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60 Threads found on Carrier Ofdm
in 802.11a, 48 sub-carriers are used to transmit data, and they are not carrying conjugate data on index like sub-carrier(x) and sub-carrier(N-x). also in some thsis I come across designs that transmit conjugate data on sub-carriers that are symmetric around the FFT size N, which results in waste of half the bandwidth. (...)
Hi, What is the performance difference of MMSE equalizer and ZF equalizer in a ofdm system. I have simulation 3 tap Rayleigh channel for QPSK ODFM system and found out that both the equalizers give the same performance. But in Single carrier Frequency Domain Equalization, MMSE performs significantly better than ZF. I modeled the equal
........ from the introduction in this link i understand that ofdm carrier is generated by modulating a complex waveform with original data and this resulting waveform is the ofdm subcarriers and these sub carriers r bundled by ifft to obtain the ofdm signal... (correct me if i'm wrong)....
Hello all, Why when we use space-time block coding (STBC) with single-carrier frequency-domain equalization (SC-FDE) we use a permutation matrix, while we don't use it in case of orthogonal frequency division multiplexing (ofdm)? Thanks
please explian me synchronisation and frequency offset problem in ofdm
Hi, I am working on the ofdm transmitter system. I have observed that the carrier signal peak power level is -3dBm whereas the peak power level of the ofdm (256 sub carriers) signal observed is -42dBm. Also the channel power measured is -42dBm . Frequency of operation is 2.45GHz. Power amplifier used is MMZ25332BT1. I (...)
One reference says that: "we know that the CFO (carrier frequency offset) causes the phase distortion in the ofdm symbol which can be denoted as 2πβn/N where B describes the CFO effect.."" so, any one can explain how this phase distortion (2πβn/N) is obtained?? Plz explain...
This picture is from book MIMO-ofdm Wireless Communications with Matlab by Cho Y.S. The MATLAB code is located in book directly below the figure. function y_CFO=add_CFO(y,CFO,Nfft) % add CFO (carrier frequency offset) % y : Received signal % CFO = IFO (integral CFO) + FFO (fractional CFO) % Nfft = FFT size nn=0:length(y)-1; y_CFO = y.*exp(j*2*pi*C
I am trying to understand the relations between ofdm symbol duration and subcarriers far as i went ,i understood that regarding W and R as total bandwidth & transmission rate of transmission respectively the duration of a distinct subcarrier is just T ,where T=N*Ts with Ts the symbol duration in the single carrier case (...)
My input signal is a multi-channel/carrier ofdm. Each channel have 5MHz bandwitdh. Now, I would like to simulate a 2-tone test for its IMD. I plan to measure the 3rd order at say +/-0.2 MHz offsets from the edge (4.8MHz and 5.2MHz). My computation is a spacing of Fcarrier +/-1.8GHz, in order to create the 3rd order tones. Is this correct?
My system uses 0to2khz freqs. Hence I do not want to use any RF it possible to generate ofdm signal in this BW range and transmit it without using any carrier. If so what factors determine the carrier freqs and no of carriers. My BW and Symbol time is known and fixed. Thanks
Hai What is difference between carrier interferometry uwb signal format and uwb-ofdm signal format......Please give answer.....
The following code is used to estimate and correct the frequency offset errors for a single carrier system %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% freqOffset = 0; phaseOffset = 0; hPFO = comm.PhaseFrequencyOffset('FrequencyOffset', freqOffset, ... 'PhaseOffset', phaseOffset, ... 'SampleRate', samplesPerSymbol/Ts); rx_signal1l = step(
ofdm Receiver: non-synchronous sampling scheme Hi all, we want to implemented an ofdm receiver in SDR (software defined radio),so for this reason we have the below problems 1-symbol timing synchronization(correct symbol start position before FFT) 2- the carrier frequency synchronization 3-the sampling clock (...) com discrete carriers(present in ifft) modulate input sequence? Whay call the carriers "discrete". each of them is a continuous signal, they are at discrete frequencies, if you want. Each individual carrier is modulated (eg QPSK) by the input data sequence. 2.which parameter of carrier is changing?(after modlation) (...)
Here is a better explanation of the PAR (crest factor): As you see, almost every signal have some kind of peak to average. For a multi-carrier signal (as ofdm) generally the peak-to-average can be calculated with: PAR = 10*LOG(Number-of-carriers) For example the PAR of a 12 carriers signal would
In MIMO-ofdm system a delay (cyclic delay diversity) is added to the sub-carrier in each antenna in order to have different spacial dimensions for the signals but this done before adding the cyclic prefix for a reason what is it???
