LTE: Long Term Evolution
With Long Term Evolution (LTE) there is a new radio platform technology that will allow operators to achieve even higher peak throughputs than HSPA+ in higher spectrum bandwidth. Work on LTE began at 3GPP in 2004, with an official LTE work item started in 2006 and a completed 3GPP Release 8 specification in March 2009. Initial deployment of LTE is targeted for 2010 and 2011.
LTE is part of the GSM evolutionary path beyond 3G technology, following EDGE, UMTS, HSPA (HSDPA and HSUPA combined) and HSPA Evolution (HSPA+). Although HSPA and its evolution are strongly positioned to be the dominant mobile data technology for the next decade, the GSM family of standards must evolve toward the future. HSPA Evolution will provide the stepping-stone to LTE for many operators.
The overall objective for LTE is to provide an extremely high performance radio-access technology that offers full vehicular speed mobility and that can readily coexist with HSPA and earlier networks. Because of scalable bandwidth, operators will be able to easily migrate their networks and users from HSPA to LTE over time.
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. However, in the same way that 3G coexists with second generation (2G) systems in integrated networks, LTE systems will coexist with 3G and 2G systems. Multimode devices will function across LTE/3G or even LTE/3G/2G, depending on market circumstances.
Standards development for LTE is continuing with 3GPP Release 9 (Rel-9) and targets the completion of the specification by December 2009. 3GPP recognizes the need to develop a solution and specification to be submitted to the International Telecommunication Union (ITU) for meeting the IMT-Advanced requirements. Therefore, in parallel with Rel-9 work, 3GPP is working on a study item called LTE-Advanced which is likely to define the bulk of the content for Rel-10, and will include significant new technology enhancements to LTE/EPC.
For many years now, a true world cellular standard has been one of the industry’s goals. GSM dominated second generation (2G) technologies but there was still fragmentation with CDMA and TDMA as well as iDEN. With the move to third generation (3G), nearly all TDMA operators migrated to the GSM technology path. Yet the historical divide remained between GSM and CDMA. It is with the next step of technology evolution that the opportunity has arisen for a global standard technology. Many operators have converged on the technology they believe will offer them and their customers the most benefits. That technology is Long Term Evolution. All roads lead to LTE – for the first time, leading GSM and CDMA operators are building towards global consensus on their planned deployments of LTE beginning with trials in 2009 and initial deployments in 2010 and 2011. Informa Telecoms & Media lists more than 100 operators as of 1Q 2009 who have various levels of commitment in a future with LTE.
In June of 2008, the Next Generation Mobile Networks Alliance (NGMN) selected LTE as the first technology that matched its requirements successfully. 3G Americas, GSMA, UMTS Forum, and other global organizations have reiterated their support of the 3GPP evolution to LTE. Additionally, the LSTI Trial Initiative has provided support through early co-development and testing of the entire ecosystem from chipset, device and infrastructure vendors.
LTE products have been tested, trialed and commercially announced in the market by more than 100 manufacturers that are already part of a well-planned LTE eco-system. Building upon the evolution of GSM, the LTE ecosystem will be able to continue the benefits of scope and scale.
LTE uses Orthogonal Frequency Division Multiple Access (OFDMA) on the downlink, which is well suited to achieve high peak data rates in high spectrum bandwidth. WCDMA radio technology is, essentially, as efficient as Orthogonal Frequency Division Multiplexing (OFDM) for delivering peak data rates of about 10 Mbps in 5 MHz of bandwidth. Achieving peak rates in the 100 Mbps range with wider radio channels, however, would result in highly complex terminals and is not practical with current technology. This is where OFDM provides a practical implementation advantage.
The OFDMA approach is also highly flexible in channelization, and LTE will operate in various radio channel sizes ranging from 1.25 to 20 MHz. LTE also boosts spectral efficiency.
On the uplink, however, a pure OFDMA approach results in high Peak to Average Ratio (PAR) of the signal, which compromises power efficiency and, ultimately, battery life. Hence, LTE uses an approach for the uplink called Single Carrier FDMA (SC-FDMA), which is somewhat similar to OFDMA, but has a 2 to 6 dB PAR advantage over the OFDMA method used by other technologies such as WiMAX IEEE 802.16e.
