SDR Implementation of a 5G-Oriented Ultra-Dense Distributed MIMO Prototype System

Ultra-dense distributed MIMO system is a key of promoting the development of the 5G communication industry. In this paper, we design and implement a 5G-oriented ultradense distributed MIMO prototype system, by using software-defined radios (SDR) as remote radio processing units (RRU) and adopting a multi-core general purpose processor as band width based unit (BBU). For building the ultra-dense distributed MIMO system, timing and frequency synchronization is a core challenge. A synchronized network named White Rabbit is used in our system to make sure synchronization of different RRUs. A new UDP protocol is designed to solve problems of data loss when BBU receives data from different RRUs. We realize main long-term evolution-like physical transmission technologies successfully in our system. An 8 × 2 demo system is built to show the robustness of our system in different scenarios. Indoor and outdoor scenario tests show obvious constellation points of QPSK and 16 QAM and great bit error rate performance. Further, our system is scalable and can be expanded into a larger system.