LTE Advanced in Unlicensed Spectrum

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Extending benefits of LTE Advanced to unlicensed spectrum.

LTE in unlicensed 5GHz spectrum is ideal for new small cell deployments and offers higher capacity and coverage and enhanced user experience in a unified LTE network.

Extending LTE Advanced to Unlicensed Spectrum

May 14, 2018


LTE Unlicensed has Multiple Flavors

The four main options for deploying LTE Unlicensed depends on the specific deployment scenario and the region: 


Based on 3GPP Rel. 12, LTE-U targets early mobile operators deployments in USA, Korea and India, with coexistence tests defined by LTE-U forum


Defined in 3GPP Rel. 13, LAA (Licensed Assisted Access) targets deployments in Europe, Japan, & beyond.


Defined in 3GPP Rel. 13, LWA (LTE - Wi-Fi link aggregation) targets deployments where the operators already has carrier Wi-Fi deployments.


MulteFire™ broadens the LTE ecosystem to new deployment opportunities by operating solely in unlicensed spectrum without a licensed anchor channel

Best Performance by Aggregating Spectrum

LTE-U and LAA combines LTE in unlicensed spectrum (5GHz) with LTE in the licensed band through carrier aggregation in the downlink. This aggregation of spectrum provides for a fatter pipe with a more responsive user experience. By also maintaining a persistent anchor in the licensed spectrum to carry all of the control and signaling information, the user experience is both seamless and reliable.


For operators with carrier Wi-Fi deployments there is an alternative called LTE – Wi-Fi link aggregation (LWA) that bring similar benefits from aggregating licensed and unlicensed spectrum in the downlink. LWA also utilizes LTE in licensed spectrum as an anchor, but in the unlicensed spectrum LWA instead utilizes Wi-Fi in 2.4 GHz and 5 GHz.

LTE-U and LWA supported in Snapdragon X12 LTE Modem

LTE-U, along with LWA, is supported by the Qualcomm® Snapdragon™ 820 processor with X12 LTE , as well as by the discrete Snapdragon X12 LTE modem. This is a good example of how multiple technologies are required to make the best use of all spectrum: LTE Advanced carrier aggregation, tri-band Wi-Fi with 802.11n, 802.11ac MU-MIMO and 802.11ad, and now also LTE-U and LWA.

Going above and beyond minimum requirements

To ensure fair coexistence, apart from adhering to spectrum regulations, LTE unlicensed will support relevant standards with coexistence features, as well as go through rigorous conformance testing before commercialization. LTE-U coexistence specifications have been published by LTE-U forum, and implemented with features such as CSAT. 3GPP defines LAA as part of release 13, and will also develop coexistence/performance requirements and tests.

LBT – Listen Before Talk; CSAT – Carrier Sensing Adaptive Transmission; LAA – Licensed Assisted Access

Fair Wi-Fi Coexistence a Key Design Principle

Fair Wi-Fi coexistence is a key principle in LTE unlicensed design - if we replace one Wi-Fi node with LTE-U or LAA, the remaining Wi-Fi nodes should not be negatively impacted, in many cases they are actually better off. A key benefit of LTE-U and LAA is better performance than carrier Wi-Fi through extended coverage and higher capacity, especially for dense deployments. The combined effect is that an operator switching from Wi-Fi to LTE-U/LAA will get more than 2X performance increase without negatively impacting neighboring Wi-Fi.


Qualcomm has demonstrated fair coexistence at many global events such as CES and MWC and performed extensive over-the-air testing in the lab and in the field. Extensive Industry collaboration across the Wi-Fi and mobile industries are helping to further refine coexistence, to ensure that LTE Unlicensed is a good neighbor to Wi-Fi.

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