In this paper, the extension of the orthogonal frequency division multiplexing (OFDM) index modulation (IM) from single-antenna systems to multiple-antenna systems is studied. And a multiple-input multiple-output (MIM...
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ISBN:
(纸本)9781509016983
In this paper, the extension of the orthogonal frequency division multiplexing (OFDM) index modulation (IM) from single-antenna systems to multiple-antenna systems is studied. And a multiple-input multiple-output (MIMO) OFDM IM scheme with circular-shift-based activation pattern is proposed for the rapidly time-varying (RTV) channel. In the proposed scheme, the IM is applied in the joint antenna and sub-carrier dimension. Concretely, a constructive generation method of the IM pattern matrix based on the circular shift of a sparse column vector is presented, which makes the frequency-domain signal is sparse in both antenna and sub-carrier dimensions. The performance of the proposed scheme in the RTV channel is demonstrated by computer simulations.
multiple-input multiple-output (MIMO) channel estimation algorithm is proposed in this paper. A pilot scheme that uses complete complementary sequence (CCS) with complete orthogonality (the sidelobes of the auto-corre...
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ISBN:
(纸本)9781467390262
multiple-input multiple-output (MIMO) channel estimation algorithm is proposed in this paper. A pilot scheme that uses complete complementary sequence (CCS) with complete orthogonality (the sidelobes of the auto-correlation function and cross-correlation function equals zero for all time shifts) was investigated in order to eliminate the mutual interference between multiple antennas. The channel estimation performance under the normalized mean square error sense (NMSE) based on CCS is derived. Results from simulated data, the efficiency and validity of the CCS applied in MIMO channel estimation are proved. The CCS opens up a new direction for channel estimation in the future wireless communication systems. Compared with traditional pilot scheme in the frequency domain, the proposed channel estimation algorithms in the time domain need not matrix inversion which can reduce the computational complexity. In contrast to the complementary pilot mode, CCS-based channel estimation acquired much more flexible configuration in selection of transmitter antenna number. At the same time, compared with the pilot sequence based on m sequence, the channel estimation performance is improved by using the orthogonality of the CCS.
In the paper, the effects of spatial correlation on the channel capacity of a multipleinputmultipleoutput (MIMO) system are studied under Rayleigh fading with correlated antennas. When the SNR is high, the closed-f...
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ISBN:
(纸本)9781457703218
In the paper, the effects of spatial correlation on the channel capacity of a multipleinputmultipleoutput (MIMO) system are studied under Rayleigh fading with correlated antennas. When the SNR is high, the closed-form expression for the channel capacity of MIMO system is given by using the properties of Wishart distribution. Computer simulation results show that the channel capacity is maximized when the antenna spacing increases to a point, and further more, the larger is the scattering angle, the more quickly the channel capacity converges to its maximum.
A compact 5.5 GHz band-notched ultra-wideband (UWB) 2-element antenna with high isolation for multiple-input multiple-output (MIMO) portable wireless devices in wireless personal area network (WPAN) application is pro...
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A compact 5.5 GHz band-notched ultra-wideband (UWB) 2-element antenna with high isolation for multiple-input multiple-output (MIMO) portable wireless devices in wireless personal area network (WPAN) application is proposed. The MIMO antenna is designed for 3.1-10.6 GHz range on Neltec substrate with compact dimension of 43 x 20 mm(2) and is tested experimentally. For the rejection band at 5.5 GHz, a slot of length 1.0 is etched into the radiator. Simple structure, i.e., receded steps at ground are used to improve isolation by 3 dB between two UWB antennas. The simulated and measured results show |S-11|-10 dB and |S-21|-20 dB in most of the frequency range excluding the reject band at 5.5 GHz in UWB range. The measured, simulated and calculated results show that the proposed UWB MIMO antenna is a good candidate for UWB MIMO systems. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1390-1394, 2016
In this paper, an iterative robust minimum-mean square error (MMSE) receiver for space-time block coding (STBC) is proposed to mitigate the performance degradations caused by channel state information (CSI) errors. Th...
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In this paper, an iterative robust minimum-mean square error (MMSE) receiver for space-time block coding (STBC) is proposed to mitigate the performance degradations caused by channel state information (CSI) errors. The proposed scheme estimates an instantaneous covariance matrix of the effective noise, which includes additive white Gaussian noise and the effect of CSI errors. For this estimation, multiple solution candidate vectors are selected based on the distances between the MMSE estimate of the solution and the constellation points, and their a-posteriori probabilities are utilized to execute the estimation of the covariance matrix. To improve the estimation accuracy, the estimated covariance matrix is updated iteratively. Simulation results show that proposed robust receiver achieves substantial performance gains in terms of bit error rates as compared to conventional receiver schemes under CSI errors.
