What is WLAN? Basics, Advantages, Disadvantages & Applications

Introduction: A Wireless Local Area Network (WLAN) provides a cable free solution for connecting devices over short distances using RF technology. It powers seamless connectivity in homes, businesses and public spaces by utilizing Wi-Fi standards. WLAN technology has transformed how we access information and communicate. In this guide, we'll discuss the basics of WLAN, its standard versions, advantages, disadvantages and key applications.

Let us understand LAN first. LAN means Local Area Network. It is connection of more than one computer using some medium. For the case of LAN this medium will be wired which include Ethernet cable, fiber optic etc. As shown in figure on the left side LAN can be formed using either Ethernet switch or hub or router. All the computers are connected with this switch/Hub/router. This Switch/Hub/router is connected with cable modem provided by ISP(Internet Service Provider). Cable modem connects with ISP's Web server i.e. Internet. The advantages of LAN are many such as speed of data communication (as Ethernet works at 10/100 Mbps), sharing of common resources such as printer, internet connection etc.

Basics of WLAN

WLAN is the short form of Wireless Local Area Network. Unlike LAN, WLAN will have Wireless medium which include radio wave, microwave etc. WLAN compatible Access points or routers are available which converts LAN to become WLAN. So that WLAN devices such as laptop, ipad, tablet can communicate any system in LAN. This wifi router is connected with cable modem on one side using cable. The other side of wifi router is wireless medium, by which it will connect with WLAN devices. There are various PC cards or USB dongles available with WLAN features so that they can be connected with WiFi network or WLAN network. The same is depicted in the figure on right hand side (laptop with wireless adapter card).

wlan

Wireless LAN works on radio frequency of usually around 2.5GHz or 5GHz. There are different flavors in WLAN for different data rates and distance coverage. They are 11a, 11b, 11g, 11n, 11ac, 11ad etc. developed and maintained by IEEE and popularly called as IEEE Standards. These IEEE standards define PHY and MAC layers of 11a/11b/11g/11n/11ac/11ad and upper layers are developed by IETF.

Key Features of WLAN

1. Wireless Connectivity: Devices connect to the network using radio frequency (RF) signals instead of Ethernet cables.
2. Access Points (APs): WLANs rely on access points to broadcast signals and manage connections with devices.
3. Mobility: Users can move freely within the network's coverage area without losing connectivity.
4. Security: Includes protocols like WPA3, WPA2, and older WEP for data encryption and secure communication.
5. Scalability: Can accommodate multiple devices and expand coverage with additional access points.

How WLAN Works

Following points summarize working of WLAN technology.
➨Access Point (AP): Acts as a hub that connects wireless devices to the wired network infrastructure or directly to the internet.
➨Communication Medium: Uses RF signals, typically operating in the 2.4 GHz and 5 GHz frequency bands, with the introduction of the 6 GHz band in Wi-Fi 6E.
➨Network Interface Card (NIC): Devices require a built-in or external NIC to communicate with the access point.
➨Protocols: Operates based on the IEEE 802.11 family of standards (e.g., Wi-Fi 4, 5, 6, 7).

WLAN Standards

WLAN devices are designed and developed as per IEEE standards. There are different versions based on RF frequency, data rate and coverage requirement. They are 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac etc. developed and maintained by IEEE. These IEEE standards define PHY and MAC layers of 11a/11b/11g/11n/11ac/11ax/11be and upper layers are developed by IETF. Wireless LAN works on radio frequency of usually around 2.5GHz or 5GHz.
•  IEEE 802.11a : This wlan standard supports OFDM Physical layer and works at 5 GHz RF center frequency.
•  IEEE 802.11b : This wlan standard supports DSSS/CCK Physical layer.
•  IEEE 802.11g : This wlan standard supports both 11a and 11b and supports RF center frequencies of 2.4 GHz and 5 GHz.
•  IEEE 802.11n (WiFi 4) : This wlan supports OFDM and also MIMO is supported to enhance the data rate. It has 40MHz bandwidth supported.
•  IEEE 802.11ac (WiFi 5): This wlan standard further extends bandwidth and increases MIMO antennas to further increase data rate compare to 11n.
•  IEEE 802.11ax (WiFi 6) : This WLAN standard is successor to IEEE 802.11ac. In addition to higher speed, 802.11ax offers greater coverage range compare to legacy wifi networks such as 802.11a/g/n/ac.
•  IEEE 802.11ax Extended (WiFi 6E) : WiFi 6 extended to the 6 GHz frequency band.
•  IEEE 802.11 be (WiFi 7) : Planned to be published in 2024, data rates of about 46 Gbps. Features include Multi-user MIMO 16 streams, MLO, 320 MHz BW, 4096 QAM etc.
•  IEEE 802.11 bn (WiFi 8) : Planned to be published in 2028, data rates of about 100 Gbps.

