Bit error performance of a cooperative spectrum sharing protocol using spatial modulation

Abstract

In this work, bit error probability for a spectrum sharing protocol applying spatial modulation (SM) at secondary users is derived. In the protocol primary transmitter (PT) applies M-ary phase shift keying (M-PSK) modulation while secondary transmitter (ST) employs spatial modulation (Nt antennas and M-PSK) to send primary M-PSK signal with respect to selective decode-and-forward strategy from the antenna it choose accord- ing to its own information. Carrying primary information by M-PSK modulation whereas secondary information by antenna indexes mitigates mutual interference between users. Upper bounds for bit error probability are analytically derived and supported via computer simulations. Performance of the protocol is compared with non-cooperation case and a reference system using M-PSK modulation at both users.