Multi-rate transmission in FH-CDMA systems: system design and performance analysis

One of the main objectives of the third-generation mobile and personal telecommunication systems is to provide wide range of services with different bit rates. For example, low bit rate signals such as voice and high bit rate signal such as image data are likely to be transmitted through a single wideband channel. A new multi-rate transmission method using FFH-CDMA is proposed. Different rates of the signal transmission are achieved by using different sizes of time-frequency matrices per symbol. The system design is discussed, and the error probabilities of the higher and lower rate signals as a function of the number of high and low-rate users are analyzed in a noiseless case (multiuser interference only environment). The use of frequency diversity to improve the high rate services is also discussed.