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The baseband representation of the proposed closed-loop system.
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In this letter, we propose a transmit antenna shuffling scheme for quasi-orthogonal space-time block codes (QO-STBCs). We show that by adaptively mapping the space-time sequences of the QO-STBC to the appropriate transmit antennas depending on the channel condition, the proposed scheme can improve its transmit diversity with limited feedback inform...
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Context 1
... block diagram of the proposed closed-loop QO-STBC with four transmit antennas and one receive antenna is de- picted in Fig. 1. We assume that the channel state information (CSI) can be estimated at the receiver. Considering that the channel interference parameter, W , strongly depends on the equivalent channel matrix, H J , we can implement an antenna shuffling structure between the QO-STBC encoder and four transmit antennas to minimize the channel ...
Context 2
... 2-bit feedback scheme with four antenna shuffling patterns. It is well known that the QO-STBC using different patterns have similar performance because the same code matrix is used during the whole signal transmission. Therefore, arbitrary four antenna shuffling patterns can be used. For the convenience, we can employ the first four patterns in Fig. 2, (1A, 2, 3, 4), (1A, 2, 4, 3), (1A, 3, 4, 2) and (1B, 2, 3, 4) in this letter. In general, for four transmit antennas, we always find six shuffling patterns with different |W | for any ...
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Citations
... A N antenna shuffling (Ant-S) transmitter maps the coded data streams to the proper antennas according to the shuffling pattern selected by feedback information from the receiver. The Ant-S can substantially improve the received signal-to-noise ratio (SNR) and the throughput of multi- antenna systems, such as double space-time transmit diver- sity (DSTTD) systems [1], [2] and quasi-orthogonal space- time block code (STBC) systems [3], [4]. On the other hand, asymmetric power amplifiers (PAs) with uneven gains are employed for high energy efficiency [5]- [7]. ...
In this paper, a novel power amplifier (PA) shuffling method is proposed for a space-time line code (STLC) system with uneven PA gains. The proposed method is composed of pre-shuffling and post-shuffling which represent the assignment of STLC symbols to PAs and the allocation of PAs to transmit antennas, respectively. Through these shuffling procedures, the proposed scheme matches the larger gain PA to the larger effective channel gain with STLC in order to maximize the STLC decoding signal-to-noise ratio (SNR). A theoretical analysis provides a formula to compute the decoding SNR, and it is shown through numerical simulations that the proposed PA shuffling method can significantly improve the performance of conventional STLC systems, regardless of the channel state information uncertainty, especially when the number of transmit antennas is large.
... Space-time wireless systems exploit multiple co-located spatial elements at the transmitter and/or receiver to overcome multipath fading or to increase transmission rates. When multiple transmit antennas are available, this is typically combined with an appropriate signal design such as space-time coding [1]–[9] to achieve spatial diversity and/or spatial multiplexing . However, implementing multiple antennas on small-size terminals becomes difficult. ...
... These codes provide partial diversity but transmission rate one [8]. There are schemes to achieve full diversity or to improve the performance of quasiorthogonal codes such as constellation rotation and transmit antenna shuffling [9]. For different sets of fading coefficients, the scheme proposed in [1] does not always result in the highest SNR at the receiver. ...
... The impact of the channel-dependent interference in (14) can be estimated by calculating the the statistical average of the absolute value of W as a function of the number of transmission patterns n. With pdf and cdf of W given in (17), and following the analysis given in [7], [9], we have ...
We propose an efficient space-time coded cooperative relay communications scheme that employs linear precoding and transmission-pattern selection. If effectively exploited, distributed spatial diversity and the cooperative nature of multihop communications could significantly increase the coverage area of a wireless network that consists of a number of power-limited relay nodes. We build upon an existing block linear precoding technique for conventional multiple-input multiple-output systems studied in to improve the diversity performance of a multihop relay network. We propose a distributed-relay-selection algorithm to maximize the signal-to-noise ratio at the receiver. We show, via simulation, that the proposed pattern-selection scheme with precoding outperforms the conventional space-time coded relay system using quasi-orthogonal space-time block codes by over 2 dB at a bit error rate of 10<sup>-3</sup>.
... These codes are full rate and provide partial diversity. Recently, many researches designed the STBC with full rate and full diversity for four transmit antennas [5]- [10]. For open-loop communication systems, the optimum constellation rotation proposed for QOSTBC with different modulation schemes is the one of good diversity improvement approaches [5]. ...
