LTE (telecommunication)

"Long-term evolution" redirects here. For the biological concept, see Evolution and E. coli long-term evolution experiment.
Shows the countries where 3GPP Long Term Evolution is available
Adoption of LTE technology as of December 7, 2014
  Countries and regions with commercial LTE service
  Countries and regions with commercial LTE network deployment on-going or planned
  Countries and regions with LTE trial systems (pre-commitment)
LTE signal indicator in Android

LTE (Long-Term Evolution, commonly marketed as 4G LTE) is a standard for wireless communication of high-speed data for mobile phones and data terminals. It is based on the GSM/EDGE and UMTS/HSPA network technologies, increasing the capacity and speed using a different radio interface together with core network improvements.[1][2] The standard is developed by the 3GPP (3rd Generation Partnership Project) and is specified in its Release 8 document series, with minor enhancements described in Release 9.

LTE is the natural upgrade path for carriers with both GSM/UMTS networks and CDMA2000 networks. The different LTE frequencies and bands used in different countries will mean that only multi-band phones will be able to use LTE in all countries where it is supported.

Although marketed as a 4G wireless service, LTE (as specified in the 3GPP Release 8 and 9 document series) does not satisfy the technical requirements the 3GPP consortium has adopted for its new LTE Advanced standard. The requirements were originally set forth by the ITU-R organization in its IMT Advanced specification. However, due to marketing pressures and the significant advancements that WiMAX, Evolved High Speed Packet Access and LTE bring to the original 3G technologies, ITU later decided that LTE together with the aforementioned technologies can be called 4G technologies.[3] The LTE Advanced standard formally satisfies the ITU-R requirements to be considered IMT-Advanced.[4] To differentiate LTE Advanced and WiMAX-Advanced from current 4G technologies, ITU has defined them as "True 4G".[5][6]

Overview

Telia-branded Samsung LTE modem
HTC ThunderBolt, the second commercially available LTE smartphone

LTE stands for Long Term Evolution[7] and is a registered trademark owned by ETSI (European Telecommunications Standards Institute) for the wireless data communications technology and a development of the GSM/UMTS standards. However other nations and companies do play an active role in the LTE project. The goal of LTE was to increase the capacity and speed of wireless data networks using new DSP (digital signal processing) techniques and modulations that were developed around the turn of the millennium. A further goal was the redesign and simplification of the network architecture to an IP-based system with significantly reduced transfer latency compared to the 3G architecture. The LTE wireless interface is incompatible with 2G and 3G networks, so that it must be operated on a separate radio spectrum.

LTE was first proposed by NTT DoCoMo of Japan in 2004, and studies on the new standard officially commenced in 2005.[8] In May 2007, the LTE/SAE Trial Initiative (LSTI) alliance was founded as a global collaboration between vendors and operators with the goal of verifying and promoting the new standard in order to ensure the global introduction of the technology as quickly as possible.[9][10] The LTE standard was finalized in December 2008, and the first publicly available LTE service was launched by TeliaSonera in Oslo and Stockholm on December 14, 2009 as a data connection with a USB modem. The LTE services were launched by major North American carriers as well, with the Samsung SCH-r900 being the world’s first LTE Mobile phone starting on September 21, 2010[11][12] and Samsung Galaxy Indulge being the world’s first LTE smartphone starting on February 10, 2011[13][14] both offered by MetroPCS and HTC ThunderBolt offered by Verizon starting on March 17 being the second LTE smartphone to be sold commercially.[15][16] In Canada, Rogers Wireless was the first to launch LTE network on July 7, 2011 offering the Sierra Wireless AirCard® 313U USB mobile broadband modem, known as the "LTE Rocket™ stick" then followed closely by mobile devices from both HTC and Samsung.[17] Initially, CDMA operators planned to upgrade to rival standards called UMB and WiMAX, but all the major CDMA operators (such as Verizon, Sprint and MetroPCS in the United States, Bell and Telus in Canada, au by KDDI in Japan, SK Telecom in South Korea and China Telecom/China Unicom in China) have announced that they intend to migrate to LTE after all. The evolution of LTE is LTE Advanced, which was standardized in March 2011.[18] Services are expected to commence in 2013.[19]

