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1.
A new exact explicit expression is derived for the ergodic capacity of maximal ratio combining (MRC) schemes over arbitrarily correlated Rician fading channels. This is used to study the effects of channel correlation on the ergodic capacity. Numerical results reveal that both the phase and the magnitude of correlation have an impact on the ergodic capacity of Rician fading channels. This is in contrast to correlated Rayleigh fading, where the phase of the correlation has no effect on the ergodic capacity. It is also observed that negatively correlated branches in Rician fading may lead to an increase in ergodic capacity beyond that obtained by uncorrelated branches. 相似文献
2.
《Communications, IEEE Transactions on》2007,55(10):1852-1856
The analytical bit error rate of hierarchical quadrature amplitude modulation formats, which include uniform and nonuniform constellations, over flat Rayleigh fading environments is studied in this paper. The analysis takes into account the effect of imperfect channel estimation and considers diversity reception with both independent identically and nonidentically distributed channels, employing maximal ratio combining. 相似文献
3.
Spectral Efficiency Evaluation for MRC Diversity Schemes Over Generalized Rician Fading Channels 总被引:1,自引:0,他引:1
Vidhyacharan Bhaskar 《International Journal of Wireless Information Networks》2007,14(3):209-223
In this paper, closed-form expressions for the capacities per unit bandwidth for generalized Rician fading channels are derived
for power and rate adaptation, constant transmit power, channel inversion with fixed rate, and truncated channel inversion
adaptation policies. The closed-form solutions are derived for the single antenna reception (without diversity combining)
and maximal-ratio combining (MRC) diversity cases. Truncated channel inversion adaptation policy is the best policy for the
single antenna reception case, while the channel inversion with fixed rate policy is the best policy for the MRC diversity
case. Constant transmit power policy provides the lowest spectral efficiency as compared to the other policies with and without
diversity. 相似文献
4.
S.B.M.Priya 《中国通信》2023,(9):160-170
In this paper, we have modeled a linear precoder for indoor multiuser multiple input multiple output(MU-MIMO) system with imperfect channel state information(CSI) at transmitter. The Rician channel is presumed to be mutually coupled and spatially, temporarily correlated. The imperfection with CSI is primarily due to the channel estimation error at receiver and feedback delay amidst the receiver and transmitter in CSI transmission. Along with, the insufficient spacing between the antenna at trans... 相似文献
5.
We analyze the bit error rate (BER) performance of M-ary quadrature amplitude modulation (M-QAM) when using space-time block coding (STBC) along with packet combining triggered by automatic repeat request (ARQ) retransmission over multiple-input multiple-output (MIMO) fading channels. Specifically, adopting a log-likelihood ratio (LLR) based approach and considering the 16-QAM case of study, we provide an exact formulation for the aggregate LLR distribution in the case the STBC codeword can be transmitted twice, and derive the resulting BER. For higher number of retransmissions, an approximation of the error function is used to derive the LLR distributions and the system's ensuing BER. Considering different values of combined transmissions and M-QAM with possible constellation rearrangement (CoRe), validation of the proposed BER analytical model through simulations and assessment of the advantages of packet combining are provided for transmissions over additive white Gaussian noise (AWGN) channel and orthogonalized MIMO Rayleigh fading channels with different STBC mappings. 相似文献
6.
We study the effect of imperfect channel estimation (ICE) on the error probability performance of M-level quadrature amplitude modulation ( M-QAM) with maximal-ratio combining and equal-gain combining diversity formats in Nakagami fading channels. We provide a novel formulation of the bit-error rate (BER) of M-QAM with ICE in terms of the signal constellation-dependent effective signal-to-noise ratios (SNRs) or amplitudes, which allows us to derive the general, accurate, and easy-to-evaluate BER formulas for square and rectangular diversity M-QAM with channel estimation errors. Our result shows that the performance loss caused by ICE may be manifested by the signal decision space distortion and a scaling of the effective SNR. Using our analytical result, we evaluate the performance of M-QAM with pilot-symbol assisted modulation and present some insightful findings 相似文献
7.
Yang Yawpo Jong Shu-Li Liu Ji-Chyun Liu Ching-Hwa 《Wireless Personal Communications》2003,27(3):247-265
In this paper, effects of carrier frequency offset on performance of uplink MC-CDMA (Multi-Carrier Code Division Multiple
Access) system in Nakagami fading channel are investigated through the theoretical analysis and Monte Carlo computer simulations.
