PAPR and saturation effects of power amplifiers in SM OFDM and V-BLAST OFDM systems

Abstract

The paper firstly analyzes the complementary cumulative distribution function (CCDF) of the peak-to-average power ratio (PAPR) of the spatial modulation (SM) and vertical Bell Labs layered space-time (V-BLAST) transmission schemes, with both systems using the orthogonal frequency division multiplexing (OFDM). In a second step, for specific values of input back-off (IBO), we investigate the clipping effect of a hard-limiter high power amplifier (HPA) on the bit error rate (BER) performance of both systems. Moreover, for a fair comparison, the maximum likelihood (ML) detector is used in both OFDM systems. Multipath Rayleigh fading channels and uncoded signals have been considered. Simulation results show that the SM OFDM, for a large number of subcarriers, presents practically the same PAPR behavior of the V-BLAST OFDM system. On the other hand, for a small number of subcarriers, a large number of antennas and higher-order modulations it seldom attains higher PAPR values than V-BLAST OFDM, which does not implies in practical performance degradation. However, in terms of BER, it turns out that the SM OFDM system is much more sensitive to the ICI generated by clipping resultant of the HPA when its modulation cardinality is higher than the one used in the V-BLAST OFDM system.