FABIO OTUBOIn the coming decade, mobile phones will not be used just to chat, send messages and access digital content. They will connect users to their home devices, to transportation and security systems, and even to their clothes. If what is known as the Internet of Things is to become a reality, mobile networks that process more data at greater speeds are needed, in addition to a new communications system called 5G, or the fifth generation of mobile telephony, which is currently being developed and standardized. The forecast is that, early in the next decade, mobile phones with Internet connections at least 1,000 times faster will be available. They will also have huge data processing capabilities and require less battery power.
Mobile phones are basically radio systems that use electromagnetic frequencies capable of transmitting voice, data and video. These systems require digital encoding standards so that the mobile phones can connect to base stations, obtain Internet content and communicate with mobile network operators. The 5G network is expected to use very high frequencies in order to provide transmission speeds on the order of 10 gigabits per second (Gbps). This will only be possible with innovative technologies and new encoding and configuration methods, in addition to new equipment in base stations with antennas appropriate for frequencies over 24 Gigahertz (GHz). The current 4G standard uses the 2.6 GHz band. Antennas are installed in base stations and inside large buildings, such as subway stations, shopping malls and airports. Despite the plan to switch to 5G in the 2020s, 4G continues to be implemented in different parts of the world. The first 4G network began operating in Sweden in 2007. In Brazil, implementation began in 2011 and, according to the National Telecommunications Agency (Anatel), all cities with more than 100,000 inhabitants should have 4G by December 2016.
The systems dedicated to mobile phones were transformed in recent years when the devices became small, hand-held computers, with a variety of sensors, tasks and features. In order to operate under 5G, several technologies are being tried and developed by companies, universities and institutes in many countries. This time, unlike with previous systems, Brazil is participating in developing the technology. “Brazilian researchers are contributing to developing the new system,” says engineer Arismar Cerqueira, coordinator of the Wireless and Optical Convergent Access Laboratory (WOCA) of the National Telecommunications Institute (Inatel), in the city of Santa Rita do Sapucai, in southern Minas Gerais State. He leads a group at Inatel contributing to the future 5G, together with teams from the University of Campinas (Unicamp) and Pontifical Catholic University of Rio de Janeiro (PUC-Rio).
Although several companies are giving demonstrations of equipment and software that will become part of 5G technology, final system standardization details will only be approved by the International Telecommunication Union (ITU), the United Nations agency (UN) for information and communication technologies, which is based in Geneva, Switzerland. The entity began preparing in 2012 and, in September 2015, presented a plan to be implemented by 2020 with initial technical parameters and recommendations. For example, it decided that the minimum data rate for the end user should be 10 Gbps. In the current system, 4G, the maximum is 10 Mbps. The density — the number of devices that can operate at the same time in one square kilometer — should be one million. The current density is 100,000. Proposed battery efficiency is 100 times greater than that of 4G. Battery consumption is not restricted to the device itself, but also occurs when connecting to the system.
New proposals for configurations and equipment will begin to be presented in late 2017, and an assessment of the technologies developed will take place at an international conference in 2019. The final specifications will be defined in early 2020. “Like other researchers around the world, we are participating in initiatives that might or might not be incorporated into an advanced communication system such as 5G,” says engineer Michel Daoud Yacoub, coordinator of the Wireless Technology Laboratory (WissTek) of the Unicamp School of Electrical and Computer Engineering (FEEC). “Researchers are free to delve into topics that may be of interest to the system,” says Cerqueira, from Inatel, the institution that coordinates the largest Brazilian 5G project – a R$20 million investment funded by the Fund for the Technological Development of Telecommunications (Funttel). The Institute is maintained by the National Institute of Telecommunications Foundation (Finatel) and 55% of revenues come from services and development provided to hundreds of companies. In addition to Unicamp and PUC-Rio, companies such as Ericsson, an equipment manufacturer, and TIM and Algar, mobile telephone operators, also participate.
