ece401 lecture 2
TRANSCRIPT
8/3/2019 Ece401 Lecture 2
http://slidepdf.com/reader/full/ece401-lecture-2 2/9
No physical link or wire
Radio Communication
Examples of Wireless Communication
Systems used in everyday life areGarbage door opener, remote controllersfor home entertainment equipment,cordless telephones, walkie-talkie, pagersand cellular telephones.
8/3/2019 Ece401 Lecture 2
http://slidepdf.com/reader/full/ece401-lecture-2 3/9
Mobile: Any radio terminal that could bemoved during operation and is attachedto a high moving (speed) mobile platform
e.g. a cellular telephone in a fast movingvehicle.
Subscriber: A user who pays subscriptioncharges for using a mobile
communication system.
Roamer: A mobile station which operatesin a service area other than that from
which the service has been subscribed.
8/3/2019 Ece401 Lecture 2
http://slidepdf.com/reader/full/ece401-lecture-2 4/9
Base Station: A fixed station in a mobileradio system for radio communicationwith mobile stations. They are located at
the center or on the edge of a coveragearea (or region) and consist of radiochannels and transmitter and receiverantennas mounted on a tower
Forward Channel: Radio channel used forthe transmission of information from thebase station to mobile.
8/3/2019 Ece401 Lecture 2
http://slidepdf.com/reader/full/ece401-lecture-2 5/9
Reverse Channel: Radio channel used forthe transmission of information from themobile to base station.
Control Channel: Radio channels used forthe transmission of call setup, callrequest, call initiation, and other controlpurposes.
Handoff: The process of transferring amobile station from one channel or basestation to another.
8/3/2019 Ece401 Lecture 2
http://slidepdf.com/reader/full/ece401-lecture-2 6/9
Mobile Switching Center (MSC): Switchingcenter which coordinates the routing of calls in a large service area. In a cellular
radio system, the MSC connects the basestations and the mobiles to the PSTN orother network. An MSC is also calledMobile Telephone Switching
Office(MTSO). Transceiver: A device which is capable of
simultaneously transmitting andreceiving radio signals.
8/3/2019 Ece401 Lecture 2
http://slidepdf.com/reader/full/ece401-lecture-2 7/9
It may be classified in three categories: Simplex Systems e.g. pager.
Half Duplex system e.g. Walkie-Talkie, Radio Systems.
Full Duplex system e.g. Telephones
Simplex Systems: Paging systems, in whichmessages are received but notacknowledged, are simplex systems.
Half Duplex Systems: Half duplex radio
systems allow two-way communication, butuse the same radio channel for bothtransmission and reception. But at any time,a user can only transmit or receiveinformation.
8/3/2019 Ece401 Lecture 2
http://slidepdf.com/reader/full/ece401-lecture-2 8/9
The fundamentals features of this systemare: Push-to-talk Release-to-listen
Full Duplex Systems: Such systemsallows simultaneous radio transmissionand reception between a subscriber anda base station, by providing twosimultaneous but separate channels(Frequency division duplexing or FDD) oradjacent time slots in a single radiochannel (Time division duplexing or TDD)
for communication to and from the user..
8/3/2019 Ece401 Lecture 2
http://slidepdf.com/reader/full/ece401-lecture-2 9/9
Frequency Division Duplexing or FDD: FDDprovides simultaneous radio transmissionchannels for the subscriber and the base
station so that they both may constantlytransmit by simultaneously receiving signalfrom one another.
Time Division Duplexing or TDD: In this type
a single radio channel is shared in such away with respect to time so that a portion of time is used to transmit from the basestation to the mobile and the remaining time
is used to transmit from the mobile to thebase station.