Advanced Digital Signal Processing Research Articles

Photonics-Assisted Technologies for Extreme Broadband 5G Wireless Communications

We summarize the enabling technologies for photonics-assisted broadband millimeter-wave (mm-wave) communication, which is a promising candidate for the enhanced mobile broadband (eMBB) communications, one of the three main typical application scenarios of 5G wireless networks. These enabling technologies, mainly focusing on the improvement of the system structure, include broadband mm-wave signal generation with simple and cost-effective schemes, multiple-input multiple-output architecture with polarization-multiplexing optical mm-wave signal, advanced multilevel modulation, optical or electrical multicarrier modulation, antenna polarization multiplexing and the employment of the high-gain mm-wave antenna, multi-band multiplexing, and broadband mm-wave signal detection. We also review the advanced digital signal processing (DSP) for heterodyne coherent detection, which can be applied into the photonics-assisted mm-wave communication systems, to further enhance the system performance for a given system structure and certain available devices. Based on these enabling technologies and advanced DSP, we have realized over 1 Tb/s wireless signal transmission at D-band and over 2.5 km wireless transmission with a bit rate up to 54 Gb/s at W-band. Our work verifies the photonics-assisted broadband mm-wave communication can meet the high-data-rate demand of eMBB.

Squeezing out the last few bits from band-limited channels with entropy loading.

The past decade witnessed the stirring development of advanced optical modulations and digital signal processing, which have been pushing optical transmission systems towards the capacity limit. Recent research has sought to squeeze out the last few bits from bandwidth-limited optical channels. One straightforward path is to expand the signal spectrum beyond the bandwidth limit while keeping the single-carrier modulation, which inevitably induces huge inter-symbol interference. To cope with such penalty, sophisticated digital nonlinear equalization on single-carrier signals should be exploited to reduce the burden of the subsequent forward error corrections (FEC). On the other hand, a more instinctive capacity-approaching method for bandwidth-deficient channels is the well-known water-filling realized by multicarrier modulation. As its approximation, bit loading (BL) has been a well-established algorithm to maximize the bit rate of a discrete multitone (DMT) channel with fixed-rate FEC. Built on probabilistic constellation shaping (PCS), multicarrier entropy loading (EL) goes beyond BL by continuous source entropy adaptation and has proven its superiority over the single-carrier PCS counterpart. In this paper, we reveal the EL advantage over BL on both achievable information rate (AIR) and FEC, aiming to prove EL as the optimum capacity-approaching solution for bandwidth-limited channels with frequency-selective fading. In a 100G direct detection system with a bandwidth-deficient directly modulated laser, EL improves the AIR by 5%-10% over BL using identical FEC overhead. EL will be critical for short-reach interconnects dominated by low-cost optical components to squeeze out the last few bits from the bandwidth-constrained system.

Implementation of Processing Functions for Autonomous Power Quality Measurement Equipment: A Performance Evaluation of CPU and FPGA-Based Embedded System

Motivated by the effects of deregulation over power quality and the subsequent need of new types of measurements, this paper assesses different implementations of an estimate for the spectral kurtosis, considered as a low-level harmonic detection. Performance of a processor-based system is compared with a field programmable gate array (FPGA)-based solution, in order to evaluate the accuracy of this processing function for implementation in autonomous measurement equipment. The fourth-order spectrum, with applications in different fields, needs advanced digital signal processing, making it necessary to compare implementation alternatives. In order to obtain reproducible results, the implementations have been developed using common design and programming tools. Several characteristics of the implementations are compared, showing that the increasing complexity and reduced cost of the current FPGA models make the implementation of complex mathematical functions feasible. We show that FPGAs improve the processing capability of the best processor using an operating frequency 33 times lower. This fact strongly supports its implementation in hand-held instruments.

4D PAM-7 Trellis Coded Modulation for Data Centers

We propose a novel seven-level pulse amplitude modulation (PAM-7) combined with trellis coded modulation (TCM) for data center applications. Four symbols are combined in the 4D space to encode ten information bits. The novel scheme called 4D PAM-7 TCM is experimentally demonstrated with commercially available devices at 1550 nm at rates of 210/225 Gbit/s. Excellent performance is achieved by employing advanced digital signal processing algorithms both at transmitter and receiver. The TCM scheme is compared with the PAM-6 modulation format which has the same spectral efficiency. The 4D PAM-7 TCM format improves the sensitivity by 5.5 dB compared to the best PAM-6 results assuming that the system works with the KP4 FEC. The TCM solution may transport the next Ethernet data rate of 800G using $4\times 200\text{G}$ transceivers.

