一个MTCM-OFDM系统模型及其性能的分析  

A type of MTCM-OFDM system model and its performance analysis

作　　者：杨程[1,2] 刘琪[1,2] 王树彬[1,2] 周正[1,2] 

机构地区：[1]北京邮电大学无线网络实验室,北京100876 [2]泛网无线通信教育部重点实验室,北京100876

出　　处：《高技术通讯》2009年第1期1-7,共7页Chinese High Technology Letters

基　　金：国家自然科学基金(60432040;60772021);北京市自然科学基金(4052021);教育部博士点基金(20060013008);韩国仁荷大学IT研究中心(INHA UWB-ITRC)资助项目

摘　　要：提出了一种将多网格编码调制(MTCM)与正交频分复用(OFDM)系统相结合的方法,建立了一个MTCM-OFDM系统模型,并对其进行了性能分析和仿真。分析表明,MTCM可提高系统的误码率性能,将MTCM应用于OFDM系统,能增大OFDM符号内一组子载波上符号序列之间的欧氏距离,从而降低误码率,但不会造成信息速率和带宽效率的损失。根据MTCM网格图中不同状态下输出符号序列可以有较大欧氏距离的特点,给出了一种符号序列的两步检测算法:首先利用最大似然序列检测以较大概率检测出网格图的状态序列,然后在两个连续的状态之间检测判决符号序列。该算法利用了MTCM编码调制的特点,因而时延小、复杂度低,性能逼近直接的一步最大似然检测。理论分析和仿真结果均证明了MTCM-OFDM系统和这种检测算法的上述性能特点。By applying the technique of multiple trellis coded modulation （MTCM） to an orthogonal frequency division multiplexing （OFDM） system, the paper proposes a type of MTCM-OFDM system model, and gives the results of analysis and simulation of it. The analysis indicates that the MTCM has its exclusive merit that the information rate and frequency band utilization are not sacrificed after coding and modulating, and an OFDM system in combination with MTCM can enlarge the signal Euclidean composed by k sub carriers signals, so the bit error rate （BER） performance is improved. According to the MTCM design, the output sequences from different state can have much larger Euclidean distance. Based on this fact, the symbols carried by sub carriers can be determined by two steps： first, the state sequence of the trellis diagram can be determined for a larger probability by the maximum likelihood sequence detection method, and then the symbol sequence is determined between the two successive determined states. This algorithm is advanced based on the design character of MTCM, so its decoding delay is lower and the complexity is reduced. The BER performance can approach that of the direct maximum likelihood detection. The theoretic analysis and the Monte-Carlo simulation results can prove the above performance features.

关 键 词：多网格编码调制(MTCM) 正交频分复用(OFDM) 欧氏距离 度量 

分 类 号：TN919.3[电子电信—通信与信息系统]