Wireless Communication

Chapter: Network Concepts and Standards
Section: Telephone Systems, Cellular telephony

IS-54 and IS-136 (Digital AMPS)

IS-54 is the standard for the digital version of the US AMPS system. Recently IS-54 has been replaced by the IS-136 standard. The system uses and hybrid Frequency Division Multiple Access and Time Division Multiple Access concept as it accepts 3 users per carrier. The carrier spacing 30 kHz, similar to the analog AMPS. Thus, assuming that the analog and digital system use the same frequency reuse pattern, the digital version can accommodate three times more users. In terms frequency planning the digital system behaves similar to analog AMPS. Carrier frequencies are in the 800 and 1900 MHz bands.

Although the digital system has advantages for the operator, marketers found it difficult to convince subscribers to go digital, i.e., to buy a new phone. The advantages of improved security in a digital system were intentionally not used, to avoid that subscribers would be alerted that the analog AMPS system had less security.

Radio Aspects



contents chapter next

JPL's Wireless Communication Reference Website 1993, 1995.