Table 1 Notation

x(t)

A continuous-time signal with finite energy

X(f)

The Fourier transform of x(t)

x[n]

Bounded energy sequence

v

Vector

v _i , or v(i)

i th entry of v

v(f)

Vector that depends on a continuous parameter f

Φ

Matrix

Φ _ik

ik th entry of Φ

Φ _i

i th column of Φ

r _t

Samples vector of a signal at time domain

r _f

Samples vector of a signal at frequency domain

$\mathcal{F}$

Non-zero frequency-domain support

q,L

q number of blocks and L denotes the number of all blocks

B,B _i

Bandwidth of sub-band, B _i denotes the i-th sub-band

Q

Threshold for blind spectrum reconstruction

∥x∥₀

ℓ₀-norm of x

∥x∥ _p

ℓ _p -norm of x, which is defined as${\parallel \mathbf{x}\parallel }_p={\left(\sum _{i=1}^N\right|{\mathbf{x}}_i{|}^p)}^{1/p}$

I(A)

Support of A

$\mathcal{M}$

Denote a set of signals in CRN