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Is the IFFT block really necessary in OFDM?
If we want to send a bunch of complex-numbers (vectors), then most OFDM discussions involve presenting those numbers to an IFFT block, and the output of the IFFT block will then have a bunch of complex numbers for which to transmit in a queued fashion through a QAM block. Can I ask —– is the IFFT block really necessary?
What does the ” O ” stand for in OFDM?
The “O” in OFDM stands for orthogonal. The IFFT takes a complex number (1 bin of the input) and turns it into samples of a sinusoid of a frequency that, over a certain length (of time), is orthogonal to (and thus, under ideal linear conditions, won’t interfere with) any other frequency subcarrier output by the IFFT.
Can you use a QAM block instead of Ifft?
Instead of using the IFFT block, is it possible to just place the original set of complex numbers (vectors) on the queue….and then transmit those numbers (real and imaginary components) – one at a time – through a QAM block? The signal (without using IFFT) is still going to be OFDM, right? Thanks for any comments/advice!
Which is a principle of the principle of OFDM?
The basic principle of OFDM is to split a high‐rate data. stream into a number of lower rate streams and transmit.
How are AC and F C ( T ) represented in OFDM?
Both Ac(t)and f c(t),the amplitude and phase of the carrier, can vary on a symbol by symbol basis. The values of the parameters are constant over the symbol duration period t . OFDM consists of many carriers. Thus the complex signals ss(t)(Fig. 4) is represented by:
How is crest factor reduction used in OFDM?
Introduction Crest factor reduction (CFR) is a technique for reducing the peak-to- average ratio (PAR) of an orthogonal frequency division multiplexing (OFDM) waveform. An OFDM signal is made up in the frequency domain as a set of orthogonal carriers that are each modulated by a constellation symbol.
How to decode the space time block code Alamouti?
First generate H matrix (Channel matrix) and then generate X matrix (16-QAM modulated input symbols) . Y=HX+N is the received matrix. For decoding Alamouti code, there are several methods like Zero Forcing (ZF), Minimum Mean Square Estimation (MMSE) ,Brute Force ML decoding etc..
What is the BER of the Alamouti Code?
The bit error rate (BER) of this STBC is equivalent to 2nR -branch maximal ratio combinig (MRC). This is a result of the perfect orthogonality between the symbols after receive processing — there are two copies of each symbol transmitted and nR copies received. This is a very special STBC.