MIMO systems and applications

International Conference and Business Expo on Wireless Communication & Network September 21-23, 2015 Baltimore, USAThe use of multiple antennas at both the transmitter and receiver aims to improve performance or to increase symbol rate of systems, but it usually requires higher implementation complexity. The antenna spacing must be larger than the coherence distance to ensure independent fading across different antennas. Alternatively, uncorrelated signals in different antennas can be assured through the use of orthogonal polarizations. Multiple Input Multiple Output (MIMO) architectures can be used for combined transmit and receive diversity, for the parallel transmission of data or spatial multiplexing. When used for spatial multiplexing, MIMO technology promises high bit rates in a narrow bandwidth. Therefore, it is of high significance to the spectrum users. In this case, MIMO system considers the transmission of different signals from each transmit element so that the receiving antenna array receives a superposition of all transmitted signals. All new ideas about how to improve performance, capacity and/or spectrum efficiency while keeping computational cost at an acceptable level have been described. Multi-user MIMO (MU-MIMO) has also been introduced, where multiple streams of data are simultaneously allocated to different users, using the same frequency bands. This concept is similar to Space Division Multiple Access (SDMA). Nevertheless, while SDMA is typically employed in the uplink, MU-MIMO is widely used in the downlink. MU-MIMO presents several constraints, as downlink channel state information is required at the base station side (transmitter), and the processing is implemented using pre-coding (instead of the conventional post-processing approach). Ideas and concepts on MIMO applications, such as base station cooperation, coordinated multi-point transmission or multi-hop relay are also described. These are effective mechanisms that improve the performance at the cell edge, while mitigating the negative effects of near-far problem and adjacent cell interference, resulting in a more homogenous service quality, regardless the users’ positions. These concepts can be viewed as special types of MIMO systems, but where the different transmit or receive antennas are not collocated, but positioned in different locations. It is known that around 50% of the operational costs associated to cellular communications rely on the energy consumption, which also has an implication in the carbon emission footprint. MIMO Systems and Applications can contribute to the concept of Green Radio Communications, while supporting a reduction in the energy consumption. This presentation will provide a technical assessment of each of the technologies associated to MIMO systems and applications, while indicating the constraints associated to each one

Multimedia Communications and Networking

This book aims to present a detailed and comprehensive description of most important state-of-the-art fundaments and system details in the fields of multimedia, networking, digital communications, and network security. It describes several subjects which are key aspects in the development and understanding of the current and emergent services. The objective of this textbook is to concentrate in a single book the author's view about current and emergent multimedia, digital communications and networking services and technologies. Different bibliographic sources normally cover each one of these topics independently, without the required relationship. On one hand, the proposed book allows the reader to reduce the time and cost required to learn and improve skills and knowledge in the covered fields, with a relationship between the covered topics. Moreover, this book presents a compilation of the latest developments in the area, which is the outcome of several years of research and participation in many international projects. This book covers most of the relevant subjects with examples and end of chapter questions, properly designed to be used in BSc or MSc in computer science or electrical engineering. The approach used in this textbook aims to facilitate the learning of the covered subjects by students of several disciplines such as multimedia, networking, telecommunications and network security. Moreover, this book may also be used by academic, institutional or industrial professionals, in order to support the planning, design and development of multimedia, telecommunications or networking systems

The 4th Industrial Revolution and the Future of Linguistics

The 4th Industrial Revolution and the Future of Linguistic

Project Management in the Fourth Industrial Revolution

The Fourth Industrial Revolution (also referred to as Industry 4.0) is driven by a massive utilization of new technologies, such as robots, artificial intelligence, Internet of Things (IoT), Big Data, Quantum Computing and Quantum Communications, replacing humans by machines in certain tasks or the development of new or more efficient tasks. The Fourth Industrial Revolution is originating huge modifications in society and organizations. Human adaptation to the new paradigm is required, as it will have a high impact on jobs and on the required skills

A Combined Precoding scheme with Selective Transmit Diversity

We propose the use of the precoding (PC) scheme, which can be used to combat both the Multiple Access Interference (MAI) and Inter-Path Interference (IPI), combined with the Selective Transmit Diversity (STD) for high data rate transmissions. The proposed scheme is considered over frequency selective Rayleigh fading channels jointly with a RAKE in the receiver. With the PC, the increase in performance is achieved with a small increase in power processing in the BS, avoiding any need to increase complexity in the Mobile Station (MS). It is shown that the use of the proposed PC scheme, alone or combined with the STD achieves a performance improvement over the corresponding schemes without PC

