WiFi networks

In the past few years there has been a boom in wireless local access networks (WLANs) following the IEEE-802.11 standards series. Two major factors have driven the development of this type of network:

• They are easy to install and maintain: no cables have to be laid or maintained; and

• Wider use of portable systems, be they notebooks, person digital assistants (PDAs), or wireless telephones.

These two factors make it likely that a large number of wireless local access networks will be installed in the next few years: in libraries and university cafeterias, in airports and various kinds of transportation facilities; in cyber-cafés and telephone booths; in enterprises in which personnel need to be mobile; and in homes and small offices in which there is only one access to the Internet but several users.

Nevertheless, use of the air as the shared vehicle for the exchange of information has one big drawback: the inherent problem of security. For that reason there are three fundamental problems with WLANs: Privacity: The information transmitted through the medium is only supposed to be heard by the person it is intended to reach. Furthermore, sometimes the idea is to keep the names of the senders and recipients of the information secret.

• Authentication: Although access to the physical medium cannot be prevented, access to the wireless network should be restricted to authorized persons (for instance, in a pay-for-services network, to subscribers only). Therefore, it is necessary to identify the users.

• Interference: Electromagnetic noise produced by electrical appliances (for example, microwaves use the 2.4 GHz band, which is common in one of the specifications of WLANS and is also used in wireless telephony systems; adjacent (own or third-party) networks; or even malicious interference or “jamming.”

A new course, entitled “WiFi Networks” is being offered for anyone who would like to be up to date with the details of the technology needed for serious planning, installation, and maintenance of a WLAN. This course will deal in detail with the whole set of IEEE-802.11 standards, covering the physical layer and the media access control layer, and introducing the main security concepts addressed in the IEEE 802.11i standard and in other industry standards, such as WPA and WPA2.

Pablo I. Fierens PhD
Centro Avanzado de Comunicaciones
(Center for Advanced Studies in Communications (CAT))
Buenos Aires Institute of Technology (ITBA)