The Telecommunications Industry Association (TIA) IS–136 specification is the basis of the time-division multiple access (TDMA) PCS air-interface technology. IS–136 is designed to operate in both the 800-MHz and the 1900-MHz frequency bands, thus providing seamless operation on cellular and PCS systems.

The Digital Control Channel (DCCH)

The DCCH forms the core of the IS–136 specification and is the primary enhancement to TDMA digital-wireless technology. It is a new control-channel mechanism added to the analog control channel (ACC), the analog voice channel (AVC), and the digital traffic channel (DTC) of the TDMA air interface. The IS–136 DCCH TDMA technology provides the platform for PCS, introducing new functionalities and supporting enhanced features that make PCS a powerful digital system.

Dual-Band Dual-Mode Operation

PCS dual-band phones operating at 800 MHz and 1900 MHz enable users to receive full PCS features and services for IS–136 systems wherever they roam. The dual-mode capability provides service continuity and interoperability between analog and digital networks. As a result, a PCS phone can provide access to all outdoor wireless services, be used in a private in-building system, and serve as a flat-rate digital cordless phone at home.

Features and Capabilities

Table 1 shows important PCS features and capabilities.

Feature	Capability
sleep mode	extends phone standby time and enhances battery life
short message service (SMS)	transfers alphanumeric messages to and from cellular and PCS phones
voice and data privacy	increases resistance to eavesdropping
superior voice quality	results in less background noise and fewer dropped calls
hierarchical environment	provides support for macrocell-microcell operation
intelligent rescan	allows tighter control of system selection
private and residential system IDs	provide more simplified and controlled wireless office service (WOS) and personal base station (PBS) features
seamless roaming	enables roaming between frequencies using dual-band phones and provides support for international roaming
circuit-switched data support	provides highly reliable data transmission for wireless e-mail, faxing, and Internet access
authentication	increases phone security and resistance to cloning
calling number identification (CNI)	allows callers to be identified before answering
message waiting indicator (MWI)	notifies users that they have voice-mail messages
text dispatch service	Live operators take caller messages and send text messages to the PCS phone.

Table 1. PCS Features and Capabilities

Comparison of Cellular and PCS Spectrums

Figure 1 illustrates the wireless cellular 800-MHz spectrum and the PCS 1900-MHz spectrum.

Figure 1. Comparison of Cellular and PCS Spectrums