Thursday, June 18, 2015

Wireless Networks cont'd

Previous: Wireless LANs

3)Wireless WANs
The radio n/w used for cellular telephones is an example of a low bandwidth wireless system.This system has gone through 3 generations-
1)First generation-analog & voice only
2)Second generation-digital & for voice only
3)Third generation-digital & is for both voice & data

Wireless LANs can operate at 50 Mbps.
Cellular system operate at about 1 Mbps.
Wireless internet service is often called local multipoint distribution service eg.mts
Almost all wireless n/ws hook up to the wired n/w at some point to provide access to files,databases & the internet.
Many n/ws exist in the world,often with different h/w & s/w.
The fulfillment of this desire requires that different & frequently incompatible n/ws be connected by means of machines called gateways to make the connection and provide the necessary translation, both in terms of h/w and s/w called internetwork or internet.
If the system within the gray area contains only routers it is a subnet.
If it contains both routers & hosts it is a WAN.
As an analogy,the telephone system consists of telephone switching offices connected to one another by high speed lines & to houses & business by low speed lines.
These lines and equipment,owned and managed by telephone company form the subnet of telephone system.

Next:Network Connecting Devices