multiple-inputmultiple-output (MIMO) systems employing adaptive modulation have been widely used for their potential to optimize the spectral efficiency while keeping the bit error probability (BEP) under a certain t...
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ISBN:
(纸本)9781424493326
multiple-inputmultiple-output (MIMO) systems employing adaptive modulation have been widely used for their potential to optimize the spectral efficiency while keeping the bit error probability (BEP) under a certain target level. In this paper, we examine a MIMO system using square orthogonal space-time block codes (OSTBCs) with rate-adaptive M-QAM and operating over arbitrarily correlated Rayleigh fading channel with imperfect channel estimation. Assuming finite-rate feedback without delay, we derive accurate closed-form expressions for the average BEP, spectral efficiency and bit error outage of our system. The presented expressions allow to easily study the impact of channel estimation errors and fading correlation on the performance of rate-adaptive MIMO OSTBC systems.
multipleinputmultipleoutput (MIMO) techniques for wireless communication systems have attracted in the last years huge research activity due to the possibility of improving the link performance by increasing the ch...
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ISBN:
(纸本)9783642357541
multipleinputmultipleoutput (MIMO) techniques for wireless communication systems have attracted in the last years huge research activity due to the possibility of improving the link performance by increasing the channel capacity and decreasing the bit-error rate (BER). Due to the strongly increasing demand in high-data rate transmission systems, frequency non-selective MIMO links have reached a state of maturity and frequency selective MIMO links are in the focus of interest. In this field, the combination of MIMO transmission and OFDM (orthogonal frequency division multiplexing) can be considered as an essential part of fulfilling the requirements of future generations of wireless systems. However, single-user scenarios have reached a state of maturity. By contrast multiple users' scenarios require substantial further research, where in comparison to ZF (zero-forcing) multiuser transmission techniques, the individual user's channel characteristics are taken into consideration in this contribution. Furthermore, the use of multiple antennas both at the transmit and the receive front-ends introduces a correlation effect between the antennas due to their proximity producing interference. In consequence, the BER increases and the channel capacity decreases. The goal of the present contribution is to analyze the system performance under different spatial antennas distributions for Multiuser MIMO-OFDM systems in correlated and non-correlated fading channels. The performed joint optimization of the number of activated MIMO layers and the number of transmitted bits per subcarrier along with the appropriate allocation of the transmit power shows that not necessarily all user-specific MIMIO layers per subcarrier have to be activated in order to minimize the overall BER under the constraint of a given fixed data throughput.
In this paper we consider the design of multi-stream demodulators for multiple-inputmultiple-output (MIMO) systems. Our proposed MIMO demodulator is based on the stack tree-search strategy and provides soft-outputs i...
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ISBN:
(纸本)9781424456383
In this paper we consider the design of multi-stream demodulators for multiple-inputmultiple-output (MIMO) systems. Our proposed MIMO demodulator is based on the stack tree-search strategy and provides soft-outputs in the form of exact max-log log-likelihood ratios (max-log LLRs). We prove that our proposed demodulator is optimally efficient in that it visits the least number of nodes among all optimal tree-search based demodulators. We conduct a comprehensive complexity analysis of the optimally efficient demodulators. We also identify key parameters associated with our proposed demodulator that can be tuned to realize near max-log performance with substantially reduced complexity, as demonstrated via simulations.
We propose a computationally efficient lattice reduction (LR) algorithm for multiple-inputmultiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems in frequency-selective fading channels. In ou...
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ISBN:
(纸本)9781424477425
We propose a computationally efficient lattice reduction (LR) algorithm for multiple-inputmultiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems in frequency-selective fading channels. In our proposed algorithm, we exploit the inherent feature of unimodular transformation matrix P that remains the same for frequency components which have relatively high amplitude correlation. We eliminate the redundant calculations by reducing brute-force LR iterations among adjacent subcarriers. We simulate the error performance and complexity of the proposed algorithm under various MIMO-OFDM system configurations. The results demonstrate that the proposed algorithm could significantly reduce the LR complexity by up to 90% multiplications and 99% divisions of brute-force LR while maintaining the system performance.
Wireless communication systems always demand higher data rates and better quality of service (QoS). Transmission reliability in a wireless channel with high path loss, time-varying multipath fading and power and bandw...
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ISBN:
(纸本)9788996865018;9781467331487
Wireless communication systems always demand higher data rates and better quality of service (QoS). Transmission reliability in a wireless channel with high path loss, time-varying multipath fading and power and bandwidth limitations, is a testing issue. multiple-inputmultiple-output (MIMO) systems can reduce the effect of these channel interferences and achieve reliable signal transmission at high data rate. Space-time block code (STBC) is a coding scheme for the use of multiple transmits antennas providing a simple transmit diversity scheme. In certain MIMO fading environments, the offered channel capacity can be very low, where despite rich local scattering and uncorrelated transmit and receive signals, the system has a single degree of freedom. This effect has been termed as keyhole or pinhole effect. This contribution analyzes the average symbol error rate (SER) performance of MIMO systems employing orthogonal STBC with M-PSK constellations over fading channels in the presence of the keyhole. The Nakagami-m distribution has been considered for MIMO channel modeling. We derive the probability density function (PDF) of instantaneous signal-to-noise ratio (SNR) and an integral equation to calculate the average SER after space-time block decoding in such channels. Numerical results show that the keyhole significantly degrades the SER performance of the STBC in MIMO channels. The performance of such channels is a function of fading figure, m and diversity.
