1xRTT

1xRTT, short for one times Radio Transmission Technology, is a CDMA2000 air-interface technology used to provide mobile data and voice services in early 3G networks. It is part of the CDMA2000 family and was designed to offer higher data rates than the original IS-95 system, enabling packet-switched data alongside circuit-switched voice.

Technical overview

1xRTT uses a single 1.25 MHz CDMA channel with a chip rate of about 1.2288 Mcps. It supports bidirectional data transmission with a maximum theoretical data rate of up to 144 kbps in either direction, though real-world throughput is typically lower. The technology carries both circuit-switched and packet-switched traffic and employs forward error correction and other radio-layer techniques to improve reliability over fading wireless channels. It is standardized within the IS-2000 family and is distinct from the later, higher-rate cdma2000 air interfaces such as 1xEV-DO.

Deployment and role

1xRTT was implemented by several CDMA networks in the United States and other regions in the early to mid-2000s as a stepping stone to more advanced 3G services. It enabled mobile broadband applications, email, and web access with greater efficiency than earlier 2G CDMA technologies. In many networks, 1xRTT coexisted with later data-focused technologies, such as 1xEV-DO, which provided higher, faster data rates for mobile data traffic.

Legacy and successors

As networks evolved, 1xRTT was gradually complemented or replaced for data by higher-rate technologies (notably 1xEV-DO) and later by LTE and other 4G/5G standards. Today, 1xRTT is primarily of historical and interoperability interest, reflecting the transitional phase from 2G to true 3G data capabilities in CDMA2000 networks.