An Energy-Efficient Controller for Wirelessly-Powered Communication Networks

In a wirelessly-powered communication network (WPCN), an energy access point (E-AP) supplies the energy needs of the network nodes through radio frequency wave transmission, and the nodes store their received energy in their batteries for possible data transmission. In this paper, we propose an online control policy for energy transfer from the E-AP to the wireless nodes and for data transfer among the nodes. With our proposed control policy, all data queues of the nodes are stable, while the average energy consumption of the network is shown to be within a bounded gap of the minimum energy required for stabilizing the network. Our proposed policy is designed using a quadratic Lyapunov function to capture the limitations on the energy consumption of the nodes imposed by their battery levels. We show that under the proposed control policy, the backlog level in the data queues and the stored energy level in the batteries fluctuate in small intervals around some constant levels. Consequently, by imposing negligible average data drop rate, the data buffer size and the battery capacity of the nodes can be significantly reduced

Towards a model for e-learning using web services and fuzzy logic

Many colleges and universities are adopting an e-learning approach in order to offer a variety of courses to a global student audience. This approach is vital to gain a market share in an increasingly competitive world and stay abreast with deployment and usage of new technologies. The process, by which e-learning courses are offered, maintained and updated in terms of syllabus and content vary amongst institutions mainly due to limitations in available resources. This paper presents current, ongoing work on building a prototype for an e-learning model that is based on fuzzy logic and web services to analyze, deploy, maintain and update an arbitrary course syllabus and its content by way of effective communication between players of the e-learning environment

Joint Sum Rate And Error Probability Optimization: Finite Blocklength Analysis

We study the tradeoff between the sum rate and the error probability in downlink of wireless networks. Using the recent results on the achievable rates of finite-length codewords, the problem is cast as a joint optimization of the network sum rate and the per-user error probability. Moreover, we develop an efficient algorithm based on the divide-and-conquer technique to simultaneously maximize the network sum rate and minimize the maximum users' error probability and to evaluate the effect of the codewords length on the system performance. The results show that, in delay-constrained scenarios, optimizing the per-user error probability plays a key role in achieving high throughput.Comment: Accepted for publication in IEEE Wireless Communications Letter

Robust Successive Compute-and-Forward over Multi-User Multi-Relay Networks

This paper develops efficient Compute-and-forward (CMF) schemes in multi-user multi-relay networks. To solve the rank failure problem in CMF setups and to achieve full diversity of the network, we introduce two novel CMF methods, namely, extended CMF and successive CMF. The former, having low complexity, is based on recovering multiple equations at relays. The latter utilizes successive interference cancellation (SIC) to enhance the system performance compared to the state-of-the-art schemes. Both methods can be utilized in a network with different number of users, relays, and relay antennas, with negligible feedback channels or signaling overhead. We derive new concise formulations and explicit framework for the successive CMF method as well as an approach to reduce its computational complexity. Our theoretical analysis and computer simulations demonstrate the superior performance of our proposed CMF methods over the conventional schemes. Furthermore, based on our simulation results, the successive CMF method yields additional signal-to-noise ratio gains and shows considerable robustness against channel estimation error, compared to the extended CMF method.Comment: 44 pages, 10 figures, 1 table, accepted to be published in IEEE Trans. on Vehicular Tec

On Energy Allocation and Data Scheduling in Backscatter Networks with Multi-antenna Readers