The LTE specification provides downlink peak rates of 300 Mbit/s, uplink peak rates of 75 Mbit/s and QoS provisions permitting a transfer latency of less than 5 ms in the radio access network. LTE has the ability to manage fast-moving mobiles and supports multi-cast and broadcast streams. LTE supports scalable carrier bandwidths, from 1.4 MHz to 20 MHz and supports both frequency division duplexing (FDD) and time-division duplexing (TDD). The IP-based network architecture, called the Evolved Packet Core (EPC) designed to replace the GPRS Core Network, supports seamless handovers for both voice and data to cell towers with older network technology such as GSM, UMTS and CDMA2000.[20] The simpler architecture results in lower operating costs (for example, each E-UTRA cell will support up to four times the data and voice capacity supported by HSPA[21]).

TD-LTE

Long-Term Evolution Time-Division Duplex (LTE-TDD), also referred to as Time-division Long-Term Evolution (TD-LTE), is a 4G telecommunications technology and standard co-developed by an international coalition of companies, including China Mobile, Datang Telecom, Huawei, ZTE, Nokia Solutions and Networks, Qualcomm, Samsung, and ST-Ericsson. It is one of two variants of the Long Term Evolution (LTE) technology standard, the other being Frequency-Division Long-Term Evolution (LTE-FDD).

Overview of technology

Time-Division Duplex LTE, abbreviated as TD-LTE, TDD LTE, or LTE-TDD is one of the two mobile data transmission technologies that fall under the international standard of LTE, the other being Frequency-Division Duplex (LTE-FDD).[22][23][24] LTE-TDD was developed specifically with idea of migration to 4G from the third generation 3G TD-SCDMA networks in mind.[25]

There are two major differences between LTE-TDD and LTE-FDD: how data is uploaded and downloaded, and what frequency spectra the networks are deployed in. While LTE-FDD uses paired frequencies to upload and download data,[26] LTE-TDD uses a single frequency, alternating between uploading and downloading data through time.[27][28] The ratio between uploads and downloads on a LTE-TDD network can be changed dynamically, depending on whether more data needs to be sent or received.[29] LTE-TDD and LTE-FDD also operate on different frequency bands,[30] with LTE-TDD working better at higher frequencies, and LTE-FDD working better at lower frequencies.[31] Frequencies used for LTE-TDD range from 1850 MHz to 3800 MHz, with several different bands being used.[32] The LTE-TDD spectrum is generally cheaper to access, and has less traffic.[30] Further, the bands for LTE-TDD overlap with those used for WiMAX, which can easily be upgraded to support LTE-TDD.[30]

Despite the differences in how the two types of LTE handle data transmission, LTE-TDD and LTE-FDD share 90 percent of their core technology, making it possible for the same chipsets and networks to use both versions of LTE.[30][33] A number of companies produce dual-mode chips or mobile devices, including Samsung and Qualcomm,[34][35] while operators China Mobile Hong Kong Company Limited and Hi3G Access have developed dual-mode networks in China and Sweden, respectively.[36]

History

The creation of LTE-TDD involved a coalition of international companies that worked to develop and test the technology.[37] China Mobile was an early proponent of LTE-TDD,[30][38] along with other companies like Datang Telecom[37] and Huawei, which worked to deploy LTE-TDD networks, and later developed technology allowing LTE-TDD equipment to operate in white spaces—frequency spectra between broadcast TV stations.[23][39] Intel also participated in the development, setting up a LTE-TDD interoperability lab with Huawei in China,[40] as well as ST-Ericsson,[30] Nokia,[30] and Nokia Siemens (now Nokia Solutions and Networks),[23] which developed LTE-TDD base stations that increased capacity by 80 percent and coverage by 40 percent.[41] Qualcomm also participated, developing the world's first multi-mode chip, combining both LTE-TDD and LTE-FDD, along with HSPA and EV-DO.[35] Accelleran, a Belgian company, has also worked to build small cells for LTE-TDD networks.[42]

