A cognitive radio (CR) is a transceiver which automatically detects the available unused channels in the wireless spectrum. A cognitive radio network (CRN) is formed by either allowing the secondary users (SUs) to coexist with the primary users (PUs) or enabling the SUs to use the unoccupied portion of the spectrum. In this paper, the ergodic capacity maximization problem is studied in Rayleigh...

We present a new technique for measuring refractive index changes using the technique of phase-shift keying of holographic gratings. Based on this technique, we have realized an holographic interferometer to gauge refractive index variations in gases. We present experimental data for standard atmosphere under laboratory conditions and theoretical calculations for the measured transfer function ...

Reconfigurable intelligent surface (RIS)-assisted transmission and space shift keying (SSK) appear as promising candidates for future energy-efficient wireless systems. In this article, two RIS-based SSK schemes are proposed to efficiently improve the error throughput performance of conventional systems, respectively. The first one, termed RIS-SSK with passive beamforming (RIS-SSK-PB), employs ...

9.953 GHz phase-modulated continuous-wave laser combs are spectrally broadened via nonlinear propagation in normal and anomalous dispersion media and experimentally characterized using a differential phase shift keying (DPSK) decoder. DPSK bit-error rate data are in qualitative agreement with radio-frequency spectrum analyzer measurements.

Fundamental optics such as lenses and prisms work by applying phase shifts of several radians to incoming light, and rapid control of such phase shifts is crucial to telecommunications. However, large, controllable optical phase shifts have remained elusive for isolated quantum systems. We have used a single trapped atomic ion to induce and measure a large optical phase shift of 1.3±0.1 radians...

The impact of quantization on the energy efficiency of phase and frequency modulation is investigated. Transmission over the additive white Gaussian noise (AWGN) channel, and coherent and noncoherent fading channels is considered. It is assumed that the receiver quantizes the received signals by performing hard-decision detection. Closed-form expressions for the first and second derivatives of ...

In this paper, a performance of M-ary signals for optimum combining with multiple co-channel interferers is analyzed in a flat Rayleigh fading channel. The closed-form expressions of average symbol error rate of M-ary phase shift keying and M-ary differential phase shift keying are derived by using the moment generating function-based approach and the orthogonal approximation which is employed ...