With Long Term Evolution (LTE) there is a new radio platform technology that will allow operators to achieve even higher peak throughputs than HSPA+ in higher spectrum bandwidth. Work on LTE began at 3GPP in 2004, with an official LTE work item started in 2006 and a completed 3GPP Release 8 specification in March 2009. Initial deployment of LTE is targeted for 2010 and 2011.
LTE is part of the GSM evolutionary path beyond 3G technology, following EDGE, UMTS, HSPA (HSDPA and HSUPA combined) and HSPA Evolution (HSPA+). Although HSPA and its evolution are strongly positioned to be the dominant mobile data technology for the next decade, the GSM family of standards must evolve toward the future. HSPA Evolution will provide the stepping-stone to LTE for many operators.
The overall objective for LTE is to provide an extremely high performance radio-access technology that offers full vehicular speed mobility and that can readily coexist with HSPA and earlier networks. Because of scalable bandwidth, operators will be able to easily migrate their networks and users from HSPA to LTE over time.
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. However, in the same way that 3G coexists with second generation (2G) systems in integrated networks, LTE systems will coexist with 3G and 2G systems. Multimode devices will function across LTE/3G or even LTE/3G/2G, depending on market circumstances.
Standards development for LTE is continuing with 3GPP Release 9 (Rel-9) and targets the completion of the specification by December 2009. 3GPP recognizes the need to develop a solution and specification to be submitted to the International Telecommunication Union (ITU) for meeting the IMT-Advanced requirements. Therefore, in parallel with Rel-9 work, 3GPP is working on a study item called LTE-Advanced which is likely to define the bulk of the content for Rel-10, and will include significant new technology enhancements to LTE/EPC.
For many years now, a true world cellular standard has been one of the industry’s goals. GSM dominated second generation (2G) technologies but there was still fragmentation with CDMA and TDMA as well as iDEN. With the move to third generation (3G), nearly all TDMA operators migrated to the GSM technology path. Yet the historical divide remained between GSM and CDMA. It is with the next step of technology evolution that the opportunity has arisen for a global standard technology. Many operators have converged on the technology they believe will offer them and their customers the most benefits. That technology is Long Term Evolution. All roads lead to LTE – for the first time, leading GSM and CDMA operators are building towards global consensus on their planned deployments of LTE beginning with trials in 2009 and initial deployments in 2010 and 2011. Informa Telecoms & Media lists more than 100 operators as of 1Q 2009 who have various levels of commitment in a future with LTE.
In June of 2008, the Next Generation Mobile Networks Alliance (NGMN) selected LTE as the first technology that matched its requirements successfully. 3G Americas, GSMA, UMTS Forum, and other global organizations have reiterated their support of the 3GPP evolution to LTE. Additionally, the LSTI Trial Initiative has provided support through early co-development and testing of the entire ecosystem from chipset, device and infrastructure vendors.
LTE products have been tested, trialed and commercially announced in the market by more than 100 manufacturers that are already part of a well-planned LTE eco-system. Building upon the evolution of GSM, the LTE ecosystem will be able to continue the benefits of scope and scale.
LTE uses Orthogonal Frequency Division Multiple Access (OFDMA) on the downlink, which is well suited to achieve high peak data rates in high spectrum bandwidth. WCDMA radio technology is, essentially, as efficient as Orthogonal Frequency Division Multiplexing (OFDM) for delivering peak data rates of about 10 Mbps in 5 MHz of bandwidth. Achieving peak rates in the 100 Mbps range with wider radio channels, however, would result in highly complex terminals and is not practical with current technology. This is where OFDM provides a practical implementation advantage.
The OFDMA approach is also highly flexible in channelization, and LTE will operate in various radio channel sizes ranging from 1.25 to 20 MHz. LTE also boosts spectral efficiency.
On the uplink, however, a pure OFDMA approach results in high Peak to Average Ratio (PAR) of the signal, which compromises power efficiency and, ultimately, battery life. Hence, LTE uses an approach for the uplink called Single Carrier FDMA (SC-FDMA), which is somewhat similar to OFDMA, but has a 2 to 6 dB PAR advantage over the OFDMA method used by other technologies such as WiMAX IEEE 802.16e.
