Sandhya Pattanayak

Identification of spectrum holes using ANN model for cognitive radio applications

With the burgeoning popularity & necessity of all things wireless, the radio spectrum has become a scarce utility; cognitive radio (CR) is now the relevant technology under development that enables one to utilize the spectrum more efficiently. Here we propose a new artficial neural network (ANN) model that predicts the channel capacity of the received signal. This information is analyzed theoretically which is subsequently verified by a suitable simulation scheme for identifying possible white space in a given band.

Electronically Tunable Differential Integrator: Linear Voltage Controlled Quadrature Oscillator

A new electronically tunable differential integrator (ETDI) and its extension to voltage controlled quadrature oscillator (VCQO) design with linear tuning law are proposed; the active building block is a composite current feedback amplifier with recent multiplication mode current conveyor (MMCC) element. Recently utilization of two different kinds of active devices to form a composite building block is being considered since it yields a superior functional element suitable for improved quality circuit design. The integrator time constant (τ) and the oscillation frequency (ω o) are tunable by the control voltage (V) of the MMCC block. Analysis indicates negligible phase error (θ e) for the integrator and low active ω o-sensitivity relative to the device parasitic capacitances. Satisfactory experimental verifications on electronic tunability of some wave shaping applications by the integrator and a double-integrator feedback loop (DIFL) based sinusoid oscillator with linear f o variation range of 60 KHz~1.8 MHz at low THD of 2.1% are verified by both simulation and hardware tests.

Spectrum hole detection in TV band using ANN model for opportunistic radio communication

Here we propose an artificial neural network (ANN) model for spectrum sensing in TV band specifically for identifying presence of audio signals. The ANN model is trained with parameters which are a combination of cyclostationary and SNR based features like channel capacity, bandwidth efficiency, autocorrelation. The ANN model is trained based on a new decision making factor termed as utilization factor based on the above combination of attributes which lead to a method for detection of spectrum holes. This unique combination of hypotheses tries to remove the disadvantages of energy detection and cyclostationary feature detection technique, which is helpful for opportunistic cognitive radio applications.

An Improved Energy Detector for Spectrum Sensing in Cognitive Radio System with Adaptive Noise Cancellation and Adaptive Threshold

Over the years the usage of wireless communication systems has increased rapidly leading to scarcity of bandwidth. Hence the concept of utilizing the existing system to its fullest has become very important. Cognitive radio is a technique based on this concept which identifies the unutilized white spaces in the spectrum, and are allotted to the secondary user in a non-interfering manner. The energy detection technique does not work at low SNR. In this paper we attempted to improve the efficiency by performing adaptive noise cancellation and adaptive threshold in the energy detector.

Electronically Tunable Dual-Input Integrator: Synthetic Immittance Function Realizability

ABSTRACT A new electronically tunable differential input integrator (ETDII) using the composite current feedback amplifier (CFA) and multiplication-mode current conveyor (MMCC) building block is presented, wherein the control voltage (Vc) of the MMCC tunes its time constant (τ). Effects of the device parasitic capacitances had been examined and appropriate compensation design is proposed to obtain high-quality (q) realization. Analysis shows that τ is practically active insensitive to device port mismatch errors (ϵ). A quadrature voltage controlled oscillator (VCO) is implemented utilizing the ETDII after suitably configuring a double-integrator loop with grounded capacitors in the same topology. With the loop closed, the ETDII topology realizes some new electronically tunable synthetic immittance function at appropriate nodes. Satisfactory experimental results for the proposed realizations had been verified with PSPICE macro-model simulation and by hardware test.