Communications that occur in the sellular using radio waves. Radio communication utilizing electromagnetic waves in the transmission of data on the air interface. The data is passed over the interface is not always accepted in the Receiver intact, but the data will have a disability.
Likewise for the transmission of the signal (the conversation) in the water interface will have several obstacles that lead to sound/voice can not be accepted by both.
Constraints in the transmission of signals that there may be caused by:
Decrease the signal strength that occurs depending on the distance between the transmitter and Receiver. So that MS is beyond the reach of the BTS.
Time used for the transmission of MS signals that are influenced by distance from the BTS to MS.
Interference signal reception / signal caused by the weak signals received are some signals that the reflection from the nearest object and not a signal that is received directly.
Transmission constraints that occur when the digital signal to reach the same Receiver in a different time because there is a rebound occurs that causes a signal not synchronized.