The Design Of Digital Intermediate Frequency System Based On System Generator In MIMO Emission System

The design of digital intermediate frequency subsystem in MIMO emission system is discussed in this paper.MIMO is the core technology in the new mobile communication, which uses several masts to carry signal on receivers and transmitters. MIMO can improve the system capacity under the condition of not take up the excessive bandwidth. The experiment system inspects some theory parameter and provides a platform for MIMO research. In this case, it's necessary to make up experiment system for ferivying interrelated MIMO theory. Transmitter is so important that it's essential to design a emission system with SWR, in view of some practical transmitter problem of sise, power consumption and costs at the same time. However, SWR can just digitize IF signal because of the device limit. So, this paper will study the design of digital intermediate frequency subsystem., which completes mainly the full process from baseban signal to IF signal with 70MHz.A new FPGA development tool-System Generator is used in this paper, which extends MATLAB/Simulink platform of Math Works company in so many ways, and provides DSP modeling surroundings. It can accomplish FPGA design using Simulink modeling and simulation environment without knowing RTL HDL, which is the greatest attribute. This way, it can save design cycle and make the designer play the biggest performance and flexbility based on FPGA or DSP.This paper introduces simply the state-of-the-art of mobile communication and the research trends of MIMO system. Then, describes the use method of System Generator for DSP, introduces principle of MIMO transmitterk, which is divided into three parts. And then, introduces the design idea of computer processing system and RF front-end subsystem, extracts the function module of digital IF system intensively. The design of digital up-conversion(DUC) is the core of the all design. Some correlative skill of DUC are introduced detailedly next, such as multispeed signal processing skill, digital filtering technique, and digtal area orthogonality mixing skill, which all come ture by System Generator. Then explans the sampling rate converting proposal of 2 channels, finally, completes the sampling rate converting of 2 channels, which owes symbol rate with 2Msps and 3.75Msps respectively. Last part of the design is intermediate frequency system, which includes deserilize module and differential coding module besides DUC module. At last, completes the design of digital IF subsystem with 2 channels, and verify the simulation result.