4,753 research outputs found
A Novel Algorithm for Cooperative Distributed Sequential Spectrum Sensing in Cognitive Radio
This paper considers cooperative spectrum sensing in Cognitive Radios. In our
previous work we have developed DualSPRT, a distributed algorithm for
cooperative spectrum sensing using Sequential Probability Ratio Test (SPRT) at
the Cognitive Radios as well as at the fusion center. This algorithm works
well, but is not optimal. In this paper we propose an improved algorithm-
SPRT-CSPRT, which is motivated from Cumulative Sum Procedures (CUSUM). We
analyse it theoretically. We also modify this algorithm to handle uncertainties
in SNR's and fading.Comment: This paper has been withdrawn by the author due to the submission of
detailed journal version of the same paper, to arXi
Energy Detection of Unknown Signals over Cascaded Fading Channels
Energy detection is a favorable mechanism in several applications relating to
the identification of deterministic unknown signals such as in radar systems
and cognitive radio communications. The present work quantifies the detrimental
effects of cascaded multipath fading on energy detection and investigates the
corresponding performance capability. A novel analytic solution is firstly
derived for a generic integral that involves a product of the Meijer
function, the Marcum function and arbitrary power terms. This solution
is subsequently employed in the derivation of an exact closed-form expression
for the average probability of detection of unknown signals over *Rayleigh
channels. The offered results are also extended to the case of square-law
selection, which is a relatively simple and effective diversity method. It is
shown that the detection performance is considerably degraded by the number of
cascaded channels and that these effects can be effectively mitigated by a
non-substantial increase of diversity branches.Comment: 12 page
Distributed Nonparametric Sequential Spectrum Sensing under Electromagnetic Interference
A nonparametric distributed sequential algorithm for quick detection of
spectral holes in a Cognitive Radio set up is proposed. Two or more local nodes
make decisions and inform the fusion centre (FC) over a reporting Multiple
Access Channel (MAC), which then makes the final decision. The local nodes use
energy detection and the FC uses mean detection in the presence of fading,
heavy-tailed electromagnetic interference (EMI) and outliers. The statistics of
the primary signal, channel gain or the EMI is not known. Different
nonparametric sequential algorithms are compared to choose appropriate
algorithms to be used at the local nodes and the FC. Modification of a recently
developed random walk test is selected for the local nodes for energy detection
as well as at the fusion centre for mean detection. It is shown via simulations
and analysis that the nonparametric distributed algorithm developed performs
well in the presence of fading, EMI and is robust to outliers. The algorithm is
iterative in nature making the computation and storage requirements minimal.Comment: 8 pages; 6 figures; Version 2 has the proofs for the theorems.
Version 3 contains a new section on approximation analysi
Generalized detector as a spectrum sensor in cognitive radio networks
The implementation of the generalized detector (GD) in cognitive radio (CR) systems allows us to improve the spectrum sensing performance in comparison with employment of the conventional detectors. We analyze the spectrum sensing performance for the uncorrelated and spatially correlated receive antenna array elements. Addi¬tionally, we consider a practical case when the noise power at the output of GD linear systems (the preliminary and additional filters) is differed by value. The choice of the optimal GD threshold based on the minimum total error rate criterion is also discussed. Simulation results demonstrate superiority of GD implementation in CR sys¬tem as spectrum sensor in comparison with the energy detector (ED), weighted ED (WED), maximum-minimum eigenvalue (MME) detector, and generalized likelihood ratio test (GLRT) detecto
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