Modulation network coding

In this study, we propose a four-dimensional modulation, referred to as modulation network coding (MNC), to address the problem of decoding a signal from multiple source node transmissions in mobile fast fading channels. The MNC scheme judiciously mixes a two-dimensional (2D) pilot symbol with a 2D information symbol, and makes use of a π/4 rotated M-pulse-amplitude modulation (PAM) constellation to guaranty an effective decoding of all the interfering symbols even in the case of a smaller channel Doppler spread compared with the period of the MNC symbol. In addition, because the MNC scheme makes use of an additional dimension introduced through orthogonal pulse waveform, the use of the pilot symbols does not reduce the effective information rate. The analytical and simulation results show that it is possible to achieve a low symbol error probability with a good signal-to-noise ratio when controlling a few parameters impacting the performance of the system such as the synchronisation in time and in frequency of the source nodes.