Since 2013, the global TD-LTE network has entered a period of vigorous development, and domestic TD-LTE network deployment and development are also in full swing. At present, TD-LTE deployed in China mainly adopts the world's most advanced 8-channel technology, and the impact of antennas on network performance is more and more concerned. This article summarizes and analyzes the problems during the first phase of TD-LTE deployment and combines with the latest developments in the current antenna industry to provide some new ideas for subsequent TD-LTE antenna deployment and selection.
According to statistics, at present in large and medium-sized cities in China, it is difficult to add antennas to more than 50% of sites due to problems such as property coordination and site location. At the same time, it is necessary to consider the D frequency band when constructing the FA frequency band, to avoid the need to revisit the subsequent D frequency band construction. The antenna is adjusted, so in the first phase of TD-LTE construction, a large number of FA / D dual-band built-in combined non-electrically adjustable antennas are used, that is, the FA and D bands use the same fixed built-in electrical downtilt angle, and the adjustment of the downtilt angle is passed The mechanical downtilt is completed. Theoretical analysis and practical tests show that the FA / D dual-band built-in combined antenna will have a huge impact on network performance. The specific analysis is as follows:
1. FA band and D band cannot be independently optimized and adjusted, resulting in a sharp decline in network performance
Because the FA and D bands have different wireless propagation performance, at the same downtilt angle, for the same transmit power, the difference between the average value of the outdoor FA band and the D band is about 2dB, and the difference between the average value of the indoor electricity is about 4 ~ 6dB. When feeding, the optimal downtilt of the FA frequency band differs from the D frequency band by about 2 degrees. If the same downtilt angle is adopted, the network performance will decrease sharply. According to the survey data of a city in the first phase of TD-LTE, the downtilt angle of 68% of the antennas constructed in the FA and D bands in the project optimization needs to be adjusted, otherwise the performance will be reduced by 35%.
2. Mechanical downtilt causes neighboring cell interference, reduces user experience at the edge of the cell, and has low optimization efficiency
FA / D dual-band built-in combined non-electrically adjustable antenna can only adjust the downtilt angle by mechanical downtilt. In the case of mechanical downtilt, the antenna pattern does not change proportionally. By comparing the mechanical downtilt and electric downtilt antenna pattern projection It can be seen that the mechanical downtilt adjustment causes lobe distortion and is likely to cause interference to neighboring cells. At the same time, the mechanical support can only be adjusted at the site, resulting in problems such as high labor costs at the site, difficult coordination of the property at the site, and low optimization efficiency.
In response to the above problems, the industry has launched FA / D dual-band independent ESC antennas. The comparison test verification results of this antenna on the existing network show that the above problems can be effectively solved. The verification conclusion is as follows:
1. The performance of the FA / D dual-band independent ESC antenna network is significantly improved by 16% compared to the FA / D built-in combined non-ESC antenna, which is equivalent to the independent antenna network performance.
Test method: Under different networking methods, keep the same engineering parameters (base station configuration, antenna hanging height, etc.), only replace the antenna
Test Results:
1. Compared with FA / D built-in combined non-ESC network, the average downstream throughput of FA / D dual-band independent ESC network is increased by 16%
2. Compared with the independent FAD broadband network, the average downstream throughput of the FA / D dual-band independent ESC network is equivalent.
2. Compared with FA / D built-in combined non-electrically adjustable antenna, FA / D independent electrically adjustable antenna improves cell edge throughput by 28%
Test method: Select the overlapping area of ​​two cells and compare the performance of the FA / D independent ESC antenna and the FA / D built-in combined non-ESC antenna at the edge of the network under the same total downtilt angle.
The test results show that the FA / D independent electronically tuned antenna has much better lateral interference control capability than the traditional mechanical downtilted antenna under the condition of large downtilt, and the average throughput at the cell edge is increased by 28%.
It can be seen that compared to the FA / D built-in combined non-electrically adjustable antenna, the FA / D dual-band independent electrically adjustable antenna can effectively improve the performance of the TD-LTE network, which is equivalent to the performance of the independent sky and the antenna management efficiency is higher. The FA / D built-in combined non-electrically adjustable antenna cannot be independently adjusted and optimized due to the downtilt angle, and the directional pattern distortion caused by the mechanical downtilt will cause the performance of the TD-LTE network to deteriorate. At present, the performance of the FA / D dual-band independent ESC antenna has been fully verified on the existing network, and many antenna manufacturers have launched related products. Based on this, it is recommended to construct FA bands in limited sky space or consider D bands. In the case of, use the FA / D dual-band independent ESC antenna to completely replace the FA / D built-in combined antenna.
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