Trials of LTE-TDD technology began as early as 2010, with Reliance Industries and Ericsson India conducting field tests of LTE-TDD in India, achieving 80 megabit-per second download speeds and 20 megabit-per-second upload speeds.[43] By 2011, China Mobile began trials of the technology in six cities.[23]

Although initially seen as a technology utilized by only a few countries, including China and India,[44] by 2011 international interest in LTE-TDD had expanded, especially in Asia, in part due to LTE-TDD 's lower cost of deployment compared to LTE-FDD.[23] By the middle of that year, 26 networks around the world were conducting trials of the technology.[24] The Global LTE-TDD Initiative (GTI) was also started in 2011, with founding partners China Mobile, Bharti Airtel, SoftBank Mobile, Vodafone, Clearwire, Aero2 and E-Plus.[45] In September 2011, Huawei announced it would partner with Polish mobile provider Aero2 to develop a combined LTE TDD and FDD network in Poland,[46] and by April 2012, ZTE Corporation had worked to deploy trial or commercial LTE-TDD networks for 33 operators in 19 countries.[36] In late 2012, Qualcomm worked extensively to deploy a commercial LTE-TDD network in India, and partnered with Bharti Airtel and Huawei to develop the first multi-mode LTE-TDD smartphone for India.[35]

In Japan, SoftBank Mobile launched LTE-TDD services in February 2012 under the name Advanced eXtended Global Platform (AXGP), and marketed as SoftBank 4G (ja). The AXGP band was previously used for Willcom's PHS service, and after PHS was discontinued in 2010 the PHS band was re-purposed for AXGP service.[47][48]

In the U.S., Clearwire planned to implement LTE-TDD, with chip-maker Qualcomm agreeing to support Clearwire's frequencies on its multi-mode LTE chipsets.[49] With Sprint's acquisition of Clearwire in 2013,[26][50] the carrier began using these frequencies for LTE service on networks built by Samsung, Alcatel-Lucent, and Nokia.[51][52]

As of March 2013, 156 commercial 4G LTE networks existed, including 142 LTE-FDD networks and 14 LTE-TDD networks.[37] As of November 2013, the South Korean government planned to allow a fourth wireless carrier in 2014, which would provide LTE-TDD services,[28] and in December 2013, LTE-TDD licenses were granted to China's three mobile operators, allowing commercial deployment of 4G LTE services.[53]

In January 2014, Nokia Solutions and Networks indicated that it had completed a series of tests of voice over LTE (VoLTE) calls on China Mobile's TD-LTE network.[54] The next month, Nokia Solutions and Networks and Sprint announced that they had demonstrated throughput speeds of 2.6 gigabits per second throughput using a LTE-TDD network, surpassing the previous record of 1.6 gigbits per second.[55]

LTE Direct

A new LTE protocol named LTE Direct works as an innovative device-to-device technology enabling the discovery of thousands of devices in the proximity of approximately 500 meters.[56] Pioneered by Qualcomm, the company has been leading the standardization of this new technology along with other 3GPP participants. LTE Direct offers several advantages over existing proximity solutions including but not limited to Wi-Fi or Bluetooth. One of the most popular use cases for this technology was developed by a New York City based company called Compass.to. The core feature of proximal discovery among devices included a targeted discount voucher to a nearby device which matched specific interests.[57] The Compass.to use case was featured at global conferences and events such as CES 2015, MWC 2015, and said to be extended to many other scenarios including film festivals, theme parks and sporting events. “You can think of LTE Direct as a sixth sense that is always aware of the environment around you,” said Mahesh Makhijani, technical marketing director at Qualcomm, at a session on the technology. Additionally, the protocol offers less battery drainage and extended range when compared to other proximity solutions.

