共查询到20条相似文献,搜索用时 12 毫秒
1.
In this paper we consider the use of differential detection when there aremultiple transmitter and receiver antennas. Our differential scheme is based on the theory ofSpace-Time Block Codes that are used to achieve space-time diversity. Compared to the existingdifferential schemes for multiple antennas our scheme has a much smaller computationalcomplexity. It has the same encoding and decoding complexities as the coherent detection based on space-time block codes and achieves the same rate for up-to 8 transmitterantennas. The performance of the differential detector (which assumes no knowledge of the flat fading channel) is 3 dB less than that of the coherent detector (which uses exact channelstate information for reception). We also show that the proposed receiver is a Maximum Likelihood detector. 相似文献
2.
3.
4.
5.
6.
基于TBH和Jafarkhan编码方案的两组准正交空时分组码,引入自适应旋转因子构造出四种差分调制酉矩阵,该方法不仅没有带来星座扩展,还使新的码字具有较大的欧氏距离。同时在接收端基于角度算子,形成了简化的成对译码方法。仿真结果表明:尽管此设计方法增加了一定的复杂度,但它比没有加入旋转因子的差分酉空时分组码具有更好的误码性能。 相似文献
7.
从理论上给出一种Rice衰落条件下Reed-Solomon码级联空时分组码系统的差错性能分析方法,并推导给出级联码误比特率上界的数学表达式。理论分析和仿真结果表明,随着信噪比的增加,级联码系统的性能曲线迅速变好,获得了很高的编码增益。在误比特率为10-4时,与Reed-Solomon码的级联可以使衰落条件下空时分组码的性能提高大约5 dB。 相似文献
8.
Differential Space-Time Block Codes (DSTBC) do not require any radio channel measurement and channel state information neither
on the transmitter nor at the receiver side. Therefore, they are an attractive alternative to coherent Multiple-Input Multiple-output
(MIMO) systems. The classical technical proposal for differential techniques is based on M-ary phase shift keying (M-PSK)
modulation schemes for DSTBC (PSK-DSTBC). One advantage of this scheme is the constant envelop of the transmit signal, but
it is well known that higher-order PSK is less efficient due to the small distance between adjacent points in the constellation
diagram. Therefore, in this paper an alternative modulation technique for DSTBC is discussed, which is based on quadrature
amplitude modulation (QAM-DSTBC). The signal envelope of the transmit signal is not any more constant in this case. Therefore,
the technical challenge of integrating QAM into the DSTBC system design is to control the transmit power in order to avoid
an increase or a decrease in transmit power to some extreme values. The mechanism, which is used in this paper to control
the transmit power is based on an extension of the original QAM constellation diagram. The additional points, which are integrated
into the constellation diagram are used in this case for the mapping procedure to select one of the modulation symbols with
high or alternatively low signal power. This means for each single bit pattern there are almost always two modulation symbols
available in the mapping procedure one with low and one with high signal power, which gives the basis for a signal power control
algorithm. The resulting bit-error-rate (BER) performance of QAM-DSTBC is compared finally to the performance figures of the
original proposal of PSK-DSTBC.
相似文献
Hermann RohlingEmail: |
9.
10.
基于Alamouti提出的BPSK调制下空时分组码在Rayleigh衰落信道中的码性能原理,推导出高阶(M ary)调制下Rician衰落信道中空时分组码的符号差错率的最小距离球界,并进行计算机仿真分析了两信道下引入空时分组码的多天线系统中发射和接收天线的分集增益,发射天线数量的“地板效应”以及Rician因子K对符号差错性能的影响。 相似文献
11.
本文提出了一种采用分布式差分空时分组编码和检测的协同分集方案,在不需要信道状态信息(CSI)的情况下可以实现满分集和全速率发射,并推导了相关瑞利信道下该方案误码率(BER)性能上限的解析表达式。传统的差分空时分组编码对整个码块进行差分,而协同分集下的任何一个协同用户进行差分编码时都不知道整个码块的信息。本文所提出的差分BPSK调制方案,通过将两协同用户的信息分别被调制到相互正交的实轴和虚轴上,从而将码块的联合差分转化为各用户独立差分。分析了在协同用户间不同的信道状态信息(CSI)和协同用户到接收用户不同的CSI情况下本文所提出发射方案的性能。仿真结果表明本文所提出的方案获得了明显的分集增益,同时也较好的吻合了理论分析的结果。 相似文献
12.
