Frequency hopping CDMA for future cellular radio

Abstract

A code-division multiple access (CDMA) system based on slow frequency hopping (FH) is proposed. The hopping sequences are selected such that all users of each cell are using mutually orthogonal codes, and intercell correlation of hopping sequences is minimal. FEC and interleaving are used to mitigate the remaining interference. It is shown that with proper selection of system parameters, FH-CDMA enjoys the advantages so far claimed by DS-CDMA, i.e. FH-CDMA capacity benefits from interference averaging and can take advantage of the duty cycle associated with voice activity. It also yields a sectorization capability and one-cell frequency reuse pattern. Moreover, due to the orthogonal operation, the interference from cell co-users is eliminated. Since this is the major source of interference in nonorthogonal systems like DS-CDMA, FH-CDMA yields higher capacity capabilities (35 times AMPS). Other advantages of FH-CDMA with its implementation as a cellular system are discussed.<>