Gigabit LTE is an important milestone for operators as they are progressing on the road towards 5G. Achieving Gigabit LTE is a big challenge for operators, as it requires additional licensed spectrum that in most cases is limited. A previous survey showed that only 16% of global operators can achieve Gigabit LTE solely on licensed spectrum.
Unlicensed spectrum in the 5GHz range seems therefore to be a key in the solution and multiple technologies are promising, including LTE-U and LTE-LAA.
Why do we need Gigabit LTE and what is it?
Operators are facing an enormous challenge due to the increasing demand from their subscribers for improved performance of the mobile connectivity.
The latest Ericsson mobility report forecasted that smartphones will be using 11 Gigabytes of data a month by 2022. Such numbers require bigger data speeds (throughput) to be supported by operators.
Gigabit LTE is defined as the capability of the network to support peak data rates of 1 gigabit per second (1 Gbps). While initial deployments are focusing on supplemental downlink mode only, full two-way operation is in the roadmap as part of carrier aggregation.
How can Gigabit LTE be achieved?
The end-user throughput is dependent on spectrum. As licensed spectrum is simply not available for operators to reach gigabit-per-second throughput, a solution is the aggregation of licensed with unlicensed spectrum to create a high capacity radio channel.
This solution needs to be fair, as the unlicensed spectrum is used by Wi-Fi, so the aggregation should not introduce problems to Wi-Fi networks.
Gigabit LTE technologies
Multiple technologies have emerged that address the Gigabit LTE challenges. The most important are LTE-U, LTE-LAA, LWA and MulteFire.
What is LTE-U?
LTE-U is a broad term for LTE Unlicensed, detailed in 3GPP’s release 12. LTE-U targets deployments in USA, Korea, India etc. as in these countries a protocol called Listen-Before-Talk (LBT) that was designed to ensure fair coexistence is not enforced as a regulatory requirement.
LTE-U, as the name suggests, works by augmenting a carrier’s LTE service by utilizing the unlicensed spectrum in the 5GHz range.
What is LTE-LAA?
LTE-LAA can be considered a subset of LTE-U and was defined in 3GPP’s release 13. LTE-LAA targets deployments in Europe, Japan and other countries, as it supports a contention protocol known as listen-before-talk (LBT) that is mandatory in some European countries.
What is LWA?
LWA stands for LTE-WLAN Aggregation. Unlike LTE-U and LTE-LAA, LWA configures the network to utilize both networks simultaneously. This has the important advantage that hardware changes are not necessary for unlicensed LTE transmission to coexist with WiFi signals.
LWA can split a single data flow, accounting for both channel conditions, to use both LTE and WiFi channels for all applications. That brings increased performance and quality of service as the LTE signal is not competing with WiFi but rather using WLAN connections seamlessly to increase capacity.
LWA reduces network deployment costs (compared to LTE-U and LAA), while also simplifying WLAN operation.
What is MulteFire?
MulteFire is based on 3GPP R13 LAA, but is different in the sense that unlike LTE-U/LAA, MulteFire is expected to operate solely in unlicensed spectrum without requiring an LTE anchor in licensed spectrum.
The MulteFire Alliance will propose changes to the 3GPP standard required to operate LTE without an anchor in the licensed spectrum. As 3GPP evolves LTE and the next generation mobile cellular technology, MulteFire will also evolve and stay aligned with 3GPP to leverage these enhancements.
MulteFire is ideal for local area small cell deployments, especially for dense environments for indoor and outdoor locations. It is envisioned to be deployed by small businesses, enterprises, venue owners, Internet service provider/cable companies and mobile operators in various deployment models such as coverage islands, or bigger clusters for mobility (within the clusters)
How Gigabit LTE avoids competition with Wi-Fi
The new technologies are design to co-exist with Wi-Fi and not compete with it.
Both LTE-U and LTE-LAA coexist well with Wi-Fi, as they dynamically select the unused channels with the least interference, thus avoiding Wi-Fi.
In case no clear channel exists, both LTE-U and LTE-LAA adjust on-off LTE cycling by sensing other users (LTE-U) or sensing channel availability by a region specific policy (LTE-LAA)
Gigabit LTE deployments & other info
Gigabit LTE related organizations
The technologies mentioned above are developed and defined by LTE-U Forum, 3GPP, Wi-Fi Alliance, IEEE, Multefire Alliance.
These organizations have participating members from device & industry manufacturers and mobile operators and organize frequent workshops with broad participation.
Gigabit LTE Deployments
Here are some recent deployments of Gigabit LTE reported in the news lately:
- Telstra, Australia’s leading mobile network operator, was the first to officially achieve gigabit speeds and launch a commercial Gigabit LTE network using their licensed spectrum at the start of the year.
- AT&T in the US conducted trial in downtown San Francisco, Calif. using LAA achieving 750Mbps throughput
- T-Mobile US
- Conducted trial in Los Angeles Calif. with LTE-LAA achieving 741Mbps throughput
- Deployed live LTE-U in networks in Bellevue Wash., Brooklyn N.Y., Dearborn Mich., Las Vegas Nev., Richardson Texas, Simi Valley Calif.
- Verizon Wireless in the US deployed commercially LTE-LAA achieving 953 Mbps downlink in Boca Raton Fla.
- SK Telecon in Korea achieved a 1 Gbps (exact number not known) downlink throughput in an indoor environment, by aggregating one 20MHz LTE channel with three 20 MHz Wi-Fi channels.
- Telecom Italia (TIM) demoed a downlink up to 1 Gbps on a live network using LAA. This solution is planned to be deployed in Milan and Turin and is considered very effective for hot spot coverage (stadiums, malls, parks, squares)
- MTS Russia conducted their first successful live trial during the summer with a commercial small cell product of Rel-13 Licensed Assisted Access (LAA) technology from Ericsson in Russia.
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