Wireless communication implemented while on the move is commonly referred to as mobile communication, and the two are collectively known as wireless mobile communication. The development of modern telecommunications over the past 150 years, from the earliest telegraph, is the result of the hard work of tens of thousands of scientists, engineers, and researchers from all walks of life. Only a few individuals independently responsible for the inventions achieved fame, while most of the pinnacle inventions were the work of many individuals. This section gathers some historical figures who played important roles in the development of radio communication. Wireless communication mainly includes microwave communication and satellite communication. Microwaves are a type of radio wave that typically transmits over distances of only tens of kilometers. However, microwaves have a wide bandwidth and a large communication capacity. Microwave communication requires a microwave relay station every tens of kilometers. Satellite communication uses communication satellites as relay stations to establish microwave communication links between two or more earth stations or between mobile vehicles.
Wi-Fi (Wireless Fidelity/Wireless LAN) is a technology used for data transmission over a wireless local area network. It uses wireless signals to transmit data, allowing devices to connect to the internet or a local area network without a physical connection (such as a cable). The following is a detailed explanation of Wi-Fi wireless communication technology:
#MillionCreatorsPlan#
1. Wi-Fi Basics:
Wi-Fi is a wireless local area network technology based on the IEEE 802.11 standard, typically operating in the 2.4 GHz and 5 GHz frequency bands.
It uses radio frequency signals to transmit data and provides internet connectivity through a wireless access point (usually a router).
Wi-Fi enables communication between wireless devices, such as smartphones, tablets, laptops, and smart home devices.
2. Basic working principle:
Wi-Fi devices (such as laptops and smartphones) include a wireless network adapter that communicates with a wireless router or access point.
Communication is based on radio frequency signals, and data is transmitted between devices through modulation and demodulation.
A wireless router acts as an access point, converting data from a wired internet connection into a wireless signal, enabling devices to connect to the internet.
3. Key features:
Speed and range: Wi-Fi speed and coverage vary depending on the standard and device. The latest Wi-Fi standards, such as 802.11ax, offer higher speeds and greater range.
Security: Wi-Fi networks can protect data security through encryption and password protection to prevent unauthorized access.
Versatile: Wi-Fi can be used for a variety of applications, including web browsing, streaming media, VoIP calls, remote work, and more.
4. Wi-Fi Standards:
Different Wi-Fi standards specify parameters such as communication frequency range, speed, and channel bandwidth. Some common Wi-Fi standards include:
802.11b: The original Wi-Fi standard with a maximum speed of 11 Mbps.
802.11g: Maximum speed is 54 Mbps.
802.11n: Maximum speed up to 600 Mbps.
802.11ac: Maximum speed up to 1 Gbps.
802.11ax: also known as Wi-Fi 6, offers higher speeds and performance.
5. Application areas:
Wi-Fi is widely used in various fields, including homes, businesses, public places, schools, hospitals, hotels, cafes, etc.
It provides users with wireless internet access, supporting various online activities such as browsing web pages, watching videos, and downloading files.
6. Wi-Fi security:
Wi-Fi networks are vulnerable to security threats, including unauthorized access and data breaches. Therefore, network administrators and users need to take security measures such as using strong passwords, enabling encryption, and setting up firewalls.
In summary, Wi-Fi technology has become an important part of modern life and work, providing people with convenient wireless internet access. With continuous technological innovation, Wi-Fi networks have become faster and more reliable, supporting more devices and more applications.
The core technologies of wireless communication include modulation and demodulation technology, encoding and decoding technology, and non-orthogonal multiple access technology.
1. Modulation and Demodulation Techniques: Modulation is the process of converting digital signals into analog signals suitable for transmission over wireless channels, while demodulation is the process of converting received analog signals back into digital signals. Modulation and demodulation techniques include various modulation schemes, such as amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM), as well as corresponding demodulation techniques.
2. Encoding and Decoding Techniques: Encoding techniques are used to compress and correct errors in digital signals to improve the reliability and efficiency of signal transmission. Common encoding techniques include differential coding, Hamming coding, and convolutional coding. Decoding techniques are used to restore the received encoded signal to the original signal.
3. Non-Orthogonal Multiple Access (NOMA): This is a multi-user multiplexing technology designed to achieve multiplexing by utilizing different path losses. By adding a SIC (Continuous Interference Cancellation) device at the receiver and then using channel coding (such as Turbo Code or Low-Density Parity-Check Code (LDPC)), the signals of different users can be distinguished at the receiver. NOMA can use the differences in path losses to superimpose multiple transmitted signals, thereby improving signal gain. It allows all mobile devices within the same cell coverage area to obtain maximum accessible bandwidth, addressing network challenges arising from large-scale interconnection. Another advantage of NOMA is that it does not require knowledge of the CSI (Channel Status Information) of each channel, thus potentially achieving better performance in high-speed mobile scenarios and forming better mobile node backhaul links.
In addition, there are other core technologies for wireless communication, such as channel modeling, channel equalization, diversity, and frequency hopping. These technologies all have a significant impact on the performance and reliability of wireless communication.
