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To further mitigate the BER error floor of M-ary differential chaos shift keying modulation for impulsive noise, a low-cost high-reliability coded modulation scheme without equalizations is desirable for impulsive noise. In this paper, a protograph-based low-density parity-check coded MDCSK-based bit-interleaved coded modulation scheme is proposed for the scenario with impulsive noise. Considering the Gaussian distribution of protograph extrinsic information transfer and the benchmark of coding design, the U-shaped non-coherent capacity is derived with optimal code rate for square MDCSK, showing that the code rates are stable with E_b/N_0 increasing but still much lower than that of DS-16DQAM at code rate >0.145. The derived joint probability density function can be considered as approximately a Gaussian distribution, which is used to improve the impulsive noise fitted PEXIT. Finally, a new code under a novel principle is designed for better bit error rate performance based on the improved PEXIT analysis. Both PEXIT analysis and simulation results demonstrate that the proposed scheme achieves a better BER than that with a traditional scheme, and suggesting a research approach based on simple methods. This basic research work provides a guide to establish a framework and optimize the performance of transmission systems over practical power line communication.

This article investigates using imbalanced two- and three-wire terminations for ac main cables, as suggested by the standard group. These terminations provide the basis for a new line impedance stabilization network (LISN) whose objective is to improve test repeatability between labs while also providing better estimation of real-world emissions. Standard balanced LISNs do not reproduce the imbalanced terminations seen in practice. An imbalanced two- or three-wire very high-frequency LISN was built, which can handle up to 15 A on each line. The LISN operates from 30 to 200 MHz and provides greater than 50-dB isolation between the input and output. The imbalanced termination allows the device to create a specified degree of conversion from differential-mode to common-mode current, which can increase radiated emissions. This conversion was evaluated to be as high as 12 dB in measurements of a power line communication device. 3-D full-wave simulations of two- and three-wire applications demonstrate that the radiated emissions from the prototype LISN and the ideal imbalanced termination are nearly equal. The new LISN was further evaluated to show promise for improving measurement reproducibility, reducing the standard compliance uncertainty by 6 dB in this study, from 15.5 dB in CISPR 16-4-1 to 9.5 dB with the LISN.

The evolution toward the so-called smart grid (SG) needs to be supported by robust and cost-efficient Advanced Metering Infrastructure (AMI). The focus of this paper is on technology selection and gateway placement in hybrid SGs, wherein each smart meter (SM) is equipped with either a Power Line Communication (PLC) or a LoRaWAN node to connect to its serving gateway. The latter is endowed with both technologies. In particular, we introduce an analytical framework to characterize the performance-cost trade-offs using a multi-criteria optimization approach. For each technology, a set of performance objective functions (i.e. sum-rate and max-min) has been derived based on the ergodic capacity, whereas the cost is represented by SG hardware expenses. Then, the NSGA-II algorithm has been exploited using an appropriate chromosome structure to provide the suitable access technology for each SM along with the optimal number and the placement of the serving GWs. Extensive numerical simulations have shown that hybrid solutions provide a good interplay between performance and investment costs, spurring the need to redefine the conventional SG designs traditionally operating in single communication technologies.

The integration of the fifth-generation (5G) wireless communication with power line communication (PLC) provides an efficient solution to accommodate the connection demands of massive industrial internet of things (IIoT) devices. Moreover, edge computing can provide sufficient computing services for IIoT devices. By empowering PLC-wireless integrated networks with edge computing, devices can offload task data to adjacent edge servers through either PLC or 5G subchannels by leveraging orthogonal frequency division multiplexing (OFDM). However, task offloading in the edge computing-empowered PLC-wireless integrated network faces several challenges such as channel access conflict, dynamic network state, as well as long-term queue stability assurance. In this article, we construct a one-to-many task offloading architecture to maximize the total throughput. Lyapunov optimization is adopted to convert the NP-hard task offloading problem. Then, a pricing-based matching with quota task offloading algorithm is proposed to handle channel access conflicts among IIoT devices. Simulation evaluation demonstrate that the proposed algorithm realizes excellent performances in throughput, energy consumption, and queuing backlog.