对于接收端和发送端均不具备信道状态信息的MIMO系统,本文将Cayley变换与对角块正交空时分组码结合,提出了一种新的酉空时分组码构造方法。新构造的空时分组码适用于任意发送天线数为偶数的MIMO系统,能提供满发送分集度和1.5符号/信道利用的信息传输率,并可采用球检测法等低计算复杂度检测算法得到准最优的检测结果。 相似文献
13.
Chadi Abou-Rjeily Norbert Daniele Jean-Claude Belfiore 《Wireless Personal Communications》2007,43(1):107-121
In this paper, we extend the Amplify-and-Forward cooperative diversity scheme to the context of impulse radio ultra-wideband.
In particular, we present the construction of two families of distributed algebraic space-time codes. The first family is
based on totally real cyclic division algebras. The second family encodes the pulses used to transmit one information symbol
and permits to achieve high-performance levels with lower complexity. Both families of codes achieve full rate, full diversity
with non-vanishing determinants with various numbers of relays. Simulations performed over realistic indoor UWB channel models
show important performance gains. 相似文献
14.
15.
准正交空时分组码对发射天线数大于2的复信号能够实现全速率的发射,它在低信噪比的情况下有比较好的性能,但是由于准正交空时分组码不是全发射分集的,因而在高信噪比时性能并不优越。为了改善准正交空时分组码在高信噪比时的性能,本文采用对准正交空时分组码进行混合星座编码的形式来提高准正交空时分组码的分集度。仿真及计算结果显示,采用混合星座编码能在少量频带利用率损失的情况下大幅提高准正交空时分组码的性能。 相似文献
16.
1 IntroductionRecently,anewspace timecodeadaptedtomultipleantennaswirelessfadingchannelhasbeenproposed[1~6] .Thecodesarethejointdesignofcoding ,modulation ,transmissionandreceptiondi versityto providethebesttradeoffbetweendatarates,diversityadvantageandcodes… 相似文献
17.
Orthogonal ASK/DPSK labeling, which encodes label information on optical carriers in a modulation format, is regarded as a competing scheme to subcarrier multiplexed optical labeling. However, the inherent cross-talk limits the extinction ratio (ER) of the payload and label sensitivity. In this paper, two optical coding methods-Manchester coding and 8B10B coding-which can remarkably improve the system quality to obtain acceptable ER are discussed. A novel optical packet encoding methodmark-insertion coding-is demonstrated to significantly reduce cross-talk between the amplitude shift keying ASK) payload and the differential phase shift keying (DPSK) label through spectrum shaping. The performance of mark-insertion coding depends on the number of inserted 'marks'. Finally, the transmission over a 40 km single mode fiber (SMF) is compared with optical label swapping for a. 40 Gbit/s ASK payload and 2.5 Gbit/s DPSK label under these coding schemes. The experimental result is consistent with the theoretical analysis. 相似文献
18.
19.
研究了一类非平稳信号具有随机幅度的多项式相位信号的时延估计问题。充分利用信号的高阶循环平稳性,提出了一种基于信号高阶循环矩的时延估计方法。该方法容易实现,估计精度能有效地抑制加性平稳非高斯和任何高斯噪声。试验结果证明了提出方法的正确性。 相似文献
20.
We introduce a new design method for space-time trelliscodes (STTC's) in orthogonal frequency-division multiplexing(OFDM) systems with frequency-selective fading. First, byanalyzing the pairwise error probability (PEP), we conclude thatlarge effective length and random interleaving are twocritical principles in designing robust space-time codes (STC's)for OFDM systems. Then, based on the analogy between the proposedSTC design principles for multiple-antenna OFDM systems and thetrellis-coded modulation (TCM) code design criteria forsingle-antenna flat-fading channels, we develop a new STTC designmethod. At each trellis stage, this method converts the singleoutput code symbol of a traditional TCM code into several STTCcode symbols, which are to be simultaneously transmitted frommultiple transmitter-antennas, and hence results in a new class ofSTTC's. In this way, the effective lengths that have beenoptimized for traditional TCM codes are preserved in the resultingSTTC's; together with a random interleaver, the proposed new classof STTC's can robustly and efficiently exploit both the spatialand the frequency-selective fading diversity resources inmultiple-antenna OFDM systems. Finally, the excellent performanceof the proposed STTC's are demonstrated through computersimulations. 相似文献