LTE Advanced continues to evolve toward LTE Advanced Pro with the objective to connect new industries, enable new services and empower new user experiences, pushing the boundaries and capabilities of LTE toward 5G. Licensed Assisted Access (LAA) is a key LTE Advanced Pro feature that extends the benefits of LTE to unlicensed spectrum, not only to help satisfy the increasing demand for data, but also enabling more operators to offer Gigabit-class speeds to end-users through the aggregating of unlicensed spectrum with licensed—a glimpse of the 5G future.
A major LAA milestone was achieved when Deutsche Telekom and Qualcomm Technologies, Inc. conducted the world’s first LAA over-the-air trial November 2015 in Nuremberg Germany. The trial was completed on November 20th after a three-week period of extensive testing that spanned a wide range of network at indoor and outdoor topologies using multiple LAA small cells, Wi-Fi access points, LAA devices, Wi-Fi devices and LWA devices (LTE Wi-Fi Link Aggregation). Deutsche Telekom provided the licensed spectrum for the LTE anchor carrier, augmented with 5 GHz unlicensed spectrum in a test network deployed over Qualcomm’s Nuremberg campus.
The trial LAA test equipment was designed and deployed by Qualcomm Research, the R&D division of Qualcomm Technologies Inc. The LAA test equipment complies with current 3GPP Release 13 development and is particularly designed to meet global unlicensed band regulations, including “Listen-Before-Talk” features using extended Clear Channel Assessment procedures and channel occupancy limits required in regions such as Europe and Japan.
An extensive set of tests were performed, exemplified here with two examples, to demonstrate LAA’s extended coverage and increased network capacity compared to Wi-Fi 802.11ac, as well as seamless mobility with opportunistic aggregation of unlicensed spectrum during drive tests. The test conditions in the unlicensed spectrum were the same for both LAA and Wi-Fi, including antennas, transmit power, channel frequency, speed, 2x2 MIMO, etc.
Test case example showing how LAA’s fair coexistence improves the performance for everyone.
The first example from the outdoor OTA trial that shows that LAA is an excellent neighbor to Wi-Fi; two out of the four outdoor Wi-Fi access points are replaced with LAA small cells to demonstrate the LAA impact on the other two Wi-Fi access points; as shown, all users are better off with LAA as a neighbor and the remaining Wi-Fi users experience a much higher throughput. In the complete set of test cases, the fair coexistence between LAA and Wi-Fi in unlicensed 5 GHz bands was demonstrated under different radio conditions and for a varied number of interfering nodes.
Test case example showing coverage benefits of LAA compared to Wi-Fi outdoors.
The second example shows the LTE and Wi-Fi coverage in unlicensed spectrum using a slow- moving van along a drive route through the Nuremberg campus. Not only does LAA reach farther to provide longer range in general, it also consistently provides higher user throughput speeds over a larger portion of the test route.
In addition to these examples a wide range of test cases were performed including: indoor and outdoor deployment scenarios, different combinations of LAA, LWA and Wi-Fi, single and multiple users, stationary and mobile users, handover between multiple small cells and a range of different radio conditions.
Following the success of the OTA LAA trial with Deutsche Telekom, the Qualcomm Research team plans to expand the OTA LAA network with new features and enhancements as LAA system design and standardization progress, and to demonstrate LAA enhancements at MWC 2016 such as link aggregation with unlicensed spectrum also in the uplink. For more details on LAA, see our website.