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Wireless Networks

Notes
Figure 1.5: Point-to-Multipoint Wireless MAN Interconnects Users Through a Common,
Centralized Transceiver

Point-to-Multipoint

Source: http://etutorials.org/Networking/wn/Chapter+6.+Wireless+MANs+Networks+for+Connecting+Buildings+and+
Remote+Areas/Wireless+MAN+Systems/

Packet Radio Systems

A packet radio system (see Figure 1.6) utilizes special wireless routers that forward data
contained within packets to the destination. Each user has a packet radio NIC that transmits
data to the nearest wireless router. This router then retransmits the data to the next router. This
hopping from router to router occurs until the packet reaches the destination. This mesh type
networking is not new. Amateur Ham radio operators have used it for decades, and companies
such as Metricom have been deploying these types of systems in cities for nearly 10 years.
Figure 1.6: Packet Radio System Hops Data Packets from the Source to Destination

Packet Radio Routers

Possible
Route

Source Destination

Source: http://etutorials.org/Networking/wn/Chapter+6.+Wireless+MANs+Networks+for+Connecting+Buildings+and
+Remote+Areas/Wireless+MAN+Systems/
A city government might want to deploy a packet radio system to offer wireless connectivity
for supporting applications through the entire city area. The installation of routers in strategic
places through the city provides the necessary infrastructure. There’s no need for wires for
interconnecting the routers. Each router is capable of receiving and retransmitting?hopping? the
packets to their destination.

!
Caution This form of networking is also survivable. If one router becomes inoperative,
perhaps because of a lightning strike or sabotage, adaptive routing protocols automatically
update routing tables in each router so that data packets will avoid traversing the
inoperative router.

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