Question

In GSM systems the signal direction from the mobile station to the network or the base station is referred to as uplink. Why are lower frequencies given to the uplink? A mobile network operator was allocated uplink frequency (890-915MHz) and downlink frequency (935-960MHz). Calculate the number of available RF channels for this operator and the duplex distance if the spectrum has a carrier separation of 100kHz. Why are Telco’s more interested in Radio channels?

Answer 1

The frequencies cannot be higher because the devices in GSM devices cannot cope with high power usage that the signals need.

Thus, lower frequencies are given to GSM devices to help them save power. The GSM devices have small batteries that have limited power hence the need to use low frequencies thus the use of free space path loss applied.

RF frequencies are found by:

• Lamda=Wave length(m)
• C is equal to light speed.
• The channels are 62
• Duplex distance is 40 MHz
• Radio channels arc widely used by customers hence more profits.
  

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