Joint multi-user detection and intersymbol interference cancellation for WCDMA satellite UMTS

In this work we present two different intersymbol interference (ISI) cancellation systems, namely the commutation signaling (CS) and orthogonal code-division transmit diversity (O-CDTD) in combination with satellite path diversity, which leads to a high diversity order. The ISI is due to the use of satellite path diversity (in order to introduce multipath diversity artificially). This work combines the proposed ISI cancellation systems with subtractive multi-user detectors—a variation of the conventional parallel interference cancellation (PIC) and successive interference cancellation (SIC) for the downlink channel of S-UMTS. The blind detection is also considered without knowledge of spreading sequences or the channel state information (CSI) of the interfering users with a noise whitening matched filter (NWMF) that combats the MAI through the whitening of the interfering power spectrum, also with and without the ISI cancellation systems—CS and O-CDTD. It is shown that the proposed PIC is a very promising detector to be used for the downlink of S-UMTS, especially when combined with CS or O-CDTD, the NWMF being efficient only when we consider jointly any of the proposed ISI cancellation systems for low number of interfering user

MAI Cancellation with Commutation Signaling

This paper deals with PIC-parallel interference cancellation with and without the ISI cancellation system-commutation signaling (CS), in a deep Rayleigh fading environment, time and frequency selective, assuming the spreading sequences and the features of the channels of the several interfering users is known. It is proved that PIC lead to good profits especially when the CS technique is used together, because these systems subtract the MAI estimated for each user. These estimates improve when the ISI is cancelled, since the MAI estimated depends upon the estimate of the transmitted symbols by each interfering user. Additionally, it considers the blind detection (without knowledge of spreading sequences nor the features of the channels of the interfering users) with a noise whitening matched filter (NWMF) that combats the MAI through the whitening of the interfering power spectrum (following the single-user philosophy

Interference Cancellation with combined Pre-distortion filtering and Transmit Diversity

It is intended to specify a new pre-distortion (PD) filtering technique, which can be used to combat the multiple access interference (MAI), combined with two kinds of transmit diversity (TD), namely the selective transmit diversity (STD) and the space-time transmit diversity (STTD) for high data rate transmissions over frequency selective Rayleigh fading channels. By pre-distorting the signals to be transmitted by the base station (BS) with a minimum variance (MV) algorithm, the orthogonality between the desired signal and all interfering signals can be improved. We combine the PD with STD and with STTD, allowing a reduction in the MAI and combating the fading. The increase in performance is achieved with a small increase in power processing in the BS, avoiding any need to increase complexity in the mobile station (MS)

Space Time Block Coding for 4 antennas with coding rate 1

In this paper we propose a new space time transmit diversity (STTD) scheme for M (M4) transmit antennas and one receive antenna. The new diversity scheme belongs to the open loop class and consists of an extension to the work presented in [1,2,3]. The coding rate of the new scheme is one and in spite of the presence of inter-symbol interference it achieves, at least, the full diversity after applying a multi-dimensional orthonormal rotation to the original constellation. Each sequence with an integer multiple of M receive

On the 5G and beyond

UIDB/50008/2020This article provides an overview of the fifth generation of cellular communications (5G) and beyond. It presents the transmission techniques of current 5G communications and those expected of future developments, namely a brief study of non-orthogonal multiple access (NOMA) using the single carrier with frequency domain equalization (SC-FDE) block transmission technique, evidencing its added value in terms of spectral efficiency. An introduction to the sixth generation of cellular communications (6G) is also provided. The insertion of 5G and 6G within the Fourth Industrial Revolution framework (also known as Industry 4.0) is also dealt with. Consisting of a change in paradigm, when compared to previous generations, 5G supports a myriad of new services based on the Internet of things (IoT) and on vehicle-to-vehicle (V2V) communications, supporting technologies such as autonomous driving, smart cities, and remote surgery. The new services provided by 5G are supported by new techniques, such as millimeter waves (mm-wave), in addition to traditional microwave communication, and by massive multiple-input multiple-output (m-MIMO) technology. These techniques were not employed in the fourth generation of cellular communications (4G). While 5G plays an important role in the initial implementation of the Fourth Industrial Revolution, 6G will address a number of new services such as virtual reality (VR), augmented reality (AR), holographic services, the advanced Internet of things (IoT), AI-infused applications, wireless brain–computer interaction (BCI), and mobility at higher speeds. The current research on systems beyond 5G indicates that these applications shall be supported by new MIMO techniques and make use of terahertz (THz) bands.publishersversionpublishe