An SDR-based reconfigurable multicarrier transceiver for terrestrial and satellite communications

Multicarrier modulation is one of the cornerstones of modern radio communications. Nowadays Orthogonal Frequency Division Multiplexing (OFDM) finds wide employment in terrestrial mobile standards (WiMax and LTE) and also some significant applications in satellite communications. In order to improve OFDM efficiency and reduce the impact of nonlinear amplification, some variants of OFDM have been recently proposed; the most important are: Single-Carrier OFDM (SC-OFDM), known also as Discrete-Fourier Transform (DFT)-precoded OFDM recently proposed for Digital Video Broadcasting Next Generation broadcasting system to Hand-held (DVB-NGH) standard, and the multi-user version of SC-OFDM, known as Single-Carrier Frequency-Division Multiple Access (SC-FDMA), adopted by LTE for the uplink transmissions. In our paper, we aim at proposing a novel reconfigurable multicarrier transceiver implementation based on Software-Defined Radio (SDR), where OFDM and SC-OFDM TX/RX modes can coexist in the same device. The core module of the transceiver is based on the conventional OFDM, implemented in the digital domain by means of the N-point inverse Fast Fourier Transform (I-FFT). SC-OFDM precoding, performed by means of a discrete Fourier transform (DFT) applied to a subset of M information symbols, is instantiated before I-FFT, when SC-OFDM mode is required. The SDR transceiver modules have been implemented by using open source GNU Radio tools and tested in open field by means of low cost hardware devices for RF transmission of software-generated basedband signals. Experimental trials have evidenced the viability of proposed SDR implementation, together with the recognized advantages that SC-OFDM offers in terms of improved link performance in hostile propagation environment. However, it has also been noticed that such improvement is obtained at the expense of a considerable increase of the computaional burden at the receiver side, if compared to that of regular OFDM.