System model for adaptive cellular mobile systems

The RACE Advanced Mobile Access (ATDMA) project is considering the application of advanced TDMA techniques for the design of the Radio Access system for UMTS. In the context of this work the project has identified the potential benefits of the use of an adaptive air interface, that is, an air interface whose nature changes with cell type, service needs, traffic load and propagation environment. The application of adaptive air interface to a cellular system presents a number of difficulties to the radio access system architecture. In particular, an important issue is the relative placement within a "traditional" layered architecture of control functions which are common to many users. This paper presents an alternative architecture based on the concepts of a division between Transport and Control functionalities and the use of a set of non-hierarchical, distributed functional groups. Although the resulting system model is in-line with international work on the supporting fixed network functionalities for third generation mobile systems (FPLMTS and UMTS) it is believed to be the first time a functional modeling approach has been applied to the Radio Access System and hence to the air interface description