At the 2019 China International Information Communications Exhibition, the Ministry of Industry and Information Technology held a 5G commercial launching ceremony with the three operators. On November 1st, the three operators have launched a 5G package, and China officially entered a 5G era. The 5G band is mainly divided into two technical directions, respectively, SUB-6GHz and high frequency millimeter wave (MMWave). SUB-6GHz is to develop 5G using bandwidth resources below 6GHz. Currently, commercial use is the SUB-6GHz band.
5G First, commerciality is commercially used in the SUB-6GHz band, thanks to the technology used by the SUB-6GHz band, which can be developed along with the 4G period, and the related radio frequency component industry chain is relatively mature. Although SUB-6GHz has an advantage, since the frequency band has limited resources, the industry has turned its eyes to millimeter waves. The relatively rich millimeter wave can achieve a larger bandwidth, which can achieve a multi-gigate data rate, support in intensive space reuse, and resolve key area bearer. In addition, millimeter wave has low delay characteristics that meet more demand in 5G. Thus, 3GPP is in the original SUB-6GHz band in the original SUB-6GHz band, in introduction of millimeter waves. Also accompanying 5G millimeters, it also means that the base station, radio assembly, etc. should also be adjusted accordingly.
The arrival of 5G millimeter waves will give birth to a large number of new network services and are expected to provide fast and low-delayed fixed wireless networks for industrial applications and campus deployments. During the entire process of developing to production, implementing a comprehensive and complete testing and measurement method is critical to the successful deployment of 5G. 5G products will be tested from design to commercial. Thus, 5G millimeter wave test is also one of the key links that 5G millimeter wave products can go smoothly into the market. NI believes that in order to achieve the data rate specified by the 3GPP Standard Commission, it is necessary to adopt a progressive method, not an iterative increase in existing infrastructure. In other words, there is a need for a new test method to meet millimeter wave tests under the 5G era.
From a technical point of view, whether the test equipment is in line with the carrier and 3GPP committee norms, which requires a number of different parameters, such as modulation quality, radio frequency amplifier linearity, receiver signaling ratio, transmitter efficiency, and the like. Due to the use of millimeter waves to transmit and receive signals, the test project faces many new challenges, such as communication, may encounter some of the propagation and signal path issues that have not been encountered by the current SUB-6GHz cellular technology, and in designing new components and semiconductors. The device will also encounter a lot of new problems.
At millimeter wave frequencies, the propagation loss is high, so the role of beamforming is more important. The beamforming test system for 5G needs to scan wide spectrum and can test maximum linear output and compression behavior of each path. The fast two-way multi-port switch test solution is a prerequisite for any 5G development and production test environment.
Under this requirement, it is very suitable for measuring and analyzing an OTA test of the actual performance characteristics of beamformer and FEM, which has become a new darling -3GPP in the millimeter wave test. Radio frequency consistency test of low frequency and high frequency. For the test of EVM, ACLR, OBUE and other indicators, OTA mode will be used.
OTA testing is implemented with test instrumentation through the "Over the Air", in addition to the test instrument, there is also an OTA Chamber, as well as OTA system software that implements DUT and test instruments. Using software assistance, the original equipment is upgraded to some extent, ensuring that the RF test equipment can supply market demand in time.
Specifically, OTA test will simulate the transmission scenario of the product's wireless signal in the air, and this test method can consider the internal radiation interference, product structure, antenna factor, radio frequency chip transmission algorithm, and even human body impact. In line, it is a comprehensive test method for verifying wireless product void performance in free space, very close to the actual use of the product.
However, 5G wants to use OTA testing, there is still some challenges. This is, the primary problem is that the test technology used in 5G and LTE has fundamental differences, such as millimeter wave frequencies, large-scale antenna arrays, beamforming and dynamic physical layer properties. In addition, OTA evaluation needs also take into account the problem of measurement distance.
Ni millimeter wave OTA reference solution is an OTA measurement system. The system includes a Ni high bandwidth millimeter wave vector signal transceiver (VST), high gain antenna, and radio frequency wave with high precision real-time motion control positioner. With the test sequence generator, the engineer can configure the solution to analyze the characteristics of the DUT beamforming function and verify it. The solution also includes a complete software that provides a range of visual options for measured data.
Beamforming Measurement Data Visualization (Source: Ni)
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