An Overview on Application of Machine Learning Techniques in Optical Networks

Today's telecommunication networks have become sources of enormous amounts of widely heterogeneous data. This information can be retrieved from network traffic traces, network alarms, signal quality indicators, users' behavioral data, etc. Advanced mathematical tools are required to extract meaningful information from these data and take decisions pertaining to the proper functioning of the networks from the network-generated data. Among these mathematical tools, machine learning (ML) is regarded as one of the most promising methodological approaches to perform network-data analysis and enable automated network self-configuration and fault management. The adoption of ML techniques in the field of optical communication networks is motivated by the unprecedented growth of network complexity faced by optical networks in the last few years. Such complexity increase is due to the introduction of a huge number of adjustable and interdependent system parameters (e.g., routing configurations, modulation format, symbol rate, coding schemes, etc.) that are enabled by the usage of coherent transmission/reception technologies, advanced digital signal processing, and compensation of nonlinear effects in optical fiber propagation. In this paper we provide an overview of the application of ML to optical communications and networking. We classify and survey relevant literature dealing with the topic, and we also provide an introductory tutorial on ML for researchers and practitioners interested in this field. Although a good number of research papers have recently appeared, the application of ML to optical networks is still in its infancy: to stimulate further work in this area, we conclude this paper proposing new possible research directions.

Spectrally efficient single carrier 400G optical signal transmission

In this paper, the recent progress on spectrally efficient single carrier (SC) 400G optical signal transmission was summarized. By using quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM) and 64QAM, we can realize transmission distance over 10000, 6000 and 3000 km, respectively, with large area fiber and all-Raman amplification. To improve the system performance and generate high-order QAM, advanced digital signal processing algorithms such as probabilistic shaping and look-up table pre-distortion are employed to improve the transmission performance.

Advanced Digital Signal Processing for Reach Extension and Performance Enhancement of 112 Gbps and Beyond Direct Detected DML-Based Transmission

112 Gbps per wavelength, amplification free Four-level Pulse Amplitude Modulation (PAM-4) transmissions are experimentally demonstrated with advanced digital signal processing (DSP) algorithms. Two DSP architectures are investigated for Directly Modulated Lasers (DMLs): 1) the regular DSP with Feed Forward Equalization (FFE) and Decision Feedback Equalization (DFE), and 2) the enhanced DSP with Maximum Likelihood Sequence Estimation (MLSE) equalizer. The experimental results show that with advanced DSP technologies the conventional DML can achieve 40 km transmissions with Bit Error Rate (BER) under 2.4 × 10−4 that meets RS (544, 514) Forward Error Correction (FEC) requirement; with regular-DSP the advanced DML can achieve 40 km transmissions with BER under 3.8 × 10−3, with stronger FEC. 112 Gbps and beyond per lambda DML based transmission is a promising low power, low-cost solution for 800 GbE or 1.6 TbE Ethernet.

A highly scalable parallel spike-based digital neuromorphic architecture for high-order fir filters using LMS adaptive algorithm

This brief presents a highly scalable parallel neuromorphic architecture to efficiently compute high-order adaptive FIR filters using a least mean square (LMS) algorithm. This has been achieved by eliminating critical paths because they critically affect the scalability of advanced parallel architectures. Here, the scalability is defined in terms of number of taps and bit-length. On the computation of high-order adaptive FIR filters, the multiplication is the most demanding operation. Therefore, we have made intensive efforts to create a compact new neural multiplier by improving the design and hardware implementation of an existing neural multiplier. The resulting multiplier requires 50 % fewer synapses, 40 % fewer neurons, 30 % fewer area resources and 26 % fewer clock cycles compared with the existing neural multiplier, respectively. The efficient implementation of the proposed multiplier has allowed us to eliminate critical paths significantly and thus the bit-length can be easily increased to guarantee the convergence performance when high-order adaptive filters are processed. To demonstrate its effectiveness, the proposed multiplier was included in the neuromorphic architecture to support high-order adaptive FIR filters. In addition, we employ the time multiplexing technique to maximize the utilization of the proposed neural multiplier by performing filter processing and the adaptive process because multiplication is involved in both. We mainly use this strategy to eliminate critical paths and reduce the area consumption by implementing a large number of taps. The proposed neuromorphic architecture was implemented on the Kintex-7 Field Programmable Gate Array (FPGA) development kit to validate its performance. Our results demonstrate that the neuromorphic architecture is capable of processing higher adaptive FIR filters compared with previously reported solutions. This potentially allow its practical use in many advanced digital signal processing applications such as acoustic echo cancellers, active noise control, channel equalization and system identification.

