Applied Sciences

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Special Issue Editor

Dr. Mario Marques Da Silva

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Guest Editor

1. Institute of Telecommunications, 1049-001 Lisboa, Portugal
2. Department of Engineering and Computer Sciences, Autonoma University of Lisbon, 1150-293 Lisboa, Portugal
Interests: cellular communications; 6G and beyond; massive-MIMO; millimeter-wave communications; block transmission techniques; NOMA, LIS & RIS systems
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The future digital society, in the scope of increasing automation, namely the digital society of 2030 and beyond, comprises an increasing number of connected devices (IoT), including sensors, vehicles, aerial drones, data, etc. While 5G supports autonomous vehicles, the increasing number of sensors per vehicle requires higher-speed communications and lower latencies. Society and organizations demand new services to be included in 6G, such as:

Augmented reality and extended reality;
Artificial-intelligence-infused applications;
Wireless brain–computer interactions;
Holographic services;
The integration of communications with localization, mapping, and remote control;
Emerging eHealth applications;
Improved autonomous vehicles;
More efficient support of IoT, namely smart cities and smart houses, supporting an extremely high number of low-power devices;
Support of flying vehicles and increased mobility speed.

The 6G network also aims to have higher energy efficiency and more efficient strategies for use in energy harvesting, so that the autonomy of user equipment can be increased, despite its demanding applications.

These new services and capabilities to be supported by 6G continue to require more efficient networks, such as increased data rates, lower latency, more efficient spectral efficiency, increased energy efficiency, and improved network capacity. Some of the foreseen requirements for 6G include:

A nomadic peak data rate of at least 1 Tbps (100 times higher than 5G);
A mobile data rate of 1 Gbps (10 times higher than 5G);
Energy efficiency 10 to 100 times better than 5G;
Spectral efficiency 5 to 10 times better than 5G.

While 5G requirements are achieved based on mm-Wave and m-MIMO, 6G must incorporate new concepts such as passive antennas, namely Reconfigurable Intelligent Surfaces (RISs). In order to achieve potential gains (coverage, interference cancellation, secrecy, spectral efficiency, etc.), the channel characteristics must be estimated, and this is difficult to achieve with passive elements. Recently, active antennas, such as Large Intelligent Antenna Systems (LISs), also referred to as Ultra Massive MIMOs (UL-MIMOs) or as Extremely Large Antenna Arrays (ELAAs), have been employed to achieve such gain desiderates, but with their use, the complexity also increases. In terms of frequency bands, 6G is revolutionary, as it includes Visible Light Communications (VLC) and Terahertz bands (100 GHz – 10 THz), enabling data rates in the order of hundreds of Gbps. VLC is a mature communication technique well suited for short-range coverage, although it is susceptible to interferences, such as from the Sun.

This Special Issue, “Transmission Techniques for 6G and Beyond”, will provide an overview of 6G communications and beyond, in terms of networks, services, and requirements, while describing the advancements in transmission techniques foreseen for future versions. All new ideas regarding how the performance, capacity, and/or spectrum efficiency of transmission techniques can be improved for 6G and beyond while keeping computational costs at an acceptable level are most welcome. Contributions to this Special Issue should provide an overview of how the proposed transmission techniques bring added value to the advancements in cellular communications in terms of performance and/or advanced requirements.

Dr. Mario Marques Da Silva
Guest Editor

Manuscript Submission Information

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Keywords

cellular communications
6G and beyond
LIS antenna systems
RIS antenna systems
block transmission techniques

Published Papers (2 papers)

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Research

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15 pages, 3884 KiB

Open AccessArticle

On the Performance of LDPC-Coded Large Intelligent Antenna System

by Ali Gashtasbi, Mário Marques da Silva, Rui Dinis and João Guerreiro

Appl. Sci. 2023, 13(8), 4738; https://doi.org/10.3390/app13084738 - 10 Apr 2023

Cited by 3 | Viewed by 1262

Abstract

This article studies Large Intelligent Systems (LIS) along with Single Carrier with Frequency Domain Equalization (SC-FDE), utilizing Low-Density Parity-Check (LDPC). Four different receivers are studied in the scenarios described above, namely Equal Gain Combining (EGC), Maximum Ratio Combining (MRC), Zero Forcing (ZF), and Minimum Mean Squared Error (MMSE). The results of this article show that the use of LDPC codes leads to an improvement of performance by about 2 dB for a 4X25 LIS system and by 3 dB for a 4X225 LIS system, as compared to similar systems without LDPC codes. Moreover, for all simulations, the MMSE receiver achieves the best overall performance, while EGC performs the worst. Full article

(This article belongs to the Special Issue Transmission Techniques for Future 6G Systems and Beyond)

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Other

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14 pages, 2011 KiB

Open AccessTutorial

IRS, LIS, and Radio Stripes-Aided Wireless Communications: A Tutorial

by Ali Gashtasbi, Mário Marques da Silva and Rui Dinis

Appl. Sci. 2022, 12(24), 12696; https://doi.org/10.3390/app122412696 - 11 Dec 2022

Cited by 10 | Viewed by 1959

Abstract

This is a tutorial on current techniques that use a huge number of antennas in intelligent reflecting surfaces (IRS), large intelligent surfaces (LIS), and radio stripes (RS), highlighting the similarities, differences, advantages, and drawbacks. A comparison between IRS, LIS, and RS is performed in terms of the implementation and capabilities, in the form of a tutorial. We begin by introducing the IRS, LIS, and RS as promising technologies for 6 G wireless technology. Then, we will look at how the three notions are applied in wireless networks. We discuss various performance indicators and methodologies for characterizing and improving the performance of IRS, LIS, and RS-assisted wireless networks. We cover rate maximization, power consumption reduction, and cost implementation concerns in order to take advantage of the performance increase. Furthermore, we extend the discussion to some cases of emerging use. In the description of the three concepts, IRS-assisted communication was introduced as a passive system, considering the capacity/data rate, with power optimization being an advantage, while channel estimation was a challenge. LIS is an active component that goes beyond massive MIMO; a recent study found that channel estimation issues in IRS had improved. In comparison to IRS, capacity enhancement is a highlight, and user interference showed a trend of decreasing. However, power consumption due to utilizing power amplifiers has restrictions. The third technique for increasing coverage is cell-free massive MIMO with RS, with easy deployment in communication network structures. It is demonstrated to have suitable energy efficiency and power consumption. Finally, for future work, we further propose expanding the conversation to include some cases of new uses, such as complexity reduction; design and simulation with LDPC code could be a solution to decreasing complexity. Full article

(This article belongs to the Special Issue Transmission Techniques for Future 6G Systems and Beyond)

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