Non-orthogonal multiple access (NOMA) is an essential enabling technology for the fifth-generation (5G) wireless networks to meet heterogeneous demands on low latency, high reliability, massive connectivity, improved fairness, and throughput. The key idea behind NOMA serve users in same resource block, such as a time slot, subcarrier, or spreading code. principle general framework, several recently proposed 5G schemes can be viewed special cases. This survey provides overview of latest...

A key enabler for the intelligent information society of 2030, 6G networks are expected to provide performance superior 5G and satisfy emerging services applications. In this article, we present our vision what will be describe usage scenarios requirements multi-terabyte per second (Tb/s) networks. We a large-dimensional autonomous network architecture that integrates space, air, ground, underwater ubiquitous unlimited wireless connectivity. also discuss artificial intelligence (AI) machine...

Millimeter wave (mmWave) communications have recently attracted large research interest, since the huge available bandwidth can potentially lead to rates of multiple gigabit per second user. Though mmWave be readily used in stationary scenarios, such as indoor hotspots or backhaul, it is challenging use mobile networks, where transmitting/receiving nodes may moving, channels a complicated structure, and coordination among difficult. To fully exploit high potential lots technical problems...

Optical wireless, also known as free-space optics, has received much attention in recent years a cost-effective, license-free and wide-bandwidth access technique for high data rates applications. The performance of optical (FSO) communication, however, severely suffers from turbulence-induced fading caused by atmospheric conditions. Multiple laser transmitters and/or receivers can be placed at both ends to mitigate the turbulence exploit advantages spatial diversity. Spatial diversity is...

Localization is one of the key technologies in wireless sensor networks (WSNs), since it provides fundamental support for many location-aware protocols and applications. Constraints on cost power consumption make infeasible to equip each node network with a global position system (GPS) unit, especially large-scale WSNs. A promising method localize unknown nodes use mobile anchor (MANs), which are equipped GPS units moving among periodically broadcasting their current locations help nearby...

Non-orthogonal multiple access (NOMA) systems have the potential to deliver higher system throughput, compared contemporary orthogonal techniques. For a linearly precoded multiple-input multiple-output (MISO) system, we study downlink sum rate maximization problem, when NOMA principles are applied. Being non-convex and intractable optimization problem,we resort approximate it with minorization-maximization algorithm (MMA), which is widely used tool in statistics. In each step of MMA, solve...

We study the error performance of an heterodyne differential phase-shift keying (DPSK) optical wireless (OW) communication system operating under various intensity fluctuations conditions. Specifically, it is assumed that propagating signal suffers from combined effects atmospheric turbulence-induced fading, misalignment fading (i.e., pointing errors) and path-loss. Novel closed-form expressions for statistics random attenuation propagation channel are derived bit-error rate (BER)...

We present closed-form lower bounds for the performance of multihop transmissions with nonregenerative relays over not necessarily identically distributed Nakagami-m fading channels. The end-to-end signal-to-noise ratio is formulated and upper bounded by using an inequality between harmonic geometric means positive random variables (RVs). Novel expressions are derived moment generating function, probability density cumulative distribution function product rational powers statistically...

In this paper, a downlink single-cell non-orthogonal multiple access (NOMA) network with uniformly deployed users is considered and an analytical framework to evaluate its performance developed. Particularly, the of NOMA studied by assuming two types partial channel state information (CSI). For first one, which based on imperfect CSI, we present simple closed-form approximation for outage probability average sum rate, as well their high signal-to-noise ratio (SNR) expressions. second type...

The main limitation of visible light communication (VLC) is the narrow modulation bandwidth, which reduces achievable data rates. In this paper, we apply non-orthogonal multiple access (NOMA) scheme to enhance throughput in high-rate VLC downlink networks. We first propose a novel gain ratio power allocation (GRPA) strategy that takes into account users' channel conditions ensure efficient and fair allocation. Our results indicate GRPA significantly enhances system performance compared...

