Design And Implementation Of Baseband Signal Processing Module For TETRA Base Station

TETRA digital trunked system,as a dispatching command system in dedicated mobile communication field,is widely used in public security,civil air defense,ports,airports,rail transportation and other fields.It adopts Time Division Multiple Address(TDMA)technology,? /4-DQPSK digital modulation technology and ACELP digital speech technology,and also has many characteristics of clear voice,high spectrum efficiency,long communication distance,strong anti-interference ability,electricity saving,rich voice and data business functions.At present,manufacturersof producing the TETRA digital trunked system in our country are relativelyscarce,almost all the system products are rely on imports and expensive.Considering the huge demand to products of TETRA digital trunked system,it is of great significance in breaking the bottleneck and exploiting the TETRA digital trunked system with independent intellectual property rights.TETRA digital trunked system baseband processing module contains two sub-layers: MAC layer and PHY layer.The MAC layer is directly related to many key indicatorsof the system,such as error correction ability,anti-interference ability,coverage ability and others.Overall,the baseband processing module realizes the conversion between bit stream information and air interface IQ information,has a closed relationship with system function realization and performance improvement.Hence,researching and exploiting baseband processing module is one of the keysin TETRA base station realization.This paper not only summarizes the characteristics,technology advantages,developments and applications situation both in China and abroad of TETRA digital trunked system,but also describes the overall structure and components of TETRA digital trunked system baseband processing module.It also analyzes the channel coding,channel decoding,and other algorithms in baseband processing module as well.Meanwhile,this paper designs the detailed processing flows of burst assembly module,burst dismantling module,pulse-shaping module,matched filtering module,Reed-Muller(RM)coding module,RM decoding module,Rate Compatible Punctured Convolutional(RCPC)coding module,RCPCdecoding module,CRC checking module,interleaving module,de-interleaving module,differential modulation module,differential demodulation module,synchronization module,diversity combining module.Then,according to the performance requirements of different logical channels under different wireless channel environment in standard,this paper simulates the algorithm of whole baseband signal processing firmware and also verifies the performance of algorithm prototype.It analyses and designs the realization of the DSP platform and FPGA platform in baseband signal processing module.The last is the summary of the paper,also points out the contents needing to improve.