Research On Radio Frequency Technology For Massive MIMO System

It is the fifth generation of communication technology that meets the requirements of the information society in 2020. With the rapid development of integrated circuit technology and the widely applications in wireless access, it is not only the development and optimization of technique. However, it is aimed to provide users with more perfect experience. Massive MIMO, one of the key technologies of the fifth generation of communication system, is to have a broad prospect of research.Compared with the fourth generation of wireless communication system, a great number of channels are necessary for massive MIMO system, which increases the complexity of system. Therefore, it is full of challenges for RF technology. This study focused on high-performance time-division duplex transceiver for massive MIMO system on 3.5 GHz.This paper focuses on the scheme design of the transmitter and the local oscillator, realizing low-power consumption and miniaturization design. The local oscillator is designed to be separated with the transceiver, to improve the performance of vibration, especially the phase noise. The intermediate frequency is at 215 MHz between RF and baseband. And the bandwidth of signal is 20 MHz. At first, several typical structures of transmitter and receiver have been respectively analyzed. According to the characteristics of massive MIMO system, the concrete design has been discussed. At the same time, the feasibility has been analyzed with simulation. The design of the module in transmitter has been described in the paper. And the contrast analysis of the theoretical results and the test results has also been presented.In the end, the power consumption of single channel is less than 6W, which is just 40% of the system before. And the volume is 60% of the previous one. The maximum output power can be up to 17 dBm while the gain flatness is within 0.4 dB. It achieves perfect performance in transmitter with more than 50 dBc of adjacent-channel leakage ratio both in the upper and lower sideband. The images rejection can reach-49.94 dB when the filter in radio frequency does not have a perfect selection. The EVM of 20 Msps 16 QAM is 1.1101% when the output power is 17 dBm. And the EVM of 20Msps LTE reaches 2.0763% in 17 dBm output power. The test results show that the system has excellent performance.