Feature: RF design
Figure 1: The evolution of cellular wireless communication standards
New OTA RF test methodology Te 5G networks are already rolling out, so it’s important for operators to have the methodology for RF testing of 5G mmWave over the air (OTA) standards for cellular devices. 5G massive technologies such as multiple-input/multiple-output (MIMO) devices require OTA calibration and RF measurement in a phase coherent test system. Device and antenna array size make it very challenging to measure mmWave RF performance in a true distant-field OTA environment due to the large distances involved, which also impact the link budget and test system cost. Te mmWave midfield (MF) OTA RF test methodology is designed
to minimise size and cost. Tis advanced system can perform antenna array phase coherence calibration and support RF parametric measurement per third Generation Partnership Project (3GPP) conformance test specifications. Te mmWave RF band offers huge bandwidth, unmatched by
the frequency spectrum available today for most fixed and mobile communication and radar sensor systems. Consequently, mmWave frequencies are currently being exploited for the development of emerging broadband, high-speed and high-resolution RF systems. For example, the 5G of the wireless cellular technology is expected to operate in the mm-wave band, so as to overcome the limitations of 4G. Unlike 4G, 5G networks and systems will de facto be optimised for both human-centric communication (HCC) and machine-type communication (MTC). Terefore, 5G has the potential to be the key enabler of emerging bandwidth, speed and latency-critical HCC and MTC applications, such as remote medical diagnosis and surgery, vehicle-to-vehicle and vehicle-to-infrastructure communication for autonomous driving, wireless transmission of uncompressed ultra-HD videos, augmented and virtual reality, tactile internet and a multitude of Internet of Tings (IoT) applications which provide smart solutions, such as health, energy, city, transportation, industry and the home. Te newly-developed 5G cellular networks and telephone devices
entered their early production phase in 2019, whilst several RF test solutions are being evaluated for the next phase of large-scale production. Tus, the cellular 5G system will play a critical role in meeting the bandwidth requirements of mobile customers from 2020 onwards. Te ubiquity of smartphones, particularly in developed markets, continues to dramatically increase mobile data consumption. As the load on networks rises, backhaul (connection of the base station to the core network) must keep pace. For 5G backhaul, airborne tests represent a new set of test challenges compared to products below 6GHz.
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Each system is different, and the set of RF interference
challenges varies with each combination of cellular device, system development and deployment. Tis diverse range of testing requires calibrated noise sources and programmable noise generators that are highly customisable. Tus, as industry moves toward these higher speeds and new spectrum, new components are required to build the radios necessary for 5G deployment. Devices are becoming more tightly-integrated, more MIMO devices are being incorporated into designs, and high-frequency phased-array systems are being deployed. Tese new devices require new testing techniques in the lab, in production and in the field, to ensure the high-data rates being quoted are reliable in presence of real-world noise and interference. Te OTA RF test approaches are becoming the standard for testing
5G new radio (5G NR) user equipment (UE) and base stations, especially in mmWave. Te move to higher frequencies, including sub-6GHz Frequency Range 1 (FR1) and mmWave Frequency Range 2 (FR2), arises in large part due to crowding of the RF spectrum. Terefore, for these reasons, 5G NR networks and user devices require advanced technologies and OTA measurement methods to accurately characterise performance.
Figure 2: Noise power ratio testing
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