Wireless networks can be classified into four specific groups according to the area of application and the signal range [1-3]: Wireless Personal-Area Networks (WPAN), Wireless Local-Area Networks (WLANs), Wireless Metropolitan-Area Networks (WMAN), and Wireless Wide-Area Networks (WWANs). Figure 1 illustrates these four categories.

In addition, wireless networks can be also divided into two broad segments: short-range and long-range. Short-range wireless pertains to networks that are confined to a limited area. This applies to local area networks (LANs), such as corporate buildings, school campuses, manufacturing plants or homes, as well as to personal area networks (PANs) where portable computers within close proximity to one another need to communicate. These networks typically operate over unlicensed spectrum reserved for industrial, scientific and medical (ISM) usage. The available frequencies differ from country to country. The most common frequency bands are at 2.4 GHz and at 5 GHz, which are available across most of the globe. The availability of these frequencies allows users to operate wireless networks without obtaining a license, and without charge. As a license is not required for use, this has facilitated the expansion of such networks.

In long-range networks, connectivity is typically provided by companies that sell the wireless connectivity as a service. These networks span large areas such as a metropolitan area (WMAN), a state or province, or an entire country. The goal of long-range networks is to provide wireless coverage globally. The most common long-range network is wireless wide area network (WWAN). When true global coverage is required, satellite networks are also available.