Coherent Receiver DSP Implemented on a General-Purpose Server for a Full Software-Defined Access System

To accommodate the service paradigm shift driven by the now amazingly wide variety of services, telecom operators must overcome many challenges in redesigning their network infrastructure to attain system flexibility, scalability, and cost effectiveness. A key part of the solution is the recent advent of network virtualization based on commodity hardware. We propose a unique edge-server architecture that combines network virtualiza- tion with advanced digital signal processing (DSP) technology. Our architecture has the server's central processing unit running application layer functions and a generalpurpose accelerator running dissimilar physical layer functions, including advanced DSP. To elucidate the power budget capability of our coherent detection scheme, a hardware experiment demonstrates the optical power budget of 45.2 dB for quadrature phase-shift keying signals of 5 Gbit/s bit rate.

Experimental study of single channel 100 Gbit/s PAM4 transmission over 40 km using 17 GHz EML and APD at O band

Abstract Single channel 100 Gbit/s PAM4 transmission at O band is experimentally studied based on low cost intensity modulation and direct detection (IM-DD). By the use of advanced digital signal processing algorithms, we successfully achieve a receiver sensitivity of −17.3 dBm at 7% HD-FEC threshold of 3.8E-3 over 40 km un-amplified SSMF transmission with 17 GHz (3 dB bandwidth) commercial electric absorption modulated laser (EML) and avalanche photodiode (APD). To the best of author’s knowledge, we hereby report the best receiver sensitivity for 100 Gbit/s/λ IM-DD system. Due to the low cost and high sensitivity merits, the proposed scheme will be a promising way for high speed short-haul optical transmissions in the future.

Transmitter and receiver DSP for 112 Gbit/s PAM-4 amplifier-less transmissions using 25G-class EML and APD.

The transmission performance of 112 Gbit/s PAM-4 signal with commercial 25 G-class EML and APD is experimentally studied by using advanced digital signal processing (DSP) algorithms, i.e. pre-equalization (Pre-EQ), error-table based pre-correction (ETC), least-mean square (LMS) based equalization, direct detection faster than Nyquist (DD-FTN) algorithm. Among them, Pre-EQ and ETC are implemented at the transmitter, and ETC is a symbol-pattern-dependent pre-compensation algorithm based on the look-up-table approach. In order to obtain these pre-compensated parameters readily, a joint equalization and error table generation (JEEG) module is proposed. Employing the combination of ETC, LMS, and DD-FTN, a single line 112 Gbit/s PAM-4 40 km amplifier-less transmission with a record receiver sensitivity of -16.6 dBm (at 7% HD-FEC threshold) is experimentally demonstrated. In addition, the computational complexities of different DSP schemes are analyzed and discussed in detail. The receiver computational complexity can be effectively reduced by employing appropriate ETC and Pre-EQ in the transmitter.

Physical Layer Strategies to Save Lightpath Regenerators

We investigate the viability of hybrid fiber amplifiers (HFA) and advanced digital signal processing (DSP)-based transceivers in translucent optical networks. We focus on the reduction of optical-electro-optical (OEO) regenerators required to support a 200 Gbps any-to-any traffic. In this paper, two network topologies, Pan-European and USNET, are quantitatively analyzed according to three different upgrade strategies. The first upgrade strategy includes selective placement of HFA in a network using different Raman amplification levels. The second upgrade strategy includes the use of two different DSP techniques of digital backpropagation and probability shaping (PS) at the transceivers. The third upgrade strategy involves a combination of both HFA and DSP techniques in a network. Our results indicate that by using these upgradation strategies, a prominent reduction in OEO regenerators can be obtained, which can lead to full transparency of a network. In the Pan-European topology, improving the equivalent noise figure (ENF) of the optical amplifiers by 5 dB, it is possible to reduce by 74% the amount of required regenerators. Then, by applying advanced DSP techniques like PS, this percentage grows up to 82%. In the USNET topology, by reducing the ENF by 2 dB, it is possible to reach full transparency. By using PS, it is enough to reduce the ENF by just 0.5 dB to reach the same results.