WLAN frames & network establishment

In WLAN network, there are two main devices viz. Access point (or router) and Station ( or client) . Both AP and STA should be WLAN standard compliant in order to establish WiFi or WLAN Network.

WLAN frame consists of preamble, PLCP header and Data (MAC PDUs). PLCP Header provides information (e.g. length, modulation, code rate) of DATA Burst. Data MAC PDU is composed of Header, Payload and CRC. Header provides many useful fields. Out of which are Type and Subtype fields. Type differentiates between three main types of frames used in wlan. They are control frame, data frame and management frame. Control frame helps in carrier sense and channel acquisition process to STA. This is done by way of RTS/CTS/ACK sub frames under control frame category. Data frames as the name suggests are used by STA for data communication. Management frames are used to establish the connection and to maintain the connection.

In a WLAN (Wireless Local Area Network), communication between a station (STA) and an access point (AP) involves several frame types categorized under Management, Control, and Data frames. Below are the basic frames exchanged during a typical interaction:
1. Management Frames:
Beacon Frame: Sent periodically by the AP to announce its presence and network parameters, such as SSID and supported rates.
Probe Request Frame: Sent by a station to actively search for available networks.
Probe Response Frame: Sent by the AP in response to a probe request, containing information about the network.
Authentication Frame: Exchanged between the station and AP to authenticate the station.
Association Request Frame: Sent by the station to request association with the AP.
Association Response Frame: Sent by the AP to accept or reject the association request.
2. Control Frames:
RTS (Request to Send): Sent by the station to gain access to the medium before transmitting data.
CTS (Clear to Send): Sent by the AP to grant permission to the station for data transmission.
ACK (Acknowledgment): Sent by the receiving device (AP or STA) to confirm successful receipt of data frames.
3. Data Frames:
Data Frame: Carries the actual data payload from the station to the AP or vice versa.
Null Data Frame: Sent by the station to indicate no data to transmit but to maintain connectivity.
➨These frames form the basis of WLAN communication, ensuring reliable connection establishment, medium access control and data exchange between the station and the AP.

WLAN channels

Works on 2.4 GHz and 5 GHz RF center frequencies with various Channel bandwidths as shown below.
11b channels-Non overlapping (22MHz bandwidth), North America
Channel 1- 2412 MHz
Channel 6- 2437 MHz
Channel 11- 2462 MHz
11b channels-Non overlapping (22MHz bandwidth), Europe (except France and Spain)
Channel 1- 2412 MHz
Channel 7- 2442 MHz
Channel 13- 2472 MHz
11n channels-40MHz bandwidth, occupied bandwidth of 33.75 MHz
Channel 3- 2422 MHz
Channel 11- 2462 MHz
11 g/11n -20 MHz bandwidth, occupied bandwidth of about 16.25 MHz
Channel 1 - 2412 MHz
Channel 5 -2432 MHz
Channel 9 -2452 MHz
Channel 13 -2472 MHz
➨Refer 802.11 WLAN channels for various frequencies allocated for WLAN operation.

Applications of WLAN

• Home Networking: Enables internet access for devices like smart TVs, smartphones, and laptops.
• Enterprise and Office Environments: Provides connectivity for employees and guests in corporate settings.
• Public Spaces: Wi-Fi hotspots in cafes, airports, and hotels for convenient internet access.
• Educational Institutions: Supports e-learning by connecting students and faculty to digital resources.
• Industrial Use: Facilitates communication in warehouses and factories for IoT and automation systems.

Advantages of WLAN

Following are some of the benefits of WLAN technology.
1. Mobility: Allows users to move within the network area while staying connected.
2. Ease of Installation: Requires less cabling compared to traditional LANs.
3. Cost Effective: Reduces infrastructure costs by eliminating the need for extensive wiring.
4. Flexibility: Easily adapts to new devices and changing network needs.
5. Scalability: Can expand by adding more access points.

Disadvantages of WLAN

Following are some of the drawbacks of WLAN technology.
1. Interference: RF signals are susceptible to interference from other devices like microwaves or Bluetooth.
2. Limited Range: Coverage is restricted to the range of the access points.
3. Security Risks: Vulnerable to hacking if not properly secured with encryption protocols.
4. Bandwidth Sharing: Multiple users sharing the same access point can lead to slower speeds.
5. Reliability: Environmental factors like walls and obstacles can affect signal strength.

Conclusion

WLAN offers unmatched convenience and flexibility for wireless networking. While issues like interference and security concerns persist, its ability to provide scalable, cost effective, and mobile connectivity makes it a vital technology in today’s connected world. Understanding its basics and applications ensures better utilization of this transformative wireless technology.

WiFi 6 Resources as per IEEE 802.11ax

WiFi 7 Resources as per IEEE 802.11be

Useful Links to Legacy WLAN Standards

What is?

RF and Wireless Terminologies