In this paper, we present a new spacetimeblock code for time-and frequency-selective (doubly-selective) channels. It can be interpreted as the extension of the Alamouti code to doubly-selective channels, and relies o...
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In this paper, we present a new spacetimeblock code for time-and frequency-selective (doubly-selective) channels. It can be interpreted as the extension of the Alamouti code to doubly-selective channels, and relies on a joint time frequency reversal of the transmitted sequences. Under certain channel conditions, the proposed spacetimeblock code belongs to the class that achieves full spatial, delay, and Doppler diversity using a maximum-likelihood (ML) receiver, as well as a linear zero-forcing (LZF) or linear minimum mean-squared error (LMMSE) receiver. For realistic doubly-selective channels, a real-valued linear data model is presented, for which different receiver structures can be developed.
We present a multiuser receiver for CDMA systems with the combination of turbo channel coding and space-time block coding. A turbo scheme based on multiuser detection, soft interference cancellation and decoding is pr...
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We present a multiuser receiver for CDMA systems with the combination of turbo channel coding and space-time block coding. A turbo scheme based on multiuser detection, soft interference cancellation and decoding is provided, and the algorithms for space-time decoding and separately interference suppressing are derived in this paper. The multiuser detection consists of multiuser interference suppression and single-user space-time decoding. Then we develop the iterative multiuser receiver based on the soft estimates of the interfering users' symbols. Moreover, simulation is given to verify the effectiveness of the multiuser receiver.
In this letter, the beam squint problem, which causes significant variations in radiated beam gain over frequencies in a millimeter wave communication system, is investigated. A constant modulus beamformer design, whi...
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In this letter, the beam squint problem, which causes significant variations in radiated beam gain over frequencies in a millimeter wave communication system, is investigated. A constant modulus beamformer design, which is formulated to maximize the expected average beam gain within the bandwidth with limited variation over frequencies within the bandwidth, is proposed. A semidefinite relaxation method is developed to solve the optimization problem under the constant modulus constraints. Depending on the eigenvalues of the optimal solution, either direct beamforming or transmit diversity-based beamforming is employed for data transmissions. Through numerical results, the proposed transmission scheme can compensate for beam squint effectively and improve system throughput. Overall, a transmission scheme for beam squint compensation in wide-band wireless communication systems is provided.
This paper presents a MIMO adaptive beamforming in the MC-CDMA system. At the transmitter, a space-time block coding is concatenated to MC-CDMA modulation. At the receiver, an adaptive GSC beamformer is to filter the ...
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ISBN:
(纸本)9788955191356
This paper presents a MIMO adaptive beamforming in the MC-CDMA system. At the transmitter, a space-time block coding is concatenated to MC-CDMA modulation. At the receiver, an adaptive GSC beamformer is to filter the desired user and suppress interferences by beamspace processing. Combined with the space-time block coding, the smart antenna forms multi-mainbeams toward the desired user. The system performance is evaluated by illustrating the estimated DOAs, beampatterns, weight convergence and BERs in both the flat and frequency selective fadings.
In this paper, the problem of joint antenna selection and power allocation (J-AS-PA) for Alamouti space-time block coding (STBC)-based clustered downlink nonorthogonal multiple-access (NOMA) networks is considered. Es...
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In this paper, the problem of joint antenna selection and power allocation (J-AS-PA) for Alamouti space-time block coding (STBC)-based clustered downlink nonorthogonal multiple-access (NOMA) networks is considered. Essentially, the aim is to assign a pair of antennas to each user cluster and perform power allocation to maximize the network sum-rate, while satisfying quality-of-service (QoS) requirements for all users. However, the problem is nonconvex and computationally-expensive. In turn, it is split into two subproblems; antenna selection, and power allocation over each (user cluster, antenna pairs) combination, and then solved via a two-stage solution procedure. In Stage 1, antenna selection is solved using the stable marriage matching algorithm, whereas the power allocation problem is reformulated as a concave maximization problem. In Stage 2, a swap matching algorithm is devised to ensure stability and further improve the network sum-rate. Simulation results illustrate that the proposed solution procedure achieves a near-optimal network sum-rate in comparison with the global optimal J-AS-PA scheme, and is superior to the OMA-based network. Not only that, but the Alamouti-based schemes will be shown to outperform the conventional non-Alamouti STBC counterpart schemes, which is due to the spatial-diversity gains. Lastly, light is shed on the effect of imperfect successive interference cancellation (SIC) and channel state information (CSI), where the Alamouti-based schemes demonstrate more robustness against SIC and CSI errors than other benchmark schemes.
