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physical&logical channels

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Aasem_sadek

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can anyone plz tell me the meaning & difference between logical &physical channels in gsm or any other wireless system?
 

Physical channel means that the actual channel that allocated in physical layer, performing some kind of function.

Logical channel usually refers to higher layer functionality. The content of logical channel is mapped to different physical channel.

In book "WCDMA for UMTS" by Harri Holma and Antti Toskala has good description of the definitions.
(You should be able to find the e-book on EBOOK forum.)
 

thx alot..i'll try to look for the definitions with more examples...but if u have examples or more clear defintions i'll appreciate that..but thank u anyways:D
 

Physical and logical channels are different.

Physical chanels in GSM are Control Channels , traffic channels etc. in other words they are time slots defined by time Slot no.( eg TS4) and frequecy (UL and DL).

Logical channels are SCH, FCH ,BCCH, SACCH, FACCH, RACH, AGCH, etc.
These channels carry specific information.For example BCCH is Broadcast control Channel which broadcasts the information about the System.

Sice GSM is a TDM system these logical channels are multiplexed onto physical channels and then transmitted over the air interface.
 

the main defference in these two is simple.
The physical channel is the channel you get to transmit you data in the air (i.e. The frequency & timeslot).
but the logical channel is the channel which is mapped onto ur physical channel. these logical channel are divided in two parts: Control & Traffic. these are the basic channels... there are some division in the also...
its better to read the GSM Book to get knowledge abt this...
there is post in this section..



check this link...

cheers....
 

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