Time-Division Long-Term Evolution

Time-Division Long-Term Evolution (TD-LTE), also referred to as Long-Term Evolution Time-Division Duplex (LTE TDD),^[1] is a 4G mobile-telecommunications technology and standard co-developed, since late 2007, by Datang Telecom, China Mobile, Huawei, ZTE, Nokia Siemens Networks, Alcatel Shanghai Bell, Qualcomm, ST-Ericsson, Leadcore, etc.^{[citation needed]} It is one of two variants of the 3GPP Long Term Evolution (LTE) technology, the other being Frequency-Division Long-Term Evolution (FD-LTE or LTE FDD). Likewise, TD-LTE-Advanced is an LTE Advanced time-division variant, an evolutionary upgrade version of TD-LTE.

History

The TD-LTE project was approved on 26 December 2007, at the state council executive meeting of the New Generation Broadband Wireless Mobile Communication Networks, along with TD-SCDMA.^[2]

Deployments and coverages

• In early 2011, China Mobile invested CNY 1.5 billion on the '6+1 Scheme', in which large-scale TD-LTE field trial was conducted in 6 cities including Shanghai, Guangzhou, Shenzhen, Hangzhou, Nanjing, and Xiamen.^[3] Each of the cities deployed around 500 TD-LTE femtocell base-stations. A demonstration network was set up in Beijing. In Taiwan, China Mobile built a TD-LTE network in Taipei, for testing purposes for the local GSM operator Far EasTone, .^[4]
  • As of September 2011, China Mobile has sealed agreements with 32 international telecom carriers, for launching 27 TD-LTE trial networks.^[5]

• On 10 April 2012, Airtel launched 4G services using TD-LTE technology in Kolkata, becoming the first company in India to offer 4G services. Since the initial launch, Airtel also launched 4G in Bangalore, Pune and Chandigarh.^[6]

• On 30 December 2012, Dialog Axiata launched Fixed 4G services using TD-LTE technology in Sri Lanka. Sri Lanka's first & only Fixed 4G LTE Broadband operator is Dialog.

• On 29 October 2013 Sprint Corporation formally introduced Spark, with speeds of 50-60Mbit/s utilizing TD-LTE.^[7] Launched 11 November 2013 in New York, Los Angeles, Chicago, Miami, and Tampa ^[8]

Technical highlights

TD-LTE transmissions travel in both directions on the same frequency band, a methodology formally known as "unpaired spectrum." It is distinct from "paired spectrum," where two frequencies are allocated, one for the transmit channel and the other for the receive channel (formally called "Frequency Division"). "Time Division" means the receive channel and the transmit channel take turns (i.e. divide the time between them) on the same frequency band. The time divisions are asymmetric, meaning that more time-slots are allocated to data going from the tower to the phone than from the phone to the tower.^[9] The usage patterns of the future (fewer phone calls, more Internet) are asymmetric in this manner.

The frequency bands used by TD-LTE are 3.4–3.6 GHz in Australia^[10] and UK,^[11] 2.57−2.62 GHz in the US^[12] and China,^[13] 2.545-2.575 GHz in Japan,^[14] and 2.3–2.4 GHz in India^[15] and Australia.^[10] The technology supports scalable channel bandwidth, between 1.4 and 20 MHz.^[16] A typical range is up to 200 metres (660 ft) indoors on a 2.57–2.62 GHz radio frequency link.^[17]

Equipment/component availability

Vendors that announced end-user support include Nokia and ZTE. Nokia announced a TD-LTE/FD-LTE/HSPA+/TD-SCDMA/EDGE multi-mode netbook based on the ST-Ericsson M7400 MPSoC.^[18] ZTE announced V2, a TD-LTE/TD-SCDMA/GSM multi-mode dual-standby smartphone.^[19]

Apart from the ST-Ericsson M7400 MPSoC mentioned above, other vendors which announced chipset support include Innofidei, which together with the Hong Kong Applied Science and Technology Research Institute announced the Warp drive 5000, a TD-LTE/FD-LTE dual-mode baseband processor^[20] and Sequans Communications which announced the SQN3010, a similar chip.^[21]

The following TD LTE Tablets and Phones have also been announced in China^[22]

• HTC TD 101:^[23] LTE 2500-2690 MHz
• LG Optimus Vu 2 Plus: TD-LTE Frequencies unknown
• ZTE U9810:^[24] LTE 2100 (#1), LTE 1800 (#3), LTE 2600 (#7), TD-LTE 1900 (#39), TD-LTE 2300 (#40), TD-LTE 2500 (#41)
• ZTE V9800: LTE 2300(#40), LTE 2600 (#7)
• Xolo LT900: LTE 2300 (#40)
• Huawei Ascend D2 TL: TD-LTE Frequencies unknown
• Acer TD-LTE Tablet:^[25] 2300 MHz (#40), 2600 MHz (#38)

Some models of the Apple iPhone 5c and iPhone 5s also supports TD-LTE,^[26] those are currently sold in Hong Kong and also India^[27]

Both Qualcomm and nVidia have announced TD-LTE microchips

• Qualcomm WTR1625L (RF360 software): 40 LTE frequency band transceiver ^[28]
• nVidia Tegra 4i (i500 software): TD-LTE frequency Bands 33 to 41 ^[29]

References

External links

Wikibooks has a book on the topic of: Nets, Webs and the Information Infrastructure

• Global TD-LTE Initiative Portal