This study evaluated the performance of IEEE 802.15.4 network in the case of applying Alamouti scheme using both 2 x 1 multiple-input single-output (MISO) and 2 x 2 multiple-input multiple-output (MIMO) antenna config...
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This study evaluated the performance of IEEE 802.15.4 network in the case of applying Alamouti scheme using both 2 x 1 multiple-input single-output (MISO) and 2 x 2 multiple-input multiple-output (MIMO) antenna configurations. The modulation curves, i.e., bit error rate (BER) vs. signal-to-noise ratio (SNR) of the conventional IEEE 802.15.4, switching diversity, Alamouti scheme are obtained first. Using the modulation curves, performance of IEEE 802.15.4 network is investigated. Throughput, probability of successful transmission and energy efficiency are used as measures of performance. Simulations are performed to prove the effectiveness of applied Alamouti scheme in the viewpoint of IEEE 802.15.4 network.
This paper presents an effective scheduling scheme for sphere decoding (SD) with runtime constraints, targeting the practical multiple-input multiple-output (MIMO) communication systems where neither the interleaving ...
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This paper presents an effective scheduling scheme for sphere decoding (SD) with runtime constraints, targeting the practical multiple-input multiple-output (MIMO) communication systems where neither the interleaving scheme nor its block size cannot be designed freely. The proposed scheme imposes runtime constraints on SD to distribute the errors due to the early termination of SD. Because the distributed errors may be corrected effectively by forward error correction, the error-rate performance can be improved;experimental results show that the performance improvement is approximately 2dB in terms of the signal-to-noise ratio to achieve a bit-error rate of 10(-4) in 4 x 4 16-QAM MIMO systems. Copyright (C) 2015 John Wiley & Sons, Ltd.
Most of the existing multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) channel estimation methods do not take into account the effect of the pulse-shaping filter in the transmitter ...
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Most of the existing multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) channel estimation methods do not take into account the effect of the pulse-shaping filter in the transmitter nor of the matched filter in the receiver, thus leading to an estimation solution for the composite channel including the pulse-shaping and matched filters, instead of the pure wireless channel. This solution is not sufficiently accurate because of the extra length of the composite channel induced by the two filters especially in the scenario with a small pure channel length. In this study, the authors present a novel methodology for the estimation of the pure multipath channels of pulse-shaped MIMO-OFDM systems. By utilising the knowledge of pulse-shaping and matched filters, the authors develop two channel estimation approaches, namely, a semi-blind approach for the sampling duration-based channels, in which the multipath occurs at the sampling instant and a training-based least-square technique for the upsampling duration-based channels where the multipath may occur in a fraction of sampling duration. A number of computer simulation-based experiments are conducted, and these simulation results confirm the efficacy of the proposed approaches.
With the increasing data rates and the requirement of less transmission delay, which cannot be satisfied by the fourth generation (4G) cellular systems, next generation or the fifth generation (5G) is expected to deal...
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With the increasing data rates and the requirement of less transmission delay, which cannot be satisfied by the fourth generation (4G) cellular systems, next generation or the fifth generation (5G) is expected to deal with these requirements. Among the promising techniques for 5G systems, generalized frequency division multiplexing (GFDM) would be a good candidate due to its flexibility of spectrum mapping, waveform generation, and cooperation of multiple antennas. In this work, we study the synchronization issues of carrier frequency offset (CFO) and sampling time offset (STO). Two methods of estimation of CFO and STO are proposed to combine the estimates at two receive antennas. Through simulation results, we demonstrate that MIMO technique could enhance the estimation accuracies of both CFO and STO.
The feasibility condition of interference alignment (IA) for multiple-input multiple-output two-way interference channel is studied in this paper. A necessary condition and a sufficient condition on the IA feasibility...
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The feasibility condition of interference alignment (IA) for multiple-input multiple-output two-way interference channel is studied in this paper. A necessary condition and a sufficient condition on the IA feasibility are established and the sum degrees of freedom (DoF) for a broad class of network topologies is characterized. The numerical results demonstrate that two-way operation with appropriate IA is able to achieve larger sum DoF than the conventional one-way operation.
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