Below is a list of countries by 4G LTE penetration as measured by OpenSignal.com and TIM for Italy, in 2015. [58][59]

RankCountry/TerritoryPenetration
1  South Korea 97%
2  Japan 90%
2  Italy 90%
3  Hong Kong 86%
4  Kuwait 86%
5  Singapore 84%
6  Uruguay 84%
7  Kazakhstan 81%
8  Netherlands 80%
9  Bahrain 79%
10  United States 78%
11  Sweden 78%
12  China 76%
13  Qatar 75%
14  Australia 74%
15  Estonia 74%

Features

See also: E-UTRA

Much of the LTE standard addresses the upgrading of 3G UMTS to what will eventually be 4G mobile communications technology. A large amount of the work is aimed at simplifying the architecture of the system, as it transitions from the existing UMTS circuit + packet switching combined network, to an all-IP flat architecture system. E-UTRA is the air interface of LTE. Its main features are:

Voice calls

cs domLTE CSFB to GSM/UMTS network interconnects

The LTE standard supports only packet switching with its all-IP network. Voice calls in GSM, UMTS and CDMA2000 are circuit switched, so with the adoption of LTE, carriers will have to re-engineer their voice call network.[62] Three different approaches sprang up:

Voice over LTE (VoLTE)
Main article: VoLTE
Circuit-switched fallback (CSFB)
In this approach, LTE just provides data services, and when a voice call is to be initiated or received, it will fall back to the circuit-switched domain. When using this solution, operators just need to upgrade the MSC instead of deploying the IMS, and therefore, can provide services quickly. However, the disadvantage is longer call setup delay.
Simultaneous voice and LTE (SVLTE)
In this approach, the handset works simultaneously in the LTE and circuit switched modes, with the LTE mode providing data services and the circuit switched mode providing the voice service. This is a solution solely based on the handset, which does not have special requirements on the network and does not require the deployment of IMS either. The disadvantage of this solution is that the phone can become expensive with high power consumption.

One additional approach which is not initiated by operators is the usage of over-the-top content (OTT) services, using applications like Skype and Google Talk to provide LTE voice service.[63]

Most major backers of LTE preferred and promoted VoLTE from the beginning. The lack of software support in initial LTE devices as well as core network devices however led to a number of carriers promoting VoLGA (Voice over LTE Generic Access) as an interim solution.[64] The idea was to use the same principles as GAN (Generic Access Network, also known as UMA or Unlicensed Mobile Access), which defines the protocols through which a mobile handset can perform voice calls over a customer's private Internet connection, usually over wireless LAN. VoLGA however never gained much support, because VoLTE (IMS) promises much more flexible services, albeit at the cost of having to upgrade the entire voice call infrastructure. VoLTE will also require Single Radio Voice Call Continuity (SRVCC) in order to be able to smoothly perform a handover to a 3G network in case of poor LTE signal quality.[65]

While the industry has seemingly standardized on VoLTE for the future, the demand for voice calls today has led LTE carriers to introduce CSFB as a stopgap measure. When placing or receiving a voice call, LTE handsets will fall back to old 2G or 3G networks for the duration of the call.

Enhanced voice quality

To ensure compatibility, 3GPP demands at least AMR-NB codec (narrow band), but the recommended speech codec for VoLTE is Adaptive Multi-Rate Wideband, also known as HD Voice. This codec is mandated in 3GPP networks that support 16 kHz sampling.[66]

Fraunhofer IIS has proposed and demonstrated "Full-HD Voice", an implementation of the AAC-ELD (Advanced Audio Coding – Enhanced Low Delay) codec for LTE handsets.[67] Where previous cell phone voice codecs only supported frequencies up to 3.5 kHz and upcoming wideband audio services branded as HD Voice up to 7 kHz, Full-HD Voice supports the entire bandwidth range from 20 Hz to 20 kHz. For end-to-end Full-HD Voice calls to succeed however, both the caller and recipient's handsets as well as networks have to support the feature.[68]

Frequency bands

The LTE standard covers a range of many different bands, each of which is designated by both a frequency and a band number. In North America, 700, 750, 800, 850, 1900, 1700/2100 (AWS), 2500 and 2600 MHz (Rogers Communications, Bell Canada) are used (bands 2, 4, 7, 12, 13, 17, 25, 26, 41); 2500 MHz in South America; 700, 800, 900, 1800, 2600 MHz in Europe (bands 3, 7, 20);[69][70] 800, 1800 and 2600 MHz in Asia (bands 1, 3, 5, 7, 8, 11, 13, 40)[71][72] and 1800 MHz and 2300 MHz in Australia[73][74] and New Zealand (bands 3, 40).[75] As a result, phones from one country may not work in other countries. Users will need a multi-band capable phone for roaming internationally.

