Low-Cost Channel Sounder Design Based on Software-Defined Radio and OFDM

In this paper we describe the design of a low-cost and portable channel sounding system. The baseband signal processing in both the transmitter and the receiver are done in software, while the up/down conversion are done by means of a Software Defined Radio (SDR) frontend. The modulation procedure is based on the Orthogonal Frequency Division Multiplexing (OFDM) technique due to its robustness against inter-symbol interference (ISI). The sounder is designed to overcome some well known important issues of any OFDM system. For example, it does not need extra resources neither to guarantee a ISI-free transmission by means of a guard interval, nor for the synchronization by means of a preamble. Moreover, the excitation signal is designed to have a peak-to-average power ratio (PAPR) close to 0 dB while maintaining a flat spectrum. The system is calibrated and validated under laboratory conditions prior to the measurement of an air-to-ground channel in the C frequency band, the results are presented and discussed.

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