In this paper, we consider a Switch and Stay Combiner (SSC) diversity scheme operating over α−η−μ fading channel. New and closed-form expressions for the average output SNR (ASNR), the moment-generating function (MGF), the outage probability (P_out), and the average symbol error rate (ASER) for M-ary quadrature amplitude modulation (QAM) signaling are derived. The expressions are obtained in terms of the well-known bivariate Fox’s H-function (BFHF). It is worth pointing out that the BFHF and the bivariate Meijer’s G-function (BMGF) have recently been used extensively in wireless communications literature to study the system's performance. The evaluated results are plotted for channel parameters of interest, and the effect of fading severity on the combiner performance is studied. Moreover, the results are shown to match those previously reported in the literature for other channel models such as η−μ as a special case, which confirms the validity of the obtained expressions. Also, insights on the optimal choice of the switching threshold are provided.

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Analysis of bifurcation of second-order analog phase locked loop (PLL) with tanlock and sawtooth phase detectors is investigated. Both qualitative and quantitative analyses are carried out. Qualitatively, the basin boundaries of the attractors were constructed by plotting the stable and the unstable manifolds of the system. The basin boundaries show that the PLL under consideration for certain loop parameters has a separatrix cycle which terminates the limit cycle (out-of-lock state) and the loop pulls-in. This behavior is known in literature as homoclinic bifurcation and the value of the bifurcation parameter where this process occurs is called the pull-in range. Quantitatively, we propose a collocation-based algorithm to compute the separatrix cycle and the pull-in range. The separatrix cycle is approximated by a finite set of harmonics N with unknown amplitudes and by utilizing the fact that this limit cycle bifurcates from a separatrix cycle, a system of nonlinear algebraic equations is derived. For given values of filter parameters and gain, the algorithm numerically solves for the unknown amplitude of the harmonics and the value of the pull-in range simultaneously by evaluating the system at the collocation points. Results demonstrate that phase locked loop with sawtooth phase detector characteristics has the wider pull-in range followed by tanlock and sinusoidal, respectively.

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The main goals of all new technologies nowadays are utilizing the available spectrum, increasing spectrum efficiency, and increasing the throughput. Cognitive radio (CR) technology can provide efficient spectrum utilization and maximize the throughput using dynamic spectrum access technique. A new medium access control (MAC) protocol is needed for CR users to access the spectrum dynamically and to maintain fairness between users. In this paper, our objective is to enhance the overall network throughput, by enhancing SMART-V MAC protocol to support D-OFDM technology. A new channel assignment scheme called SMART-O based on these two technologies is proposed. The proposed algorithm greatly increased the overall throughput of the network and solved the channel assignment and rate optimization problems. Simulation results exposed the improvement of our work compared to previous algorithms.