Research On Digital Signal Processing Platform Of Radio Remote Unit

The deployment of traditional macro base station encounters many problems when wireless communication system evolves from 2G to 3G. From perspective of wireless network planning, the 3G macro base stations need new positioning and equipment installation room, which is difficult to get. From a technical perspective, there are so many electrical cables between macro base stations and their antennas, and signal reduction on these electrical cables has great impact on system performance of TD-SCDMA which uses intelligent antenna array. From perspective of network’s evolution, base station equipments should have the ability to evolve smoothly to next generation system.The distributed base station emerges as the replacement of macro base station in the development of 3G network, and it will also become the mainstream base station in the future. Distributed base station is a base station mode in which digital baseband and RF part are separated individually and connected together by optical fiber. The distributed base station is made up of Base Band Unit(BBU) and Radio Remote Unit(RRU). RRU generally includes optical fiber module, the digital IF module, AD and DA module, RF transceiver module.In this paper, design and research of RRU digital signal processing platform is accomplished. This platform is designed according to the general functions and structure of RRU as well as considering the actual needs in project.One of the important contents in this paper is the design of the ADC and DAC module which has JESD204 B interface with FPGA. The JESD204 B interface protocol is dedicated to transferring data between converters and logical devices. It has many advantages compared with traditional parallel LVDS interface. Details of this interface protocol will be analyzed and the key points will be highlighted.The other important content is the optical fiber between BBU and RRU. In this paper Aurora protocol is used to transferring data through the optical fiber between BBU and RRU. Aurora protocol is also be analyzed and implemented on the platform. Finally, the joint test of the Aurora and ADC, DAC subsystem is performed.