Patents

According to the European Telecommunications Standards Institute's (ETSI) intellectual property rights (IPR) database, about 50 companies have declared, as of March 2012, holding essential patents covering the LTE standard.[76] The ETSI has made no investigation on the correctness of the declarations however,[76] so that "any analysis of essential LTE patents should take into account more than ETSI declarations."[77]

The table below shows the available LTE royalty:

Announced royalty rates for LTE patents
Company Royalty rate
Alcatel-Lucent 2.00%
Ericsson 1.50%
Huawei Technologies Co., Ltd. 1.50%
InterDigital Inc. 2.50%
Motorola Inc. 2.25%
Motorola Mobility Inc. 2.25%
Nokia Corporation 1.50%
Nokia Siemens Networks 0.80%
Nortel Networks Ltd 1.00%
Qualcomm Incorporated 3.25%
Samsung Electronics Co., Ltd. 2.40%
ZTE Corporation 1.00%
Total: 21.95%

See also

References

  1. ↑ "An Introduction to LTE". 3GPP LTE Encyclopedia. Retrieved December 3, 2010.
  2. ↑ "Long Term Evolution (LTE): A Technical Overview" (PDF). Motorola. Retrieved July 3, 2010.
  3. ↑ "Newsroom • Press Release". Itu.int. Retrieved 2012-10-28.
  4. ↑ "ITU-R Confers IMT-Advanced (4G) Status to 3GPP LTE" (Press release). 3GPP. 20 October 2010. Retrieved 18 May 2012.
  5. ↑ pressinfo (2009-10-21). "Press Release: IMT-Advanced (4G) Mobile wireless broadband on the anvil". Itu.int. Retrieved 2012-10-28.
  6. ↑ "Newsroom • Press Release". Itu.int. Retrieved 2012-10-28.
  7. ↑ ETSI Long Term Evolution page
  8. ↑ "Work Plan 3GPP (Release 8)". 16 January 2012. Retrieved 1 March 2012.
  9. ↑ "LSTI job complete". Retrieved 1 March 2012.
  10. ↑ "LTE/SAE Trial Initiative (LSTI) Delivers Initial Results". 7 November 2007. Retrieved 1 March 2012.
  11. ↑ Temple, Stephen. "Vintage Mobiles: Samsung SCH-r900 – The world’s first LTE Mobile (2010)". History of GMS: Birth of the mobile revolution.
  12. ↑ "Samsung Craft, the world’s first 4G LTE phone, now available at MetroPCS". Unwired View. September 21, 2010.
  13. ↑ "MetroPCS debuts first 4G LTE Android phone, Samsung Galaxy Indulge". Android and Me. 2011-02-09. Retrieved 2012-03-15.
  14. ↑ "MetroPCS snags first LTE Android phone". Networkworld.com. Retrieved 2012-03-15.
  15. ↑ "Verizon launches its first LTE handset". Telegeography.com. 2011-03-16. Retrieved 2012-03-15.
  16. ↑ "HTC ThunderBolt is officially Verizon's first LTE handset, come March 17th". Phonearena.com. Retrieved 2012-03-15.
  17. ↑ "Rogers lights up Canada's first LTE network today". CNW Group Ltd. 2011-07-07. Retrieved 2012-10-28.
  18. ↑ LTE – An End-to-End Description of Network Architecture and Elements. 3GPP LTE Encyclopedia. 2009.
  19. ↑ "AT&T commits to LTE-Advanced deployment in 2013, Hesse and Mead unfazed". Engadget. 2011-11-08. Retrieved 2012-03-15.
  20. ↑ LTE – an introduction (PDF). Ericsson. 2009.
  21. ↑ "Long Term Evolution (LTE)" (PDF). Motorola. Retrieved April 11, 2011.
  22. ↑ "Huawei rejects EU dumping, subsidy charges". China Daily (European edition). 23 May 2013. Retrieved 9 January 2014.
  23. 1 2 3 4 5 Michael Kan (20 January 2011). "Huawei: More Trials of TD-LTE in Asia Expected". PC World. Retrieved 9 December 2013.
