6.5. Transmitter power control in GSM cellular standard.

The effective operation of a cellular mobile communication system is largely determined by the alignment conditions of the signal from different MSs at the input of the base station. The higher the signal alignment accuracy, the greater the coverage area of ​​the system. As a rule, the direct (uplink) channel (from BTS to MS) is less susceptible to signal distortion due to intra-system interference and multipath fading, that is, there is always a power reserve on the BTS.

The main problems arise when adjusting the power in the reverse (downlink) channel - from MS to BTS. The higher the power control accuracy in the MS, the lower the level of mutual interference. The process of regulating (controlling) MS transmitter power in the reverse channel (MS => BTS) can be implemented in various ways (clause 4.9), with the basic idea of ​​MS power control being as follows: The MS continuously transmits information about the error level in the received signal.

Based on this information, the BSC distributes the radiated power of the BTS between subscribers in such a way that in each case to ensure an acceptable voice quality. Subscribers, on the way to the MS of which the radio signal experiences greater attenuation, receive the possibility of emitting a signal from their MS to more power.

That is, the main purpose of power control in the reverse channel is to optimize the radio coverage of the cell area.