Sobolev Duals for Random Frames and Sigma-Delta Quantization of Compressed Sensing Measurements
英文摘要:
Quantization of compressed sensing measurements is typically justified by the robust recovery results of Candès, Romberg and Tao, and of Donoho. These results guarantee that if a uniform quantizer of step size $δ$ is used to quantize $m$ measurements $y = Φx$ of a $k$-sparse signal $x \in \R^N$, where $Φ$ satisfies the restricted isometry property, then the approximate recovery $x^#$ via $\ell_1$-minimization is within $O(δ)$ of $x$. The simplest and commonly assumed approach is to quantize each measurement independently. In this paper, we show that if instead an $r$th order $ΣΔ$ quantization scheme with the same output alphabet is used to quantize $y$, then there is an alternative recovery method via Sobolev dual frames which guarantees a reduction of the approximation error by a factor of $(m/k)^{(r-1/2)α}$ for any $0 < α< 1$, if $m \gtrsim_r k (\log N)^{1/(1-α)}$. The result holds with high probability on the initial draw of the measurement matrix $Φ$ from the Gaussian distribution, and uniformly for all $k$-sparse signals $x$ that satisfy a mild size condition on their supports.
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