  24. 1 2 Liau Yun Qing (22 June 2011). "China's TD-LTE spreads across globe". ZDNet. Retrieved 9 December 2013.
  25. ↑ Yonis, A. Z.; Abdullah, M. F. L.; Ghanim, M. F. (2012). LTE-FDD and LTE-TDD for Cellular Communications. Progress In Electromagnetics Research Symposium. Kuala Lumpur, Malaysia. pp. 1467–1471.
  26. 1 2 Dan Meyer (25 February 2013). "MWC 2013: TD-LTE group touts successful global roaming trials". RCR Wireless News. Retrieved 10 December 2013.
  27. ↑ Dan Jones (16 October 2012). "Defining 4G: What the Heck Is LTE TDD?". Light Reading. Retrieved 9 January 2014.
  28. 1 2 Kim Yoo-chul (18 November 2013). "Gov't to pick 4th mobile carrier". The Korea Times. Retrieved 10 December 2013.
  29. ↑ Ian Poole. "LTE-FDD, TDD, TD-LTE Duplex Schemes". Radio-electronics.com. Retrieved 9 January 2014.
  30. 1 2 3 4 5 6 7 Cian O'Sullivan (10 November 2010). "Nokia developing TD-LTE devices for China Mobile". GoMo News. Retrieved 9 December 2013.
  31. ↑ Josh Taylor (4 December 2012). "Optus to launch TD-LTE 4G network in Canberra". ZDNet. Retrieved 9 January 2014.
  32. ↑ Ian Poole. "LTE Frequency Bands & Spectrum Allocations". Radio-electronics.com. Retrieved 9 January 2014.
  33. ↑ "MWC 2013: Ericsson and China Mobile demo first dual mode HD VoLTE call based on multi-mode chipsets". Wireless - Wireless Communications For Public Services And Private Enterprises. Noble House Media. 4 March 2013. Retrieved 9 January 2014.
  34. ↑ Steve Costello (2 August 2013). "GCF and GTI partner for TD-LTE device certification". Mobile World Live. Retrieved 9 January 2014.
  35. 1 2 3 "Qualcomm India's Dr. Avneesh Agrawal on 4G, Snapdragon and more". Digit. 8 February 2013. Retrieved 10 December 2013.
  36. 1 2 "ZTE, China Mobile Hong Kong to construct LTE-TDD network". TT Magazine. 20 July 2012. Retrieved 10 December 2013.
  37. 1 2 3 Tan Min (7 May 2013). "Competitors Try Curbing China Mobile's 4G Urge". Caixin Online. Caixin Media. Retrieved 10 December 2013.
  38. ↑ Sophie Curtis (4 January 2012). "TD-LTE 4G standard gains momentum: ABI Research". Techworld. Retrieved 10 December 2013.
  39. ↑ Nick Wood (21 October 2011). "Huawei trials white spaces TD-LTE kit". Total Telecom. Retrieved 10 December 2013.
  40. ↑ "Intel and Huawei set up LTE TDD lab in China". Global Telecoms Business. 10 April 2012. Retrieved 10 December 2013.
  41. ↑ Sharif Sakr (8 December 2011). "Nokia Siemens promises better TD-LTE and CDMA coverage, no alarms or surprises". Engadget. Retrieved 10 December 2013.
  42. ↑ Kevin Fitchard (4 July 2013). "Belgium’s Accelleran aims to corner the small cell market for that other LTE". GigaOM. Retrieved 10 December 2013.
  43. ↑ "Ericsson, Reliance showcases first LTE-TDD ecosystem". The Indian Express. 2 December 2010. Retrieved 9 December 2013.
  44. ↑ "Nokia Siemens Networks TD-LTE whitepaper" (PDF). 2010. Retrieved 5 March 2014.
  45. ↑ "LTE TDD: network plans, commitments, trials, deployments". Telecoms.com. Retrieved 11 December 2013.
  46. ↑ "Huawei partners with Aero2 to launch LTE TDD/FDD commercial network". Computer News Middle East. 21 September 2011. Retrieved 10 December 2013.
