Penetration loss test analysis of several common objects in 5G frequency band

With the development of mobile Internet communication technology and user needs, more and more mobile services are taking place indoors. Especially in the 5G era, more than 85% of services will take place in indoor scenarios, and the importance of 5G indoor coverage is gradually becoming more prominent.

With the development of mobile Internet communication technology and user needs, more and more mobile services are taking place indoors. Especially in the 5G era, more than 85% of services will take place in indoor scenarios, and the importance of 5G indoor coverage is gradually becoming more prominent.

The link budget is the basis of network planning and is of great significance to the evaluation of network coverage. In the process of link budget calculation, the accuracy of the penetration loss of objects directly affects the calculation results. Therefore, in order to do indoor coverage planning, It is particularly important to study the penetration loss of various indoor objects to accurately evaluate the network coverage capability. Literature 1 gives the calculation formulas for the penetration loss of several common objects in the 5G frequency band, but does not consider the influence of thickness and environment on the penetration loss; References 2-5 test and analyze the penetration loss of objects in the low frequency band. However, the number of indoor object samples given is small, and the penetration loss of the test object in the 5G frequency band is not mentioned, so it has limited effect in practical applications.

In the process of testing and research, this paper expanded the number of samples of the test objects, and measured the penetration loss of several common objects in the 5G frequency band, and obtained the penetration loss of these types of objects in the 5G frequency band. The analysis and research were carried out to obtain the influence of frequency band, material and thickness on penetration loss.

1 Test method

In this test, three frequency bands, 2.1 GHz, 2.6 GHz, and 3.5 GHz, are selected to measure the penetration loss of several common objects. These three frequency bands are the main frequency bands currently covered by 5G. The common objects selected are partition walls and doors. , glass, plasterboard. Since the 5G system has not yet been deployed in the 2.1 GHz frequency band, this time, by testing the 4G penetration loss of the object in the 2.1 GHz frequency band, the penetration loss of the object in 5G is estimated. The test tools mainly include 5G test mobile phones, test software and test computers. For some places without 5G coverage, in order to complete the test work, the signal source is used instead of the antenna, and the spectrum analyzer is used instead of the test mobile phone and the test computer.

In order to ensure that the test data is accurate and closer to reality, the selected test sites have indoor antenna coverage, the test object is directly opposite the transceiver antenna, and the test object is within 2 m from the transceiver antenna, so as to ensure that the signal can be directed to the test object. Diffraction and reflection almost do not occur, and the test data is more accurate. This test method adopts fixed-point test. During the test process, since the signal strength is constantly changing, in order to obtain the RSRP value inside and outside the test object, the test time of each test point is set as 2 minutes, and then the measured signal The intensity RSRP values ​​are averaged to obtain the average RSRP value, and the penetration loss of the test object is calculated according to the average RSRP value inside and outside the test object.

In the process of penetration loss inside and outside the test object, first lock the test mobile phone in the indoor test frequency band, the tester is close to the test object at the inner and outer positions of the test object, then raise the test mobile phone with one hand, and record the data with the other hand. Ensure that the mobile phone has been unobstructed and the height is consistent, as shown in Figure 1. After the test is completed, record and confirm the test data.

Penetration loss test analysis of several common objects in 5G frequency band
Figure 1 The tester’s standing position inside and outside the object

2 Test results

This study selected typical office buildings, office buildings, government offices, large venues, industrial parks and other scenarios in Zhengzhou, and then conducted penetration loss tests on different types of doors, partition walls, and glass based on fixed-point tests. Table 1 shows the penetration loss test results of objects.

Penetration loss test analysis of several common objects in 5G frequency band

3 Test analysis

It can be seen from Figure 2 that the penetration loss is positively correlated with the frequency band. For the same object, the higher the frequency band, the greater the penetration loss. It can be seen from Figure 3 that the penetration loss is also related to the material and thickness of the object. Objects of different materials have different penetration losses in the same frequency band. For example, a 24 cm brick wall and a gypsum board wall have different penetration losses in the same frequency band; while objects of different thicknesses have different penetration losses in the same frequency band. In the frequency band, the penetration loss increases with the increase of thickness. For the same frequency band, the penetration loss of a 24 cm brick wall is smaller than that of a 30 cm brick wall.

Penetration loss test analysis of several common objects in 5G frequency band

In addition, the test also found that when the penetration loss of the object is small, such as 3.5 GHz penetration loss is less than 15 dB, the frequency difference has little effect on penetration loss, and the difference is generally within 2 dB, such as ordinary hollow doors and tempered doors. Glass, their penetration loss differences at 2.1 GHz, 2.6 GHz, and 3.5 GHz are very small; but when the penetration loss of the object is larger, that is, when the penetration loss at 3.5 GHz is greater than 15 dB, the effect of frequency differences on penetration loss is compared. Obviously, such as steel thermal insulation fire doors and 24 cm concrete walls, the difference in penetration loss between 2.1 GHz and 3.5 GHz is more than 5 dB.

4 Test summary

This paper gives the measured values ​​of penetration loss of several common objects in the 5G frequency band, and analyzes and summarizes the penetration loss characteristics of the 5G frequency band based on the test data. By understanding the penetration loss characteristics of the 5G frequency band, not only the material of the object, but also the thickness of the object should be paid attention to when surveying and designing; when calculating the link budget, the penetration loss of the object in 5G can refer to the data in Table 1; For the penetration loss of some uncommon objects in the 5G frequency band, the penetration loss of these objects can be estimated according to the characteristics of the penetration loss. Therefore, this article has very important reference and guiding significance in practical engineering.

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Author: Yoyokuo