Network capacity calls for significant increase 5G cellular systems. A promising multi-user access scheme, non-orthogonal multiple (NOMA) with successive interference cancellation (SIC), is currently under consideration. In NOMA, spectrum efficiency improved by allowing more than one user to simultaneously the same frequency-time resource and separating signals SIC at receiver. These render allocation optimization in NOMA different from orthogonal 4G. this paper, we provide theoretical...

Information age is a recently introduced metric to represent the freshness of information in communication systems. We investigate minimization wireless network and propose novel approach optimizing scheduling strategy deliver all messages as fresh possible. Specifically, we consider set links that share common channel. The transmitter at each link contains given number packets with time stamps from an source generated them. address transmission problem objective minimizing overall age. This...

There is a growing interest in age of information, which newly introduced metric that measures the freshness information communication systems. We investigate wireless networks and propose novel approach optimizing scheduling strategy to deliver as timely possible. consider set links share common channel, each containing number packets with time stamps, address problem objective minimizing overall age. model this mathematically prove it NP-hard general. Fundamental insights including...

Non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC), is considered as a candidate multi-user scheme for 5G cellular systems. In this paper, we provide theoretical insights and solution algorithm optimizing multi- user power channel allocation in NOMA We mathematically formulate the resource problem prove its NP-hardness. For solving problem, propose an combining Lagrangian duality dynamic programming to deliver competitive suboptimal solution. Numerical...

In ultra-dense heterogeneous networks, caching popular contents at small base stations is considered as an effective way to reduce latency and redundant data transmission. Optimization of placement/replacement content delivering can be computationally heavy, especially for large-scale networks. The provision both time-efficient high-quality solutions challenging. Conventional iterative optimization methods, either optimal or heuristic, typically require a large number iterations achieve...

We consider the problem of minimization sum transmission energy in cellular networks where coupling occurs between cells due to mutual interference. The relation is characterized by signal-to-interference-and-noise-ratio (SINR) model. Both cell load and power, measures average level resource usage cell, interact via implicitly with power as variables interest using two equivalent equations, namely, non-linear equation (NLCE) (NPCE), respectively. By analyzing NLCE NPCE, we prove that...

We formulate a power optimization problem for non-orthogonal multiple access systems mathematically, and prove its NP-hardness. For tackling the problem, we first identify convex by relaxation. Based on this convexity, then propose an efficient "relax-then-adjust" algorithm provide results of performance evaluation.

We explore the potential of optimizing resource allocation with flexible numerology in frequency domain and variable frame structure time domain, services different types requirements. prove NP-hardness problem propose a scalable optimization algorithm based on linear programming Lagrangian duality. Numerical results show significant advantages adopting flexibility both domains for capacity enhancement meeting requirements mission critical services.

Freshness of information is critical importance for a host applications wireless communications. In order to deliver from multiple sources in timely and fair fashion through channel, we propose optimizing the link scheduling strategy respect age information, which newly introduced metric that measures how fresh is. Specifically, consider set co-channel links, each having number packets be delivered, address problem aims find optimal solution, such maximum peak minimized. We mathematically...

With the densification of nodes in cellular networks, free space optic (FSO) connections are becoming an appealing low cost and high rate alternative to copper fiber backhaul solutions for wireless communication systems. To ensure a reliable backhaul, provisions redundant disjoint paths between must be made design phase. This paper aims at finding cost-effective solution upgrade with pre-deployed optical fibers using FSO links mirror components. Since quality depends on several factors, such...

Caching popular files at the user equipments (UEs) provides an effective way to alleviate burden of backhaul networks. Generally, popularity-based caching is not a system-wide optimal strategy, especially for mobility scenarios. Motivated by this observation, we consider with presence mobility. A cost-optimal problem (COCP) device-to-device (D2D) networks modeled, in which impact mobility, cache size, and total number encoded segments are all taken into account. The hardness proved via...

Optimizing non-orthogonal multiple access (NOMA) in multi-cell scenarios is much more challenging than the single-cell case because inter-cell interference must be considered. Most papers addressing NOMA consider a single cell. We take significant step analyzing scenarios. explore potential of networks achieving optimal resource utilization with arbitrary topologies. Towards this goal, we investigate broad class problems consisting optimizing power allocation and user pairing for any cost...

Internet of Things (IoT) devices can be equipped with multiple heterogeneous network interfaces. An overwhelmingly large amount services may demand some or all these interfaces' available resources. Herein, we present a precise mathematical formulation assigning to interfaces resources in one more rounds. For reasonable instance sizes, the presented produces optimal solutions for this computationally hard problem. We prove NP-Completeness problem and develop two algorithms approximate...

