摘要
分析了多径衰落信道下Turbo编码OFDM系统特性,推导出OFDM系统中Turbo码的译码算法,确定平均信噪比是影响系统性能的重要参数;研究了译码迭代次数对Turbo-OFDM系统的影响,提出一种自适应Turbo-OFDM系统方案,可以兼顾译码性能和译码速度,得到较低的平均误比特率和较高的平均译码速度。仿真结果说明,在平坦慢衰落信道下,采用该文提出的OFDM系统中Turbo码译码算法,不损失性能的同时,降低了对信道估计精度的要求;对于目标误比特率为10时,采用自适应Turbo-OFDM系统方案,与固定迭代4次的方案相比,平均误比特率降低了33%,提高了系统-4性能;而与固定迭代8次的方案相比,迭代次数降低了约1/3,提高了译码速度。
With the knowledge of Turbo coded OFDM system over multipath fading channel,a new Turbo decoding al-gorithm for Turbo-OFDM is proposed.Through studying the effect of the iterations on the turbo-coded system,we pro-pose a new scheme based on adaptive selection of iterations for decoding under the condition of little SNR variance.Considering both performance and speed of the decoding,the proposed scheme is proved to decrease the mean BER and accelerate the decoding.The simulation results show that the proposed decoding algorithm can reduce the complexity of the channel estimation without the loss of performance.Also,given the target BER of10 -4 ,the adaptive scheme can bring out the increase of mean BER by33%versus4-iteration scheme and the decrease of iterations by33%versus8-iteration scheme.
出处
《计算机工程与应用》
CSCD
北大核心
2005年第6期19-21,205,共4页
Computer Engineering and Applications
基金
国家973重点基础研究发展规划项目(编号:51308)
关键词
OFDM
TURBO码
平坦慢衰落信道
自适应
近代译码
Orthogonal Frequency Division Multiplexing(OFDM),Turbo code,slow flat fading channel,adaptive,iterative decoding
