Multiple access is an indispensable technique for efficient radio spectrum utilization in mobile radio systems, because a large number of subscribers can be connected only when they require radio channels. Frequency division multiple access (FDMA) scheme using single channel per carrier (SCPC) has been widely used. However, the SCPC–FDMA scheme has some problems, such as difficulty in setting up a large number of base station transceivers and in realizing a low-cost highly stabilized local oscillator. A time and frequency division multiple access (TD/FDMA) scheme, which is a combination scheme of TDMA and FDMA, is proposed as one of the possible solutions for these problems. After explaining the background of the proposal, some of the restrictions of the TD/FDMA scheme resulting from the land mobile radio channel characteristics are described. Basic concept of the digital mobile radio telephone system using TD/FDMA scheme is then presented. An example of the possible system design is finally shown.
ASJC Scopus subject areas
- Automotive Engineering
- Aerospace Engineering
- Electrical and Electronic Engineering
- Applied Mathematics