Both perfect maximal-ratio combining (MRC) and equal gain combining (EGC) receivers are analyzed; the impact of imperfect
channel fading estimation on the performance of MRC is also explored. The performance of MC-CDMA system is also compared with
that of the conventional single-carrier DS-CDMA system. Our results indicate that the performance of MC-CDMA system is sensitive
to even small values of carrier frequency offset and that the performance of MC-CDMA system improves as number of subcarriers
increases. In perfect channel fading estimation, the overall performance of MRC is superior to EGC. However, when imperfect
or inaccurate channel fading estimation exists, which leads to serious performance degradation, EGC becomes superior to MRC.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Anh Pham Vo Tuan Bao Vo Nguyen Quoc Le Khoa N. 《Wireless Personal Communications》2018,103(2):1859-1870
Wireless Personal Communications - This Letter studies performance of a dual-hop decode-and-forward relaying network employing a wireless-powered relay antenna with transmit antenna selection for... 相似文献
9.
Jun Tao Jingxian Wu Chengshan Xiao 《International Journal of Wireless Information Networks》2009,16(4):197-208
In this paper, we present a new Doppler spread estimation algorithm for broadband wireless orthogonal frequency division multiplexing
(OFDM) systems with fast time-varying and frequency-selective Rayleigh or Rician fading channels. The new algorithm is developed
by analyzing the statistical properties of the power of the received OFDM signal in the time domain, thus it is not affected
by the influence of frequency-domain inter-carrier interference (ICI) introduced by channel variation within one OFDM symbol.
The operation of the algorithm doesn’t require the knowledge of fading channel coefficients, transmitted data, or signal-to-noise
ratio (SNR) at the receiver. It is robust against additive noise, and can provide accurate Doppler spread estimation with
SNR as low as 0 dB. Moreover, unlike existing algorithms, the proposed algorithm takes into account the inter-tap correlation
of the discrete-time channel representation, as is the case in practical systems. Simulation results demonstrate that this
new algorithm can accurately estimate a wide range of Doppler spread with low estimation latency and high computational efficiency. 相似文献
10.
We present a simple closed-form expression for the BER of orthogonal space-time block codes (OSTBCs) with MMSE channel estimation, assuming PAM and QAM constellations and flat Rayleigh block fading. The BER expression is exact for a certain class of OSTBCs, and provides a very accurate approximation for other OSTBCs. 相似文献
11.
An exact method is employed to analyze the bit error rate (BER) performances of differential chaos shift keying (DCSK) communication
system over fading channels. The exact BER performances of DCSK in Nakagami-m Rayleigh and Rician fading channels are derived, respectively. The Gaussian approximation (GA) method is compared with the
exact method. The numerical results and simulation results for the two methods are presented and are compared in the fading
channels, respectively. These results support our theoretical analysis. 相似文献
12.
In this letter, we study the influence of receiver imperfections on bit error rate (BER) degradations in detecting low‐density parity‐check coded multilevel phase‐shift keying signals transmitted over a Rician fading channel. Based on the analytical system model which we previously developed using Monte Carlo simulations, we determine the BER degradations caused by the simultaneous influences of stochastic phase error, quadrature error, in‐phase‐quadrature mismatch, and the fading severity. 相似文献
13.
在基于信道信息有限反馈的无线多入单出系统中,发射机可采用简单的波束成形技术实现发射分集增益和阵列增益。已有的相关研究大多包含块衰落信道、准确信道估计或无反馈延迟等理想假设。该文建立了更为实际的Jakes时变信道中存在信道估计误差和反馈延迟的系统模型,分析了方形和矩形正交幅度调制星座图的平均误码率。研究表明:误码率的理论分析和仿真结果完全相符;增加反馈比特数可提高阵列增益,但不能增加分集增益;在慢变信道中,波束成形要显著优于正交空时分组码;误码率受信道估计误差和反馈延迟影响,且对后者尤为敏感。 相似文献
14.
