This paper presents a transmit diversity scheme that allocates space-time block codes (STBC) to beamspace and spreading codes for two-dimensional spreading orthogonal frequency-division multiplexing code-division mult...
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This paper presents a transmit diversity scheme that allocates space-time block codes (STBC) to beamspace and spreading codes for two-dimensional spreading orthogonal frequency-division multiplexing code-division multiplexing (OFDM-CDM) downlink transmission. In this scheme, the STBC output symbols are beam-steered using a pair of neighboring beams selected via closed-loop beam selection. The beam-steered symbols in two adjacent time slots are spread by two distinct spreading codes and multiplexed in the same spreading segment. User signals transmitted from different pairs of beams, but that share the same beam, interfere with each other when decoding STBC. Spreading codes are thus allocated to users according to beam pairs used. This is to suppress the interference in time-direction despreading that precedes decoding of STBC. Simulation results demonstrated that the proposed scheme provides beam gains or beam diversity gains or both and that it alleviates inter-code interference by spatially separating user signals by using transmit beam. The proposed scheme also provides high tolerance to large Doppler spread.
This letter evaluates the peak-to-average power ratio (PAR) performance in a space-time block coded (STBC) multicode CDMA (MC-CDMA) system using a selected mapping (SLM) approach. The ordinary method is to apply the S...
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This letter evaluates the peak-to-average power ratio (PAR) performance in a space-time block coded (STBC) multicode CDMA (MC-CDMA) system using a selected mapping (SLM) approach. The ordinary method is to apply the SLM scheme for each transmit antenna individually, while the investigated SLM-based STBC MC-CDMA system selects the transmitted sequence with the lowest average PAR over all transmit antennas concurrently. SLM-based STBC MC-CDMA system retrieves the side information very accurately at the expense of a slight degradation of the PAR performance, which can improve the overall detection performance of the STBC MC-CDMA system in the presence of erroneous side information compared to the ordinary SLM approach.
Three design requirements of space-time block code, full diversity order, full data rate and orthogonality, cannot be achieved simultaneously when the number of transmit antenna is more than two. In this paper, we pro...
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Three design requirements of space-time block code, full diversity order, full data rate and orthogonality, cannot be achieved simultaneously when the number of transmit antenna is more than two. In this paper, we propose a transmit diversity scheme-circular shifted transmit diversity (CSTD). CSTD can always achieve the full data rate and has very low decoding complexity. Through the performance analysis and simulation comparison in the case of same spectrum efficiency between CSTD and other well-known proposed schemes, it can be proved that CSTD always significantly outperforms the other transmit diversity schemes with full data rate. Additionally, compared with the transmit diversity schemes with full diversity order, CSTD has lower complexity and approximately the same performance when channel coding is concatenated. Copyright (C) 2004 John Wiley Sons, Ltd.
In this letter, a simple adaptive transmit diversity technique with side information is presented. The proposed scheme has a number of attractive characteristics. First, it is simple to implement. Second, it is effici...
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In this letter, a simple adaptive transmit diversity technique with side information is presented. The proposed scheme has a number of attractive characteristics. First, it is simple to implement. Second, it is efficient in terms of bandwidth requirements for side information feedback. Finally, it adapts to the quality of the side information to accordingly configure the space-time signal set to be transmitted so that additional gain in signal-to-noise ratio can be achieved at the receiver. In effect, it can be viewed as a flexible combination of suboptimal beamforming and space-timeblock coding.
We design a DAB system using space-time coding for reliable transmission in the multipath fading channel. This letter assess the performance evaluation of space-timecoded DAB system. For channel estimation in the spa...
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We design a DAB system using space-time coding for reliable transmission in the multipath fading channel. This letter assess the performance evaluation of space-timecoded DAB system. For channel estimation in the space-timecoded DAB system, we introduce two training sequences and derive the mean square error of each training sequence. We then represent the average symbol error rate of the space-timecoded DAB system for the specific cases of two, three, four transmit antennas.
Coherent decoding of orthogonal space-time block codes (OSTBC) takes advantage of transmit/receive diversity to mitigate fading channel effects. Thanks to the orthogonality of OSTBC, a low-complexity linear maximum li...