The impact of spread-spectrum techniques used to mitigate EMI from power converters on Power Line Communication (PLC) systems is studied in this paper. A buck converter, utilizing a Random Carrier Frequency Modulation with Fixed Duty cycle (RCFMFD) based control is considered as a source of conducted EMI and a narrowband G3-PLC as the victim. It is shown that, although considered to be an EMI mitigating technique, the spread spectrum technique has a detrimental effect on the communication channel, which can be explained in the framework of Shannon’s information theory. Conventional emission evaluation methods are therefore incompatible with modern day’s technology.

In this letter, we analyze the performance of reconfigurable intelligent surface (RIS) assisted mixed power line communication (PLC)/radio frequency (RF) system in smart grid application. In a smart grid, the data concentrator (DC) plays an important role in communication between the home appliances through the access point (AP). The DC can communicate using the existing PLC up to the AP, and the AP interacts with the home appliances with advanced communication technology like RIS-based RF communication. The modulation scheme is considered here as binary phase-shift keying (BPSK) modulation. Based on the system model, a closed-form expression for average bit error probability (ABEP) and outage probability (OP) are derived and analyzed by varying the various parameters like the number of reflectors in the RIS, impulsive noise scenario in the PLC channel.

The article describes a project to use PLC technology in railway light signs. The proposal presents a solution for the separation of supplying circuits with the use of filters. The necessity of separation is a result of long distance data transmission between sign controllers and LED railway signs using PLC modems which work on the same frequency. Problems in the selection of filter parameters are presented due to the fact that there is no specification for the characteristic of the separation filter, there are only requirements for the reliability communication system. To meet these requirements, the circuits separation efficiency must be assessed. The paper presents a quick method to evaluate separation efficiency. Structure of the network, as well as the set of devices which realize this specific kind of wired sensor network for supervising railway LED sign network and maintenance parameters are also presented in this article.

In order to implement the concepts of smart grid and residential automation, this article presents a SmartPlug prototype for power consumption monitoring in smart homes. It is a device that, when coupled to the sockets, measures electrical voltage and current, and thereafter provides the power consumption to the consumer using the power line communication (PLC) technology. With the knowledge of the consumption, provided by the smart metering, of each outlet, the consumer is able to establish the concept of segmented energy consumption, which is an important allied of energy saving and power demanding. With commercial current and voltage sensors, the SmartPlug was built using the Arduino platform and the end user interface was created using the open source software ScadaBR. After performance evaluation in a laboratory, tests in real electrical plants were performed to validate the prototype, considering bit rates and signal spectrum in the PLC systems.

A distributed zero-sequence-current (ZSC) carrier signal injection via current transformer (CT) is proposed for underground cable single-phase-to-ground fault location in neutral isolated medium voltage (MV) distribution networks. High-frequency ZSC carrier signal is directly injected to a high-voltage underground cable of an energized distribution network via CT. The injected carrier signal travels along the cable to the receiving center in the substation, and is processed for quick fault line selection and fault location. No external power supplies or signal generators are needed due to the self-contained nature of the injector. The device can be constructed as a sleeve to be mounted around the underground power cable. This permits economical retrofitting to existing installations of power line communication (PLC) devices. In this paper, the operational principle and the application considerations for such an injection device and fault location tricks are explained, followed by the theory behind the proposed technique. Finally, MATLAB based numerical simulations are performed and a low-voltage prototype is tested to verify the validity of the proposed approach.

International audience; Techniques that improve interfacing between powerline communication (PLC) systems and LED-based visible light communication (VLC) systems start to gain attention in recent years. Indeed, this hybrid system is able to provide simultaneously power, lighting, and data transmission. Contrariwise, if the integration between PLC and commercial LED bulbs is done unintentionally, the risks of PLC data leakage by commercial LED bulbs must be carefully analyzed. Thus, in this paper, the risks of eavesdropping on the PLC network via commercial LED bulbs are studied. The impact of the LED driver on PLC data leakage through LED bulbs is explained. The electrical-optical channel transfer function for different LED bulbs and the power spectral density of the signal received through the LED bulbs when two commercial powerline modems are plugged into the same power line are measured. Afterwards, pseudo random binary sequence signals are injected into the electrical-optical channel in order to assess quantitatively the possibility to extract information from the received signal. Finally, simple LED driver modifications that foster and increase the leakage are analyzed.

Optical fiber‐based technologies and Power Line Communication (PLC) are the most relevant access wireline fixed‐network solutions for the Smart Grid. This chapter elaborates on Passive Optical Network (PON) and PLC technologies, covering the most relevant systems in each of them. PONs are intrinsically different from active optical networks, and electrical power is only required at the transmit and receive points, easing the rollout. PLC technologies are a unique set of technologies that use the power system cables for telecommunication purposes. PLC is undoubtedly recognized as an enabler of the Smart Grid. Broadband‐PLC technologies make use of the spectrum starting at 1.8MHz and offer a higher transmission data rate that comes at the expense of a higher attenuation that limits coverage. Optical fiber allows electric isolation in substations and electricity‐related premises in general, and PLC technology is by default available in Smart Grids.

An energy storage system (ESS) requires high reliability with low electromagnetic (EM) interference, communication capability between ESS applications, and bidirectional power conversion for charging and discharging operations. However, a conventional ESS separately has power converters, communication devices, and large-sized EM interference filters for its stable operation. In this article, a current-fed capacitor-inductor-inductor-capacitor (CLLC) resonant converter employing asymmetric pulsewidth modulation and spread spectrum modulation is proposed to obtaining three functions, bidirectional power conversion with tight output voltage regulation, EM noise mitigation, and power line communication capability among ESSs, simultaneously. It can improve the cost-effectiveness, system's form factor, and communication flexibility. The proposed integration of three functionalities has design constraints on the implementation of each function. Design methodologies of power stage and control algorithm are also proposed for achieving the simultaneous operation of each function. The performance of the proposed converter and control algorithm are verified through a 20-W prototype converter.

With the rapid development of broadband carrier communication technology, the power line communication market is growing. However, the frequency band of power line communication overlaps with other radio services, mainly the High Frequency (HF) radio services. In addition, power line communication may have electromagnetic leakage in the open air. Large-scale power line communication system will give a much greater interference to some critical HF radio services. In this paper, the standards and researches relative to the power line communication system are reviewed. Based on existing studies, impact analysis which includes the impact probability and severity of the power line communication system on HF equipment is proposed. In addition, explicit explanations are provided. The proposed impact analysis methods are applied to simulations and evaluations. Numerical results demonstrate that a large-scale power line communication system will cause additional ambient noise, which affects the performance and reliability of HF equipment with a high probability.

This paper introduces a small-area, low-power delta-sigma DAC that can support power line carrier communication. In order to achieve the oversampling ratio of 128, a three-stage cascaded half-band filter is utilized. An optimized sturdy MASH Δ Σ modulator was used to avoid instability caused by high-order shaping and reduce the area at the same time. The postanalog reconstruction includes a switched-capacitor DAC (SC DAC) and a 4-tap FIR/IIR hybrid filter, which not only meets the requirements of low power but also promotes the out-of-band SNR. The final chip is fabricated in a 55 nm CMOS process, occupies 0.08 mm2, and consumes 1.5 mW of analog power at 2.5 V supply. The simulation results show that the dynamic range is 85.7 dB, while the out-of-band SNR is 40.5 dB.

There are a lot of noises in the low-voltage power line communication (LVPLC) channel, which seriously damages the LVPLC system. The noise in the low voltage power line can be divided into general background noise and random pulse noise. These two noises will cause serious interference to the communication process based on LVPLC, reduce the signal-to-noise ratio of LVPLC system, and the communication quality cannot meet the requirements. To ensure the communication quality, this paper uses the time-frequency peak filtering algorithm to eliminate the noise in the LVPLC in the experimental environment. Firstly, this paper studies the noise characteristics based on the measured LVPLC channel noise. Secondly, the memory noise model is established, and the time-frequency peak filtering algorithm is used to eliminate the noise. In order to analyze the denoising effect of time-frequency peak filtering algorithm, the algorithm is simulated. Finally, the application effect of the algorithm is verified by experimental test. The simulation and application results show that the time-frequency peak filtering algorithm can improve the signal-to-noise ratio by about 5 dB in the actual noise environment of LVPLC, which can adapt to the changeable environment of LVPLC channel noise, and has good noise suppression effect and good application value. The application in the solar panel data transmission system shows that the time-frequency peak filtering algorithm can meet the communication performance requirements of the laboratory, reduce the bit error rate by about 2 % under the general background noise interference, and reduce the bit error rate by about 3 % under the pulse interference environment, and improve the transmission quality of LVPLC system.

Standalone microgrids are used in various industrial operations to supply critical loads. The authors have proposed a stable and robust decentralized ac microgrid architecture that provides an automatic and equitable load sharing between distributed generators, without the use of droop control. To deal with faults or real-time changes in the distributed generation levels, a flexible reconfiguration of the microgrid can be advantageous. To achieve that, this article proposes the use of power line communication (PLC). Two PLC strategies are explored in this article: the first is based on using a single and constant PLC frequency, and the second is based on using a variable PLC frequency within a given range. This article details PLC injection, detection, and suppression methods, as well as the overall communication logic. It demonstrates the ability of the microgrid to adapt to changes while minimizing the amount of battery support. Findings of this article are supported by simulations and validated by experiments.

This letter studies physical layer security (PLS) in non-orthogonal multiple access (NOMA) power line communication (PLC) networks. A source node transmits information to two nodes of near and far users with different power allocations. We consider two different cases of eavesdropping: internal and external. The PLC channel and noise are modeled by correlated log-normal fading and Bernoulli-Gaussian random process, respectively. We derive closed-form expressions for the secrecy outage probability (SOP) of both the internal and external cases by applying Gauss-Chebyshev quadrature, which are verified by Monte Carlo simulations. We observe that higher impulsive noise degrades the SOP while higher channel correlation can improve the SOP. In addition, the analytic results reveal the impact of power allocation on the SOP performance.

With the increase in the number of Internet users, due to digital inclusion, it is necessary to find the best possible way to provide this service. Among all forms of data transmission, PLC (Power Line Communication) is the one that has stood out the most in recent years, mainly due to its infrastructure, which allows users in semi-urban or even rural regions, and by the fact of ensuring high speed rates (up to 200 Mbps), through the broadband PLC, the BPL (Broadband Power Line), which uses the HomePlug AV standard. However, because the infrastructure used is the power lines, PLC is subject to numerous problems, such as interference, noise and attenuation. Therefore, there is a need to evaluate the performance of this broadband technology with regard to its use in domestic environments, analyzing its effectiveness amidst electrical interference. This paper presents an analysis of the performance of a PLC network that uses the HomePlug AV standard, with the objective of evaluating its viability in a domestic environment, since it presents several challenges for this technology Esde

Energy balance is one of the main criteria to operate the grid in stable condition. If there is any energy imbalance occurs due to increase in demand then the grid will not operate in stable condition. Increase demand is one of the major issues facing by grid. To address this problems many countries promoting the renewable energy generation this will support the grid to avoid energy imbalance problem. Prosumerplay a key role in this situation, where they can utilize the generated energy and remaining surplus power can integrate it to the grid. While utilising the renewable power generate it should be controlled and monitored effectively so that we can reduce the tariff cost. Solar panels installed in house need to bemonitored continuously to improve the performance of battery. In this paper, the power line communication (PLC) compliant with Home Plug is implementing to check energy consumption. The system design is composed of three components: Driver circuit, ac supply, and smart device application. This system will switch over from solar energy consumption to AC supply according to the load requirement. This scheme will maintain the performance of a PV system and contribute to enhancing home energy management system. The system design was stimulated with Matlaband verified with the hardwareresults.

This paper presents a simplified method of system stability improvement and cost-effective solution by accelerated distance protection using direct fiber optic signal between the (end-to-end) relays. Transmission line protection is one of the important priority of protection, as their correct and selective tripping and fast fault clearance will avoid instability in the grid, which otherwise may result in cascade tripping leading to instability of the grid. This paper proposes a new approach by using optical ground wire (OPGW) direct relay-to-relay teleportation in association with modern numerical distance relay for accelerated distance protection, instead of carrier aided power line communication protection scheme. This methodology enhances the tripping function faster. Thus, quick isolation of the fault improves the stability of the grid. In this new technique, there is significant reduction in circuit complexity which reduces in cost for PLCC equipments and scheme and also saving the control room area.

