Satellite communication Access
by barkkathulla[ Edit ] 2012-09-20 16:48:52
<font color=#000066>SATELLITE MULTIPLE ACCESS TECHNIQUES</font>
FDMA (FREQUENCY DIVISION MULTIPLE ACCESS)
In FDMA, all usrs share the satellite at the same time.but each transmits in its own unique frequency band.
ï No of user in frequency
ï 900mhz -930mhz
ï 1200 users
TDMA (TIME DIVISIONAL MULTIPLE ACCESS)
In TDMA, only one user transmit at any time and that user can use the entire available bandwidth. so the instantaneous data rate is proportional to the available bandwidth.
ï Digital communication
ï IMIE(international mobile equipment no )
ï SIM ( subscriber identity module)
ï Low security
CDMA COMMUNICATION (CODE DIVISION MULTIPLE ACCESS)
In CDMA, many earth stations simultaneously transmit orthogonally coded spread-spectrum signals that occupy the same frequency band.
A CDMA communication system is disclosed comprising at least one base station and at least one mobile station having means for controlling their transmitted powers, the mobile station including means for measuring its transmitted power as well as means for controlling its transmitted power in the event of a malfunction.
ï ESI- equipment serial identity
ï Data loss can be avoided
ï ISP- internet service provider
ï If tower is long distance it can absorbed the signals.
ï We cannot change the sim cards by our convenient.
ï E.g. reliance,tata
