Clustering based two-stage blind channel estimation for special QPSK transmission

Special QPSK has been demonstrated to have superiority of spectral efficiency. However, due to its scatter of constellations and no pilots inserted, the channel estimation is a challenge. In this Letter, clustering based two-stage blind channel estimation is proposed for special QPSK transmission. For the scheme, k-means clustering is applied to reduce the complexity and improve the accuracy of channel estimation in the first stage, while frame synchronisation helps to confirm the estimated result. Simulation results show that this scheme presents small mean square error and good BER performance. Furthermore, this scheme can implement frame synchronisation and channel estimation simultaneously.