If you watch closely on campus, you will see more and more students use portable notebooks to browse on the Internet, register courses or check e-mail in public areas like the Library, Student Canteen, the 4/F Mall and Covered Terrace. One may begin to ask how these notebooks get connected to the network without the fuss of wiring them to specific network points. The answer is the Wireless Local Area Network (WLAN). To be exact, it is a flexible data communication system using electro-magnetic waves (radio or infrared) to transmit and receive data over the air. It can be integrated with the existing wired network seamlessly and easily so that users can enjoy network computing without the physical constraint of looking for a network port to plug in.

Advantages of WLAN

Comparing with the traditional wired networks, WLAN has the following advantages:

1. Freedom of Mobility
   WLAN users can access to real-time information in most areas inside the campus. This mobility and convenience are not possible or very hard to achieve with wired networks.

2. Fast and Easy Installation
   Installing WLAN is comparatively fast and easy, and we can eliminate the need to lay cables through walls and ceilings.

3. Installation Flexibility and Scalability
   Using wireless technology, we can extend the campus network to those areas which are hard for cables to reach.

1. High initial cost
   The initial cost of wireless devices is much higher than that of the traditional network devices. For example, a WLAN card costs 3 to 10 times more than that of a wired LAN card.

2. Limited bandwidth
   We use wired LAN for speed and WLAN for convenience. Typically, a WLAN Access Point (AP) of IEEE 802.11b standard can provide a maximum data rate of shared 11Mbps to its clients while the traditional Ethernet can provide 10 or 100 Mbps to each client. Therefore, more APs have to be installed in the same location to increase the throughput. Maximum of 3 APs operating at different channels can provide up to 33 Mbps aggregate bandwidth.

   Due to the limited bandwidth provided and the fact that many users share the same bandwidth, WLAN is not suitable for bandwidth intensive applications such as multimedia and video applications.

3. Limited coverage
   In our environment, the coverage of a single Access Point (AP) is about 10 - 50 meters in radius in a closed office depending on the barriers and partitions used. More APs have to be installed to cover larger area.