Reliable, with high data rate, acoustic communication in time-valTing, multipath shallow water environment is a hot research topic recently. Passive time reversal communication has shown promising results in improveme...
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Reliable, with high data rate, acoustic communication in time-valTing, multipath shallow water environment is a hot research topic recently. Passive time reversal communication has shown promising results in improvement of the system performance. In multiuser environment, the system performance is significantly degraded due to the interference among different users. Passive time reversal can reduce such interference by minimizing the cross-correlated version of channel impulse response among users, which can be realized by the well-separated users in depth. But this method also has its shortcomings, even with the absence of relative motion, the minimization sometimes may be impossible because of the time-varying environment. Therefore in order to avoid the limitation of minimizing the cross-correlated channel function, an approach of passive time reversal based on space-time block coding (STBC) is presented in this paper. In addition, a single channel equalizer is used as a pest processing technique to reduce the residual symbol interference. Experimental results at 13 kHz with 2 kHz bandwidth demonstrate that this method has better performance to decrease bit error rate and improve signal to noise ratio, compared with passive time reversal alone or passive time reversal combined with equalization.
A detector for space-time block coding is proposed to combat time-selective fading. To suppress both noise and interference, a minimum mean square error (MMSE) based detector is introduced for space-time block coding....
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A detector for space-time block coding is proposed to combat time-selective fading. To suppress both noise and interference, a minimum mean square error (MMSE) based detector is introduced for space-time block coding. It is shown by simulations that the proposed detector outperforms the conventional detectors when the channel is time-selective fading.
Analytical expressions concerning the capacity and bit error rate (BER) of multiple-input multiple-output systems with space-time block coding (STBC) are derived. Two fading environments are examined, log-normal and R...
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Analytical expressions concerning the capacity and bit error rate (BER) of multiple-input multiple-output systems with space-time block coding (STBC) are derived. Two fading environments are examined, log-normal and Rician channels. A tight closed-form upper bound is presented for the BER of systems operating in log-normal fading environments in addition to an upper bound for the capacity of this type of systems. The latter bound applies to systems that operate under Rician fading as well. The analytical results were validated against ample numerical simulations for three STBC schemes and three phase-shift-keying modulations. The proposed bounds proved to. be a tractable way to evaluate the system performance when no closed-form expression for the probability density function or the moment generating function is known.
The capacity enhancement for random coherent optical multiple-input multiple-output (MIMO) channels in multi-mode fiber (MMF) links is investigated theoretically. Additionally, the performance of space-timeblock codi...
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The capacity enhancement for random coherent optical multiple-input multiple-output (MIMO) channels in multi-mode fiber (MMF) links is investigated theoretically. Additionally, the performance of space-time block coding (STBC) techniques for achieving high reliability optical MIMO transmission is numerically examined. A comparative study is performed by considering several schemes that employ multiple transmitters/receivers. Simulation results of these schemes, in terms of bit error rate (BER) as a function of optical signal to noise ratio (OSNR), are provided. (C) 2012 Elsevier GmbH. All rights reserved.
Intelligent reflecting surface (IRS) can realize information manipulation and signal modulations to perform space-timecoding wireless communication. This article introduces a novel model to perform space-timeblock c...
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Intelligent reflecting surface (IRS) can realize information manipulation and signal modulations to perform space-timecoding wireless communication. This article introduces a novel model to perform space-time block coding (STBC), where the base station transmits multiple symbols to a destination through multiple IRS that are utilized to adjust the phase shift and establish strong links. To maximize the end-to-end SNR, we propose a graph theory based method to obtain the optimal transmit antenna selection (TAS) scheme. Based the optimal TAS scheme, we derive the statistical characterizations of the sum of independent generalized gamma random variables to obtain end-to-end signal-to-noise ratio expressions. Then, the closed-form expressions of outage probability (OP) and symbol error rate (SER) are formulated respectively to evaluate the coverage and reliability performance in wireless communication systems. Furthermore, the asymptotic expressions for OP and SER at a high transmission power are given, then the diversity order is discussed to observe the performance limit. To verify this theoretical performance analysis, extensive computer simulations are conducted to prove its effectiveness. The simulation results show that the multi-IRS-aided STBC system can attain the same or even better performance as the STBC system based on multiple amplify-and-forward relays using a little number of reflecting elements. More interestingly, the OP and SER of this system decrease more than that of the relays-aided system as transmission power increases.
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