Journal of Communications and Information Networks, Vol.3, No.2, Jun. 2018
DOI: 10.1007/s41650-018-0016-3 Research paper
Adaptive Data-Driven Wideband Compressive
Spectrum Sensing for Cognitive Radio Networks
Mohsen Ghadyani, Ali Shahzadi
Abstract—This paper presents a novel adaptive wide-
band compressed spectrum sensing scheme for cognitive
radio (CR) networks. Compared to the traditional CSS-
based CR scenarios, the proposed approach reconstructs
neither the received signal nor its spectrum during the
compressed sensing procedure. On the contrary, a precise
estimation of wide spectrum support is recovered with
a fewer number of compressed measurements. Then,
the spectrum occupancy is determined directly from the
reconstructed support vector. To carry out this process,
a data-driven methodology is utilized to obtain the mini-
mum number of necessary samples required for support
reconstruction, and a closed-form expression is obtained
that optimally estimates the number of desired samples as
a function of the sparsity level and number of channels.
Following this phase, an adjustable sequential framework
is developed where the first step predicts the optimal
number of compressed measurements and the second
step recovers the sparse support and makes sensing
decision. Theoretical analysis and numerical simulations
demonstrate the improvement achieved with the proposed
algorithm to significantly reduce both sampling costs
and average sensing time without any deterioration in
detection performance. Furthermore, the remainder of
the sensing time can be employed by secondary users for
data transmission, thus leading to the enhancement of the
total throughput of the CR network.
Keywords—saving in the sampling resources, sparse
support estimation, spectrum occupancy, throughput en-
hancement, wideband spectrum sensing
I. INTRODUCTION
I
n recent years, opportunistic spectrum utilization has re-
ceived significant interests, especially in fifth-generation
Manuscript received Sept. 18, 2017; accepted Mar. 21, 2018. The asso-
ciate editor coordinating the review of this paper and approving it for publi-
cation was J. H. He.
M. Ghadyani, A. Shahzadi. Faculty of Electrical and Computer
Engineering, Semnan University, Semnan 35196-45399, Iran (e-mail:
ghadyani@semnan.ac.ir; shahzadi@semnan.ac.ir).
(5G) wireless networks where the unlicensed users sense a
wide range of spectrum and dynamically change their param-
eters to access the licensed spectrum
[1]
. As a result, fast and
accurate spectrum sensing plays the main role in a cognitive
radio (CR) system, allowing it to optimally employ the spec-
trum resources without any harmful interference for primary
users (PUs)
[2]
. In wide band spectrum sensing (WBSS), sec-
ondary users (SUs) monitor a large number of sub-bands to
find idle channels for data transmission. However, the band-
width of wide band signals is so large that existing analog-
to-digital converters are unable to handle the signal’s Nyquist
rate (R
Nq
)
[3]
. In addition, such a high sampling rate generates
an enormous number of samples to be processed, thus affect-
ing the efficiency and power consumption of the system
[4]
.
To overcome this sampling rate challenge, several sub-
Nyquist sampling methods have been proposed
[5-10]
. Com-
pressed sensing (CS)
[11]
is a revolutionary technique in signal
processing that can successfully bypass the traditional limi-
tations of data acquisition. In CS, the original signal is re-
constructed with a few random linear measurements acquired
with a sampling rate that is lower than the signal’s Nyquist
rate
[12]
. To accomplish this task, the desired signal or some
linear transform of it is made sparse in a proper domain
[13]
.
Many effective methods have been introduced to reconstruct
the wide band spectrum from the compressed measurements
extracted by the CR receiver with a low sampling rate. Unfor-
tunately, almost all of the existing algorithms assume that the
sparsity level of the spectrum is known. However, in practical
scenarios and because of the dynamic characteristics of PUs,
the actual sparsity level is usually unknown and varies with
time. On the contrary, the minimum sampling rate required
for spectrum reconstruction is a function of the sparsity level.
The smaller the sparsity level is, the lower sampling rate is
needed to successfully recover the wide band spectrum. As a
result, exact and adaptive estimation of sparsity level helps to
save the sampling resources in wide band compressive spec-
trum sensing
[14]
.
In recent years, several methods have been proposed to per-
form CS without any prior knowledge about the sparsity level
of the signal of interest. In Ref. [15], a novel method has been
investigated for sparsity level estimation that uses the gap be-