Analysis of OFDM system using DCT-PTS-SLM based approach for multimedia applications

In last decade, wireless communications have observed a substantial development. However, wireless channels involve some disadvantages, like multipath fading, which make them hard to cope with. A modulation that efficiently deals with selective fading channels is an orthogonal frequency division multiplexing (OFDM), which consists on N orthogonal subcarriers generated and modulated when you look at the frequency domain. The orthogonal subcarriers allows, the use of the Fourier transform without introducing interference that is inter carrier interference. The advancements in digital signal processing and extremely large scale integrated circuits allow efficient and cost-effective utilization of the fast Fourier transform operations making OFDM an appealing solution for wireless channels. In OFDM system peak to average power ratio (PAPR) is a big risk which can be avoided using various techniques. This paper deals with performance analysis of multicarrier OFDM using combination of discrete cosine transform, partial transmit sequence and selective mapping. A video signal has been given as an input and MATLAB simulations were carried out. BER has been immensely improved and PAPR is reduced to 4 dB which is appreciable performance for multimedia devices.

Advanced digital signal processing methods for effective noise cancellation of vehicle related signals. State of the Art

The current trend of vehicle technology’s evolution points towards a further automation of the automobile. The information that such a vehicle processes and handles becomes therefore more important from the performance but also from the safety point of view. The main target of this research is to improve the reliability, accuracy and timing of the information measured by mass produced sensors, whether the sensors are set up in single or array configuration. The scope of the considered sensors covers those related to the automotive sector, both current and potential ones. It is planned to achieve the main target by 1) actively reducing the noise to increase the SNR of the sensor measurements and/or by 2) using advanced processing methods that remove/minimize the delay they introduce in the processing system.

100 Gbit/s THz Photonic Wireless Transmission in the 350-GHz Band With Extended Reach

In this letter, we experimentally demonstrate terahertz (THz) photonic wireless transmission of high-speed quadrature-phase-shift-keying (QPSK) and 16 quadrature amplitude modulation (16-QAM) signals in the 350-GHz band, with an effort to extend the wireless reach of ultrafast 100 Gbit/s. In the experiment, a narrowband unitraveling-carrier photodiode (UTC-PD) is used for heterodyne generation of THz communication signals, which is transparent to optical modulation formats. Experimental results show that 30 GBd/s QPSK (60 Gbit/s) and 25 GBd/s 16-QAM signals (100 Gbit/s) are successfully transmitted over a 350-GHz wireless link with an extended distance of 2 m. This enhancement is enabled by combining the techniques of employing cutting-edge narrowband UTC-PD as the photomixing THz emitter, spectrally efficient modulation format and advanced digital signal processing algorithms. The achievement makes 100 Gbit/s THz wireless communication systems promising for future smart wireless services.

Room Response Equalization—A Review

Room response equalization aims at improving the sound reproduction in rooms by applying advanced digital signal processing techniques to design an equalizer on the basis of one or more measurements of the room response. This topic has been intensively studied in the last 40 years, resulting in a number of effective techniques facing different aspects of the problem. This review paper aims at giving an overview of the existing methods following their historical evolution, and discussing pros and cons of each approach with relation to the room characteristics, as well as instrumental and perceptual measures. The review is concluded by a discussion on emerging topics and new trends.

Photonics-Assisted Millimeter-Wave Wireless Communication

High-speed millimeter-wave (mm-wave) wireless transmission at 40 Gb/s or higher will be required in the near future. Due to bottleneck in electrical devices, mm-wave wireless signal at such high bit rates cannot be generated in an all-electrical method. Photonics-assisted mm-wave generation technology has become an effective solution to handle this problem of bandwidth limitation. Recent efforts with a single modulator to generate optical mm-wave signal largely simplify the architecture of the optical transmitter. Heterodyne detection based on advanced digital signal processing can overcome nonlinear effects in optical and electrical devices, and it also can improve the spectral efficiency and receiver sensitivity. Multidimensional multiplexing techniques can reduce the baud rate of each subchannel, and hence it can realize mm-wave signal long distance transmission. In this tutorial, we will describe these key enabling technologies and principle for the realization of ultrahigh speed, large capacity mm-wave signal transmission. These enabling technologies can effectively improve the transmission capacity and distance, as well as reduce the required bandwidth for optical and electrical devices.

