Advanced Mobile Phone Service: Voice and Data Transmission

Voice and Data Transmission By G. A. ARREDONDO, J. C. FEGGELER, and J. I. SMITH (Manuscript received July 28, 1978) Use of the AMPS (Advanced Mobile Phone Service) microwave channel, operating in the 800- to 900-MHz band, creates unique problems in addition to those connected with conventional land communications. Because the channel characteristics are not fixed, they present design challenges and impairments that must be dealt with to protect mobile telephone users from experiencing excessive variabilities in voice transmission quality and in control and signaling reliability. This paper describes the radio transmission features of the AMPS system, emphasizing the processing and control techniques designed to deal with the dynamic nature of the mobile radio channel. I. INTRODUCTION Transmission of voice and digital control information over the AMPS microwave radio channel in the 800- to 900-MHz frequency range presents significantly different problems than those encountered in conventional land communication systems. Unlike wire-line systems, the channel characteristics are never fixed, but vary with movement of the vehicle and changes in its surroundings. These dynamics give rise to a formidable set of design challenges since the character of the radio channel can change dramatically during a single call as the vehicle moves through the service area and is "handed o f f ' to successive cell sites. Although these channel variations will occur, the radio transmission parameters, and consequently the voice and data transmission functions, have been designed to prevent the user as much as possible from experiencing corresponding changes in voice quality and in control and signaling reliability.