C 900 - An Advanced Mobile Radio Telephone System with Optimum Frequency Utilization

The paper presents a survey of a new approach to advanced system solutions for mobile radio telephone systems. It is shown that, by the combination of both radio techniques and microprocessor data capabilities, improved means are available for controlling the specific multiple propagation and interference influences within the mobile radio environment. The aim of the system structure is to achieve the best possible frequency channel utilization, system availability, and cost benefits for deployment and users if traffic demand grows. The paper shows the different types of switching functions in public land mobile networks. Problems, as caused purely by radio conditions, are controlled within a defined radio exchange function, allowing the optimization of individual cell parameters. It is shown that distance measurement is the most reliable means of detecting cell boundaries. New approaches for system control channels lead to synchronous operation of base stations. The system operates with off-air call setup and queueing to improve channel utilization. Full national and international roaming capabilities are provided. During all calls, continuous digital link control is maintained to allow the radio exchange function in call condition. This new approach leads to different types of handoff to suit specific situations. Speech scrambling provides subscriber privacy.