System EVM Characterization and Coverage Area Estimation of 5G Directive mmW Links

Abstract

RF performance of 5G new radio (NR) millimeter wave (mmW) system will be characterized over-the-air (OTA) in 3GPP 5G NR performance and type approval testing. Total system Error Vector Magnitude (EVM) performance has not been standardized in 3GPP since mobile and base stations are certified separately. In this paper, we extend the OTA measured system EVM concept to cover EVM performance testing with beam steering for 5G mmW radio link. We show that the OTA measured system EVM inside of an electromagnetic compatibility (EMC) chamber can be directly converted to an expected link range, and this has been verified with outdoor measurements. The EVM measurements are performed for a set of beamforming directions to form an expected coverage area. The OTA measured system EVM results confirm that the 5G mmW Proof-of-Concept radio supports 5G NR 16-QAM and 64-QAM modulations as well as 256-QAM modulation, which is currently specified for sub-6 GHz, only. The maximum estimated range of the 5G PoC mmW link is 840 m with 16-QAM modulation and 150 m with 256-QAM modulation. The estimated cell coverage with ±15 degrees beam steering varies from 205 000 m2 to 6 500 m2 using 16-QAM and 256-QAM modulations, respectively. Usable beam width (BW) of the transceiver array is dependent on the system EVM requirement. It varies based on modulation, coding, and link distance. This phenomenon is called cell breathing, which is similar to any cellular system with adaptive coding techniques, although BW might be much narrower in 5G mmW systems.

Combined Sidelobe Reduction and Omnidirectional Linearization of Phased Array by Using Tapered Power Amplifier Biasing and Digital Predistortion

“…The measured EVMs in the main lobe are improved from 8.3% and 8.9% to 4.9% and 4.8% with DPD. The achievable EVM values are limited also by other RF nonidealities, such as IQ-imbalance and phase noise [41]. The measured main-lobe efficiencies are above η EIRP = 22% and total radiated efficiencies are better than η TRP = 2.8% with DPD.…”

The Role of Millimeter-Wave Technologies in 5G/6G Wireless Communications

“…Also, a few new OTA parameters have been investigated for better describing the performance of the AAU systems. For instance, Leinonen et al demonstrated the use of the EVM-based beamwidth of the radiated beam for characterizing the coverage of the mmWave BSs [166]. A beam EIRP (BEIRP) was proposed to reflect a certain beam radiated transmit power in multibeam mmWave AAU system [167].…”

Implementation Challenges and Opportunities in Beyond-5G and 6G Communication

“…That is due to difficulty of reliable measurement interfaces when even very small parasitics have a major impact on the result and antennas need to be either integrated on-chip or otherwise with very small parasitic load to RF electronics. Fortunately, with advanced OTA methods it is possible to evaluate link performance and even noise figure, other RF parameters, and maximum link ranges based on Error Vector Magnitude (EVM) or other means for the whole system [55]. Of course, extracting details from the whole system, including both receiver and transmitter, is not straightforward and information of separate parts from stand-alone probe measurements is highly preferred.…”