Cyclic Delay Diversity with Phase Shift in Low Rate SC-FDMA Uplink

Abstract

This paper proposes a phase shift scheme in cyclic delay diversity (CDD) for single-carrier frequency division multiple access in Internet of Things (IoT) applications. The proposed scheme is assumed to be applied to the uplink of long term evolution (LTE) systems. Since the transmission rates of IoT applications are small, each uplink connection may occupy less than 12 subcarriers that corresponds to one resource block of the LTE. Since the length of the data sequence in time domain is short so that CDD may provide limited frequency diversity. The proposed scheme shifts the phases of the data symbols in time domain and spreads each subcarrier component over multiple subcarriers. Thus, more diversity gain can be realized with CDD. Numerical results obtained through computer simulation shows that the proposed scheme improves the performance by about 5–7 dB at the bit error rate of 10−4 for the data sequence length of 4. It is also shown that no increase of peak-to-average power ratio is observed with the proposed scheme.