixed value ...

Hallo everybody, I am just starting a C++ project about V.34 fax demodulation and decoding on PC. In all my previous DSP projects I had an...

Hallo everybody, I am just starting a C++ project about V.34 fax demodulation and decoding on PC. In all my previous DSP projects I had an analog front-end which provided me the baseband samples, or I could recovery them in some other tricky way (e.g. FFT in narrow-band OFDM systems). Anyway, all my processing ever took place at baseband. In this case, on the contrary, my input is a digit...

Eric Jacobsen wrote: > On Thu, 15 Jan 2009 13:54:10 -0800 (PST), HardySpicer > wrote: > > > > Well not much I suppose since we...

Eric Jacobsen wrote: > On Thu, 15 Jan 2009 13:54:10 -0800 (PST), HardySpicer > wrote: > > > > Well not much I suppose since we use it for Wi-Fi - but what about > > commercial broadcast radio propagation? The UK has had digital radio > > for some time but it has not really caught on. I heard it had problems > > in moving vehicles though it is supposed to be immune to m

Hi all, i'd like to ask about pilot based interpolation in channel estimation of OFDM cells. I have a block of reference cells which i need...

Hi all, i'd like to ask about pilot based interpolation in channel estimation of OFDM cells. I have a block of reference cells which i need to interpolate in time and frequency domain. An example : xo....................oxooxooxooxooxooo oo....................ooxoooxooooxoooox ox....................ooxoooxoooxoooxoo xo....................ooooxoooxooooxooo oo....................oxooooxo...

Season's greetings! I've posted the same question in the Matlab workgroups, but nobody replied so i guess i try it out there. Hope u guys wont...

Season's greetings! I've posted the same question in the Matlab workgroups, but nobody replied so i guess i try it out there. Hope u guys wont mind. I'm currently trying to build a preamble detector for my OFDM transceiver which i have built in Simulink for the purpose of frame synchronization. This is kinda a lenghty post, but i hope those who can help me please take some time and take ...

Hi guys To synchronise OFDM systems for Timing error, we usually use algorithms like Maximum Likelihood to find correlation between CP & end of...

Hi guys To synchronise OFDM systems for Timing error, we usually use algorithms like Maximum Likelihood to find correlation between CP & end of frame. But this only gives us coarse starting point. To do fine synchronisation, most papers I read say we should use the pilot signals. But because of noise, these will be corrupted, so we have no way of knowing which are the pilots, & which is data...

Hello, I have background in DSP both theory as well as practical. But I do not have much experience in the area of wireless or...

Hello, I have background in DSP both theory as well as practical. But I do not have much experience in the area of wireless or digital communications. Could someone help me define a problem that could be taken up as work towards successful completion of PhD? I am looking for problems related to wireless/ofdm. Thanks, Bharat

Hi, i want to know ,how kalman filter is useful in channel estimation of MIMO-OFDM system.what key property of kalman filter helps...

Hi, i want to know ,how kalman filter is useful in channel estimation of MIMO-OFDM system.what key property of kalman filter helps in estimation.kindly reply soon. smriti singh,

Hi guys, I was doing the simulations for the multitap frequency domain equalization for multicarrier system (DMT based). It seems though...

Hi guys, I was doing the simulations for the multitap frequency domain equalization for multicarrier system (DMT based). It seems though the at the band edges (First few tones and last few tones) higher performance can be achieved if we use higher number of equalizer taps. Can you people please suggest me any reasons why that happens or at least guide me to any publication that might hel...

hi all! i am going to simulate (myself for understanding more, not using Matlab toolbox) wireless channel by M-QAM over an AWGN, so that I've...

hi all! i am going to simulate (myself for understanding more, not using Matlab toolbox) wireless channel by M-QAM over an AWGN, so that I've to choose one of the FEC coding method such as Rayleigh, LDPC, turbo, Red-Solomon or BCH. which is the better one? and is it possible to use AWGN with Rayleigh at the time? if it is possible please explain me how to make a algorithm for it. and pleas...

Hello, I recently found myself interested in digital modulation techniques. For a hobby project I plan to implement modulation and...

Hello, I recently found myself interested in digital modulation techniques. For a hobby project I plan to implement modulation and demodulation so I can later test it using soundcards for transmitting little text messages via sound between neighbouring laptops. The main goal is to learn something and have fun -- not to build something useful. I'm sure some of you could provide valuable sug...

Hi I am trying to implement an alamouti mimo-ofdm system. I am not really sure how I should go around creating the multipath channel. According...

Hi I am trying to implement an alamouti mimo-ofdm system. I am not really sure how I should go around creating the multipath channel. According to alamouti the channel has to stay constant over a period of two symbols but I can't seem to figure out how to do this with the matlab multipath function. right now what I'm doing to create the channel is: ------------------------------------------...

Hello, I think I am missing something very basic here. I am confused as to which definition of autocorrelation to use. From Wikipedia...

Hello, I think I am missing something very basic here. I am confused as to which definition of autocorrelation to use. From Wikipedia (http://en.wikipedia.org/wiki/Autocorrelation), there are two definitions. 1) Based on convolution 2) Based on 'expectation' - E[f(t).f*(t-t')] I am not sure which version to use. I am working on OFDM so I will be mostly interested in calculation the a...

The correlation factor between two channel states is equal to rho=(2*pi*fd*t). In what i read t is the time difference between the moment of...

The correlation factor between two channel states is equal to rho=(2*pi*fd*t). In what i read t is the time difference between the moment of channel estimation and transmission. In an OFDMA system would this value be equal to one frame length, several symbol lengths does it depend on the positioning of the pilots. I am quite confused. I would appreciate any help here and any typical values for thi...

Hello, I am not in the field of D-A conversion but need to know a few fundamentals or better yet some freely obtainable literature. What I am...

Hello, I am not in the field of D-A conversion but need to know a few fundamentals or better yet some freely obtainable literature. What I am basically working on is OFDM physical layer, and I want to know issues when it is D-A converted for transmission wirelessly. So basically, there will be N complex numbers which needs to be D-A converted and transmitted. The transmission signal wil...

Hi all, I implemented an OFDM receiver in C++ and it turs out that some parts are bottle necks for the speed, like e.g. Viterbi decoding and...

Hi all, I implemented an OFDM receiver in C++ and it turs out that some parts are bottle necks for the speed, like e.g. Viterbi decoding and RS decoding. Does anyone know if there is a hardware based decoding solution on the market? Ideally it would be a PCI card for PC and configurable for different codes by software. Don't tell me about general purpose DSPs or FPGA. It takes too long for me...

Hi all, I am rather new to this and would appreciate if someone would kindly enlighten me on this: My pilots symbols are inserted into a set...

Hi all, I am rather new to this and would appreciate if someone would kindly enlighten me on this: My pilots symbols are inserted into a set of subcarriers (comb type). I've seen the MMSE estimate of the FFT of the channel coefficients given as: H_mmse = R_HHls(R_HlsHls + sigma^2(XX^h)^-1)^-1 Hls where Hls is the channel estimates from the pilot symbols using the least square method. H...

Hi, Below is part of the 802.16-2004 standard. I cannot understand its exact meaning. It says RF profiles for 3.5MHz channelization. How...

Hi, Below is part of the 802.16-2004 standard. I cannot understand its exact meaning. It says RF profiles for 3.5MHz channelization. How to interprete n*0.25MHz? And some papers uses 5MHz bandwidth (for example, in IEEE communications Magazine Feb.2005, Broadband wireless access with WiMax/802.16:Current performance benchmarks and future potential. It's OFDM, not SC, but I have the same c...