In the fec part , rs ( reed - solomon ) code and interleave are chosen as the basic elements of the error correction system at first ; then the coding parameter and data structure are determined based on the results of matlab simulation ; at last , hdl modules are implemented in fpga using verilog hdl , test results and simulation diagrams are presented as well . in the designing process , the proper division of the modules and the cooperation between modules need a lot of consideration , and the top - down method is adopted to solve these questions 在前向纠错的设计部分,文章首先根据系统的误比特率要求选择了rs ( reed - solomon )码和交织器作为前向纠错部分的基本构架,再根据matlab的仿真结果得到了具体的编解码参数和码字结构,最后在fpga中用硬件描述语言veriloghdl实现了各个编解码模块,并给出了测试数据、实现结果及时序仿真波形图。
However , the wireless communication has the shortages of error often , time delay , and limited broad because of the requirement of large amount of data flow , and high true - false ratio for the video signal . thus the ratio in wireless channel is much larger than that of the wire environment . furthermore , it has large variations with the changes of positions and directions of basement and terminals 由于视频业务的数据量大、对误比特率要求高,无线信道又具有易错、时变和带限的特点,因此信道的误比特率要比有线环境大得多,且随着基站和终端位置、方向的改变而变化很大。
According to similar ft3 frame format and its checkout mode of dnp data link layer , the relationship between fer ( frame error rate ) and ber ( bit error rate ) , frame length is deduced . the computation formulas of average transmission times and repeat transmission times guaranteeing the correct transmission of telecontrol information are given as well 根据dnp3 . 0规约数据链路层类ft3帧及其校验方式，推导出帧传输失败概率(误帧率)与通道误比特率和帧长的关系，同时给出平均传输次数和重复传输次数的计算公式。
Simulation results demonstrate theoretical derivation is correct and both sequences can be used in communication . based on the presented ds / sfh communication scheme , and employing msk as fh spread spectrum modulation , the performance is studied n the presence of partial band multitone jamming and additive white gaussian noise ( awgn ) 根据所提出的混合ds sfh扩频通信系统方案，采用msk相干调制，在假设直接序列扩频后信号带宽等于跳频间隔的情况下，推导了系统在部分频带多频干扰和加性白噪声下的误比特率公式。
In this paper , we create the network , node and process model using opnet software to simulate throughput performance of aos packet service , and choose various combinations of source packet length , transfer frame length and channel error rate to form different simulation scenarios . by analyzing the throughput - packet length , throughput - frame length simulation curves at different channel ber we get the optimal packet length and frame length configurations , and give some advice for the optimization of protocol configuration parameters according to throughput performance metric ; the complete node and process model of aos protocol have been built by opnet software , and a simple network scenario has been built to simulate and verify the validation of the protocol model 本文在建模仿真方面,用opnet软件建立仿真aos协议包业务吞吐量性能的网络、节点、进程模型,选取不同的包长、帧长与信道误比特率组合建立仿真场景进行仿真,得到不同误比特率条件下吞吐量-包长、吞吐量-帧长关系曲线,经过分析得出最大吞吐量对应的最佳帧长、包长配置,给出以吞吐量性能为指标优化协议配置参数的建议;用opnet软件搭建aos协议封装节点模型和各个进程模型,建立简单网络场景进行仿真验证协议封装节点模型的有效性。
