Research And Implementation Of Downlink Control Channel For Broadband Wireless Multimedia Clusters

Broadband trunking communication(B-TrunC)system is based on a time division long term evolution(TD-LTE)broadband private network trunking communication system standard developed by the broadband industry clusters Alliance.In recent years,the field of private network communications has been widely studied and applied.In this paper,the key technology and implementation method of physical downlink control channel(PDCCH)of B-TrunC system are studied.The physical layer transmission of this channel is realized on TMSC6670 multi-core DSP chip.This paper also studies the hybrid automatic repeat request(HARQ)mechanism and its implementation on multi-core DSP platform.This paper analyzes the physical layer protocol of B-TrunC,introduced the overall structure,information format and time-frequency resource occupied by PDCCH.The processing flow and key modules of the downstream transmitter and receiver are studied.The blind detection process of the receiving end under the condition of unknown message format is studied.Based on the Matlab platform,a system-level floating-point simulation link is established to analyze the error rate performance of PDCCH under conditions of four different format at the additive-Gaussian white noise(AWGN)channel.This paper studies the specific algorithm and implementation technology of PDCCH receiver for blind detection.Due to the most severe conditions,blind detection requires iterative 44 times so that become a system complexity bottleneck,this paper has been optimized for blind detection.From the perspective of algorithm optimization,this paper use the look-up table method to optimize the rate matching part,From the perspective of optimizing the code,the use of combined cycle repeated calculation and optimization methods to enhance the efficiency of the code itself,Which ultimately makes the efficiency of the blind detection module has been effectively improved.This paper studies the TMSC6670 multi-core DSP chip,and achieve the PDCCH transmitter and receiver functions on the platform.In this paper,the bit-rate coprocessor(BCP)is used to implement CRC addition,rate matching,bitding convolutional coding and modulation.The Viterbi-Decoder Coprocessor 2(VCP2)and enhanced direct memory access3(EDMA3)is used to achieve the Viterbi decoding of receiving end.In this paper,the channel simulator is used to verify the PDCCH link in the AWGN channel transmission performance and program stability.The performance of Extended Pedestrian A model(EPA)and Extended Vehicleular A model(EVA)is tested,which verifies that the performance of the channel can meet the requirements of experimental system.In this paper,the downlink HARQ mechanism is studied,also the HARQ process and related parameters are analyzed.This paper designs the HARQ implementation process,determines the HARQ mode and timing,and adds the downstream instruction function.And on the basis of the multi-core DSP platform to achieve the downlink HARQ process.In this paper,the performance of the two simulations of using HARQ and without HARQ is compared on the channel simulator,it verified that the HARQ process can improve the block error rate of transmission.