Scaled Selection Combining for SSK in Decode and Forward Cooperative Relaying

Abstract

We consider a decode-and-forward (DF) cooperative relaying system where a source (S) and a single relay (R) use space shift keying (SSK) modulation for information transmission to the destination (D). Using the Euclidean distance between the SSK constellation points in the SD and RD links as the selection metric, selection combining (SC) can be used at D. Instead of SC, in order to take into account the average performance of SRD and SD links in the selection, scaled selection combining (SSC) is performed at D such that the selection metric in RD link is scaled by a factor α. The error performance of SSK DF SSC cooperative relaying is analyzed in this work. We derive the end-to-end symbol error probability (SEP) expression of the system in closed-form for binary SSK modulation and verify the results with simulation. Further we infer that SSK DF SSC system performs better than SSK system without cooperative relaying and SC in SSK DF cooperative relaying.