How much do you know about the “wireless” mechanism in wireless communications? (Part 1)
Communication technology is still advancing, especially through wireless technologies such as 5G, the Internet of Things, and digitization.
It is no exaggeration to say that the advancement of communication technology is a symbol of the progress of human society. The "communications" people refer to today specifically refer to communications (telecommunications) that use electricity - since telecommunications was invented more than 250 years ago, it has experienced various technological innovations. Today, the basics of life in modern society such as mobile phones, Wi-Fi, radio, transportation IC cards, and television broadcasts are completely inseparable from the support of communication technology. Moreover, the progress of communication technology continues - through 5G, the Internet of Things, etc. Wireless technology, through the development of digital technology.
Telecommunications has become part of society's infrastructure, but due to its diverse specifications and uses, it is difficult for people to fully grasp it. This article attempts to focus on wireless communication. It is aimed at beginners who need wireless knowledge and those who are interested in communication itself. While introducing the company's communication-related components and modules, it also provides the basic information needed to understand wireless communication, including technology. aspects of knowledge. The article will be published in two parts, with the content distributed as follows:
Table of contents
01. Introduction: History and Evolution of Wireless Communications
02. What is wireless communication?
03. Application examples of wireless communication
04. Basic components of wireless communication systems
05. Wireless communication methods
06. Data transmission direction
07. What is a communication protocol?
08. Appendix: Introduction to radio waves and their frequencies
History and Evolution of Wireless Communications
The history of wireless communications dates back to 1864. British theoretical physicist JC Maxwell predicted the existence of radio waves in his paper "Dynamic Theory of Electromagnetic Fields". However, it was so difficult to understand at the time that no one could understand its content.
The person who proved the existence of radio waves was the German HR Hertz. In 1888, Hertz successfully created artificial radio waves. He revealed that radio waves have the same properties as light in terms of reflection, refraction, diffraction and interference. In addition, Italian inventor G.Marconi was the first to put wireless telecommunications using radio waves into practical application. In 1896, about 60 years after Morse successfully achieved wired communication using wires in 1837, Marconi successfully achieved wireless communication of about 3km using Morse code in the UK. Additionally, radio communications successfully crossed the Strait of Dover in 1899 and the Atlantic Ocean in 1901 (picture below).
Development of wireless communications and personalization of communication distances
People naturally thought of using wireless communications on ships to achieve previously unachievable mobile communications from land to sea, from sea to land, and from sea to sea. In 1897, people implemented this experiment.
An event of great historical significance during this dawn of wireless communications was the sinking of the Titanic in 1912. As we all know, the ship collided with an iceberg and sank on its maiden voyage, but at that time it sent a distress signal "SOS" in Morse code through radio communication. The Carpathia sailing nearby received the distress signal and rushed to the scene immediately, rescuing 711 people.
In the early 1900s, radio broadcasts and television broadcasts began to use methods other than Morse code to wirelessly transmit audio and video. Radio broadcasting was first implemented in the United States in 1906, and the Tokyo Broadcasting Corporation (NHK) was opened in Japan in 1925.
It was during this same period that black and white television was invented, and television broadcasting began around 1950. In addition, color TVs appeared three years after the invention of black-and-white TVs. Developed countries introduced color TV broadcasting in the 1960s, laying the foundation for TV broadcasting. Thereafter, until the early 2000s, television broadcasting was analogue, but since the second half of 2010, the world has been gradually transitioning to digital.
Nowadays, wireless communications are penetrating into our lives in other areas besides broadcasting. With the spread of wireless dedicated to specific services such as police, firefighting, disaster prevention, railways, and airports (business wireless), as well as the spread of mobile phones as a representative of personal wireless communications, the scope of its use has expanded significantly. Around 1993, mobile phones began to be digitized in various countries (second generation: 2G), and then began to rapidly develop in the direction of faster speeds and larger capacities. 4G appeared overseas in Japan in 2009 and in Japan in 2012, and its level has improved significantly. As we enter the 2020s, 5G is already in the popularization stage (picture below), and discussions on the next generation concept of Beyond 5G/6G are making progress.
Data transmission speed increases with the development of mobile phones
So, what is "wireless communication"?
What is wireless communication?
In one sentence, wireless communications, which use electromagnetic waves (radio waves), magnetic fields, and electric fields instead of wires and cables, and optical communications, which use light, are wireless communications.
Among them, telecommunications using radio waves can carry out long-distance communications of more than kilometers and can transmit large amounts of data (information). Therefore, radio waves are used in almost all wireless communication systems. This series also focuses mainly on "radio waves" for explanation.
Wireless communication systems using radio waves use space as a transmission path (or communication path) and are configured to transmit data carried on radio waves sent from a transmitter to a receiver as signals (see figure below).
Composition of simple model in wireless communication system
Here, we often refer to "data", "information" and "signals". Their "differences" are as follows:
・Data: a collection of marks and symbols that represent facts;
・Information: Data such as sounds, text, and images that humans can understand and can be used to make judgments about things and take actions;
・Signal: Data or information transmitted over time through a transmission path (communication path) such as space or cable.
For the sake of convenience, we will no longer distinguish between “information” and “data” in the following text. Unless otherwise specified, the term “data” will be used uniformly.
Application examples of wireless communications
Wireless communications are used in many fields, and their uses and types are very wide. The following table summarizes the broad classifications of wireless communications that use air waves to transmit data and the representative uses of each classification.
In recent years, the development of wireless communications has exceeded the boundaries of these classifications. For example, satellite mobile communications services that incorporate satellite communications into mobile communications (smartphones are equipped with the function of connecting to satellites) have begun in various countries.
Classification of wireless communications and their respective uses
Here, we briefly compare the terms in the above table:
Basic components and elements of wireless communication systems
The basic model structure of a wireless communication system (as well as a wired communication system) is shown in the figure below, and its constituent elements are explained in the table below. This basic model is further simplified as shown in the above section "What is Wireless Communications".
Basic model composition of communication system
The basic model components of a communication system include:
Methods of wireless communication: modulation and demodulation
Based on the basic model of the communication system introduced in the previous figure, Figure 3 shows the components that describe the basic functions of the wireless communication system - modulation and demodulation.
The composition of wireless communication system
In wireless communications, if you try to send data directly in the form of radio waves, it cannot be transmitted over long distances. For reasons such as this, in order to make it possible to send data over long distances, the transmitter needs to convert the data into a signal that can be transmitted over long distances. ―"Modulation" operation. On the other hand, the receiver needs to perform a "demodulation" operation to restore the modulated signal to its original data.
The table below summarizes representative modulation techniques and examples of their adoption.
Modulation technologies and adoption examples for wireless communications (double-click the chart to enlarge)
There are many terms in the above table that are not generally familiar to people, but here you can think of them as technologies required by some of today's living infrastructures such as mobile phones, radios, and television broadcasts. Detailed information will be explained on other pages in the future.
To be continued: The next article will introduce you to the direction of data transmission, communication protocols, and basic knowledge about radio waves. Stay tuned!
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