A new frequency hopping-multilevel FSK system for mobile radio

The authors discuss the problem of designing a frequency hop-multilevel frequency shift keying (FH-MFSK) code division multiple access (CDMA) system for applications in mobile radio. The need for such system is explained, and a system is proposed. The system is shown have the capability of servicing an increased number of users in the same available frequency bandwidth with a higher spectral efficiency than previously proposed FH-MFSK systems. Families of frequency hop codes are reviewed, and it is shown that codes based on the number theoretic concept of linear congruences achieve the best performance in the system. The operation of the decoder at the receiver is explained, and the error probability calculated in both the synchronous and asynchronous case.