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ISBN:
(纸本)0780387945
Coherent decoding of orthogonal space-time block codes (OSTBC) takes advantage of transmit/receive diversity to mitigate fading channel effects. Thanks to the orthogonality of OSTBC, a low-complexity linear maximum likelihood (NIL) decoding becomes available if the receiver knows the channel state information (CSI). For OSTBC over time-selective channels, we develop an analytical expression of the bit error rate (BER) performance for the linear decoding with minimum mean squared error (MMSE) channel estimates in place of the true channel. Based on the expression, we derive a BER performance limit in decision-directed mode where the channel is tracked with Kalman filtering. Numerical examples are provided to see the impact of time-selective fading on the BER performance.
A differential modulation scheme using space-time block codes is put forward. Compared with other schemes,our scheme has lower computational complexity and has a simpler decoder. In the case of three or four transmitt...
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A differential modulation scheme using space-time block codes is put forward. Compared with other schemes,our scheme has lower computational complexity and has a simpler decoder. In the case of three or four transmitter antennas, our scheme has a higher rate a higher coding gain and a lower bit error rate for a given rate. Then we made simulations for space-time block codes as well as group codes in the case of two, three, four and five transmit antennas. The simulations prove that using two transmit antennas, one receive antenna and code rate of 4 bits/s/Hz, the differential STBC method outperform the differential group codes method by 4 dB. Useing three, four and five transmit antennas,one receive antenna, and code rate of 3 bits/s/Hz are adopted, the differential STBC method outperform the differential group codes method by 5 dB, 6.5 dB and 7 dB, respectively. In other words, the differential modulation scheme based on space-time block code is better than the corresponding differential modulation scheme
Coherent decoding of orthogonal space-time block codes (OSTBC) takes advantage of transmit/receive diversity to mitigate fading channel effects. If the receiver knows the channel state information (CSI), the orthogona...
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Coherent decoding of orthogonal space-time block codes (OSTBC) takes advantage of transmit/receive diversity to mitigate fading channel effects. If the receiver knows the channel state information (CSI), the orthogonality of OSTBC enables a low-complexity linear maximum likelihood (ML) decoding. To obtain CSI, the receiver estimates and/or tracks time-varying channels but channel estimation errors are inevitable. In this paper, we develop an analytical expression of the bit error rate (BER) performance for the linear decoding with minimum mean squared error (MMSE) channel estimates in place of the true channel. Based on the expression, we derive a BER performance limit when the channel is tracked with Kalman filtering.
A preposed implementation of space-timeblock encoding using channel encoding and constellation mapping is presented. It implements the space-timeblock encoding at the step of channel coding instead of modulation. Th...
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A preposed implementation of space-timeblock encoding using channel encoding and constellation mapping is presented. It implements the space-timeblock encoding at the step of channel coding instead of modulation. Thus it has simple and generalized construction of the transmitters and easy implementation. The simulation indicates that this method has performance similar to the conventional ones.
The goal of this paper is to reduce the decoding complexity of space-timeblock turbo-coded system with low performance degradation. Two block turbo-coded systems with antenna diversity are considered. These include t...
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The goal of this paper is to reduce the decoding complexity of space-timeblock turbo-coded system with low performance degradation. Two block turbo-coded systems with antenna diversity are considered. These include the simple serial concatenation of error control code with space-time block code, and the recently proposed transmit antenna diversity scheme using forward error correction techniques. It is shown that the former performs better when compared to the latter in terms of bit error rate (BER) under the same spectral efficiency (up to 7 dB at the BER of 10(-5) for quasistatic channel with two transmit and two receive antennas). For the former system, a computationally efficient decoding approach is proposed for the soft decoding of space-time block code. Compared to its original maximum likelihood decoding algorithm, it can reduce the computation by up to 70% without any performance degradation. Additionally, for the considered outer codeblock turbo code, through reduction of test patterns scanned in the Chase algorithm and the alternative computation of its extrinsic information during iterative decoding, extra 0.3 dB to 0.4 dB coding gain is obtained if compared with previous approaches with negligible hardware overhead. The overall decoding complexity is approximately ten times less than that of the near-optimum block turbo decoder with coding gain loss of 0.5 dB at the BER of 10(-5) over AWGN channel.
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