10th International Conference on Computer and Electrical Engineering

PrefaceIt is our great pleasure to welcome you to 2017 10th International Conference on Computer and Electrical Engineering which will take place in University of Alberta, Edmonton, Canada during October 11-13, 2017. ICCEE2017 is dedicated to issues related to Computer and Electrical Engineering.The major goal and feature of the conference is to bring academic scientists, engineers, industry researchers together to exchange and share their experiences and research results, and discuss the practical challenges encountered and the solutions adopted. Professors from Canada and Luxembourg are invited to deliver plenary speeches regarding latest information in their respective expertise areas. It will be a golden opportunity for the students, researchers and engineers to interact with the experts and specialists to get their advice or consultation on technical matters, sales and marketing strategies.These proceedings present a selection from papers submitted to the conference from universities, research institutes and industries. All of the papers were subjected to peer-review by conference committee members and international reviewers. The papers selected depended on their quality and their relevancy to the conference. The volume tends to present to the readers the recent advances in the field of Computer and Electrical Engineering and various related areas, such as Computer Vision, Graphics and Intelligence, Computational and Artificial Intelligence, Advanced Power Semiconductors, Analogue and Digital Signal Processing, Algorithm, etc.We would like to thank all the authors who have contributed to this volume and also to the reviewers, speakers, chair persons and all the conference participants for their support to ICCEE 2017.Best Regards!Yours sincerely,Conference Organizing CommitteeOctober 20, 2017

0.4 THz Photonic-Wireless Link With 106 Gb/s Single Channel Bitrate

To accommodate the demand of exponentially increased global wireless data traffic, the prospective data rates for wireless communication in the market place will soon reach 100 Gb/s and beyond. In the lab environment, wireless transmission throughput has been elevated to the level of over 100 Gb/s attributed to the development of photonic-assisted millimeter wave and terahertz (THz) technologies. However, most of recent demonstrations with over 100 Gb/s data rates are based on spatial or frequency division multiplexing techniques, resulting in increased system's complexity and energy consumption. Here, we experimentally demonstrate a single channel 0.4 THz photonic-wireless link achieving a net data rate of beyond 100 Gb/s by using a single pair of THz emitter and receiver, without employing any spatial/frequency division multiplexing techniques. The high throughput up to 106 Gb/s within a single THz channel is enabled by combining spectrally efficient modulation format, ultrabroadband THz transceiver and advanced digital signal processing routine. Besides that, our demonstration from system-wide implementation viewpoint also features high transmission stability, and hence shows its great potential to not only decrease the system's complexity, but also meet the requirements of prospective data rates for bandwidth-hungry short-range wireless applications.

Meeting ecodesign efficiency requirements: ensuring accuracy in power transformer loss tests via TLM system calibrations

As part of the sustainable energy policies of the european union (EU), the Ecodesign Directive puts efficiency requirements per 1 July, 2015 on medium and large power transformers. This increases the importance of unambiguous measurement of power transformer losses, and thus of the accuracy of the transformer loss measurement (TLM) systems used by power transformer manufacturers for verification of these losses. Higher accuracy measurements not only lead to increased confidence in the product at the customers, but also allows for saving costs by designing transformers close to the loss limits. To support high-quality power transformer loss measurements, van swinden laboratorium (VSL) has developed a reference system for calibration of TLM systems at the best accuracy levels. A significant advantage is that the TLM systems are calibrated as a whole, thereby covering all possible error sources. Using advanced digital signal processing techniques, high currents are generated with adjustable, stable phase with respect to the applied test voltage. Test results show that calibration accuracies of 25 μrad in phase (corresponding to 0.25% in active power at power factor of 0.01) are achieved for test voltages and currents up to 100 kV and 2 kA, respectively – a factor 10 better than typical TLM system specifications.