Qualcomm Brings LTE-U to Small Cells
The original champion of running LTE in 5 GHz unlicensed spectrum bands, Qualcomm, is taking its support for the controversial technology to the next level by integrating it into its latest small cell chipsets and RF transceivers for both small cells and mobile devices.
Qualcomm Inc. (Nasdaq: QCOM) announced its LTE-U roadmap ahead of Mobile World Congress, where it will be demoing how the technology can co-exist with WiFi without interference, a main concern of the WiFi camp. (See Jury Still Out on LTE-Unlicensed and Why Some Operators Think LTE-U Is Rude.)
This marks the first integration of LTE-U in a small cell system-on-a-chip (SoC) in Qualcomm's FSM99xx line that will become available in the second half of the year. The SoCs support 3G, 4G and 802.11ac/n WiFi and are designed for outdoor, enterprise and small to midsized business access points.
The chipmaker is also introducing the FTR8950, an RF receiver for small cells, and the WTR3950, an RF receiver for mobile devices, both of which support LTE in 5 GHz bands. Qualcomm says the WTR3950 can support up to 40 MHz intra-band contiguous carrier aggregation in the 5 GHz bands. Both will begin sampling in the second half of the year.
Neville Meijers, vice president of business development and head of Qualcomm's small cell program, says that LTE-U brings about three main advantages: First is better propagation yielding better coverage and throughput. The range of an LTE-U small cell would largely mirror its licensed anchor, but Qualcomm says its tests show a 1.5 to two times larger radius for LTE-U downlink when compared to WiFi. Second, the operator only has to manage one network because WiFi is treated as just another band to aggregate under their licensed bands. Third, he suggests that quality of service will be much higher than on WiFi alone.
"All in all, we think LTE-U is a great way to enhance the use of small cells," Meijers says. "Given the fact that small cells use licensed technology in a more efficient way, the two go hand-in-hand."
Qualcomm has been doing over-the-air testing in its San Diego, Calif., headquarters in which multiple LTE-U and WiFi access points co-existed in the unlicensed spectrum under extreme load conditions. Meijers says that the trials not only showed that LTE-U fairly coexists with WiFI, but -- in many cases -- it actually improved performance for WiFi users by more efficiently using the unlicensed spectrum.
Interference is mitigated through the RF transceivers in a process called "adaptive duty-cycle." In markets like the US, China and Korea where there aren't strict regulations on the 5GHz band, Meijers says this should be enough to prove LTE and WiFi can co-exist. Here the technology can be deployed sooner using the 3rd Generation Partnership Project (3GPP) 's LTE Release 10, 11 or 12. In areas like Europe and Japan where there are stricter regulations on the spectrum, he says deployments will have to wait on release 13, which includes the "Listen Before Talk" (LBT) protocol, a change to the physical layer of LTE, to ensure there is no interference.
[In case you were wondering why there are different monikers for this technology -- LTE-U and LTE-Assisted Access (LAA) -- Meijers says LTE-U is for release 10, 11 and 12, but it becomes LTE-LAA when release 13 is ratified. The inclusion of LBT is the differentiator.]
Qualcomm expects to launch with carriers in the first half of 2016. Meijers wouldn't name names, but T-Mobile US Inc. has said it will go live with LTE-U by the end of the year with Nokia Networks and Ericsson AB (Nasdaq: ERIC), and Verizon Wireless and SK Telecom (Nasdaq: SKM) have also been vocal about the opportunity. (See T-Mobile Gets Small & Unlicensed With Nokia, Verizon Allocating $500M to Small Cells and Ericsson Preps LTE-U for Verizon, T-Mob & SK Telecom.)
In the meantime, Meijers might find himself spending most of his time this year convincing the naysayers that LTE-U won't cause interference on WiFi -- even with the demos, lab trials and protocols underway. The fact remains that many doubt what they've found in the labs will translate to actual deployments. He says Qualcomm is currently working with WiFi standards bodies, cable industry partners and WiFi-focused vendors on this sensitive issue. (See NTT DoCoMo, Huawei Prove LTE-U Works and T-Mobile Assembles LTE-Unlicensed Team.)
"At the end of the day, we're putting together specs and co-existence tests so that vendors have to ensure that they comply with that spec and co-exist within a WiFi environment," he says. "The last thing we want to do -- given that we are a major player at both sides of the business -- is to disrupt WiFi in unlicensed bands. That wouldn’t bode well for us or our carrier partners."
— Sarah Thomas, , Editorial Operations Director, Light Reading