Hi All, I'm really in trouble because of this awgn. I am trying to add noise awgn to oversampled ofdm signal. my signal is oversampled 20 times and modulated on a high frequency carrier. After applying band pass filter I have tried to do this SNR = EbNo + 10*log10(k) - 10*log10(upsamp) corrupted = awgn(usig, SNR,'measured','dB'); where u
This could be done like this. First make twenty oscillators, 100Khz apart above 5MHz. Modulte them individualy with your signal.Combine outputs of all frequency.Filter carrier and upper side band.You will get your 20 channels in 5-7MHz. Now modulate your uhf oscilator with this signal.The output will be above and below 5-7MHz of yor uhf carrier f
Perheaps the reason of the failure is the Peak-to-Average of the modulated signal. Most of the single carrier digital modulations have a Peak to Average in a range of about 4dB to 8dB. Multi-carrier modulation types (as ofdm) have even higher peaks. If your PA works fine at P1dB using a CW signal, when the input reach higher peaks (due to (...)
Doppler shift is harmful for ofdm because you need data bins to be placed exactly on their proper subcarriers for proper demodulation, this is not the case for CDMA, or any other single carrier scheme.
Hi guys, Im trying to implement Analogue FDM on top of my single carrier modulation (eg: QAM and QPSK) or Multi carrier modulation (eg: ofdm). For an example, I have two different pair of I and Q channels, where first pair is upconverted at 2.2 GHz and the next pair at say 2.7 GHz and them MUX them together as in FDM. I model them in (...)
Hi guys, I'm currently generating ofdm signal and send it to DAC and then upconvert them to 1 GHz carrier signal. I want to multiplex several of them, like say I upconvert them to 1 GHz, 800 MHz, 1.2 GHz, which represents 3 different signals, then multiplex them together using FDM, is it possible or is there any other better way to do this?
Hi all, I'm implementing STBC-MIMO and MIMO-ofdm system using SDRs. Before doing actual coding, I'm working on MATLAB simulation of CFO estimation and recovery and channel estimation. I'm reading some Dr. Giannakis' papers about joint CFO and channel estimation. Besides Dr. G, I know that many people have researched joint CFO and channel es
Hi all, I'm performing ofdm equalizer for a pilot assisted system. The system parameters are: Signal BW = 6 MHz carrier = 700 MHz chip rate = 5.55 MHz Doppler shift corresponds to max 200 km/s receiver speed Fading channel is a Rayleigh fading channel, the problem is that when I apply the channel to signal, the channel has a very ra
Hi guys, I am currently working with my ofdm system. My back-to-back system works in perfect condition. My ofdm was done with 16-QAM, 72 subcarrier carries data and 56 carrier zero (zero padding) total 128 subcarries, then IFFT and DAC, then upconverting it to 1 GHz. Perfect back-to-back system. But when I include a (...)
IFFT takes the time domain chunk of Signals (Sub carriers) and Adds them to produce a carrier. This is similar to the FFT. Then the Frequency domain signal is produced. Which is further processed
Hi.. I am very pleased if some one give me the range of these parameters i.e min and max Bandwidth of a system Number of subcarrier FFT length Subcarrier spacing FFT period Sampling rate Sampling interval Cyclic prefix carrier center frequency Data rate symbol duration Thanks in advance
look at "Ethernet over AC power line" device on the market now, they are using ofdm modulation on the RF carrier signals in MHz over the home AC power lines, the distance can be 100meter. the data rate can be in 10 MBps or higher, For twist pair line, it should be much better in terms of distance.
Hello, can you please help me in understanding the following lines taken from the book "Fundamentals of Wireless Communication" by David Tse & Pramod Viswanath. I quote section 3.4.4, page number 95 ------------------------------------------------------------------------------------------------- Both the single-carrier system with ISI equ
Wiley - Single and Multi-carrier Quadrature Amplitude Modulation / chapter 7 it is all your needs
Hi all! There is a new method for controlling subcarrier's bandwidth. Usually it is fixed during the transmission but as i read via the internet TDM method for subcarrier's bandwidth (Adaptive Sub carrier Bandwidth) was invented. (ieee 2008, "Performance analysis of ofdm System with adaptive Sub carrier (...)
Scalable ofdmA is the ofdmA Mode used in mobile WiMAX. It adds scalability to ofdmA. Scalability is supported by adjusting the size of FFT size while fixing the sub-carrier frequency spacing to 10.94kHz. It supports channel bandwidths ranging from 1.25 MHz to 20MHz. Smaller FFT size is given to lower bandwidth channels, (...)
