https://github.com/drom/ofdm

Orthogonal Frequency Division Multiplexing pipeline
https://github.com/drom/ofdm

Last synced: about 1 year ago
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Orthogonal Frequency Division Multiplexing pipeline

• Host: GitHub
• URL: https://github.com/drom/ofdm
• Owner: drom
• License: mit
• Created: 2017-08-12T22:22:22.000Z (almost 9 years ago)
• Default Branch: master
• Last Pushed: 2018-10-19T00:44:42.000Z (over 7 years ago)
• Last Synced: 2025-04-30T23:48:22.419Z (about 1 year ago)
• Language: Python
• Size: 684 KB
• Stars: 28
• Watchers: 3
• Forks: 17
• Open Issues: 7
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# OFDM pipeline

# Protocol

Keep it simple, stupid OFDM pipeline.

## Signal structure

 * encode data bits

 * add preamble symbols

 * add 32 pilots

 * zeros in DC area [-7..7]

 * zeros left/right ends of spectrum [-128..-97, 97...127]

 * 128 data subcarriers per symbol

 * BPSK modulation

 * IFFT 256

 * 1/4 Guard Inteval

[kiss-ofdm.grc](kiss-ofdm.grc)

## Transmitter

[kiss-ofdm-tx-stream.grc](https://github.com/drom/OFDM/blob/master/kiss-ofdm-tx-stream.grc)

### Tx bit-stream

Generating randomized bit-stream, modulating with BPSK, tagging each 128 bit.

![tx_bits](kiss-ofdm-tx-bits-bd.png)

![tx_bits](kiss-ofdm-tx-bits-plot.png)

### Tx OFDM modulator

Allocating each of 128-bit to one of 256 subcarriers, FFT, CP

![tx_bits](kiss-ofdm-tx-samples-bd.png)

![tx_bits](kiss-ofdm-tx-samples-plot.png)

## Channel

Very simple AWGN channel.

![AWGN channel BD](kiss-ofdm-chan-awgn-bd.png)

![AWGN channel plot](kiss-ofdm-chan-awgn-plot.png)

## Receiver

### Rx OFDM demodulator

[kiss-ofdm-rx-stream.grc](https://github.com/drom/OFDM/blob/master/kiss-ofdm-rx-stream.grc)

![rx_samples](kiss-ofdm-rx-samples-bd.png)

![rx_samples](kiss-ofdm-rx-samples-plot-time.png)

![rx_samples](kiss-ofdm-rx-samples-plot-quad.png)