I have created an OFDM system where, at the transmitter (Tx) side, I perform IFFT, add a cyclic prefix (CP), and then on the receiver (Rx) side, I perform FFT followed by channel estimation and equalization.
However, I encountered an issue. When I pass scalar values through the IFFT and FFT blocks, everything works fine, and the constellation graph appears as expected. However, my goal is to process data in 4×1 vectors to increase the sampling rate. After processing 4×1 vectors, the constellation graph does not appear correctly, and it seems the data is not in the expected order after the IFFT block.

My question is: when converting data to the time domain with IFFT, does the order of the data change? For example, I expect the data to go through as {0,1,2,3}, {4,5,6,7}, {8,9,10,11}, {12,13,14,15}, etc. But after IFFT, should I expect it to be {0,4,8,12}, {1,5,9,13}, and so on? If this is the case, should I introduce a reordering step after the IFFT to restore the data to its original order?
Additionally, could there be issues related to bit-reversed order, or other similar problems such as "output/input in bit-reversed order"? If you could clarify the meaning of this and how it might affect my system, I would greatly appreciate it.

For your reference, I am using HDL Coder and leveraging the HDL optimized IFFT/FFT blocks in my design.
Finally, I would be grateful if you could provide any resources or further explanations on the index order and the steps needed to process data in vector form, including any additional adjustments I need to make for IFFT/FFT operations.
Thank you very much for your time and assistance. I look forward to your response.I have created an OFDM system where, at the transmitter (Tx) side, I perform IFFT, add a cyclic prefix (CP), and then on the receiver (Rx) side, I perform FFT followed by channel estimation and equalization.
However, I encountered an issue. When I pass scalar values through the IFFT and FFT blocks, everything works fine, and the constellation graph appears as expected. However, my goal is to process data in 4×1 vectors to increase the sampling rate. After processing 4×1 vectors, the constellation graph does not appear correctly, and it seems the data is not in the expected order after the IFFT block.

My question is: when converting data to the time domain with IFFT, does the order of the data change? For example, I expect the data to go through as {0,1,2,3}, {4,5,6,7}, {8,9,10,11}, {12,13,14,15}, etc. But after IFFT, should I expect it to be {0,4,8,12}, {1,5,9,13}, and so on? If this is the case, should I introduce a reordering step after the IFFT to restore the data to its original order?
Additionally, could there be issues related to bit-reversed order, or other similar problems such as "output/input in bit-reversed order"? If you could clarify the meaning of this and how it might affect my system, I would greatly appreciate it.

For your reference, I am using HDL Coder and leveraging the HDL optimized IFFT/FFT blocks in my design.
Finally, I would be grateful if you could provide any resources or further explanations on the index order and the steps needed to process data in vector form, including any additional adjustments I need to make for IFFT/FFT operations.
Thank you very much for your time and assistance. I look forward to your response. I have created an OFDM system where, at the transmitter (Tx) side, I perform IFFT, add a cyclic prefix (CP), and then on the receiver (Rx) side, I perform FFT followed by channel estimation and equalization.
However, I encountered an issue. When I pass scalar values through the IFFT and FFT blocks, everything works fine, and the constellation graph appears as expected. However, my goal is to process data in 4×1 vectors to increase the sampling rate. After processing 4×1 vectors, the constellation graph does not appear correctly, and it seems the data is not in the expected order after the IFFT block.

My question is: when converting data to the time domain with IFFT, does the order of the data change? For example, I expect the data to go through as {0,1,2,3}, {4,5,6,7}, {8,9,10,11}, {12,13,14,15}, etc. But after IFFT, should I expect it to be {0,4,8,12}, {1,5,9,13}, and so on? If this is the case, should I introduce a reordering step after the IFFT to restore the data to its original order?
Additionally, could there be issues related to bit-reversed order, or other similar problems such as "output/input in bit-reversed order"? If you could clarify the meaning of this and how it might affect my system, I would greatly appreciate it.

For your reference, I am using HDL Coder and leveraging the HDL optimized IFFT/FFT blocks in my design.
Finally, I would be grateful if you could provide any resources or further explanations on the index order and the steps needed to process data in vector form, including any additional adjustments I need to make for IFFT/FFT operations.
Thank you very much for your time and assistance. I look forward to your response. hdl coder, ifft, fft MATLAB Answers — New Questions

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