Long Term Evolution (LTE) is the global cellular-technology platform of choice for GSM-UMTS and Code Division Multiple Access (CDMA)/Evolved Data Optimized (EV-DO) operators as well as Worldwide Interoperability for Microwave Access (WiMAX) operators and many Greenfield operators. There are two varieties of LTE available and GSM and CDMA operators typically deploy LTE-Frequency Division Duplex (LTE-FDD) in licensed spectrum while WiMax operators are typically adopting LTE-Time Division Duplex (LTE-TDD).
LTE is part of the GSM evolutionary path for mobile broadband, following EDGE, UMTS, HSPA (HSDPA and HSUPA combined) and HSPA Evolution (HSPA+).
LTE assumes a full Internet Protocol (IP) network architecture and is designed to support voice in the packet domain. It incorporates top-of-the-line radio techniques to achieve performance levels beyond what will be practical with CDMA approaches, particularly in larger channel bandwidths.
LTE capabilities include:
Emerging technologies such as LTE benefit from wider radio channels. These wider channels are not only spectrally more efficient, they also offer greater capacity. The following figure shows increasing LTE spectral efficiency obtained with wider radio channels, with 20 MHz on the downlink and 20 MHz (20+20 MHz) on the uplink showing the most efficient configuration.
LTE Spectral Efficiency as Function of Radio Channel Size. 
Of some concern in this regard is that spectrum for LTE is becoming available in different frequency bands in different countries, thus creating a more challenging scenario for roaming. Roaming in many cases is based on GSM or HSPA on common regional or global bands. The organization tasked with global spectrum harmonization, the International Telecommunication Union, periodically holds World Radiocommunications Conferences (WRC). 
Underlying radio approaches have evolved from Time Division Multiple Access (TDMA) to CDMA to Orthogonal Frequency Division Multiplexing Access (OFDMA), which is the basis of LTE. The LTE standards were first introduced in 3GPP Release 8 and as of August 2014, the standard continues in development of Release 13.
The first commercial LTE networks were launched by TeliaSonera in Norway and Sweden in December 2009, and LTE became the most rapidly deployed communications technology with more than 300 commercial networks in more than 100 countries by 2014.
For more detailed information on LTE, visit our white papers section.
(August 2014) This white paper compares the mobile broadband technologies of today, as well as the future technologies that are being standardized or planned, and their ability to deliver greater performance in the increasingly complex and challenging mobile computing industry.
(May 2014) This white paper provides a synopsis of a report originally released in October 2013. It examines new technology enhancements and innovative spectrum policy approaches that are currently being developed as building blocks to address the massive data challenge.
(March 2014) This summary is intended to provide a brief review of some of the key specifications and enhancements outlined in 3GPP Release 12.
(February 2014) This white paper provides an in-depth look at 3GPP Release 11 and Release 12 technology standards, including HSPA+, LTE-Advanced and Machine Type Communications.
(October 2013) This white paper outlines the enhancements of Self Organizing Network (SON) features in 3GPP Release 11 and addresses the multi-vendor aspects of SON and its deployment challenges and opportunities.