Implementation and Analysis of Multi-Carrier Synchronization Techniques


S&C blocks

Multi-carrier synchronization for GnuRadio

Multi-Carrier systems




… from 10000 feet

Aerial Photo

Source: Google maps

Waterfall diagram

FFTing Chunks of the input stream is essentially the same thing a waterfall diagram does

Waterfall diagram

TD/FD Grid

Selecting Sample points

Frequency selective channel

Fq fading

Interfering burst

Td fading

Frequency offset

Fq offset

Time offset

Td offset

Simple synchronization

Burst sync

Schmidl & Cox - preamble

S&C preamble

Schmidl & Cox - detector

S&C block diagram

Schmidl & Cox - detector

S&C detector output

|x| and arg(x)

S&C calculation

S&C detector output

S&C calculation

S&C detector with frequency offset

S&C detector output

|x| and arg(x)

with frequency offset

Derive df from argx

Calculating the frequency offset from the S&C phase

Corrected frequency offset

Using the calculated frequency offset the symbols can be sampled correctly


GnuRadio …

GnuRadio companion

GnuRadio companion UI

Using GnuRadio

GnuRadio levels of abstraction:

The Project



XFDMSync - usage

S&C blocks

XFDMSync - output

S&C block output

The default configuration adds a tag to the sample stream whenever a S&C sequence is detected


S&C correlator

Performs the raw S&C calculation and outputs a correlation value normalized to the mean input power



S&C tagger

Adds a tag to the sample stream when set thresholds are crossed


XCorr Tagger

Xcorr tagger

Relocates incomming tags based on cross-correlation with stored preamble


What i have learned

Next steps

The software sources are released under the terms of the
GNU GPLv3 license:

This presentation is released under the terms of the
GNU FDLv1.3: