National Institute of Standards and Technology における超伝導研究及び生活

This chapter contains sections titled: Introduction Overview of Multicarrier CDMA Systems Channel Model Performance of MC-CDMA System Performance of Overlapping Multicarrier DS-CDMA Systems Performance of Multicarrier DS-CDMA-I Systems Performance of AMC DS-CDMA Systems Performance of SFH/MC DS-CDMA Systems Chapter Summary and Conclusion 
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Overview of Multicarrier CDMA

This article overviews the power line communication, which is originally devised to transmit electric power from a small number of sources to a large number of sinks. Initially the first data transmission were over power lines were primarily done only to protect sections of the power distribution system in case of faults. This paper also studies the performance of power lines for high bit rate applications. DMT technology is adopted by the homeplug standard can theoretically provide data rates of 100Mb/s. However, products based on the standard only have achieved data rates up to 14 Mb/s. To protect against the severe noisy conditions and fading in the powerline channel, very high levels of error control coding need to be provided. The efforts of the homeplug alliance and home networking technology's growth in the US portend a very bright future for DMT-based PLC home networking.

Power line communications

This paper presents a comprehensive and general optimization-based home energy management controller, incorporating several classes of domestic appliances including deferrable, curtailable, thermal, and critical ones. The operations of the appliances are controlled in response to dynamic price signals to reduce the consumer�s electricity bill whilst minimizing the daily volume of curtailed energy and therefore considering the user�s comfort level. To avoid shifting most portion of consumer demand towards the least price intervals, which could create network issues due to loss of diversity, higher prices are applied when the consumer�s demand goes beyond a power threshold level. The arising mixed integer nonlinear optimization problem is solved in an iterative manner rolling throughout the day to follow the changes in the anticipated price signals and the variations in the controller inputs while information is updated. The results from different realistic case studies show the effectiveness of the proposed controller to minimize the household�s daily electricity bill while preserving comfort level as well as preventing creation of new least-price peaks.

Automated Demand Response from Home Energy Management System under Dynamic Pricing and Power and Comfort Constraints

The ambitious high data-rate applications in the envisioned future beyond fifth-generation (B5G) wireless networks require new solutions, including the advent of more advanced architectures than the ones already used in 5G networks, and the coalition of different communications schemes and technologies to enable these applications requirements. Among the candidate communications schemes for future wireless networks are non-orthogonal multiple access (NOMA) schemes that allow serving more than one user in the same resource block by multiplexing users in other domains than frequency or time. In this way, NOMA schemes tend to offer several advantages over orthogonal multiple access (OMA) schemes such as improved user fairness and spectral efficiency, higher cell-edge throughput, massive connectivity support, and low transmission latency. With these merits, NOMA-enabled transmission schemes are being increasingly looked at as promising multiple access schemes for future wireless networks. When the power domain is used to multiplex the users, it is referred to as the power domain NOMA (PD-NOMA). In this paper, we survey the integration of PD-NOMA with the enabling communications schemes and technologies that are expected to meet the various requirements of B5G networks. In particular, this paper surveys the different rate optimization scenarios studied in the literature when PD-NOMA is combined with one or more of the candidate schemes and technologies for B5G networks including multiple-input-single-output (MISO), multiple-input-multiple-output (MIMO), massive-MIMO (mMIMO), advanced antenna architectures, higher frequency millimeter-wave (mmWave) and terahertz (THz) communications, advanced coordinated multi-point (CoMP) transmission and reception schemes, cooperative communications, cognitive radio (CR), visible light communications (VLC), unmanned aerial vehicle (UAV) assisted communications and others. The considered system models, the optimization methods utilized to maximize the achievable rates, and the main lessons learnt on the optimization and the performance of these NOMA-enabled schemes and technologies are discussed in detail along with the future research directions for these combined schemes. Moreover, the role of machine learning in optimizing these NOMA-enabled technologies is addressed.

A Survey of Rate-Optimal Power Domain NOMA With Enabling Technologies of Future Wireless Networks

Multi-carrier modulation (MCM) schemes divide the broadband frequency-selective channel into parallel, flat-fading subchannels of equal bandwidth and interspacing A cyclic prefix is appended to each symbol, in order to mitigate inter-symbol interference (ISI), however it leads to spectral inefficiency Moreover, OFDM transceivers suffer from poor frequency characteristics Perfect reconstruction wavelet packet transmultiplexer in an OFDM transceiver counters the degrading effects of ISI, and also conserves bandwidth In this paper we give the performance comparison of conventional discrete Fourier transform (DFT) with discrete wavelet packet transform (DWPT) in an OFDM transceiver Two of the most popular wavelets, namely Haar and Daubechies wavelets are used for DWPT in a multipath flat-fading and frequency selective-fading channel A comparison between wavelets and wavelet packets is also given and it is shown that wavelet packets outperform wavelets

Performance Comparison of DFT, Discrete Wavelet Packet and Wavelet Transforms, in an OFDM Transceiver for Multipath Fading Channel

A networked home is a micro-version of the Internet, connecting home appliances, PCs, and other smart devices not only to one another but also to a globally connected world through the Internet. For consumers to embrace home networking, a solution that utilizes the existing infrastructure within the home, such as electrical wiring, is significant. However, the use of power lines as a home networking platform presents quite a troublesome and noisy environment that fluctuates with varying load impedance and time, and is also plagued by impulse noise. The latest developments in VLSI and DSP technologies have enabled power line communication (PLC) networks to compensate for the impairments of the environment. This article discusses the use of discrete multitone technology at the PHY layer of an in-home PLC network, particularly with reference to bit-loading techniques.

A discrete multitone transceiver at the heart of the PHY layer of an in-home power line communication local-area network

Today's electricity grid is rapidly evolving, with increased penetration of renewable energy sources (RES). Conventional Optimal Power Flow (OPF) has non-linear constraints that make it a highly non-linear, non-convex optimisation problem. This complex problem escalates further with the integration of RES, which are generally intermittent in nature. In this article, an optimal power flow model combines three types of energy resources, including conventional thermal power generators, solar photovoltaic generators (SPGs) and wind power generators (WPGs). Uncertain power outputs from SPGs and WPGs are forecasted with the help of lognormal and Weibull probability distribution functions, respectively. The over and underestimation output power of RES are considered in the objective function i.e. as a reserve and penalty cost, respectively. Furthermore, to reduce carbon emissions, a carbon tax is imposed while formulating the objective function. A grey wolf optimisation technique (GWO) is employed to achieve optimisation in modified IEEE-30 and IEEE-57 bus test systems to demonstrate its feasibility. Hence, novel contributions of this work include the new objective functions and associated framework for optimising generation cost while considering RES; and, secondly, computational efficiency is improved by the use of GWO to address the non-convex OPF problem. To investigate the effectiveness of the proposed GWO-based approach, it is compared in simulation to five other nature-inspired global optimisation algorithms and two well-established hybrid algorithms. For the simulation scenarios considered in this article, the GWO outperforms the other algorithms in terms of total cost minimisation and convergence time reduction.

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Heuristic algorithm based optimal power flow model incorporating stochastic renewable energy sources

The non-orthogonal multiple access (NOMA) technique is a strong candidate for 5G cellular networks that enable greater multiuser capacity and user fairness through multiplexing in the power domain. The user data are pulse-shaped using the orthogonal frequency-division multiplexing (OFDM) technique based on the fast Fourier transform (FFT) for conventional NOMA. We propose a discrete wavelet transform-based pulse shaping technique for NOMA. We present a closed-form expression of the bit error rate (BER) for FFT-NOMA as well as wavelet-based NOMA (WNOMA) systems. The theoretical and simulation BER results show that WNOMA outperforms FFT-NOMA in additive white Gaussian noise.

Closed-Form BER Expression for Fourier and Wavelet Transform-Based Pulse-Shaped Data in Downlink NOMA

The hybrid power line communication (PLC) and visible light communication (VLC) systems can be effectively utilized for the efficient design of 5G communication setup However, each of these integrated communication media is not primarily meant for the specific purpose of data communication, as PLC and VLC have historically served to transfer electrical energy transfer and light, respectively With the advent of high flickering rate light emitting diodes and efficient multiplexing/modulation schemes, both technologies are observed as potential data communication carriers Therefore, this paper presents a novel approach for modifying the modulation technique in accordance with the channel requirements of a hybrid PLC-VLC-based 5G communication systems We provide a thorough analysis of the research work done to co-use these two technologies for data communication, suggest some exciting applications of integrated PLC-VLC systems and propose discrete wavelet transform (DWT)-based orthogonal frequency division multiplexing (OFDM) to tune the physical parameters as per the hybrid channel characteristics Theoretical and simulation bit-error-rate results exhibit that DWT-OFDM outperforms an OFDM-based PLC-VLC system The proposed hybrid system can be used to design smart buildings where indoor/intra-building connectivity is maintained by VLC whereas inter-building networking based on PLC communication

Sobia Baig

Papers

Performance Comparison of DFT, Discrete Wavelet Packet and Wavelet Transforms, in an OFDM Transceiver for Multipath Fading Channel

A discrete multitone transceiver at the heart of the PHY layer of an in-home power line communication local-area network

Heuristic algorithm based optimal power flow model incorporating stochastic renewable energy sources

Closed-Form BER Expression for Fourier and Wavelet Transform-Based Pulse-Shaped Data in Downlink NOMA

High Data Rate Discrete Wavelet Transform-Based PLC-VLC Design for 5G Communication Systems