Cancellation Symbol Insertion for Out-of-Band Power Reduction in SM-OFDM

Spatial modulation orthogonal frequency division multiplexing (SM-OFDM) is a promising transmission technique that combines spatial modulation (SM) with orthogonal frequency division multiplexing (OFDM). SMOFDM inherits from OFDM the ability to combat frequency selective fading channels and from SM the potential of achieving higher data rates without causing inter-antenna interference (IAI). However, like OFDM, SM-OFDM suffers from high outof-band (OOB) power leakage and thus causes strong interference to the adjacent band users. In the literature, the technique of N-continuous precoding has been applied to SMOFDM for reducing the OOB power. However, because the N continuous precoding technique introduces IAI to SM-OFDM systems, it degrades the error performance severely. To reduce the OOB power without causing IAI, this paper adopts the cancellation symbol insertion technique in SM-OFDM systems. Because the proposed SM-OFDM scheme can suppress OOB power effectively without introducing IAI, it achieves much better error performance than the N-continuous precoded SMOFDM while providing comparable OOB power reduction capability.