Time-division multiple access – digital cellular telephone standard based on TDM. Every U.S. TDMA channel has the same bandwidth as the AMPS channels, 30 KHz, and is used by three subscribers; Each subscriber’s digital signal of 64 Kbps is compressed to 8 Kbps through vocoders (IS-54 standard). Subsequently, the three subscribers’ compressed signal is transmitted over the same channel, one at a time. IS-54 and IS-136 TDMA standards, however, increase the AMPS standard threefold. The IS-136 standard differs from the IS-54 standard by introducing a digital control channel.