eiver in the AAS needs to be verified through an OTA interface. This includes a range of measurements for both the transmitter (maximum output power, EVM, ACLR, spurious emissions, intermodulation) and the receiver (sensitivity, dynamic range, band selection, in-band/ out-of-band/narrowband blocking, ACS). It is assumed that each transceiver will turn on for individual verification. Beam steering and beam tracking: Due to the high path loss and limited range of a mmWave wireless system, precise beam tracking and fast beam acquisition is required for mobile users. While in the antenna implementations of the existing cellular technol- logies static beam pattern characterization was sufficient, mmWave systems will further require dynamic beam measurement systems. In the post-production phase the following tests need to be conducted [18]: Antenna calibration: In order to accurately form beams, the phase misalignment between RF signal paths needs to be less than +1 5 degrees. This measurement can be performed for both passive and active antenna systems using either a phase-coherent receiver to measure the relative difference between all antenna elements. This is then compiled into a lookup table for the AAS to use as a reference for beam generation or to calibrate the internal self-calibration circuits inside the AAS unit. Transceiver calibration: Due to lack of RF ports on some massive MIMO systems, the individual transceivers will need to be calibrated using OTA techniques. This includes both transmitters and receivers. Five-point beam test: The AAS manufacturer specifies a reference beam direction, max- imum EIRP, and accordingly EIRP values for each declared beam. For conformance, the maximum EIRP point, and four additional points corresponding to the most extreme steering positions are measured. 744 Chapter 5 Functional tests: This is the final test performed on the completely assembled unit in production. It can consist of a simple radiated test, a five-point beam test, and aggregate transceiver functionality, s