27 Jan 2011
Long Term Evolution (LTE) is a 4G wireless broadband technology developed by the industry trade group 3GPP. Unlike its predecessor technologies, LTE’s upper layers use TCP/IP, enabling all traffic -- data, voice, video and messaging -- to be carried over an all-IP network.
LTE provides significantly higher peak data rates than the earlier 3GPP technologies, with the potential for 100Mbps downstream and 30 Mbps upstream, reduced latency, scalable bandwidth capacity, and backwards compatibility with existing GSM and UMTS technology. Future developments could yield peak throughput on the order of 300 Mbps.
LTE uses Orthogonal Frequency Division Multiplexing (OFDM), and in later releases, MIMO (Multiple Input Multiple Output) antenna technology similar to that used in the IEEE 802.11n wireless local area network (WLAN) standard. The higher signal-to-noise ratio (SNR) at the receiver enabled by MIMO, along with OFDM, provides improved coverage and throughput, especially in dense urban areas.
For many mobile operators, LTE has arisen as the preferred 4G wireless broadband option because it evolved directly from 3G. In other words, operators can upgrade existing infrastructure to support LTE rather than start from scratch, as many would have to do with Wimax, the other leading 4G contender. As a 4G technology, LTE becomes increasingly important to mobile operators as the amount of data traffic on their networks grows. Until LTE voice standards are finalized, operators can keep voice calls on the earlier 2G and 3G infrastructures, offloading data services to the LTE network.
Toward that end, some US mobile broadband providers have initiated LTE deployments. By the end of 2010, for example, Verizon Wireless reported LTE operations in 38 US cities (despite operating a CDMA rather than GSM infrastructure).
In early 2011, AT&T announced plans to accelerate its LTE deployment, with initial services slated for a mid-year launch. Both carriers have targeted 2013 as the year for LTE network completion. AT&T is evolving its network to LTE from GSM-based HSPA+ technology, which enables 4G speeds when combined with Ethernet or fiber backhaul.
Despite nominal LTE availability in 2010, operators wanted to be able to say they had a 4G service, according to Mike Jude, a telecom program manager at Frost & Sullivan. LTE’s availability is changing quickly. But by the end of 2011, some major markets could have up to three 4G networks available in the US.