Inversion of channel matrix is required for commonly used detection schemes in multiple-inputmultiple-output (MIMO) systems. In time-varying fading channels, frequent matrix inversion is computationally intensive for...
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ISBN:
(纸本)9781424425198
Inversion of channel matrix is required for commonly used detection schemes in multiple-inputmultiple-output (MIMO) systems. In time-varying fading channels, frequent matrix inversion is computationally intensive for mobile terminals operating at high data rates. Several existing papers have addressed this problem for MIMO orthogonal frequency division multiplexing systems by employing interpolation since the channel coefficients are correlated in the frequency domain. The correlation of the channel in the time domain, i.e., the channel matrices at consecutive symbol intervals vary only slightly, could also be exploited. We propose an algorithm that exploits second-order extrapolation in the time domain to lower the computational complexity of matrix inversion. While existing schemes are mainly designed for linear MIMO detection, the proposed algorithm can be applied for both non-linear detection such as ordered successive interference cancelation (OSIC) and linear detection. The proposed scheme can be efficiently implemented with only addition and integer multiplication. Simulation results of the proposed scheme applied in MIMO OSIC detection demonstrate that it can significantly reduce the matrix inversion complexity while maintaining the system performance.
In this contribution a coherent (2x2) (multipleinputmultipleoutput) MIMO transmission with iterative detection over a measured multimode fiber channel is studied. Extrinsic information transfer (EXIT) charts are us...
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ISBN:
(纸本)9781457714351
In this contribution a coherent (2x2) (multipleinputmultipleoutput) MIMO transmission with iterative detection over a measured multimode fiber channel is studied. Extrinsic information transfer (EXIT) charts are used for analyzing and optimizing the convergence behaviour of the iterative demapping and decoding. The results show BER and energy-per-hit improvements when using optimized MIMO transmission as compared to conventional (single input single output) SISO transmission techniques.
This paper presents an iterative learning control strategy for a class of multiple-inputmultiple-output (MIMO) nonlinearly parameterized systems with unknown time-varying state delays and actuator faults. To deal wit...
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ISBN:
(数字)9789881563903
ISBN:
(纸本)9789881563903
This paper presents an iterative learning control strategy for a class of multiple-inputmultiple-output (MIMO) nonlinearly parameterized systems with unknown time-varying state delays and actuator faults. To deal with the non-linearity caused by the unknown time-varying state delays and actuator faults in the MIMO nonlinear system, the P-type iterative learning controller with a fully-saturated parameter updating law is proposed. By constructing a composite energy function(CEF), the convergence analysis of the tracking error is given. Finally, a numerical simulation is used to verify the effectiveness and correctness of the control scheme proposed in this paper.
The future generation of wireless communications systems uses the generalized frequency division multiplexing (GFDM) due to its viable candidate waveform to perform multiple user scheduling. It is a non-orthogonal wav...
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The future generation of wireless communications systems uses the generalized frequency division multiplexing (GFDM) due to its viable candidate waveform to perform multiple user scheduling. It is a non-orthogonal waveform susceptible to intercarrier and intersymbol interference (ISI);still, it offers flexible pulse shaping that enhances the efficiency of user scheduling. Here, to accomplish spatial diversity, the multiple-inputmultiple-output (MIMO) is incorporated with GFDM to enhance the performance;there is also an extra inter-antenna interference problem that limits the model's performance. The issue concerning inter-antenna interference can be resolved by adopting pilot-based information transfer. The detection of a signal at the receiver based on the minimum mean square error has the issue of computational complexity while enhancing the estimation quality of a detector. Hence, a low-complexity channel estimation technique is proposed in this research using the V-degree polynomial-based channel estimation technique, wherein the cubic order computation is reduced to square order. Also, the proposed adaptive pulse shaping technique, wherein the filter coefficient is optimized using the gazelle optimization algorithm (GOA) to provide optimal pulse shaping filter parameters by employing bit error rate (BER) as the objective function. The performance of a proposed V-degree polynomial-based channel estimation is analyzed based on various assessment measures like BER and MSE and acquired the minimal values of 5.75E-05 and 2.07E-05, respectively. To design a novel technique to improve the performance of multiple-inputmultiple-output generalized frequency division multiplexing (MIMO-GFDM) system for 5G *** introduce a low-complexity channel estimation process based on an enhanced V-degree polynomial-based low-complexity channel estimator (EVd-LCE) in the MIMO-GFDM *** recommend a lifting-based wavelet transform (L-WT) with GFDM waveform to maximize
multiple-inputmultiple-output (MIMO) systems suffer from high BER in the mining environment. In this paper, the mine MIMO depth receiver model is proposed. The model uses densely connected convolutional networks for ...
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multiple-inputmultiple-output (MIMO) systems suffer from high BER in the mining environment. In this paper, the mine MIMO depth receiver model is proposed. The model uses densely connected convolutional networks for feature extraction and constructs multiple binary classifiers to recover the original information. Compared with conventional MIMO receivers, the model has no error accumulation caused by processes such as decoding and demodulation. The experimental results show that the model has better performance than conventional decoding methods under different modulation codes and variations in the number of transmitting terminals. Furthermore, we demonstrate that the model can still achieve effective decoding and recover the original information with some data loss at the receiver.
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