... For open-loop communication systems, the optimum constellation rotation proposed for QOSTBC with different modulation schemes is the one of good diversity improvement approaches [5]. Although a lot of partial feedback methods can be adopted to improve the closedloop system performance [6], [7], [10], the major problems of such systems are high cost and high complexity due to the more feedback information. For practical design of the closed-loop transmission schemes, it is desirable to have features such as a limited amount of feedback information, low decoding delay, low cost and simple decoding process. ...
Quasi orthogonal space time block codes have been proposed to achieve higher symbol transmission rates for more than 2 transmit antennas at the expense of losing the diversity gain. In this paper we propose a method to improve its transmit diversity with one bit feedback. This method useful for extend any space-time code constructed for 4 transmit antennas to M receive antennas. An improvement in transmit diversity is achieved by multiplying each QOSTBC code word with appropriate phase factor which depend on the channel information. Jafarkhani's Quasi Orthogonal Space Time Block Codes as well as its optimal constellation rotated scheme are extended and analyzed.
A transmit antenna shuffling method combined with an orthogonal space-time block code (OSTBC) is proposed for a system using M transmit antennas with asymmetric power amplifiers (PAs) having uneven gains. Considering the uneven gains of PAs, we design an optimal antenna shuffling method with ⌊log
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(M!)⌋-bit feedback to maximize the detection signal-to-noise ratio (SNR). To reduce the feedback, a suboptimal method with ⌊log
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M⌋-bit feedback is proposed. A theoretical analysis and numerical results verify that antenna shuffling can significantly improve the detection SNR of the OSTBC system with uneven PA gains and that the SNR loss of the suboptimal method is marginal.
A transmit antenna selection (TAS) multi-input multi-output orthogonal frequency-division multiplexing (MIMO-OFDM) system based on channel- orthogonalized space-frequency block coding (CO-SFBC) schemes was proposed for better performance. Firstly, the principles and enterions for designig COSTBC/SFBC schemes with angle feedback were proposed, and then the effect of quantization for the feedback angle information within such schemes was discussed. Meanwhile, the TAS scheme was applied to the system to further improve the overall performance. Simulation results show that the combination of the proposed CO-STBC and TAS schemes can significantly improve the system performance, which is much larger than only applying them to systems individually.
Aim at the problem that the channel state information (CSI) is not taken full advantage in traditional distributed generalized ABBA (GABBA) space-time codes in amplify-and-forward relay networks, an improved scheme is proposed. In this scheme, the receiver calculates and sends out the current feedback information according to the CSI. After receiving the feedback information at one of the relay nodes, some pre-process is used on the original signal of this branch. The scheme can alleviate the interference brought by channel dependence, and improve reliability of the system. Analysis and simulation result suggest that the proposed scheme can significantly decrease the system bit error rate in contrast with the former scheme at the cost of one bit feedback information.
This paper presents a novel Quasi- Orthogonal Space-Time Block Codes (QOSTBC) for using in multiple transmit antennas systems. We show that with the aid of multiplying the entries of QOSTBC code words by the appropriate phase factors which depend on the channel information, the proposed scheme can improve its transmit diversity with one bit feedback. The performances of the proposed scenario extended from Jafarkhani’s QOSTBC as well as its optimal constellation rotated scheme are analyzed. By using zero forcing decoding algorithm, simulation results show that zero-forcing algorithm has better bit error rate performance as compared to the existing typical codes and can reduce the computational complexity at receiver.
In this paper, in allusion to the problems that space-time block code with complex signals cannot achieve full transmitting rate when the transmit antennas are more than two, based on the quasi-orthogonal space-time block coding scheme with beamforming, we present a novel method of quasi-orthogonal space-time block code with feedback information, which is designed by aiming at the maximum instantaneous signal-to-noise ratio gain for compensating the performance degradation, to overcome the multi-user access interference of the previous quasi-orthogonal space-time block coding and obtain full diversity gain and maximum coding rate at the same time. The simulation results demonstrate that the proposed closed-loop beamforming scheme can obviously improve the performance of the system without increasing the decoding complexity in the meantime.
A conventional quasi orthogonal space time block code (QO-STBC) scheme can achieve full rate, but at the cost of decoding complexity. This limitation of the conventional QO-STBC scheme is mainly due to interference terms in the detection matrix. In this article, a novel QO-STBC scheme is proposed which eliminates the interference terms. The proposed method achieves improved diversity as compared to the conventional QO-STBC scheme, also providing a considerable reduction in decoding complexity. A transmit antenna shuffling scheme for the proposed code is also illustrated. It is shown that by adaptively mapping space time sequences of the proposed code to appropriate transmit antennas depending on channel condition, proposed scheme can improve its transmit diversity with limited feedback information. Lastly, simulation results show that the symbol error rate performance is improved considerably.
