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Evolution of LTE Advanced eNodeB Radio Antennas MIMO technology uses multiple antennas installed at both the source (transmitter) and destination (receiver), to improve capacity and efficiency. As shown in the previous figure, more antennas equals more data stream layers. This results in a bigger data pipe to a single user or multiple data pipes to separate users, also known as multi-user (MU) MIMO. Massive MIMO takes MIMO to the next level. Today's MIMO deployments typically consist of up to eight antennas on the base station and one or two antennas on the receiver. This allows the base station to simultaneously transmit eight streams to eight different users or double down and send two streams to four users. Massive MIMO scales to dozens or hundreds—theoretically thousands—of antennas, providing capabilities and benefits that include the following: • Vastly improved capacity and reliability • Higher data rates and lower latency • Better connections (especially with the challenging higher frequencies to be used for 5G) • Less intercell interference • Greater efficiency and better signal coverage enabled by beamforming The next figure illustrates how an AAS/full-dimension (FD) MIMO base station can direct beams in both the horizontal and vertical directions. This operation dynamically points the antenna pattern on a per-user basis, providing a better link and higher capacity to that user. In turn, this allows him to offload his traffic and free the radio resources more quickly, which can then be used by others, resulting in a net increase in aggregate capacity for the entire cell. Antenna Beam Forming The next figure below illustrates how AAS uses beam steering to provide end-to-end Fixed Wireless Access (FWA) connectivity to Customer Premise Equipment (CPE) located in commercial buildings and residential homes. 5G End-to-End Fixed Wireless Access (FWA) Networking Using Beam Stearing One of the obvious advantages of 5G FWA is its ability to support very high peak data rates without requiring dedicated fixed facilities for each individual user. To enable higher peak data rates and greater system capacity, FWA radios will make use of new higher frequency bands from 24GHz up to 42GHz and potentially even higher. Using larger antenna arrays provides additional beamforming to overcome more severe propagation challenges encountered at mmWave frequency ranges. These arrays can have hundreds of elements but due to the short wavelength are extremely compact. For example, a 64-element antenna array at 30GHz is only 40mm x 40mm. Large arrays provide very focused beams that can be redirected in less than a micro-second. In addition, the large phased array can act as a single array or as multiple independent subarrays with unique beams directed to service multiple user terminals simultaneously on the same frequency resource. The following figure shows a block diagram of the 2x2 RF front-end modules in the per-antenna RF subsystem of an AAS antenna array that comprises an AAS cell tower. | 5 | Azimuth (Horizontal) Beamforming AAS/FD-MIMO Base Station Go in Depth Learn more about 5G FWA systems: • 5 Things to Consider When Designing FWA Systems • 5G Fixed Wireless Access Array and RF Front-End Trade-Offs (Microwave Journal, Feb. 2018) • Delivering 5G mmWave Fixed Wireless Access (EDN, Sept. 2017)

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