RF Spectrum Sensing Based on an Overdamped Nonlinear Oscillator Ring for Cognitive Radios

Abstract

Existing spectrum-sensing techniques for cognitive radios require an analog-to-digital converter (ADC) to work at high dynamic range and a high sampling rate, resulting in high cost. Therefore, in this paper, a spectrum-sensing method based on a unidirectionally coupled, overdamped nonlinear oscillator ring is proposed. First, the numerical model of such a system is established based on the circuit of the nonlinear oscillator. Through numerical analysis of the model, the critical condition of the system’s starting oscillation is determined, and the simulation results of the system’s response to Gaussian white noise and periodic signal are presented. The results show that once the radio signal is input into the system, it starts oscillating when in the critical region, and the oscillating frequency of each element is fo/N, where fo is the frequency of the radio signal and N is the number of elements in the ring. The oscillation indicates that the spectrum resources at fo are occupied. At the same time, the sampling rate required for an ADC is reduced to the original value, 1/N. A prototypical circuit to verify the functionality of the system is designed, and the sensing bandwidth of the system is measured.

Versatile Tunable Voltage-Mode Biquadratic Filter and Its Application in Quadrature Oscillator

“…Active filters and oscillators are widely used in sensor, communication, instrumentation and control applications [1,2,3,4,5,6,7,8]. Especially in the sensor system, the filter is used to filter out the noise in the system [1].…”

“…Especially in the sensor system, the filter is used to filter out the noise in the system [1]. Oscillators can produce a repetitive electronic signal for sensors [2,3,4,5,6]. One of the key circuits in front-ends of sensors is the quadrature signal generator for modulation and demodulation [7].…”

A Novel Dual-Band Six-Phase Voltage-Control Oscillator

“…Most of the reference clock circuit and part of the local oscillator circuit are implemented with a ring structure [ 1 , 13 , 14 ]. These VCOs are implemented by single-ended delay cells or differential delay cells [ 1 , 3 ].…”

Dynamics of a ring of three unidirectionally coupled Duffing oscillators with time-dependent damping

“…The stability of this system was estimated using Lyapunov exponents [18]. Nevertheless, little attention was paid to a study of the effect of damping, although ring-coupled overdamped Duffing oscillators were investigated in the presence of a delay in coupling [19], multistability [20,21] and even proposed for spectrum-sensing technology application [22].…”