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 or -13 dB and -17 dB respectively for 15- and 31-chip spreading sequences.