Capture and distribute
The Inatel group developed and filed four patent applications in Brazil for 5G technology: two antennas, one amplifier and one radio-frequency converter. A total of 90 people at the institute a are developing the new technology for this project and for four smaller projects: 15 employees with PhDs, 20 with master’s degrees, and 55 other engineers. The antennas they are developing are to be used indoors in places like shopping malls and subways. Their purpose is to capture the mobile phone signals and distribute them to the network. “It’s a challenge because, in addition to 5G transmission, they must include third and fourth generation legacy systems that will work in tandem with the newer system for a while,” says Cerqueira.
Another feature of the new system, due to the electromagnetic signal transmission and reception frequencies, will be the use of more antennas — smaller than the current ones — which will have to be installed by mobile network operators, scattered throughout cities and along highways. Inatel’s indoor antenna project was led by telecommunications engineer Igor Feliciano da Costa, who developed the device while pursuing his PhD at the Technical University of Denmark (DTU). The work won second place at Momag 2016, the meeting of the Brazilian Society of Microwave and Opto-electronics (SBMO) and the Brazilian Society of Electromagnetism (SBMag). Now, Inatel researchers are working on the development of a modem with a USB port for laptops and a radio-frequency amplifier for use in base stations that operate alongside the mobile network antennas installed in high places, such as on the roofs of buildings. There are thousands of base stations just in São Paulo that connect each mobile phone to the network as it moves throughout the city.
At Unicamp, studies are being developed in four fields. “The first is emerging applications, such as the Internet of Things. We are analyzing three new digital transmission processes because the conventional techniques are inadequate given the requirements of these applications,” says Yacoub. Researchers are also studying the staggering increase in Internet traffic, principally through YouTube and Netflix applications. They are investigating the possibility of using systems that employ a large number of additional antennas to support ever denser regions in terms of data exchange demand.
WissTek, at FEEC, is also targeting device-to-device (D2D) systems that do not communicate through a base station. This type of system would allow two 5G mobile telephones to communicate directly, which would facilitate communication and save battery power. The fourth item being studied at Unicamp is channel modeling that maps wave propagation phenomena in urban or suburban environments full of obstacles, such as buildings and hills. The researchers used mathematical tools to attempt to work around these obstacles so that the system has the most appropriate frequencies for transmission.
INATEL
5G network equipment will be smaller and use less electricityINATEL“The challenge of 5G is to accommodate high data traffic and a greater number of users. Data transmission rates must be high, and at the same time latency must be better,” predicts Yacoub. Latency is the time it takes to load a video, for example. In 5G, the required latency is 1 millisecond (ms), compared to 10 ms for 4G.
“The biggest problem with 4G is the constant need to recharge the mobile phone battery. This use of the system is very intense, using many radio resources (transmission and reception),” explains Rodrigo de Lamare of the Center for Telecommunications Studies (CETUC) at PUC-Rio. He coordinates a group whose objective is to study encoding for access points, located in the base stations. “These points will have to be denser, with antennas capable of communicating with mobile phones and many household and workplace sensors, especially in intelligent buildings with technology to access the devices used in the Internet of Things, such as lighting and air-conditioning,” says Lamare.
Another line of research is related to simplifying the devices in the radio system that supports the mobile phone network. “Amplifiers, wi-fi routers and other equipment need to be smaller and cost less so that they can even be shared by multiple operators,” he says. Today, every company has to have one of these devices in every base station. If just one can be shared by all, the cost will fall significantly and will reduce energy costs.
Several examples of experiments around the world have already been published and are in development. In Finland, the University of Oulu carried out an experiment using 5G technology to control a robot for industrial use in September 2016. The same university was selected to demonstrate 5G technology during the 2018 Winter Olympic Games in Pyeongchang, South Korea. The project will be financed by the European Union and will involve collaboration with the South Korean government. In the United States, researcher Theodore Rappaport of New York University made a program available on the website of his group, NYU Wireless, in March 2016. It is a simulator for 5G telephone developers with base station infrastructure. Other researchers have access to the results of four years of measurements made on radio frequencies to be used in 5G technology.
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