Smart grid is an energy network that integrates advanced power equipment, communication technology and control technology. It can transmit two-way power and data among all components of the grid at the same time. The existing smart grid communication technologies include power line carrier (PLC) communication, industrial Ethernet, passive optical networks and wireless communication,each of which have different advantages. Due to the complex application scenarios, massive sampling points and high transmission reliability requirements, a single communication method cannot fully meet the communication requirements of smart grid, and heterogeneous communication modes are required. In addition, with the development of cellular technology, long term evolution (LTE)-based standards have been identified as a promising technology that can meet the strict requirements of various operations in smart grid. In this paper, we analyze the advantages and disadvantages of PLC and LTE communication, and design a network framework for PLC and LTE communication uplink heterogeneous communication in smart grid. Then, we propose an uplink scheduling transmission method for sampling data with optimized throughput according to the requirements of system delay and reliability. Then, we use the formula derivation to prove the stability and solvability of the scheduling system in theory. Finally, the simulation results show that under the condition of satisfying the delay requirement, our proposed framework can optimally allocate the wireless communication resource and maximize the throughput of the uplink transmission system.

In the indoor environment of multiple-story buildings, the line-of-sight (LOS) radio frequency (RF) signal is generally obstructed by walls and slabs. As a solution to this dilemma, power line communication (PLC) is an alternative to overcome the LOS RF penetration issue. PLC is a cost-effective system that uses an alternative technology approach, through the help of already existing electrical distribution network in-side the building, to transmit data. In this approach, the electrical wire acts as a radiating antenna which takes through the RF signal. Firstly, the signal is detected and demodulated by an RF receiver, which becomes mobile due to the contactless aspect of the link. The focus of this paper is to analyze the performance of such a system and propose measurement results. The overall concatenation of PLC and RF systems. Simulation results exhibit the channel frequency response of the cascaded PLC-RF and its performance is measured through practical implementation.

This article investigates the physical layer security (PLS) of a broadband in-home power line communication (PLC) system when a malicious and passive PLC device tries to eavesdrop upon private information sent by a PLC transmitter to a legitimate PLC receiver. In this setting, the ergodic achievable secrecy rate, secrecy outage probability, effective secrecy throughput, and wiretap code rates are numerically evaluated with the use of a data set obtained from a measurement campaign carried out in several Brazilian houses. This data set comprises PLC channel estimates and measured additive noises considering four distinct sets of transmitter, legitimate receiver, and eavesdropper positions. Numerical results, covering three distinct frequency bands (1.7–30 MHz, 1.7–50 MHz, and 1.7–86 MHz), quantitatively show, in practice, the level of vulnerability of broadband in-home PLC systems in terms of PLS and offer some directions for an appropriate design of PLC modems to improve PLS.

Here, we investigate a novel constrained optimization problem that minimizes an energy-efficiency based outage probability by jointly optimizing the relay location and transmit power over the cooperative power line communication (PLC). It has been shown that the problem is generalized convex and has a global solution. Further, in order to reduce the computational complexity as well as to obtain design insights on the optimization, a nontrivial low-complexity tight approximation has been discoursed that gives closed-form of the optimal solution. Lastly, we observe that the proposed joint optimization scheme can yield a significant gain of around 57% against a benchmark.

A novel mixed cooperative relay assisted indoor power line communication - visible light communication (PLC-VLC) system for indoor broadcasting purpose consisting of mobile end user nodes for Internet of Things (IoT) network is presented in this study. Here, the PLC link acts as a backbone system to the VLC link by connecting to the latter with the help of decode and forward (DF) relay. The channel gain of the VLC systems is considered to be a function of user mobility which is modeled using random waypoint (RWP) mobility model. We present novel expressions for probability density function and cumulative distribution function for the equivalent end to end instantaneous signal to noise ratio (SNR) for this cooperative system. Using these derived statistics, we further evaluate the performance of the system under consideration in terms of link failure probability and average bit error rate.

Power line communication technology is a retrofit alternative technology for last mile information technology. Despite several challenges, such as inadequate standards and electromagnetic compatibility, it is maturing. In this review, we have analysed these obstacles and its current application status.

Recently, power line communication (PLC) is receiving attention from academic and industry researchers worldwide. In particular, PLC systems have been largely investigated as a medium for transmitting control signals, diagnostic information, or data measured by sensors in Smart Grid. However, PLC systems face several challenges, such as multipath effects and impulsive noise, which may degrade data communication performance. To surpass such issues we propose CodePLC, a dynamic network coding MAC protocol for PLC. CodePLC relies on a single, yet dynamically chosen, relay node. This node stores and forwards linear combinations of PLC frames, which are then combined on their final destinations. We have evaluated the performance of CodePLC through simulations in a PLC system based on a time division multiple access orthogonal frequency-division multiplexing scheme. Simulation results indicate that, in broadcast transmissions, CodePLC enhances system performance. When compared to a PLC system that does not consider the use of CodePLC, based on a stop&wait MAC layer protocol, our new protocol presents an average of 115% of goodput increase. Moreover, CodePLC reduces the average network buffers occupancy by 112%. Finally, our protocol is capable of reducing the mean end-to-end latency by 400%.