Did you mean where frequency offset is more than 1/2 of the carrier spacing in the preamble?
In single carrier system, N number of symbols are transmitted using T time in which each of this symbol occupied T/N duration. And the bandwidth wise, each of transmitted symbol occupied the whole bandwidth B. In multi carrier system, N number of symbols are transmitted using T time in which each of this symbol occupied T duration (All the symbo
CDMA and ofdmA are two different subjects and are not related. ofdm is a multi-carrier scheme while cdma is a single carrier one. there are some other multi-carrier schemes such as mc-cdma or mt-cdma, which combine both methods. but you'll have to learn those subjects separately. for start you can learn (...)
Assume an ofdm transmitter has an EIRP of 100W. WiMax has around 256 carriers which means 100/256 Watts for each carrier DVB-T has 2k and 8K modes so the power is 100/2k and 100/8k Watts respectively. Now in theory the WiMax signal should be more reachable compared to DVB-T but DVB-T was designed for digital broadcast so it must be (...)
The origin of the DC subcarrier exception is historical. The analog implementation of TX path in the ofdm had in the past no special methods to suppress the carrier leakage or back referred DC offsets. Together with the situation in the past that there was no baseband controlled frequency offset correction in the TX path the easiest way (...)
1- ofdm : orthogonal frequency division multiplexing... the data is transmitted using a set of frequencies which are orthogonal 2- ofdmA... MA is multiple access technique for orthognal frequency division 3- SS-ofdm: is a hybrid technique using spread spectrum and ofdm 4- MC-CDMA : MCcdma is multi- (...)
Hello Everyone; What is the multi-carrier problem in power amplifiers? How it affects the performance of system? Can it be compensated or reduced?
hi I ofdm the high serial bit rate is converted to the parallel low bit rate then applied modulation mapper> then IFFF . the question for the formula OF IFFF IFFT desplay the base band of ofdm there is no carrier Fc included> the introduced of Fc comming later after the DAC > IS THIS RIGHT OR RONG IF RONG where is the position of Fc (...)
Hi Read chapter 8 of the following book : Multi carrier Digital Communications-Theory and Applications of ofdm (2nd.Ed.) by Bahai , Saltzberg & Ergen Springer_2004 you can find the ebook in the EDA ebooks upload/download section regards
Hi. I am having problem regarding the usage of IFFT in ofdm transmitter.The transmitter should take in input symbols and modulate different subcarriers with one of these symbols.On the other hand IFFT input is these symbols(X(k)'s) but the output is x(n)'s N-1 j2Πnk/N x(n)=∑ X(k)e k=0 which from
Hi, One good project can be Implementing Multi carrier (ofdm) transmitter receiver using MATLAB or any other software and specially working on its PHY layer. BR, Arif Khan
hello everyone . I need a research paper that discusses one of the following topics and a matlab code that reproduce its results.(full analysis of the paper) 1) Multi-carrier modulation (ofdm), system design and performance 2) Multi-user detection in DS-SS systems 3) Performance of mobile communication signals under nonlinear amplific
hello everyone . I need a research paper that discusses one of the following topics and a matlab code that reproduce its results.(full analysis of the paper) 1) Multi-carrier modulation (ofdm), system design and performance 2) Multi-user detection in DS-SS systems 3) Performance of mobile communication signals under nonlinear amplific
hai for 64 ifft size 48 subcarriers + 4 pilot signal + 12 zero carrier is this constant value? if then for 1024 ifft size how many pilot signals and zero carriers needed another issue is one frame contains how many symbols ?? how to fix FRAME SIZE? HELP ME PLEASE........... I AM confused with concepts regards venkatesh.
It is ratio of the wanted signal (carrier) to the noise floor (Noise). The higher the C/N ratio, the easier the baseband chip can demodulate the signal without errors. More complex modulation constellations require higher C/N to successfully demodulate. So for instance a QPSK detector requires a lower C/N than a 256 QAM detector.
In downlink, it seems to be so. In uplink, most companies advocate single-carrier transmission due to the high PAPR of ofdm. This combination is found in the evoluation of WCDMA and CDMA2000 systems.
u can implement "ofdm in matlab" "implementation of digital phase lock loop ffor carrier recovery" " implement the QPSKtransmitter and receiver with LMS based channel equilization in matlab" "transmission of data b/w two PCs using cordless telephone" ihave mentioned few projects and help can be extending regarding these projects if required th