Improving the Energy Efficiency of Mobile Terminals Using Dynamic Multilevel Priority Packet Scheduling in Cooperative Communication

Cooperative communication is an efficient method for reducing the energy consumption of mobile terminal in wireless cellular network. However, it is hard to implement due to the lack of motivations for the Mobile terminals to cooperate. For this scenario as the benchmark case, where the information of the helping mobile terminals such as the channel and battery conditions is completely known by the source node terminal, the problem is formulated as a relay selection problem. Efficient algorithms based on dichotomous search and alternative optimizations are proposed to solve the problem for the cases of split and non-split data at the source MT, respectively. The cooperative communications scheme with pricing mechanism can decrease both the battery outages and communications for the mobile node, and can also increase the average battery level during the mobile terminals operation. In this paper, we state a Dynamic Multilevel Priority (DMP) packet scheduling scheme. In the proposed system, each node, except those which are at the last level of the virtual hierarchy in the zone based topology of Wireless sensor network , have three levels of priority queues. Real-time packets are placed in the highest-priority queue and can preempt data packets in other queues. Non-real-time packets are placed in other two queues based on a certain threshold of their estimated processing time. Leaf nodes will have two queues for real-time and non-real-time data packets since they do not receive data from other nodes and so this reduce end to- end delay. The performance of the proposed Dynamic multilevel priority packet scheduling scheme through simulations for real-time and non-real-time data packet. Simulation results shows that the DMP packet scheduling scheme outperforms conventional schemes interms of average data waiting time and end-to-end delay

Research of M-PAM and Duobinary Modulation Formats for Use in High-Speed WDM-PON Systems

The exponential growth of Internet data traffic and progress of Information and Communication Technology (ICT) sector pushes hard the telecommunication infrastructure for upgrading the transmission data rate. Wavelength division multiplexed passive optical networks (WDM-PONs) can be the next generation solution for nowadays problems which are related to transmission capacity. Next-generation WDM-PON systems based on mixed wavelength transmitters are expected to become more cost-efficient at high per user data rates, e.g., over 10 Gbit/s per channel. Important advantage of this technology is to set various channel spacing and use different modulation formats to increase spectral efficiency in the same time and provide different transmission speeds for end user, based on pay-as-you-grow approach. Therefore, several modulation formats like non-return to zero (NRZ) also called 2-level pulse-amplitude modulation (PAM-2), four level PAM or PAM-4 and Duobinary (DB) are investigated to understand their limitations, advantages and disadvantages to be further used in next generation PON systems to increase its capacity and spectral efficiency

Low Dimensional MIMO Systems with Finite Sized Constellation Inputs

Non

Minimization of total harmonic distortions of cascaded H-bridge multilevel inverter by utilizing bio inspired AI algorithm

Minimizing total harmonic distortion (THD) with less system complexity and computation time is a stringent constraint for many power systems. The multilevel inverter can have low THD when switching angles are selected at the fundamental frequency. For low-order harmonic minimization, selective harmonic elimination (SHE) is the most adopted and proficient technique but it involves the non-linear transcendental equations which are very difficult to solve analytically and numerically. This paper proposes a genetic algorithm (GA)-based optimization technique to minimize the THD of cascaded H-bridge multilevel inverter. The GA is the finest approach for solving such complex equations by obtaining optimized switching angles. The switching angles are calculated by the genetic algorithm by solving the nonlinear transcendental equations. This paper has modeled and simulated a five-level inverter in MATLAB Simulink. The THD comparison is carried out between step modulation method and optimization method. The results reveal that THD has been reduced from 17.88 to 16.74% while third and fifth harmonics have been reduced from 3.24%, 3.7% to 0.84% and 3.3%, respectively. The optimization method along with LC filter significantly improves the power quality providing a complete sinusoidal signal for varying load

Voronoi Constellations for Coherent Fiber-Optic Communication Systems

The increasing demand for higher data rates is driving the adoption of high-spectral-efficiency (SE) transmission in communication systems. The well-known 1.53 dB gap between Shannon\u27s capacity and the mutual information (MI) of uniform quadrature amplitude modulation (QAM) formats indicates the importance of power efficiency, particularly in high-SE transmission scenarios, such as fiber-optic communication systems and wireless backhaul links. Shaping techniques are the only way to close this gap, by adapting the uniform input distribution to the capacity-achieving distribution. The two categories of shaping are probabilistic shaping (PS) and geometric shaping (GS). Various methods have been proposed for performing PS and GS, each with distinct implementation complexity and performance characteristics. In general, the complexity of these methods grows dramatically with the SE and number of dimensions.Among different methods, multidimensional Voronoi constellations (VCs) provide a good trade-off between high shaping gains and low-complexity encoding/decoding algorithms due to their nice geometric structures. However, VCs with high shaping gains are usually very large and the huge cardinality makes system analysis and design cumbersome, which motives this thesis.In this thesis, we develop a set of methods to make VCs applicable to communication systems with a low complexity. The encoding and decoding, labeling, and coded modulation schemes of VCs are investigated. Various system performance metrics including uncoded/coded bit error rate, MI, and generalized mutual information (GMI) are studied and compared with QAM formats for both the additive white Gaussian noise channel and nonlinear fiber channels. We show that the proposed methods preserve high shaping gains of VCs, enabling significant improvements on system performance for high-SE transmission in both the additive white Gaussian noise channel and nonlinear fiber channel. In addition, we propose general algorithms for estimating the MI and GMI, and approximating the log-likelihood ratios in soft-decision forward error correction codes for very large constellations

Combined Source and Channel Strategies for Optimized Video Communications

ISBN 978-953-7619-70-