In LTE-U, LTE technology over an unlicensed band is paired with a "licensed" LTE signal as an anchor preserving the necessary signaling and handshaking required for a reliable connection.

The thirst for greater bandwidth (and higher data speeds) for our wireless world is unquenchable.

The cellular industry has moved from 2G to 3G and now 4G to offer higher capacity, faster downloads, and better user experience. 4G is enabled through LTE technology that has progressed maximum download speeds from 100Mbps (3GPP Category 3) and to 300Mbps (Cat 6) last year.

This year, LTE-A (Cat 9) speeds of up to 450Mbps are enabled by aggregating three LTE bands for the higher speed.

Operators have to utilize all of their spectrum resources to meet growing market needs. Now, there is a new technology that aggregates a conventional “licensed” LTE signal and a second, LTE-U, signal employing “unlicensed” spectrum to effectively augment capacity.

LTE-U and Wi-Fi signals
Qualcomm claims that LTE-U is less disruptive to Wi-Fi than other Wi-Fi signals in the same band.

Qualcomm has demonstrated that LTE-U can fairly coexist with Wi-Fi and that the two can work even better together. In counties such as the U.S., China, Korea and India, LTE-U can be deployed based on existing REl-10/11/12 standard along with fair coexistence protocols that Qualcomm calls Carrier Sensing Adaptive Transmission (CSAT). In this scheme, LTE eNodeB base stations (usually small cells) share 5GHz spectrum with Wi-Fi on a time division multiplexed schedule, based on the eNB's dynamic assessment of available bandwidth slices and Wi-Fi traffic density.

For deployments in regions such as Europe and Japan, who have specific channel occupancy requirements called Listen Before Talk (LBT), new standard is needed (see chart). The global wireless standards body, 3GPP, is preparing release 13 that addresses LBT requirements. This version of LTE-U is also known as License-Assisted Access (LAA) LTE.

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