Electric vehicles (EVs) are without a doubt one of the hottest topics of our time because of their advantages over combustion engine vehicles. This has persuaded many developers to try improving EVs so they will be more reliable and cheaper and as a result suitable for a broader range of consumers.In this paper we dive into the proper way of measuring and understanding the impedance of one prismatic cell from 100 kHz up to 1 GHz. Some common measurement mistakes and important points to notice are also explained. The effect of a power bar is shown as well. In order to make sure of the accuracy and the consistency of the measurements, they are compared with finite element simulations as well as with mathematical calculations.Investigations of conducted emissions are also of key importance since it has a direct influence on selecting a suitable frequency range. Accordingly, a thorough lab measurement is conducted to see the distortion harmonics and their influence on the carrier frequency. This knowledge can then be used to implement the power line communication (PLC) method.The PLC technique helps us to reduce the wire harness of a battery pack by using the existing high-voltage lines of the vehicle as the main transmission channel. This leads to cheaper battery packs by reducing the amount of used material for the wire harness and production time as well as assembly complexity.

In this study, a time-domain reflectometry (TDR) system based on a baseband version of the orthogonal chirp-division multiplexing (OCDM) scheme, which is relies on a modified discrete Fresnel transform (DFnT), is proposed for power line sensing. After a detailed description of the system model, a multiple access scheme that exploits the contolution theorem of the modified DFnT for enabling distributed reflectometric and transferometric sensing of the monitored power line. Considering typical European underground low-voltage and US overhead medium-voltage (MV) power distribution networks, range resolution and maximum unambiguous range for the measurements are assessed for the proposed scheme. Next, a comparison with multiple access schemes based on the Hermitian symmetric orthogonal frequency-division multiplexing (HS-OFDM) discussed in a previous work is performed considering a Brazilian MV overhead scenario, being the number of measurements obtained over time, as well as signal-to-interference-plus-noise ratio (SINR) used as performance metrics. The attained results show that the proposed multiple access scheme results in the same range resolution as the others. Also, the highest number of measurements over time is obtained by the proposed scheme, which produces orthogonality among signals transmitted by different power line modems (PLMs) neither and time nor frequency domains, but rather in the Fresnel domain. Meanwhile, although its yielded SINR values are fair among the PLMs consisting the distributed sensing system, the proposed scheme is slightly outperformed by the HS-OFDM based on code-division multiple access and by the HS-OFDM based on frequency-division multiple access at some PLMs., arXiv admin note: text overlap with arXiv:1901.08404

We propose a novel simulation approach of the Middleton Class-A model for impulsive noise generation considering symbol-wise transmission in a real Power Line Communication environment. Then, we validate the proposed approach for both single carrier binary FSK based—and multi-carrier OFDM-based communication systems. Established analytical formulations and obtained simulation results for the impulsive noise variance distribution and the communication system error probability show that in a binary FSK system, the second order of the noise variance per symbol, as well as the error floor, are closely related to the impulsive index A. The error floor decreases when A becomes large, and its asymptotic value is equal to the Bit Error Rate (BER) for an additive white Gaussian noise channel with noise variance equal to the average variance of the impulse noise. However, in an OFDM-based system, the noise variance per symbol at the output of the demodulator, as well as the error floor in the BER curves, are fixed and independent of the impulsive index A. The proposed analysis allows us to compare binary FSK and OFDM under the same theoretical noise conditions.

In this paper, we analyze the performance of relay-assisted, single-stage (SS) non-orthogonal multiple access (NOMA) and dual-stage (DS) NOMA power line communication systems. Specifically, derive closed form expressions for the outage probabilities of the SS NOMA and DS NOMA schemes. Subsequently, we formulate optimization problems and obtain closed-form solutions for the optimal power allocation coefficients of the SS NOMA and DS NOMA scheme, such that the probability of overall outage is minimized. The accuracy of our analysis and the tightness of the approximations employed are validated through Monte Carlo simulations and numerical techniques. Moreover, we show that the DS NOMA scheme outperforms the SS NOMA scheme, in terms of the overall outage probability.