Page 21 - DCAP311_DCAP607_WIRELESS_NETWORKS

Unit 1: Introduction to Wireless Networks

1.4.4 Wireless MANs Notes

Wireless MANs offer connections between buildings and users within a city or campus area
through several system configurations. In most cases, the wireless MAN beams RF or infrared
light from one point to another using directive antennae.
WirelessMAN® is a family of wireless networking standards created by the Institute of Electrical
and Electronics Engineers (IEEE). The standards, officially known as IEEE 802.16, complement
other wireless technologies like Wi-Fi®. The 802.16 group of standards are meant for use in large,
city-sized wireless networks that can deliver broadband Internet access and compete against
wired technologies like Digital Subscriber Line (DSL) and cable modems. The WirelessMAN®
standards form the basis for WiMAX® and several other wireless broadband technologies.
The organization which created the 802.16 standard, the IEEE, was also responsible for ratifying
the popular Bluetooth® and Wi-Fi® wireless standards. Each of these standards enables wireless
networks to be built on different scales. Bluetooth®, for example, allows very short-range
personal area networks (PANs). Wi-Fi® popularized whole-house wireless Local Area Networks
(LANs), and WirelessMAN® is designed for larger Metropolitan Area Networks (MANs) meant
to cover entire cities or geographical areas. In many cases, these different types of networks
can be complementary. A LAN using Wi-Fi®, for example, could be connected to the Internet
through a MAN using 802.16.

Point-to-Point Systems

A point-to-point solution uses RF or infrared signals that utilize either semidirectional or highly
directional antennae to extend range across metropolitan areas, such as college campuses and
cities. Range can be as high as 30 miles for RF systems using highly directional antennae. Figure
1.4 illustrates a point-to-point wireless MAN system.
Figure 1.4: Point-to-Point Wireless MAN Directly Connects Two Points in the Network

Point-to-Point

Source: http://etutorials.org/Networking/wn/Chapter+6.+Wireless+MANs+Networks+for+Connecting+Buildings+and+
Remote+Areas/Wireless+MAN+Systems/
A medical center, for example, can use a point-to-point wireless MAN to provide a communications
link between the main hospital and a remote clinic within the same city. This resulting system,
however, does not provide as much flexibility as point-to-multipoint solutions. However, if there
is a need to connect only a couple sites, the cost of implementing a point-to-point system is less
compared to a point-to-multipoint system.

Point-to-Multipoint System

A typical point-to-multipoint link (see Figure 6-6) utilizes a centralized omnidirectional antenna
that provides a single transceiver point for tying together multiple remote stations. For example,
a building within the center of a city can host the omnidirectional antenna, and other nearby
metropolitan-area buildings can point directional antennae at the centralized location. The
central transceiver receives and retransmits the signals.
A strong advantage of the point-to-multipoint wireless MAN is that it makes the addition of new
connections easy. In fact, this approach can be less expensive compared to point-to-point systems
when there are multiple sites to interconnect or connect to a central location. For example, a
company headquarters having many remote warehouses and manufacturing plants within the
same city or rural area would benefit from a point-to-multipoint system.

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