Generalised spatial modulation (GSM) is a recently developed multiple-input
multiple-output (MIMO) technique aimed at improving data rates over conventional spatial modulation (SM) systems. However, for identical antenna
array size and configurations (AASC), the bit error rate (BER) of GSM systems
in comparison with SM systems is degraded. Recently, a GSM system with constellation reassignment (GSM-CR) was proposed in order to improve the BER
of traditional GSM systems. However, this study focused on M-ary quadrature
amplitude modulation (M-QAM) schemes. The focus of this paper is the application of a circular constellations scheme, in particular, amplitude phase shift
keying (APSK) modulation, to GSM and GSM-CR systems. An analytical
bound for the average BER of the proposed M-APSK GSM and M-APSK GSMCR systems over fading channels is derived. The accuracy of this bound is verified using Monte Carlo simulation results. A 4 × 4 16-APSK GSM-CR system
achieves a gain of 2.5 dB at BER of 10−5 over the traditional 16-APSK GSM system with similar AASC. Similarly, a 6 × 4 32-APSK GSM-CR system achieves
a gain of 2 dB at BER of 10−5 over equivalent 32-APSK GSM system.
