LTE in unlicensed spectrum

LTE in unlicensed spectrum (LTE-U) is a proposal, originally developed by Qualcomm, for the use of the 4G LTE radio communications technology in unlicensed spectrum, such as the 5 GHz band used by dual-band Wi-Fi equipment.[1][2] It would serve as an alternative to carrier-owned Wi-Fi hotspots.

LTE in Unlicensed spectrum (LTE-U)

LTE-U would allow cellphone carriers to boost coverage in their cellular networks, by using the unlicensed 5 GHz band already populated by Wi-Fi devices. T-Mobile and Verizon Wireless have indicated early interest in deploying such a system as soon as 2016.[3] While cell providers ordinarily rely on the radio spectrum to which they have exclusive licenses, LTE-U would share space with Wi-Fi equipment already inhabiting that band – smartphones, laptops and tablets connecting to home broadband networks, free hotspots provided by businesses, and so on.

LTE-U is intended to let cell networks boost data speeds over short distances, without requiring the user to use a separate Wi-Fi network as they normally would. It differs from Wi-Fi calling; there remains a control channel using LTE, but all data (not just phone calls) flows over the unlicensed 5 GHz band, instead of the carrier's frequencies.[4]

License Assisted Access (LAA)

Ericsson uses the term License Assisted Access (LAA) to describe similar technology.[5] LAA is the 3rd Generation Partnership Project's (3GPP) effort to standardize operation of LTE in the Wi-Fi bands. It uses a contention protocol known as listen-before-talk (LBT), mandated in some European countries, to coexist with other Wi-Fi devices on the same band.[3][6] The 3GPP's final determination of LBT's requirements is still under standardization.

LTE-U Forum

In 2014, the LTE-U Forum was created by Verizon, in conjunction with Alcatel-Lucent, Ericsson, Qualcomm, and Samsung as members.[6][7] The forum collaborates and creates technical specifications for base stations and consumer devices passing LTE-U on the unlicensed 5 GHz band, as well as coexistence specs to handle traffic contention with existing Wi-Fi devices.

Controversy

The proposed use of LTE-U by mobile phone network operators is the subject of controversy in the telecommunications industry.[8] In June 2015, Google sent the Federal Communications Commission of the United States a 25-page protest, making an argument against LTE-U in highly technical detail.[6] Since Google's study did not use actual LTE-U equipment in the tests, some industry experts have called its conclusions into question, with one commenter calling the study "utterly artificial and speculative" and "embarrassing".[9]

In August 2015, the Wi-Fi Alliance and National Cable & Telecommunications Association (NCTA) also voiced opposition to LTE-U approval before more testing can be done, citing concerns that it would severely degrade performance of other Wi-Fi devices.[4] Also in August 2015, Qualcomm responded to the allegations made in Google's whitepaper in a detailed filing with the FCC.[10] Qualcomm stated that it conducted tests that were "specifically designed to replicate (to the fullest extent possible) the test scenarios cited in Google’s FCC filing, in particular", and that they "collectively showed that LTE-U coexists very well with Wi-Fi when LTE-U is operating either above or below Wi-Fi’s Energy Detect ('ED') level." Qualcomm explained that the divergence in results was caused by the fact that "the testing the opposing parties conducted for LTE-U/Wi-Fi coexistence below the ED level utilized extremely pessimistic and impractical technical assumptions", whereas Qualcomm's tests were conducted "using a far more realistic setup", including actual LTE-U equipment (versus signal generators in Google's study).

In May 2016, the New York City Mayor's Office sent a letter to the FCC, 3GPP, Wi-Fi Aliiance, and IEEE, expressing concern over LTE-U interference with Wi-Fi, given the City's broad investment in the technology.[11] These concerns were discussed at a public event.[12]

In June 2016 the Wi-Fi Alliance announced its co-existence test plan would be ready in August. In FCC filings, Qualcomm, Verizon and T-Mobile said they plan to use this plan, some with the aim of full implementation before the end of 2016.[13] However, in August 2016, Qualcomm demurred. “The latest version of the test plan released by the Wi-Fi Alliance lacks technical merit, is fundamentally biased against LTE-U, and rejects virtually all the input that Qualcomm provided for the last year, even on points that were not controversial,” said Dean Brenner, senior vice president of government affairs.[14] Qualcomm asserts that the plan biased in favor of Wi-Fi, and also that the testing regimen is extended to cover not just LTE-U, but also LAA, despite it already being a 3GPP standard.[14] Verizon also opposed the test plan, saying it was "fundamentally unfair and biased".[15]

Tests

In November 2016 Verizon, separate to the Wif-Fi Alliance coexistence plan, filed a Special Temporary Authority (STA) application with the FCC[16] to test 40 small cells in the 5Ghz band. According to a separate filing, Verizon will conduct the tests in Oklahoma City, Raleigh and Cary, North Carolina, and Irving, Texas.[17]

See also

References

  1. ↑ Richard Thanki (12 March 2014). "Jury Still Out on LTE-Unlicensed". Light Reading.
  2. ↑ Joey Jackson (6 January 2015). "CES 2015: Qualcomm takes on Wi-Fi with LTE-U". RCR Wireless News.
  3. 1 2 Sarah Thomas (6 May 2015). "T-Mobile Expects LTE-U to Feature Listen-Before-Talk". LightReading. Retrieved 28 August 2015.
  4. 1 2 Jon Brodkin (27 August 2015). "LTE over Wi-Fi spectrum sets up industry-wide fight over interference". Ars Technica. Retrieved 28 August 2015.
  5. ↑ Auri Aittokallio (10 February 2015). "Ericsson demonstrates live LAA for Verizon, SK Telecom, T-Mobile US". telecom.com.
  6. 1 2 3 Google, Inc. (11 June 2015). "Google whitepaper on LTE-U/WiFi coexistence". Retrieved 28 August 2015.
  7. ↑ "Home Page". LTE-U Forum. Retrieved 28 August 2015.
  8. ↑ Sarah Reedy (5 May 2014). "Why Some Operators Think LTE-U is Rude". Light Reading.
  9. ↑ Bennett, Richard. "Can LTE Unlicensed Steamroll Wi-Fi?". High Tech Forum. Retrieved 6 September 2015.
  10. ↑ Brenner, Dean. "REPLY COMMENTS OF QUALCOMM INCORPORATED". FCC.gov. Retrieved 4 August 2015.
  11. ↑ "NYC Mayor's Office letter" (PDF). 2 May 2016. Retrieved 5 August 2016.
  12. ↑ "Fast and Free New York's Vision for Public Wi-Fi Everywhere". New America Foundation. Retrieved 5 August 2016.
  13. ↑ Goovaerts, Diana (June 3, 2016). "LTE-U/Wi-Fi Co-existence Test Plan Coming In August". Wireless Week. Retrieved 5 August 2016.
  14. 1 2 Alleven, Monica (August 4, 2016). "Wi-Fi group claims 'extraordinary compromise' on LTE-U, but Qualcomm begs to differ". FierceWireless. Retrieved 5 August 2016.
  15. ↑ Dano, Mike (Aug 12, 2016). "Verizon: Wi-Fi Alliance's LTE-U test plan 'fundamentally unfair and biased'". FierceWireless. Retrieved August 16, 2016.
  16. ↑ Verizon 5 GHz Experiment Proposal
  17. ↑ Dano, Mike (Nov 11, 2016). "Verizon to test pre-commercial LTE-U small cells in unlicensed 5 GHz band". FierceWireless. Retrieved August 16, 2016.
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