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July 1st, 2010

LTE (Long Term Evolution) technology, a next-generation 3G protocol that uses ODFMA (Orthogonal Frequency Division Multiple Access) technology in the air is still making news in the mobile and wireless industry.

The all-new 3GPP standard not only promises to unify UMTS and CDMA2000 but to also deliver on throughput, latency and jitter metrics comparable to wired broadband networks.

The higher LTE data rates are a direct result of support for higher bandwidth (up to 20 megahertz), higher-order modulation (up to 64 QAM) and MIMO (up to 4x4) while lower latencies and jitter are derived from architectural improvements in the LTE radio access network), called E-UTRAN

In order to rebalance the high peak to average power ratio problem inherent in OFDMA technology, LTE specifies the use of a low-PAPR, single-carrier FDMA modulation in the uplink. High-PAPR OFDM signals pose challenges for mobile handset power amplifiers operating in the linear region which would need to back off from the saturation power level by the amount of PAPR.

The first wave of LTE infrastructure is based on the 3GPP Release 8 specification, frozen in late 2008, and supports peak data rates of up to 300 megabits per second in the downlink and 75 Mbps in the uplink. The peak spectral efficiency for Release 8 stands at 15 in the downlink and 3.75 in the uplink.

Release 9 specifications support incremental improvements in uplink and downlink data rates. Release 10, currently in beta, is currently part of the LTE-Advanced technology and is being evaluated as a potential candidate for the next generation IMT-Advanced technology.

LTE-Advanced is proposing peak downlink speed of one gigabit per second and uplink speed of 500 Mbps in low-mobility and downlink speed of 100 Mbps in high-mobility environments, which is pretty fast by today's standards.

While HSPA, CDMA-2000 and TD-SCDMA mobile operators are all moving towards LTE technology, CDMA-2000 operators in developed regions remain under significantly higher pressure as a result of their aging EV-DO Release 0 and Revision A networks unable to compete with their HSPA counterparts.

For instance, Verizon Wireless is scheduled to be the first major CDMA operator to launch a commercial LTE network during the fourth quarter of this year, and in 25 to 30 U.S. markets covering a population of 100 million people.

Japan-based KDDI Corp., another major CDMA operator, has also announced its own plans for LTE in the 2011/2012 timeframe. But as a direct result of its existing Wi-MAX network, KDDI is not under the same pressure to move to LTE as in the case of Verizon Wireless.

Contrary to HSPA, LTE RAN has only one node type, eNodeB, which is the result of a fundamental design philosophy of minimizing the number of nodes, and that's a good thing after all. In its attempt to further reduce mobile network latencies, and while fully supporting legacy HSPA Node-B functionality, the LTE eNodeB also inherits most of the HSPA radio network controller functions.

Consequently, the eNodeB in LTE can autonomously deal with functions such as single cell radio resource management decisions, handover decisions and scheduling users in both uplink and downlink directions in its cells.

Overall, LTE is rapidly gaining operator traction and on a worlwide basis. In just over a year since March 2009, when 26 wireless carriers originally committed to deploying LTE, there were currently about 100 credible operator commitments. The key drivers are its higher spectral efficiency (lower cost per bit) coupled with higher capacity, resulting from the availability of wideband spectrum, relieving their increasingly congested 3G spectrum.

The end-to-end QoS (quality of service) capability of LTE is also driving mobile operators in developed regions as well, such as Europe and North America, to adopt newer business models and offer stronger value propositions to their subscribers by combining LTE’s wired-broadband-like performance with an IP multimedia subsystem platform for delivering differentiated, premium value added services.

These next-generation services will enable operators to capture higher ARPU (average revenue per user), reduce customer churn and further offset declining voice revenue.

In the recent past, mobile service operators in developed regions have been largely unsuccessful in adopting new business models such as application portals, content, on / off services and even proprietary devices. LTE, coupled with IMS technology will provide operators a completely packet-based capability (called all-IP - Internet protocol) that will provide the opportunity to deliver innovative next-generation services on a standardized platform more effectively and at a lower cost than third parties.

With native support for TDDM (time-division duplex mode) in addition to FDDM (frequency-division duplex mode), most broadband wireless access (Wi-MAX operators) will choose to switch to TD-LTE to benefit from the long-term evolution economies of scale.

Contrary to popular belief, as an IMT-2000 standard Release 8 and Release 9 LTE are 3G technologies. If LTE-Advanced ends up becoming an IMT-Advanced standard as proposed, only then would Release 10 and beyond qualify as 4G technologies.

Beginning only later this year, LTE is forecast to become one of the fastest growing cellular technology, reaching about 87 million subscribers in 2014 registering a CAGR (compounded annual growth rate) of 250 percent or more.

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Source: LTEFH.