S-54 and IS-136 are standards for TDMA American Digital Cellular
| Mobile Frequency Range | Rx: 869-894; Tx: 824-849 |
| Multiple Access Method | TDMA/FDM |
| Duplex Method | FDD |
| Number of Channels | 832 (3 users per channel) |
| Channel Spacing | 30Khz |
| Modulation | DQPSK |
| Channel Bit Rate | 48.6Kb |
IS-54 and IS-136: TDMA Security
IS-54 and IS-136 use the CAVE (Cellular Authentication, Voice Privacy and Encryption) algorithm for authentication and the CMEA (Cellular Message Encryption Algorithm) for encryption.
CAVE and CMEA are documented in Common Cryptographic Algorithms and Interface Specification for Common Cryptographic Algorithms.
David Wagner, Bruce Schneier and John Kelsey published Cryptanalysis of the Cellular Message Encryption Algorithm, which documents deep flaws in the CMEA algorithm.
