The Application Of Mixed Adc Receiver Under Massive MIMO

Along with the development of modern wireless communication technology, massive MIMO system as the core technology of the next generation wireless communication system has been more and more widely recognized, in order to further enhance the transmission performance of wireless communication system. For massive MIMO system, hundreds or thousands of antennas need to be configured at the base station. So there comes the big problem for the whole system ADC that the large number of antennas will cause the large consumption of resource, high complexity and power consumption. And how to configure a high speed and high performance ADC becomes very important in the future massive MIMO 5G wireless communication.At present to fulfill the massive MIMO system with high speed and high performance ADC, the mainstream approach is to adopt a low-resolution architecture. Differ from 12-bit quantization ADC, the low resolution ADC has the feature of lower power consumption and faster speed. In order to pursue the performance of the same level of high-resolution ADC, a variety of algorithms are proposed for the detector for low-resolution ADC. The mainstream of which is based on the maximum likelihood estimation of the EM algorithm and GAMP algorithm. These three algorithms are all using the method that replacing the maximum likelihood estimation which has high complexity with loop iteration.However, the low-resolution ADC is some what different in the performance of quantized signal, compared with the high-resolution ADC. In order to estimate some CSI information accurately, the high-resolution architecture is necessary. So the mixed-ADC receiver is a very useful architecture in the massive MIMO system. In this paper, the PDQ detector and linear detector which are based on the DQ ideal detector are introduced.The two detectors mix the low-resolution ADC and the high-resolution ADC in architecture. At the same time, the requirements of high performance, high speed ADC and accurate estimation of CSI information are considered. Finally the two detectors are simpler to calculate than the DQ ideal detector.In this paper, I did some simulation to the DQ ideal detector, PDQ detector and linear detector. And a mix-ADC architecture receiver mode is established. This paper verified the error rate and MSE performance of the three detectors under this mode. At the same time this paper also makes a lot of simulation on the quantization step size, the quantization variance and the mixed architecture. Then I analyzed the effects of the quantization variance and the mixed architecture on different detectors. Finally, the simulation results show that the performance of the PDQ detector is less than that of the DQ detector, but less computation. So it is proved that the PDQ detector of the GAMP algorithm is a good architecture for the mix-ADC receiver.