Measuring total nitrogen (TN) and phosphorus (TP) is important in managing heavy polluted urban waters China. This study uses high spatial resolution IKONOS imagery with four multispectral bands, which roughly correspond to Landsat/TM bands 1–4, determine TN TP small rivers lakes By using Lake Cihu the lower reaches of Wen-Rui Tang (WRT) River as examples, this paper develops both multiple linear regressions (MLR) artificial neural network (ANN) models estimate concentrations from remote...

We study route scheduling of a UAV for data collection from sensor nodes (SNs) with battery recharging. The freshness the collected information is captured by metric age (AoI). objective to minimize average AoI cost all SNs over time horizon. prove that problem in its general form NP-hard. Then, special case problem, we optimum can be computed polynomial time. Next, develop an algorithm based on graph labeling. Finally, show effectiveness our comparison greedy scheduling.

In this article, we investigate the joint task assignment and power control problems for Device-to-Device (D2D) offloading communications with energy harvesting. Exploiting D2D links data allows reducing traffic load of cellular base stations. The consumed by transmitters can be compensated main objective is to maximize efficiency (EE) under causality delay constraints, assuming a harvest–transmit model. Hence, proposed model results in nonconvex problem. We first derive an equivalent more...

Many downscaling techniques have been developed in the past few years for projection of station-scale hydrological variables from large-scale atmospheric to assess impacts climate change. To improve simulation accuracy methods, Bayesian Model Averaging (BMA) method combined with three statistical which are support vector machine (SVM), BCC/RCG-Weather Generators (BCC/RCG-WG), and Statistics Downscaling (SDSM), is proposed this study, based on relationship between larger scale predictors...

Optimizing activation and deactivation of base station transmissions provides an instrument for improving energy efficiency in cellular networks. In this paper, we study optimal cell clustering scheduling duration each cluster, with the objective minimizing sum energy, subject to a time constraint delivering users' traffic demand. The cells within cluster are simultaneously transmission napping modes, deactivation, respectively. Our optimization framework accounts coupling relation among due...

Non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC), is considered as a candidate multi-user scheme for 5G cellular systems. In this paper, we provide theoretical insights and solution algorithm optimizing multi- user power channel allocation in NOMA We mathematically formulate the resource problem prove its NP-hardness. For solving problem, propose an combining Lagrangian duality dynamic programming to deliver competitive suboptimal solution. Numerical...

In this paper, we study a class of minimum-energy scheduling problems in non-orthogonal multiple access (NOMA) systems. NOMA is adopted to enable efficient channel utilization and interference mitigation, such that base stations can consume minimal energy empty their queued data presence transmission deadlines, each user obtain all the requested timely. Due high computational complexity resource stringent execution-time constraints practical systems, providing time-efficient high-quality...

Reducing the signaling overhead for tracing user equipment (UE), while maintaining improved performance over time despite changes in UE location and mobility patterns, is a challenging issue area of management. Flexibility automatic reconfiguration are two significant features Long Term Evolution (LTE) systems. The Tracking Area List (TAL) novel concept LTE systems, which allows more flexible configurations, expecting to reduce overall overhead. In this paper, we first present "rule thumb"...

Reducing the overhead required for tracing mobile devices is one of major aspects in study mobility management a cellular network. The Long Term Evolution (LTE) systems give more flexible configuration Tracking Area (TA) design by means List (TAL). Being novel concept, TAL goes beyond capability conventional TA approach. Although expected to be able reduce overall signaling overcoming couple limitations how apply large scale networks, remains unexplored. In this paper, we present approach...

Joint channel and rate allocation with power minimization in orthogonal frequency-division multiple access (OFDMA) has attracted extensive attention. Most of the research dealt development suboptimal but low-complexity algorithms. In this paper, contributions comprise new insights from revisiting tractability aspects computing optimum solution. Previous complexity analyses have been limited by assumptions fixed on each subcarrier or power-rate functions that locally grow arbitrarily fast....

Caching popular contents at cell edge has been recognized as a promising way to facilitate rapid content delivery and alleviate backhaul burden. The popularity is greatly influenced by recommendations providers. In this paper, we leverage fact jointly optimize caching recommendation towards higher efficiency. We focus on both personalized incumbent-aware recommendation. incumbent refers the that user currently browsing, resulted user's short-term interest. model formulate resulting cache...