Benefits of combined TDMA/CDMA operation for third generation mobile radio systems

The multimedia landscape requires a new approach to powerful mobile radio systems, termed Universal Mobile Telecommunication System (UMTS), which must be suited for both narrowband and broadband transmission. The UMTS therefore requires a balanced hybrid multiple access scheme. This paper presents an attempt to combine the F/TDMA and F/CDMA advantages in F/T/CDMA which facilitates a favourably high economical efficiency, regarding the investments of future network operators, as well as high channel efficiencies, in terms of a high number of traffic channels per transceiver. F/T/CDMA thus leads to a low number of small base stations (BSs) and a high spectral efficiency by dense frequency reuse. Furthermore, F/T/CDMA allows backward compatibility with GSM. The paper explains the basic relations of mobile radio systems in regard to spectral efficiency, economical efficiency and multiple access schemes as well as the most important ETSI-UMTS requirements. A novel approach to assessing F/T/CDMA by means of joint detection (JD) techniques, termed JD-CDMA, is presented. JD-CDMA allows one to overcome the drawbacks of conventional CDMA mobile radio systems