The performance of digital communication systems over generalized-K (K/sub G/) fading channels is analyzed and evaluated. Novel closed form expressions for the SNR statistics, average Shannon's channel capacity bit error rate (BER) are derived. These used to study important criteria such as outage performance, BER a great variety modulation formats in K/sub G/ channels. proposed mathematical analysis accompanied with various evaluation results, which demonstrate usefulness approach.

In this letter, we investigate the error rate performance of free-space optical (FSO) links over strong turbulence fading channels together with misalignment (pointing error) effects. First, present a novel closed-form expression for distribution stochastic FSO channel model which takes into account both atmospheric turbulence-induced and misalignment-induced fading. Then, evaluate average bit-error in closed form system operating environment, assuming intensity modulation/direct detection...

A generic and novel distribution, referred to as Nakagami, constructed the product of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> statistically independent, but not necessarily identically distributed, Nakagami- xmlns:xlink="http://www.w3.org/1999/xlink">m</i> random variables (RVs), is introduced analyzed. The proposed distribution turns out be a very convenient tool for modelling cascaded fading channels analyzing performance digital...

We provide closed-form expressions for the outage and bit error probability (BEP) of uncoded, threshold-based opportunistic relaying (OR) selection cooperation (SC), at arbitrary signal to noise ratios (SNRs) number available relays, assuming decode-and-forward relays Rayleigh fading channels. Numerical results demonstrate that SC performs slightly better in terms probability; BEP, both systems may outperform one another, depending on SNR threshold determines set participate forwarding process.

We study the effect of outdated channel state information on outage and error rate performance amplify-and-forward (AF) relay selection, where only one out set available relays is activated. consider two variations AF namely best selection partial when based upon estimates. For both these variations, closed-form expressions for probability are obtained, along with approximate symbol in medium to high signal-to-noise-ratio (SNR) regime. The diversity gain coding above schemes also explicitly...

We consider the use of Fisher-Snedecor F distribution, which is defined as ratio two chi-squared variates, to model composite fading channels. In this context, root-mean-square power a Nakagami-m signal assumed be subject variations induced by an inverse Nakagamim random variable. Comparisons with physical channel data demonstrate that proposed provides good, and in most cases better, fit compared generalized-K model. Motivated result, simple novel expressions are derived for key statistical...

In this letter, a downlink multiple-input-multiple-output non-orthogonal multiple access scenario is considered. We investigate dynamic user clustering problem from fairness perspective. order to solve optimization problem, three sub-optimal algorithms, namely, top-down A, B, and bottom up, are proposed realize the different tradeoffs of complexity throughput worst user. addition, for each given case, we optimize power allocation coefficients users in cluster by adopting bisection...

We investigate the impact of cochannel interference on security performance multiple amplify-and-forward (AF) relaying networks, where N intermediate AF relays assist data transmission from source to destination. The are corrupted by interferers, and information transmitted destination can be overheard eavesdropper. In order deal with wiretap, best out is selected for enhancement. To this end, we derive a novel lower bound secrecy outage probability (SOP), which then utilized present two...

In this paper, we study the impact of correlated fading on secrecy performance multiple decode-and-forward (DF) relaying with outdated relay selection. It is assumed that information transmission, assisted by N DF relays from source to destination, can be overheard an eavesdropper. Particularly, consider realistic scenario where eavesdropper's and main channels are correlated. order enhance network security, best selected among available assist secure transmission. Due time-varying channel...

We study a wireless-powered uplink communication system with non-orthogonal multiple access (NOMA), consisting of one base station and energy harvesting users. More specifically, we focus on the individual data rate optimization fairness improvement show that formulated problems can be optimally efficiently solved by either linear programming or convex optimization. In provided analysis, two types decoding order strategies are considered, namely fixed time- sharing. Furthermore, propose an...

Plug-in hybrid electric vehicles (PHEVs) have emerged as an important tool in reducing greenhouse gas emissions, due to their lower dependency on fossil fuel. Since, for cost efficiency, PHEVs a limited battery capacity, they must be recharged often and especially after trips. Thus, efficient charging plays role the success of commercial adoption. This paper surveys state-of-the-art existing PHEV schemes. We classify these schemes into four classes, namely, uncontrolled, indirectly...