共查询到16条相似文献,搜索用时 109 毫秒
1.
2.
3.
4.
在研究传统的空时编码 OFDM 系统模型及误码率性能的基础上,提出了 Turbo 码级联空时格码的 OFDM 系统方案;并给出了该系统在无线瑞利衰落信道中的性能上界和误码率仿真结果,仿真结果表明:该系统能最大限度地利用所有的分集资源,获得相当大的分集增益和编码增益。 相似文献
5.
6.
MIMO与OFDM技术相结合成为4G宽带移动通信的核心技术。全面介绍了MIMO-OFDM技术及其特点,分析了3种空时编码技术,探讨了空时编码技术在MIMO-OFDM系统中的应用,并展望了其发展前景。 相似文献
7.
研究了空时分块编码的OFDM(正交频分复用)系统,对系统进行了Turbo均衡,并讨论了此时系统的译码算法和均衡算法。系统信道编码采用Turbo码,通过对BCJR(Bahl,Cocke,Jelinek,Raviv)算法的简单修改得到SISO(单输入单输出)MAP(最大后验概率)译码算法;均衡器采用SISOMMSE(最小均方差)Turbo均衡算法,并利用OFDM系统的循环前缀特性进一步降低算法复杂度。通过仿真对系统性能进行了比较分析,仿真结果表明,采用迭代均衡的空时分块编码OFDM系统性能要明显优于未空时编码和未迭代均衡的OFDM系统。 相似文献
8.
9.
10.
11.
该文提出了将LDPC码与自适应比特功率分配相结合应用于MIMO-OFDM系统中的算法。文中分别对两种不同码率的LDPC码与自适应OFDM,自适应MIMO-OFDM相结合的算法进行了仿真,同时还对未编码的自适应OFDM以及MIMO-OFDM进行了仿真。仿真结果显示,在相同的传输带宽以及相同的传输信息量(即数据净码率)情况下,采用低码率LDPC编码的自适应OFDM系统的性能要比未编码的自适应OFDM以及自适应 MIMO-OFDM系统的性能好;采用高码率LDPC编码的自适应OFDM系统的性能比未编码的自适应OFDM系统性能好,但比未编码的自适应MIMO-OFDM系统性能差。 相似文献
12.
13.
多输入多输出正交频分复用(MIMO-OFDM)可以提高系统在频率选择性衰落信道的传输性能.与OFDM系统一样,MIMO-OFDM系统也存在高峰值平均功率比(PAPR)的问题.为此,提出了一种降低空时分组编码MIMO-OFDM系统PAPR的正交部分传输序列算法,运用这种算法,利用傅里叶变换的性质,通过调整空时编码与基带正交调制的顺序,对两天线发射端,可以降低算法近一半的复杂度,且可以减少一半的边信息.利用高功率放大器的非线性模型,得到了瑞利衰落信道下PAPR降低后系统的误码率性能.仿真结果证明了该方法的有效性. 相似文献
14.
Space-Time/Frequency Coding for MIMO-OFDM in Next Generation Broadband Wireless Systems 总被引:1,自引:0,他引:1
With the advent of next generation (4G) broadband wireless communications, the combination of multiple-input multiple-output (MIMO) wireless technology with orthogonal frequency division multiplexing (OFDM) has been recognized as one of the most promising techniques to support high data rate and high performance. In particular, coding over the space, time, and frequency domains provided by MIMO-OFDM will enable a much more reliable and robust transmission over the harsh wireless environment. In this article we provide an overview of space-time (ST) coding, space-frequency (SF) coding, and space-time-frequency (STF) coding for MIMO-OFDM systems. Performance results show that STF coding can achieve the maximum diversity gain in an end- to-end MIMO-OFDM system over broadband wireless channels. Furthermore, for orthogonal frequency division multiple access (OFDMA), we propose a multiuser SF coding scheme that can achieve the maximum diversity for each user while minimizing the interference introduced from all the other users. 相似文献
15.
Broadband MIMO-OFDM wireless communications 总被引:48,自引:0,他引:48
Stuber G.L. Barry J.R. McLaughlin S.W. Ye Li Ingram M.A. Pratt T.G. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2004,92(2):271-294
Orthogonal frequency division multiplexing (OFDM) is a popular method for high data rate wireless transmission. OFDM may be combined with antenna arrays at the transmitter and receiver to increase the diversity gain and/or to enhance the system capacity on time-varying and frequency-selective channels, resulting in a multiple-input multiple-output (MIMO) configuration. The paper explores various physical layer research challenges in MIMO-OFDM system design, including physical channel measurements and modeling, analog beam forming techniques using adaptive antenna arrays, space-time techniques for MIMO-OFDM, error control coding techniques, OFDM preamble and packet design, and signal processing algorithms used to perform time and frequency synchronization, channel estimation, and channel tracking in MIMO-OFDM systems. Finally, the paper considers a software radio implementation of MIMO-OFDM. 相似文献
16.
介绍了MIMO技术,OFDM的基本原理,利用两者的优点将其结合起来运用到未来移动通信系统中,并将成为未来移动通信中的关键技术。空时编码技术在MIMO-OFDM系统中的应用,通过仿真表明OFDM技术通过FFT变换能将频率选择性的多径衰落信道分成多个平坦衰落信道,使空时编码技术的应用不再受到平坦信道条件的限制。 相似文献