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WLAN, or Wireless Local Area Network, is a wireless communication technology that combines the benefits of wireless communication with computer networking. It uses wireless channels as the transmission medium to enable short-range wireless network communication. The foundation of WLAN is traditional wired LAN, and it enables wireless connectivity through devices such as wireless access points (APs), wireless bridges, and wireless network cards, all built on top of a wired network infrastructure.
WLAN offers several advantages, including ease of installation, scalability, maintenance, mobility, high speed, and the use of open frequency bands. Both enterprises and individuals have recognized the benefits of WLAN in wireless data transmission. It can be seamlessly integrated with Ethernet, which is widely used today, allowing users to access the internet, conduct online transactions, and work remotely. As the application scope of WLAN expands, new requirements for speed, security, QoS, and roaming have emerged. In addition to data transmission, there is growing interest in applying WLAN to wireless voice communications. The following sections will explore the current trends and developments in WLAN technology.
**Rate**
Bandwidth is the foundation of any wireless network. Most commonly used WLAN devices operate under the 802.11b standard, offering a maximum wireless rate of 11 Mbps. However, due to overhead from wireless frame headers and access control mechanisms, the actual throughput experienced by users is typically around half of the theoretical maximum. Devices based on 802.11a and 802.11g offer higher speeds of 54 Mbps, but their real-world throughput is approximately 30 Mbps. The IEEE 802.11n working group is developing a faster standard that could support rates up to 108 or 320 Mbps, while also improving management efficiency and overall performance.
**Security**
Since WLAN transmits data over wireless signals, it is inherently more vulnerable than wired networks. Any device within range can potentially intercept the signal, making security a major concern. While technologies like SSID, ACL, and WEP are widely used, they have known limitations. The IEEE 802.11i standard was introduced to enhance WLAN security. It includes two key components: Wi-Fi Protected Access (WPA) and Robust Security Network (RSN). WPA improves upon WEP using the Temporal Key Integrity Protocol (TKIP), which provides dynamic key updates. RSN, on the other hand, utilizes AES encryption and the 802.1x protocol to ensure stronger authentication and secure data transmission.
**QoS**
One of the main challenges in WLAN is supporting quality of service (QoS) for applications like VoIP and video streaming, which require low latency, consistent bandwidth, and minimal packet loss. To address this, the IEEE established the 802.11e task group, which enhances the MAC layer to support differentiated services. Two key mechanisms—Enhanced Distributed Channel Access (EDCA) and Hybrid Coordination Function (HCF)—were introduced. EDCA prioritizes traffic based on different service types, while HCF allocates dedicated time slots for specific data streams, ensuring better QoS control.
**Roaming**
As users move between access points, seamless roaming is essential. The IEEE 802.11f protocol defines the Inter-Access Point Protocol (IAPP), which allows mobile devices to switch between APs without losing connectivity. This ensures continuous service and supports the growing demand for mobility in wireless networks.
**Voice Application**
The integration of Voice over IP (VoIP) with WLAN has led to the development of Voice over WLAN (VoWLAN). Wi-Fi-enabled phones are now available, though they are currently limited to enterprise environments. Future developments may see them used in home and mobile settings. Some manufacturers are also working on dual-mode devices that combine WLAN with GSM or CDMA, enabling voice services across different networks.
**WiMAX: The New Wireless Metropolitan Area Network**
WiMAX, or Worldwide Interoperability for Microwave Access, is a wireless broadband technology designed for metropolitan area networks. It is based on the IEEE 802.16 standard, which covers a wide range of frequencies, including both line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. WiMAX combines the mobility of Wi-Fi with the high bandwidth and QoS capabilities of traditional broadband technologies like DSL and CableModem.
One of its key advantages is the ability to support non-line-of-sight transmission, making it ideal for urban and rural areas where traditional wired connections are difficult to deploy. WiMAX also offers flexible deployment options, allowing operators to adjust channel bandwidth based on available spectrum. It supports advanced QoS features, making it suitable for voice, video, and mission-critical applications.
WiMAX is being widely adopted in various sectors, including enterprise, residential, and remote communication. It can serve as an alternative to DSL and cable in areas where these services are not feasible. The WiMAX Forum plays a crucial role in ensuring interoperability and certification of devices, similar to how Wi-Fi operates under the IEEE 802.11 standard.
In conclusion, both WLAN and WiMAX represent significant advancements in wireless communication. They are continuously evolving to meet the growing demands for speed, security, and mobility, and are expected to play a vital role in the future of wireless networking.