Experimental over-the-air testing for coexistence of 4G and a spectrally efficient non-orthogonal signal

Abstract

This work investigates several experimental validations for the bandwidth compressed multicarrier signal termed spectrally efficient frequency division multiplexing (SEFDM). The signal compresses bandwidth, therefore improved spectral efficiency, by packing sub-carriers closer. Unlike typical orthogonal frequency division multiplexing (OFDM) signals, SEFDM violates the orthogonality criterion, therefore self-created inter carrier interference (ICI) is introduced. In this work, to ameliorate the effect of interference, a method based on sub-carrier pulse shaping, targeting massive machine-type communication (mMTC), is developed and tested experimentally. Practical over-the-air testing of the proposal is operated on commercially developed software defined radio platforms. Results show that in the condition of coexistence scenario SEFDM can significantly reduce interference when used with existing long term evolution (LTE) signals leading to improved quality of service. The throughput of LTE signals is therefore improved from 49.92 Mbps to 63.21 Mbps. Additionally, the proposed pulse shaping Nyquist-SEFDM performs well in scenarios where the spectrum is limited and in fact it outperforms pulse shaped OFDM significantly, both in terms of bandwidth saving and throughput, which is boosted from 4.35 Mbps to 43.36 Mbps.