Novel Pilot-Assisted Spectrum Sensing for OFDM Systems by Exploiting Statistical Difference Between Subcarriers

• Published in: IEEE transactions on communications Vol. 61; no. 4; pp. 1264 - 1276
• Main Authors: Zhengwei Lu, Yi Ma, Cheraghi, P., Tafazolli, R.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.04.2013; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Exact sciences and technology; Frequency domain analysis; Information, signal and communications theory; Multiplexing; Noise; OFDM; Orthogonal frequency-division multiplexing (OFDM); pilot; Semiconductor optical amplifiers; Sensors; Signal and communications theory; Signal representation. Spectral analysis; Signal, noise; spectrum sensing; statistical difference; subcarriers; Telecommunications and information theory; Timing; Vectors; Availability; Performance evaluation; Second order; pilot; Useful information; Computer simulation; Order statistic; Frequency domain method; subcarriers; Doppler effect; Subcarrier; False alarm rate; Statistical method; Orthogonal frequency-division multiplexing (OFDM); Spectrum analysis; First order; Analytical method; spectrum sensing; Orthogonal frequency division multiplexing; statistical difference; Signal analysis
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2013.020813.120323

This paper presents a novel pilot-assisted spectrum sensing technique for orthogonal frequency-division multiplexing (OFDM) systems. The main idea is based upon the physical nature that subcarriers carrying pilots or payload data have different first-order and second-order statistical properties. These differences vanish when the spectrum of interest is unoccupied. Therefore, the decision of spectrum availability can be formed based upon these differences, which can be explored through employment of frequency-domain differential operations. Thanks to the differential operations, the proposed technique has less sensitivity of the noise power uncertainty problem caused by imperfect hardware. Performance of the proposed technique is analytically formulated in terms of probability of false alarm (PFA) and probability of detection (PD). Computer simulations are carried out to elaborate the analytical results. It is shown that the second-order statistics based proposed technique outperforms the conventional pilot-assisted technique up to 7 dB. Moreover, it is shown that the first-order statistics based proposed technique outperforms the second-order statistics based proposed technique for small normalized Doppler shifts (≤ 0.013). However, the second-order statistics based proposed technique offers better performance for larger normalized Doppler shifts.