Development of a TDMA digital cellular system based on Japanese standard

A three-channel TDMA (time-division multiple-access) digital cellular system based on a Japanese standard is being developed. The system, designed according to the OSI (open systems interconnection) model, will be connected to ISDN (integrated services digital network) to achieve the flexibility needed to provide enhanced services. The proposed system achieves efficient spectrum utilization by employing narrowband digital modulation and a low-bit-rate speech codec. In addition, enhanced radio link control, assisted by the TDMA technique, provides a far smaller cell layout, which further improves spectrum efficiency. An OSI-based layered signaling structure is used to maintain system flexibility for enhanced link control and new services. The authors present the network architecture and the system structure of the proposed system. Spectrum-efficient and flexible channel/signaling structures are described. Economical and compact infrastructure configurations are given