Abstract
The modulated wideband converter (MWC) is a kind of sub-Nyquist sampling system which is developed from compressed sensing theory. It accomplishes highly accurate broadband sparse signal recovery by multichannel sub-Nyquist sampling sequences. However, when the number of sparse sub-bands becomes large, the amount of sampling channels increases proportionally. Besides, it is very hard to adjust the number of sampling channels when the sparsity changes, because its undersampling board is designed by a given sparsity. Such hardware cost and inconvenience are unacceptable in practical applications. This paper proposes a distributed modulated wideband converter (DMWC) scheme innovatively, which regards one sensor node as one sampling channel and combines MWC technology with a broadband cooperative spectrum sensing network perfectly. Being different from the MWC scheme, DMWC takes phase shift and transmission loss into account in the input terminal, which are unavoidable in practical application. Our scheme is not only able to recover the support of broadband sparse signals quickly and accurately, but also reduces the hardware cost of the single node drastically. Theoretical analysis and numerical simulations show that phase shift has no influence on the recovery of frequency support, but transmission loss degrades the recovery performance to a different extent. Nevertheless, we can increase the amount of cooperative nodes and select satisfactory nodes by a different transmission distance to improve the recovery performance. Furthermore, we can adjust the amount of cooperative nodes flexibly when the sparsity changes. It indicates DMWC is extremely effective in the broadband cooperative spectrum sensing network.
Highlights
Cognitive radio is considered as a potential technology which improves spectral efficiency drastically [1,2]
fusion center (FC) allocates spectrum holes, allows the access requests. This mechanism aims at ensuring the communication synchronization between the FC and second users (SUs), which can avoid compromising the quality of service (QoS) of the authorized channels
InInthis wewe propose an original treats atreats singlea geographical sensor sensor node as a sampling channel, turns node-based sensing into network-based and node as a sampling channel, turns node-based sensing into network-based sensing, and sensing, reduces the reduces cost the drastically hardware for cost drastically for a single node.and
Summary
Cognitive radio is considered as a potential technology which improves spectral efficiency drastically [1,2]. In order to search as many spectrum holes as possible, cognitive radio must apply to the high frequency (HF) field This idea is subject to the Nyquist sampling rate. Sensors 2016, 16, 1602 the sub-Nyquist sampling sequence [8,9]. we can locate the all spectrum holes by the frequency support This approach is energy detection in essence, which is unreliable in a low SNR situation. Modulated wideband converter (MWC) is a kind of analog sub-Nyquist sampling system [14] It reconstructs the broadband signal of interest accurately by the low-speed sampling sequences. We propose a distributed modulated wideband converter (DMWC) scheme It can combine undersampling technology with broadband cooperative spectrum sensing skillfully. Theoretical analysis and numerical simulations indicate phase shift has no influence on the recovery of frequency support, but transmission loss degrades the recovery performance to a different extent
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