Frequency Agile Interference-Aware Channel Sounding for Dynamic Spectrum Access Networks

In this paper, we propose a novel channel sounding technique, called the multicarrier direct sequence swept time delay cross-correlation (MC-DS-STDCC), which is designed to minimize the interference with incumbent licensed transmissions within the context of a dynamic spectrum access (DSA) network. Conventional channel sounders employ the same transmit power level when operating over a specific frequency band. However, the maximum-tolerable transmit power levels permitted across the spectrum within a DSA network can potentially be non-uniform. Our proposed channel sounder is designed to tailor the transmit power level across the frequency band of operation, limiting it to the constraints imposed by both licensed and unlicensed devices, as well as by regulatory agencies. Employing a combination of multicarrier spread spectrum modulation and a conventional channel sounding approach, our proposed technique achieves a mean squared error of the estimated channel impulse response of 10^-3 at an SNR of -13 dB and -17 dB respectively for 15- and 31-chip spreading sequences.