UMTS-TDD

UMTS-TDD, an acronym for Universal Mobile Telecommunications System (UMTS) - time-division duplexing (TDD), is a 3GPP standardized version of UMTS networks that use UTRA-TDD. UTRA-TDD is a UTRA that uses time-division duplexing for duplexing. While a full implementation of UMTS, it is mainly used to provide Internet access in circumstances similar to those where WiMAX might be used. UMTS-TDD is not directly compatible with UMTS-FDD: a device designed to use one standard cannot, unless specifically designed to, work on the other, because of the difference in air interface technologies and frequencies used.

UTRA-TDD HCR

UTRA-TDD HCR is one of the air interfaces used for UMTS-TDD. It uses increments of 5 MHz of spectrum, with each slice divided into 10 ms frames containing fifteen time slots (1500 per second). The time slots are allocated in fixed percentage for downlink and uplink. TD-CDMA is used to multiplex streams from or to multiple transceivers.

UTRA-TDD LCR

UTRA-TDD LCR is an alternative air interface used for UMTS-TDD. It is based on TD-SCDMA, and uses 1.6 MHz slices of spectrum, and is standardized in UMTS by the 3GPP.