WLANs (Wireless Local Area Networks) use radio transmission techniques. This makes them more flexible than their wired equivalents. You will learn in this article how the technology evolved in the past and will develop in the future. Important necessary components and services are described.
WLAN – What is it?
Wireless Local Area Network (WLAN) is a radio transmission technology mainly for mobile in-house communication.
The predecessor of today’s wired Ethernet network was a radio transmission technique that used universities to exchange data between teaching and research facilities. Its name “ALOHA” recalls the initial use in Hawaii.
The “Ethernet” standard of companies DEC, Intel, and Xerox specified a similar, wire-bound technology for the first time. IEEE then specified a manufacturer-independent standard that is still in use today.
The IEEE 802.11 standard for wireless local area networks (WLANs) was developed in the 1990s. The main application area at that time was data communication. The standard includes the radio interface (signal technology of layer 1 according to the OSI model) and the media access procedure (layer 2 functionality according to the OSI model).
Additional documents describe various physical signal transmission techniques with radio signals of different frequencies and bit transmission speeds. The documents are available.here for free download.
The transmission of voice communication was not yet required at these days. The widespread use of WLAN technology and the use of voice transmission via the Internet Protocol (Voice over IP) also led to the need to transmit voice over radio networks (WLANs). Adjustments to the standards followed so that it can be assumed today that the solutions offered on the market can also transmit digitized speech with high quality.
To meet the demands of users for even higher bit rates in WLANs, IEEE specified new interface techniques for bit rates of up to theoretically 7 Gbps. However, some products already support a multiple of this speed.
The frequencies used today are usually 2.4 or 5 GHz. Interfaces with frequencies around 60 GHz are specified in standard IEEE 802.11ad (for very high bit rates, but also very short ranges).
Um ein WLAN zu realisieren, sind unterschiedliche Komponenten erforderlich. Die wichtigsten sind hier angeführt. Je nach Anwendungsfall (z.B. Bürobereich, Firmengelände, öffentlicher Hotspot) sind unterschiedliche Rahmenbedingungen und Anforderungen (Klima, geographische Besonderheiten, Umgebung, Stromversorgung, Funkeigenschaften, Anwendungen, Datenmengen, Sicherheitsvorschriften, etc.) zu beachten.
In order to implement a WLAN, different components are required. The most important ones are listed here. Depending on the application (eg office area, company site, public hotspot), different conditions and requirements (climate, geographical peculiarities, environment, power supply, radio characteristics, applications, amounts of data, safety regulations, etc.) have to be considered.
Clients in wireless LANs are usually mobile data terminals that use radio communication. The radio interface is usually built-in in notebooks or smartphones today. Some special devices require interface converters (“WLAN adapters”) for integration into wireless networks.
WLAN Access Points
Access points are the central points for information exchange between radio terminals. In a professional environment, WLAN access points are connected to the wired local area network (LAN). This allows authorized WLAN users to access required company resources. The access points forwards all kinds of information between communicating WLAN users.
The built-in electronics in the access points and the clients include, among other things, radio modules that emit and receive electromagnetic waves (radio signals) via integrated antennas. External antennas are available for directional transmission of radio signals from many manufacturers on the market. Different antennas are available for special applications.
For larger networks, manufacturers offer their own controllers to manage access points, clients, and other components. The controllers define the services provided by access points for WLAN clients These include e.g. roaming, radio channels or signal strength. Depending on the implementation, they support the entire “logic” of the wireless LAN (frequency channel selection, signal strength setting, media access control, prioritization, roaming, etc.)
Cloud services adopt the tasks of WLAN controllers. Some of the well-known manufacturers of WLAN components have recognized the need and offer these services.
In addition to the elements listed here, management tools for device and user authentication and authorization, monitoring of radio channels and devices or detection and prevention of security violations are required. Also pay attention to required cables (for example, to connect access points to external antennas) and special connectors.
I will describe in additional blog posts what services, features, and functions today´s WLANs support and what you have to consider when choosing your WLAN technology.
Seminars on mobile radio technologies
Slideshare presentation „Elements of Wireless Local Area Networks“
Books on mobile radio technology
Download relevant standards from:
About the Author
Ronald Schlager is an independent trainer, consultant, book author and blogger with the focus on communications technologies and their applications.
Image source: pixabay.com, artist: geralt