Khaled Almustafa Serguei Primak Tricia Willink Kareem Baddour 《Wireless Personal Communications》2009,50(1):69-81
Achievable rates of wireless communication systems with pilot-based channel estimation are investigated for the case of time-selective
fading. Novel analytical expressions for the maximum achievable rates of such systems are derived in terms of the system signal-to-noise
ratio (SNR), fading rate and estimation scheme deployed. The frame size is optimized jointly based on the SNR and the fading
rate. The maximum rate achieving coding scheme is suggested and shown to be a modified version of the classical water-filling
algorithm that accounts for imperfect channel state information (CSI) at the transmitter. The impact of the estimation scheme
and the angular spread of the received signal on the quality of estimation and achievable rates is evaluated. A number of
numerical simulations are provided to illustrate the dependence of the optimal block length and achievable rates on SNR, fading
rate, estimation scheme and angular spread of the channel.
相似文献
Kareem BaddourEmail: |
15.
《Wireless Communications, IEEE Transactions on》2008,7(10):3674-3678
Significant throughput improvements can be obtained in multiple-inputmultiple-output (MIMO) fading channels by merging beamforming at the transmitter and maximal ratio combining (MRC) at the receiver. In general, accurate channel state information (CSI) is required to achieve these performance gains. In this paper, we analyze the impact of channel prediction error on the bit error rate (BER) of combined beamforming and MRC in slow Rayleigh fading channels. Exact closed-form BER expressions are obtained in terms of elementary functions. Numerical results show that imperfect CSI causes little BER degradation using channel prediction of moderate complexity. 相似文献
16.
We propose novel low-complexity iterative channel estimators based on B-splines. Local splines are adopted for computational simplicity. Minimum mean square error (MMSE) local splines with integral sampling are derived. The MSE of the proposed estimators depends on signal-to-noise ratio, fading rate, sampling interval, spline order and the number of weighting coefficients; these dependencies are investigated. The linear and cubic local splines with as few as seven weighting coefficients are capable of achieving MSE and BER performance comparable to those of the Wiener filter and the spheroidal basis expansion. However, a significantly lower complexity is achieved using B-splines 相似文献
17.
量化噪声对衰落信道下MRC合并信噪比的影响 总被引:1,自引:1,他引:0
文中主要研究瑞利平衰落信道下量化噪声对最大比合并(MRC)接收分集合并输出信噪比的影响.文中推导了量化噪声与信道噪声、信道参数之间的数学关系.仿真结果阐明量化对分集度几乎没有影响,只是使系统产生了固定的信噪比恶化.无论是1%中断率对应的信噪比,还是平均信噪比,1bit量化造成的损失约为2dB,而4bit量化的损失则在0.2~0.9dB左右. 相似文献
18.
With the deployment of small cells and device to device communications in future heterogeneous networks,in many situations we would encounter mobile radio channels with partly blocked line of sight component,which are well modeled by the Rician shadowed(RS) fading channel.In this paper,by the usage of Kummer transformation,a simplified representation of the RS fading channel with integral fading parameter is given.It is a finite series representation involving only exponential function and low order polynomials.This allows engineers not only the closed-form expressions for exact performance analysis over RS fading channel,but also the insights on the system design tactics. 相似文献
19.
A blind receiver scheme for narrowband separately- correlated Rician block fading coded MIMO systems is described. It is shown that this receiver (which can be interpreted as a limiting case of the optimum pilot-aided receiver) attains the maximum achievable throughput at sufficiently high Eb/N0 ratio. The influence of the Eb/N0 ratio and of the channel Rice factor on the receiver performance are studied and it is shown that, as either of these parameters increases, the advantage of the blind versus the pilot-aided receiver becomes more sensible. The results obtained support the intuition that, if the line-of-sight component is sufficiently strong, a blind scheme using only the knowledge of the fading statistics parameters matches or outperforms pilot- aided detection. 相似文献
20.
Escribano F.J. Lopez L. Sanjuan M.A.F. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(6):581-585
In this brief, we analyze a kind of chaos-coded modulations over both Rician and Rayleigh frequency non-selective uncorrelated fading in the presence of additive white Gaussian noise. We provide bounds both for the case when perfect channel-state information (CSI) is available at the decoder and when there is no CSI. We show that the bounds proposed can be tight enough to give reason of the behavior of these systems in a flat fading channel. We compare the results with a related trellis-coded modulation and show that the degradation in performance can be at least as low as with conventional coded modulation systems. 相似文献