What Is a Wireless LAN?
Wireless LAN refers to the technology that enables multiple computers and mobile devices to wirelessly connect on a Local Area Network (LAN).
Similar to wired LAN, it divides data into small packets for transmission and reception. Unlike wired LAN, it utilizes radio waves for communication, eliminating the need for cables.
Uses of Wireless LAN
Wireless LAN finds applications in various scenarios, including:
1. Internet Connectivity
It is utilized in homes, offices, or situations where wired connections are impractical, allowing the use of mobile devices such as smartphones and tablets.
2. Long-Distance Communication
Deployed in environments where laying LAN cables between buildings or in challenging areas is difficult.
3. Mobile Communications
Enables wireless connections between moving objects (trains, cars) and ground stations, facilitating systems for information gathering, commands, and instructions.
4. Public Wireless LAN
Utilized in public facilities, commercial spaces, parks, etc., offering public wireless LAN access. This allows internet connectivity and email access on the go.
Principles of Wireless LAN
Wireless LAN operates by using frequency bands specified in the 802.11 standard, such as 2.4GHz and 5GHz. The data transmitted by the wireless LAN chipset is amplified by antennas for long-distance communication. However, sending data as radio waves without modulation would make it accessible to anyone, posing a security risk. To address this, transmitted data is modulated during signal transmission and then propagated as radio waves, ensuring secure data communication that is less prone to interception.
Due to potential interference from surrounding noise and signals, error correction techniques such as Forward Error Correction (FEC) are often employed in wireless communication to detect and correct errors.
Wireless LAN communication modes include “Ad-Hoc Mode” and “Infrastructure Mode.” Ad-Hoc Mode allows direct communication between multiple devices, while Infrastructure Mode enables communication through an access point.
Types of Wireless LAN
Wireless LAN is defined by the IEEE 802.11 standard of the Institute of Electrical and Electronics Engineers of America, and there are multiple methods using different frequency bands. Typical methods include IEEE802.11b/g/n/ax, which uses the 2.4GHz band, and IEEE802.11a/j/n/ac/ax, which uses the 5GHz band. (n/ax supports both 2.4GHz and 5GHz bands).
Although the 2.4GHz band is resistant to obstacles and can be used outdoors, it has the disadvantage that it is a commonly used frequency band and has many sources of radio wave interference. On the other hand, the 5GHz band has few sources of radio wave interference, but due to its high frequency, it is vulnerable to obstacles, and communication must be temporarily suspended due to the DFS (Dynamic Frequency Selection) function that prioritizes aviation weather radar and air traffic control radar in the same band. may not be possible.
How to Choose Wireless LAN
When selecting industrial wireless LAN for applications demanding high reliability and robustness, attention should be given to:
1. Robustness
Choose robust wireless LAN devices suitable for environments like factories or warehouses, where equipment may be exposed to vibration and shocks.
2. High Reliability
In industrial settings, where equipment failures and radio interference may occur, opt for wireless LAN devices with high reliability.
3. High Data Transfer Capacity
For environments like factories requiring large data transfers, select wireless LAN devices capable of high-speed and high-capacity data transfers, suitable for the specific environment.
4. Availability
Ensure that the chosen wireless LAN devices are available for an extended period, providing long-term stability to the system.
5. Maintenance
Consider the ease of maintenance, especially in situations where quick recovery from equipment failure is crucial to prevent significant losses in production.
6. Scalability
Select wireless LAN devices with high scalability, allowing flexible and adaptable network expansion in different environments.
Other Information on Wireless LAN
1. Advancements in Wireless LAN
Until now, wireless LAN has been considered slower in communication speed compared to wired LAN. However, starting from IEEE802.11n, the speed has begun to improve, surpassing not only wired LAN but achieving communication speeds higher than wired LAN. Wi-Fi, as defined by 802.11, continues to progress, significantly enhancing communication bandwidth as shown below:
- 802.11n – 600Mbps (Wi-Fi 4)
- 802.11ac – 6.9Gbps (Wi-Fi 5)
- 802.11ax – 9.6Gbps (Wi-Fi 6)
The improvement in communication performance in Wi-Fi is not dependent on CPU performance, such as in personal computers. Instead, it is achieved through advancements in various mechanisms, including:
OFDMA (Orthogonal Frequency Division Multiple Access)
Traditional modulation used OFDM, where uniform subcarriers were assigned individually, leading to inefficiencies in networks with diverse communications. OFDMA allocates resources per user, assigning the most efficient subcarrier to each user, contributing to better propagation efficiency. This individual assignment of subcarriers makes bandwidth usage more efficient, reducing latency.
QAM (Quadrature Amplitude Modulation)
QAM is a digital modulation method that varies the amplitude and modulation of the carrier to transmit signals. While 802.11n used 64QAM, and it was believed at the time that more complex modulation wouldn’t be necessary, 802.11ac adopted 256QAM. With further advancements in 802.11ax, 1024QAM has been introduced. This enhances the data amount sent per transmission from 64QAM (6 bits) to 1024QAM (10 bits), becoming a crucial factor in improving communication bandwidth in Wi-Fi 6. Additional updates include MU-MIMO, power consumption reduction, and enhanced security features like WPA3, among others.
2. Devices Used in Wireless LAN
Wireless LAN Router
A wireless LAN router is a device used for connecting terminals utilizing a wireless LAN and connecting them to a wired LAN. It is mainly responsible for internet connection and network configuration.
Wireless LAN Access Point (AP)
Serving as a base station for connecting to a wireless LAN router, the wireless LAN access point (AP) plays the role of a base station for wireless LAN connections. APs have the functionality to connect wired and wireless LANs. Some products integrate AP functionality into wireless LAN routers, allowing versatile usage. When using wireless LAN in environments like factories or warehouses, where signals need to be transmitted over a wide range, products with higher transmission power and faster communication speeds capable of simultaneous connections to numerous devices are essential.
Wireless LAN Client
A wireless LAN client is a device connected to a wireless AP, enabling the wirelessization of a wired network. By establishing a relationship where a wireless LAN AP serves as the parent and a wireless LAN client as the child, one route becomes wireless.
Additionally, connecting a wireless LAN client to devices without built-in wireless functionality allows for easy wireless integration. While certain limitations may prevent straightforward wirelessization, industrial wireless LAN clients often feature functions to overcome such restrictions. These devices are indispensable for utilizing wireless LAN comfortably, requiring appropriate selection, installation, and configuration.