Large-scale array antennas are commonly used in 5G, and traditional conduction test methods are no longer applicable. The 3GPP standard stipulates that the Over the Air (OTA) method must be adopted for the test of the Active Antenna System (AAS). At present, the 5G OTA test specification TS38.141-2 has not been frozen, resulting in bottlenecks in product certification tests, which hindered the commercial process of 5G AAS products.
In response to the above problems, ZTE and China Academy of Information and Communication Technology (hereinafter referred to as “CAICT”) proposed a test solution based on Rayleigh Optimal Sampling Element (ROSE). The test solution uses the 3GPP standard specification proposed by ZTE.
Firstly, the principle of non-destructive sampling is proposed theoretically, and the optimal non-destructive sampling scheme is also given. The test solution is validated for a 5G mmWave base station with a measurement error of less than 0.2 dB and a test time of less than 5 minutes. On the contrary, the common test system takes more than 20 hours. The ROSE system uses a small compact field darkroom from CAICT, and the test space is reduced to 45 m³ from 250 m³, please refer to figure 1 below, and also supporting the automated testing of 3GPP OTA specifications.
Total Radiated Power (TRP) is the most challenging indicator in OTA testing. According to the traditional Cellular Telecommunications and Internet Association (CTIA) OTA specification, the measurement is performed at a sampling grid of 15°, and serious error fluctuations occur in the large-scale array antenna test. Taking the common 16×8 array as an example, the error fluctuation exceeds 15 dB.
At present, the common solution of the darkroom adopts a 1° grid to guarantee the TRP measurement accuracy, which also introduces over 32 thousand sample points, leads to the measurement time exceed 20 hours, the test efficiency is unacceptable.
In addition, OTA indicators are generally measured in the far-field darkroom. The far-field distance is determined by the measured antenna aperture and signal frequency. For commonly used 5G millimeter-wave devices, the far-field distance is about 10 meters, while the Sub 6G base station far-field is more than 50 meters. ZTE proposed that the Rayleigh Optimal Sampling Element includes two methods: Rayleigh resolution sampling and normalized wave vector sampling.
This test solution theoretically proposes how to determine the non-destructive sampling grid algorithm, and how to reduce the sampling grid algorithm. It has the characteristics of non-destructive and high efficiency, and solves the key problems in the 5G multi-antenna system test. Compared with the traditional test method, the efficiency is improved by more than 300 times by reducing the sample size dramatically, the 1° grid requires over 32 thousand sample points, the Rayleigh resolution sampling method only uses 325 points, combined with the Rayleigh resolution sampling method, the Wave Vector Space method can reduce the sample points even more to 93, which provides the best test standard for 5G commercialization.
Detailed comparing data can be found in figure 2 below:
The successful development and verification of the ROSE test system proposed by ZTE and CAICT:
1. Achieve accurate, fast and low-cost RF indicator test of the 5G millimeter wave base station.
2. Significantly improve the accuracy and R&D production efficiency of the 5G millimeter wave base station.
3. Promote the maturity of 5G millimeter wave technology and accelerate the subsequent commercial progress and scale, which will deliver ultra-high speed access services for future 5G users.
The fast and low-cost features of the ROSE test system will greatly reduce the test cost of 5G mmWave, reduce the development time of 5G high-frequency system, and bring significant social benefits. The accurate and reliable 5G AAS base station measurement solution implemented by this test solution will effectively promote the application of 3GPP AAS test standards and promote the maturity of the 5G industry chain. The precise, fast and low-cost features of the ROSE test system will greatly reduce over 40% of the test cost of 5G mmWave, reduce the development time of 5G mmWave system from one day to 5-14 minutes, and the test space is reduced to 2-5 meters from 10 meters, and increase the efficiency by 300 folds.
Test time reduction will reduce the mmWave product’s time to market, and accelerate iteration of these products. Thanks to ZTE and CAICT’s new test method provide new options for equipment vendors, the whole telecommunication industry will benefit from this innovation.Subscribe to our daily newsletter Back