The Design Of UMTS System’s CPRI Interface Based On FPGA

In 1978, the emergence of the world’s first cellular mobile communication system was considered as the greatest invention within mankind’s communication history. From then on, mobile communications have rapidly entered the people’s lives with an incredible geometric growth rate. The most important reason is that they have brought unprecedented and irreplaceable convenience and upgraded the quality of human life significantly. The mobile communication is characterized by its individualization and its mobility not limited by space and time, which precisely cater to the fast-paced rhythms of today’s human society, satisfying people’s desire to communicate with any person at any time and any place.With the increasing competition of communication industry and the rising requirement of users in communication services, the Third Generation of UMTS mobile communication systems with high speed, high stability and high compatibility to replace the second generation of GSM communication systems has become an inevitable trend. But nowadays 2G is still dominating the communication industry. To achieve the globalization of 3G telecommunications industry, it has been the first threshold in front of all the businesses whether 2 G can transit to 3 G smoothly.CPRI interface (Common Public Radio Interface) is a kind of protocol standard within the UMTS base station, which is also called Common Public Radio Interface Alliance. It’s a kind of interface standard protocol to standardize the relationship of radio equipment controller REC and radio equipment RE within the radio base station. It is just because of its emergence that the transition from 2G to 3G of the communication systems can be taken into realization.In this paper we mainly take CPRI interface chip for study. Firstly we will introduce the historical background of CPRI protocols, and then some basic concepts of CPRI protocols will be described. After a detailed analysis of the features of CPRI interface, we will divide the system into three main modules by using the design method of Top-To-Down:. Among these modules the power reporting module is the focal point and the difficult point as well. The focal point is because that its design is directly related to the goal of Huawei’s design team: to achieve NodeB power controllable. And the difficult point lies in a large number of math calculations involved in this module. The frame encoding of uplink data and the frame decoding is designed to achieve the data format conversion between REC and RE, also, RE and RE. We finish the design of each module by using Verilog-HDL language after classifying the system function modules carefully and we simulate the whole module for functions, finishing the front work of this design. Next, the compiling results of these overall CPRI interfaces are presented in this paper, and we select the appropriate FPGA device Cyclone to draw the circuit layout. After the final simulation and timing verification, this design is fully proved to meet the development needs of UMTS base station totally.