Verifying Traffic Throughput of Point-to-Point Wireless Links
Wireless Links
Transcript of Wireless Links
-
8/4/2019 Wireless Links
1/13
Summer training report on
WIRELESS SYSTEMS
Training undergone at:
Reliance communications
-
8/4/2019 Wireless Links
2/13
Structure of a typical wireless
system
-
8/4/2019 Wireless Links
3/13
Major elements of the system:
Wireless base stations
The switch
The base station controller
Home location register
-
8/4/2019 Wireless Links
4/13
Wireless base stationsProvides radio connectionbetween the mobile users and theswitch.One wireless system may have100s of base stations.
Many base stations implyunbroken coverage and sufficientcapacity to handle potentialcustomers.
-
8/4/2019 Wireless Links
5/13
The switch Each call involves joining a circuit leading to one
customer (usually on the radio side of the system)
and a circuit leading to another person (usuallyout in the Public Switched Telephone Network(PSTN).
The device that makes the actual physical
connection is called the switch. The switch is also responsible for storing billing
records, interpreting dialled numbers, routingcalls, and implementing all calling features.
-
8/4/2019 Wireless Links
6/13
The base station controller The Base Station Controller (BSC) interfaces the
Switch and the base stations
Compresses speech signals for more efficienttransmission over the scarce radio spectrum
Controls the base stations and implements thehandoff of calls from one base station to another as
users drive across the system
-
8/4/2019 Wireless Links
7/13
Home location register
The HLR (Home Location Register) is the officialdatabase of all customers on a wireless system.
It can be part of the switch, or held in a server at a
central location where multiple switches caninterrogate it.
Information held in the HLR:
current account status/validity
phones technical parameters
whether the phone is presently turned on, and if so,the identity of switch which is presently serving the
phone.
-
8/4/2019 Wireless Links
8/13
Delivering an incoming wireless call
-
8/4/2019 Wireless Links
9/13
Managing handoff
As a mobile travels through the service area, it passesfrom the coverage zone of one base station into thecoverage of another.
Signal strength measurements by the mobile or thebase station trigger the BSC and switch to hand offthe call from base station to base station, avoidingdropped calls and interference.
Each wireless technology uses its own methods toimplement the handoffs. CDMA can even simulcastto the mobile from multiple base stations to reducefading effects (this is called soft handoff).
-
8/4/2019 Wireless Links
10/13
Multiple Access Multiple Access is the simultaneous use of a
communications system by more than one user
Each users signal must be kept uniquelydistinguishable from other users signals, to allowprivate communications on demand
Users can be separated in many ways:
physically: on separate wires by arbitrarily defined channels established in
frequency, time, or any other variable imaginable
-
8/4/2019 Wireless Links
11/13
Multiple access
-
8/4/2019 Wireless Links
12/13
Wireless multiple access
methods
-
8/4/2019 Wireless Links
13/13
Thank you