The GSM uses what type of CODEC for digital mobile radio system communications?

The correct choice, Regular-Pulse Excited (RPE), is the codec used in GSM (Global System for Mobile Communications), specifically using a variant known as RPE-LTP (Regular-Pulse Excited Linear Predictive Coding). This compression technique is tailored to optimize speech quality while maintaining a relatively low bit rate, making it ideal for mobile communication environments where bandwidth may be limited.

The RPE codec operates by modeling speech signals as a combination of periodic tones and noise, allowing it to efficiently encode the information while preserving the significant characteristics of human speech. This capability is crucial for mobile communication, as it ensures improved call clarity and efficient use of the available radio spectrum.

When looking at alternatives, Linear Predictive Coding (LPC) is also a technique for speech coding, but it is not the specific codec used in GSM. Adaptive Differential Pulse-Code Modulation (ADPCM) is another form of speech coding but typically finds applications in other systems and formats, rather than GSM. G.711 is a standard codec widely used in VoIP systems but is not designed for the low bit rates required in mobile contexts like GSM. This context solidifies why Regular-Pulse Excited is the suitable choice for GSM communications.