共查询到19条相似文献,搜索用时 46 毫秒
1.
2.
本文将基于平衰落信道提出的空时块编码(STBC)方案应用到OFDM系统中,理论分析和仿真证明在理想信道估计下这种STBC-OFDM系统在频率选择性信道下能够获得对应的STBC在平衰落信道下的性能。 相似文献
3.
4.
5.
6.
7.
8.
基于Alamouti提出的BPSK调制下空时分组码在Rayleigh衰落信道中的简单分集方案。推导出多发射和多接收天线系统中正交空时分组码在Nakagami衰落信道的BPSK调制下的比特差错率的最小距离球界,并推广到在高阶调制下衰落信道中系统符号差错率的性能。仿真分析和比较了空时分组码的多天线系统中发射和接收天线分集增益,以及信道相关参数的变化对系统误比特性能的影响。 相似文献
9.
10.
本文介绍了两种空-时传输机制,通过在频率选择性衰落信道上使用两根传输天线,来得到全速率和全分集非相干性.第一种机制结合了频域的OFDM微分空-时分组编码;第二种机制采用微分反时空-时分组编码,这样可以保证在不需要当前过采样或多根接收天线的情况下保证盲信道估计. 相似文献
11.
12.
Ümit Ayglü Mehmet E. elebi 《AEUE-International Journal of Electronics and Communications》2004,58(4):268-273
In this paper, 4-state and 8-state space-time trellis codes with full rate, full diversity and high coding gain are proposed for MSK modulation, based on a technique similar to the super-orthogonal space-time trellis code (SOSTTC) design. Since the phase continuity requirement of MSK is the main constraint in space-time MSK code design not all the signal matrices corresponding to the trellis branches are orthogonal. The paper shows that the SOSTTC design technique can be extended to nonorthogonal coding structures. The new space-time MSK codes have frame error performances very close to those of their space-time QPSK counterparts given in [1] 相似文献
13.
In this paper we describe a coding strategy for binary duplex channels (BDC's) that essentially matches the performance of a system with two identical binary forward channels using a systematic rate-frac{1}{2} convolutional code on each of these channels. In other words, our coding strategy achieves the same effect as would the turning around of the feedback channel. 相似文献
14.
15.
16.
Sason I. Goldenberg I. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(7):2394-2428
The transmission of coded communication systems is widely modeled to take place over a set of parallel channels. This model is used for transmission over block-fading channels, rate-compatible puncturing of turbo-like codes, multicarrier signaling, multilevel coding, etc. New upper bounds on the maximum-likelihood (ML) decoding error probability are derived in the parallel-channel setting. We focus on the generalization of the Gallager-type bounds and discuss the connections between some versions of these bounds. The tightness of these bounds for parallel channels is exemplified for structured ensembles of turbo codes, repeat-accumulate (RA) codes, and some of their recent variations (e.g., punctured accumulate-repeat-accumulate codes). The bounds on the decoding error probability of an ML decoder are compared to computer simulations of iterative decoding. The new bounds show a remarkable improvement over the union bound and some other previously reported bounds for independent parallel channels. This improvement is exemplified for relatively short block lengths, and it is pronounced when the block length is increased. In the asymptotic case, where we let the block length tend to infinity, inner bounds on the attainable channel regions of modern coding techniques under ML decoding are obtained, based solely on the asymptotic growth rates of the average distance spectra of these code ensembles. 相似文献
17.
18.
本文对非规则LDPC码在RICE信道的性能进行了分析和仿真,修正了BP译码算法,证明了RICE信道满足对称性,给出了RICE信道译码稳定性条件,推导出了RICE信道的Shannon容量限,采用VC编程对码长N=49512和3072进行了仿真,同时与同码长的Turbo码进行了比较;仿真结果表明LDPC码在码长N=49512、码率R=1/3时,与Shannon限相差1dB以内、在低信噪比时其性能优于Turbo码,以及LDPC码本身有很好的交织特性和抗衰落的能力;这进一步表明了LDPC码在包括RICE信道在内的各种信道中的性能都是非常优良的. 相似文献
19.
通过对空时分组码在快衰落信道的研究,说明在快衰落信道空时分组码性能衰减的原因,并且提出了用插入正交导频序列对信道进行估计的方法。通过对快衰落信道估计误差引起的性能降低的仿真表明误差地板是由于初始信道估计误差和导频符号组正交性的损失引起的,信道时变越快,误差地板越高。 相似文献