In this paper, we study the throughput utility functions in buffer-equipped monostatic backscatter communication networks with multi-antenna Readers. In the considered model, the backscatter nodes (BNs) store the data in their buffers before transmission to the Reader. We investigate three utility functions, namely, the sum, the proportional and the common throughput. We design online admission policies, corresponding to each utility function, to determine how much data can be admitted in the buffers. Moreover, we propose an online data link control policy for jointly controlling the transmit and receive beamforming vectors as well as the reflection coefficients of the BNs. The proposed policies for data admission and data link control jointly optimize the throughput utility, while stabilizing the buffers. We adopt the min-drift-plus-penalty (MDPP) method in designing the control policies. Following the MDPP method, we cast the optimal data link control and the data admission policies as solutions of two independent optimization problems which should be solved in each time slot. The optimization problem corresponding to the data link control is non-convex and does not have a trivial solution. Using Lagrangian dual and quadratic transforms, we find a closed-form iterative solution. Finally, we use the results on the achievable rates of finite blocklength codes to study the system performance in the cases with short packets. As demonstrated, the proposed policies achieve optimal utility and stabilize the data buffers in the BNs

Stochastic Geometry Modeling and Analysis of Single- and Multi-Cluster Wireless Networks

This paper develops a stochastic geometry-based approach for the modeling and analysis of single- and multi-cluster wireless networks. We first define finite homogeneous Poisson point processes to model the number and locations of the transmitters in a confined region as a single-cluster wireless network. We study the coverage probability for a reference receiver for two strategies; closest-selection, where the receiver is served by the closest transmitter among all transmitters, and uniform-selection, where the serving transmitter is selected randomly with uniform distribution. Second, using Matern cluster processes, we extend our model and analysis to multi-cluster wireless networks. Here, the receivers are modeled in two types, namely, closed- and open-access. Closed-access receivers are distributed around the cluster centers of the transmitters according to a symmetric normal distribution and can be served only by the transmitters of their corresponding clusters. Open-access receivers, on the other hand, are placed independently of the transmitters and can be served by all transmitters. In all cases, the link distance distribution and the Laplace transform (LT) of the interference are derived. We also derive closed-form lower bounds on the LT of the interference for single-cluster wireless networks. The impact of different parameters on the performance is also investigated

The Relationship between Spiritual Well-Being and Academic Achievement

The present study aimed to investigate the relationship between spiritual well-being and academic achievement among students. Among 18,465 statistical populations, 320 people were selected by Morgan Table with the stratified random sampling method. This research method was descriptive correlational and spiritual well-being questionnaire was used by using face validity and Cronbach's alpha reliability. The results showed that the mean of the spiritual well-being of the students is not satisfactory. There is a significant and positive relation between spiritual well-being and academic achievement of students of economics, management and humanities. But, there is no significant relationship between spiritual well-being and academic achievement of students of engineering and basic sciences and art and architecture. On the other hand, a significant relationship was observed between spiritual well-being and academic achievement of students of economics and management, humanities, engineering, basic sciences and students of art and architecture

The Relationship between Happiness and Academic Achievements

The present study is aimed to investigate the relationship between happiness and academic achievement among students. From the statistic population of 18465 people, 320 were chosen by stratified random sampling method using Morgan table. The research method is of correlation kind and the Oxford Happiness Questionnaire was used for data collection. The results showed that students' happiness is not satisfactory. In addition, the mean scores of academic achievement of girls are more than the boys and the mean happiness score among female students is more than male ones. But, the total score is less than the mean happiness score of both male and female students. Finally, there is a significant positive relationship between happiness and achievement of students. There is also a significant positive correlation between happiness and the progress of students (by discipline)

The Relationship between Spiritual Well-Being and Academic Achievement

The present study aimed to investigate the relationship between spiritual well-being and academic achievement among students. Among 18,465 statistical populations, 320 people were selected by Morgan Table with the stratified random sampling method. This research method was descriptive correlational and spiritual well-being questionnaire was used by using face validity and Cronbach's alpha reliability. The results showed that the mean of the spiritual well-being of the students is not satisfactory. There is a significant and positive relation between spiritual well-being and academic achievement of students of economics, management and humanities. But, there is no significant relationship between spiritual well-being and academic achievement of students of engineering and basic sciences and art and architecture. On the other hand, a significant relationship was observed between spiritual well-being and academic achievement of students of economics and management, humanities, engineering, basic sciences and students of art and architecture