Low-complexity welch power spectral density computation

TY - JOUR

T1 - Low-complexity welch power spectral density computation

AU - Parhi, Keshab K

AU - Ayinala, Manohar

PY - 2014/1/1

Y1 - 2014/1/1

N2 - This paper presents a low-complexity algorithm and architecture to compute power spectral density (PSD) using the Welch method. The Welch algorithm provides a good estimate of the spectral power at the cost of high computational complexity. We propose a new modified approach to reduce the computational complexity of the Welch PSD computation for a 50% overlap. In the proposed approach, an N/2-point FFT is computed, where N is the length of the window and is merged with the FFT of the previous N/2-point to generate an N-point FFT of the overlapped segment. This requires replacing the windowing operation as a convolution in the frequency domain. Fortunately, the frequency-domain filtering requires a symmetric 3-tap or 5-tap FIR filter for raised cosine windows. The proposed method needs to compute (L+1) N/2-point FFTs instead of L N-point FFTs, where L is the number of overlapping segments. In the proposed novel merged FFT approach, the even samples are computed exactly, while the odd samples require a shift by a half-sample delay and are estimated using a bidirectional fractional-delay filter. The complexity reduction comes at the cost of slight performance loss due to the approximation used for the implementation of the fractional-delay filter. The performance loss is about 8% using fractional-delay filter with 2 multipliers. A novel architecture is presented based on the proposed algorithm. The proposed architecture not only consumes 33% less energy compared to the original method but also reduces the latency by about 44% for 8 overlapping segments. Further a low-complexity architecture is presented to compute a special case of the short-time Fourier transform based on the proposed PSD computation algorithm.

AB - This paper presents a low-complexity algorithm and architecture to compute power spectral density (PSD) using the Welch method. The Welch algorithm provides a good estimate of the spectral power at the cost of high computational complexity. We propose a new modified approach to reduce the computational complexity of the Welch PSD computation for a 50% overlap. In the proposed approach, an N/2-point FFT is computed, where N is the length of the window and is merged with the FFT of the previous N/2-point to generate an N-point FFT of the overlapped segment. This requires replacing the windowing operation as a convolution in the frequency domain. Fortunately, the frequency-domain filtering requires a symmetric 3-tap or 5-tap FIR filter for raised cosine windows. The proposed method needs to compute (L+1) N/2-point FFTs instead of L N-point FFTs, where L is the number of overlapping segments. In the proposed novel merged FFT approach, the even samples are computed exactly, while the odd samples require a shift by a half-sample delay and are estimated using a bidirectional fractional-delay filter. The complexity reduction comes at the cost of slight performance loss due to the approximation used for the implementation of the fractional-delay filter. The performance loss is about 8% using fractional-delay filter with 2 multipliers. A novel architecture is presented based on the proposed algorithm. The proposed architecture not only consumes 33% less energy compared to the original method but also reduces the latency by about 44% for 8 overlapping segments. Further a low-complexity architecture is presented to compute a special case of the short-time Fourier transform based on the proposed PSD computation algorithm.

KW - FFT

KW - Welch method

KW - fractional-delay filter

KW - frequency-domain convolution

KW - low-complexity

KW - low-power

KW - power spectral density

KW - windowing

UR - http://www.scopus.com/inward/record.url?scp=84892594837&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84892594837&partnerID=8YFLogxK

U2 - 10.1109/TCSI.2013.2264711

DO - 10.1109/TCSI.2013.2264711

M3 - Article

VL - 61

SP - 172

EP - 182

JO - IEEE Transactions on Circuits and Systems I: Regular Papers

JF - IEEE Transactions on Circuits and Systems I: Regular Papers

SN - 1549-8328

IS - 1

M1 - 6525419

ER -