We study the problem of optimizing the performance of cognitive radio users with opportunistic real-Time applications subject to primary users quality-of-service (QoS) constraints. Two constrained optimization problems are formulated; the first problem is maximizing the secondary user throughput while the second problem is minimizing the secondary user average delay, subject to a common constraint on the primary user average delay. In spite of the complexity of the optimization problems, due to their non-convexity, we transform the first problem into a set of linear programs and the second

This paper investigates the achievable total degrees of freedom (DoF) of the MIMO multi-way relay channel that consists of K users, where each user is equipped with M antennas, and a decode-and-forward relay equipped with N antennas. In this channel, each user wants to convey K - 1 private messages to the other users in addition to a common message to all of them. Due to the absence of direct links between the users, communication occurs through the relay in two phases: a multiple access channel (MAC) phase and a broadcast (BC) phase. We derive cut-set bounds on the total DoF of the network

In this paper, we study the problem of scalable videos multicast streaming over multi-channel multi-radio wireless mesh networks over a contention-based MAC, with the objective of maximizing the overall received videos quality. We propose a three-stage heuristic framework solution for the complex joint channel assignment, video quality selection and multicast routing problem. That framework is called Channel Assignment with Iterative Routing and Quality Selection (CAIRoQS), it is implemented using C and evaluated with NS2 using video traffic traces. Our performance evaluation shows noticeable

We consider a cooperative relaying system with any number of source terminals, one shared relay, and a common destination. We assume a slotted time division multiple access (TDMA) framework in which each source terminal is allocated a fraction of the time. We propose a novel hybrid cooperative scheme for the described network. In contrast to former works which assume that the relay only transmits in the idle time slots, we assume that the relay can, simultaneously, transmit with the source terminals via multi-access channel (MAC). In the hybrid cooperative scheme, the relay operates in two

In this paper we characterize the proactive diversity gain of a cognitive network with predictable primary and secondary requests. Network performance is analyzed under two proposed proactive service policies that preserve higher priority for the primary user. The first policy preserves the primary diversity bound as if there is no secondary user in the network, whereas the second policy boosts the secondary diversity with guaranteed higher primary diversity. For each policy, we derive diversity gain bounds for primary and secondary users. We show that the predictability of secondary requests

This paper studies the decentralized coded caching for a Fog Radio Access Network (F-RAN), whereby two edge-nodes (ENs) connected to a cloud server via fronthaul links with limited capacity are serving the requests of K r users. We consider all ENs and users are equipped with caches. A decentralized content placement is proposed to independently store contents at each network node during the off-peak hours. After that, we design a coded delivery scheme in order to deliver the user demands during the peak-hours under the objective of minimizing the normalized delivery time (NDT), which refers

Caching at Roadside Units (RSUs) is a promising technique to alleviate the load on network backhaul in Vehicular AdHoc Networks (VANETs). It also allows us to minimize communications latency between RSUs and connected vehicles, which are interested in massive multimedia contents. This work proposes novel proactive caching schemes at RSUs for the city mobility environment. We adopt the Manhattan city model, where streets are arranged in an organized manner and movable nodes are allowed to traverse along the grid of horizontal and vertical streets. Exploiting the information about vehicles

This study evaluates the performance of a secure ground-to-satellite free-space optical (FSO) system using a bipolar pulse amplitude modulation over modulated gamma fading channel. A closed-form expression is derived for the joint probability of a satellite-based continuous-variable quantum key distribution (CV-QKD) protocol that uses dual-threshold detection. Furthermore, to study the system behaviour, closed-form expressions for quantum bit-error-rate (QBER) and quantum bitdiscard rate (QBDR) are given. The accuracy of the proposed derivations is validated using Monte-Carlo simulations and

Real parameter optimization is one of the active research fields during the last decade. The performance of LSHADE-SPACMA was competitive in IEEE CEC’2017 competition on Single Objective Bound Constrained Real-Parameter Single Objective Optimization. Besides, it was ranked fourth among twelve papers were presented on and compared to this new benchmark problems. In this work, an improved version named ELSHADE-SPACMA is introduced. In LSHADE-SPACMA, p value that controls the greediness of the mutation strategy is constant. While in ELSHADE-SPACMA, p value is dynamic. Larger value of p will

In the past few decades, a lot of optimization methods have been applied in estimating the parameter of photovoltaic (PV) models and obtained better results, but these methods still have some deficiencies, such as higher time complexity and poor stability. To tackle these problems, an enhanced success history adaptive DE with greedy mutation strategy (EBLSHADE) is employed to optimize parameters of PV models to propose a parameter optimization method in this paper. In the EBLSHADE, the linear population size reduction strategy is used to gradually reduce population to improve the search