  47. ↑ Sam Byford (20 February 2012). "SoftBank launching 110Mbps AXGP 4G network in Japan this week". The Verge. Retrieved 7 June 2015.
  48. ↑ Zahid Ghadialy (21 February 2012). "SoftBank launching 110Mbps AXGP 4G network in Japan this week". The 3G4G Blog. Retrieved 7 June 2015.
  49. ↑ Phil Goldstein (22 June 2012). "Report: TD-LTE to power 25% of LTE connections by 2016". FierceWireless. Retrieved 10 December 2013.
  50. ↑ Rachel King (9 July 2013). "Done deal: Sprint now owns 100 percent of Clearwire". ZDNet. Retrieved 10 December 2013.
  51. ↑ Kevin Fitchard (30 October 2013). "What’s igniting Spark? A look inside Sprint’s super-LTE network". GigaOM. Retrieved 10 December 2013.
  52. ↑ Sarah Reedy (12 July 2013). "Sprint's LTE TDD Future to Boost Current Vendors". Light Reading. Retrieved 10 December 2013.
  53. ↑ Richard Lai (4 December 2013). "China finally grants 4G licenses, but still no iPhone deal for China Mobile". Engadget. Retrieved 10 December 2013.
  54. ↑ Ben Munson (31 January 2014). "China Mobile, NSN Complete Live VoLTE Test on TD-LTE". Wireless Week. Retrieved 11 February 2014.
  55. ↑ "NSN and Sprint achieves huge leap in TD-LTE network speeds". TelecomTiger. 6 February 2014. Retrieved 11 February 2014.
  56. ↑ "LTE Direct | Research Project | Qualcomm". Qualcomm. Retrieved 2015-10-20.
  57. ↑ "LTE Direct: A thriving ecosystem and amazing use cases on full display at MWC 2015 [VIDEOS] | Qualcomm". Qualcomm. Retrieved 2015-10-20.
  58. ↑ https://www.tim.it/verifica-copertura
  59. ↑ http://opensignal.com/reports/2015/09/state-of-lte-q3-2015/
  60. ↑ Sesia, Toufik, Baker: LTE – The UMTS Long Term Evolution; From Theory to Practice, page 11. Wiley, 2009.
  61. ↑ "Evolution of LTE". LTE World. Retrieved October 24, 2011.
  62. ↑ "Voice and SMS in LTE Technology White Paper, Rohde & Schwarz, 2011"
  63. ↑ Huawei Communicate Magazine, Issue 61, September 2011.
  64. ↑ VoLGA whitepaper
  65. ↑ Qualcomm Chipset Powers First Successful VoIP-Over-LTE Call With Single Radio Voice Call Continuity
  66. ↑ Erricsson - LTE delivers superior voice, too
  67. ↑ Fraunhofer IIS Demos Full-HD Voice Over LTE On Android Handsets
  68. ↑ "Firm Set to Demo HD Voice over LTE"
  69. ↑ "EC makes official recommendation for 790–862 MHz release". 29 October 2009. Retrieved 11 March 2012.
  70. ↑ "Europe plans to reserve 800MHz frequency band for LTE and WiMAX". 16 May 2010. Retrieved 11 March 2012.
  71. ↑ CSL begins dual-band 1800/2600 LTE rollout
  72. ↑ Oredoo - The Technology
  73. ↑ Telstra switches on first LTE network on 1800MHz in Australia
  74. ↑ Optus still evaluating LTE
  75. ↑ "New Zealand 4G LTE launch". 28 February 2013.
  76. 1 2 "Who Owns LTE Patents?". ipeg. March 6, 2012. Retrieved March 10, 2012.
  77. ↑ Elizabeth Woyke (2011-09-21). "Identifying The Tech Leaders In LTE Wireless Patents". Forbes. Retrieved March 10, 2012. Second comment by the author: "Thus, any analysis of essential LTE patents should take into account more than ETSI declarations."

Further reading

External links

White papers and other technical information

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