The uplink of a space-timeblock coded multicarrier modulation code division multiple access (MC-CDMA) system equipped with a uniform linear array (ULA) at the base station is studied. A blind decoder that provides cl...
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The uplink of a space-timeblock coded multicarrier modulation code division multiple access (MC-CDMA) system equipped with a uniform linear array (ULA) at the base station is studied. A blind decoder that provides closed-form solutions of both transmitted symbol sequences and directions of arrival (DOAs) for all active users in one macrocell is derived without the uplink space-time vector channel estimation. The decoder uses an ESPRIT-like method to separate multiple co-channel users with different impinging DOAs. As a result, the DOAs of multiple users are obtained. In particular, a set of signal spaces, every one of which is spanned by the coded symbol sequences of an individual user, are also obtained. From these signal spaces, the original symbol sequences of multiple users are estimated by exploiting the special structure of space-time block coding (STBC) in combination with the finite alphabet property of transmitted symbols. Performance of the proposed scheme is evaluated by extensive computer simulations.
Group layered space-time architecture (GLST) combines space-time block coding and layered space-time processing, where the transmit stream is partitioned into different groups, and in each group, space-timeblock codi...
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Group layered space-time architecture (GLST) combines space-time block coding and layered space-time processing, where the transmit stream is partitioned into different groups, and in each group, space-time block coding is applied. In the traditional receiver of GLST, group detection is applied first to suppress the interference from other groups, and then decoding is performed for the desired group. In this letter, a novel detector is proposed in which the entire groups are decoded first, and then group detection is performed next. Theoretical analysis will demonstrate that the new detector can achieve a significant capacity gain compared with the traditional one. Simulation results will further show that the proposed detector can obtain at least 4 dB gain at a frame-error rate of 10(-2), for instance.
A new approach to blind and semi-blind channel estimation for space-timeblock codes (STBCs) is presented. By exploiting the recently proposed generalized space-timeblock code framework, an STBC system is reduced fro...
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A new approach to blind and semi-blind channel estimation for space-timeblock codes (STBCs) is presented. By exploiting the recently proposed generalized space-timeblock code framework, an STBC system is reduced from multiple-input multiple-output to a single-input multiple-output system. A conventional blind algorithm based on the subspace algorithm is then used to identify the channel impulse responses and achieve equalization. Simulation results demonstrate the performance of the proposed algorithm and a comparable scheme.
In this paper, a new computationally simple approach to blind decoding of orthogonal space-timeblock codes (OSTBCs) is proposed. Using specific properties of OSTBCs, the authors' approach estimates the channel ma...
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In this paper, a new computationally simple approach to blind decoding of orthogonal space-timeblock codes (OSTBCs) is proposed. Using specific properties of OSTBCs, the authors' approach estimates the channel matrix in a closed form and in a fully blind fashion. This channel estimate is then used in the maximum-likelihood (ML) receiver to decode the information symbols. The proposed estimation technique provides consistent channel estimates, and, as a result, the performance of the authors' blind ML receiver approaches that of the coherent NIL receiver, which exploits the exact channel state information (CSI). Simulation results demonstrate the performance improvements achieved by the proposed blind decoding algorithm relative to the popular differential space-time modulation scheme.
Closed-loop, rate-one, channel orthogonalized space-timeblock codes (CO-STBCs) for three and four transmit antennas using a single (real) phase feedback term have been proposed [1]. These codes achieve full diversity...
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Closed-loop, rate-one, channel orthogonalized space-timeblock codes (CO-STBCs) for three and four transmit antennas using a single (real) phase feedback term have been proposed [1]. These codes achieve full diversity and result in maximum likelihood (ML) decoding with only linear processing at the receiver similar to OSTBCs. In this paper, we propose a closed-loop STBC for five and six transmit antennas with rate 3/4, where the one parameter feedback angle can be evaluated in closed form. These codes achieve full diversity and are delay optimal. Simulation results comparing the error-rate performance of the CO-STBC with open-loop OSTBC as well as some quasiorthogonal space-timeblock codes are also provided. While the 1- to 5-dB gain accrued by the closed-loop scheme (over the open-loop methods) is not surprising, the novel contribution of this work is in the approach taken to derive the feedback parameter as a single phase term, which is purely a function of the channel gains.
Antenna diversity is an effective technique for improving the transmission performance in a multi-path fading channel. Recently, transmit diversity has been attracting much attention since it can alleviate the complex...
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ISBN:
(纸本)0780391527
Antenna diversity is an effective technique for improving the transmission performance in a multi-path fading channel. Recently, transmit diversity has been attracting much attention since it can alleviate the complexity problem of the mobile terminal. However, by distributing antennas between the transmitter and receiver, similar performance improvement can be achieved to the case of implementing all antennas only at the transmitter or receiver side. In this paper, we propose a space-timeblock coded-transmit/receive diversity (STBC-TRD), which requires the channel state information (CSI) only at the transmitter side. Unlike STTD, STBC-TRD can use arbitrary number of transmit antennas, while the number of receive antennas is limited to 4. STBC-TRD achieves a larger diversity gain than joint STTD and receive antenna diversity. The performance improvement of STBC-TRD is confirmed by computer simulation.
Outdoor channels can be modelled as as a sum of array response vectors of varying gain at different Angles of Departure (AoDs) from different point sources. Based on this characteristics, we derive a hybrid of Beam-Fo...
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ISBN:
(纸本)081945804X
Outdoor channels can be modelled as as a sum of array response vectors of varying gain at different Angles of Departure (AoDs) from different point sources. Based on this characteristics, we derive a hybrid of Beam-Forming (BF) and space-time block coding (STBC), where the space-time code is transmitted over the beams generated by array response vectors. This is for the practical case where the transmit array may have adequate information on the departure angles of the dominant paths between transmitter and receiver. In the case where the transmitter has knowledge on the associated complex path gains, a power loading scheme is designed when We compute analytically the Signal-to-Noise Ratio (SNR) of the proposed hybrid for the specific case of a two-path channel model and using the orthogonal Alamouti code, and compare the result to the SNR of optimal Linear Precoding (LP) and the theoretically possible SNR of Orthogonal STBC (OSTBC). Simulation results show that the performance of the BF/STBC hybrid with and without power loading can be very close to LP-under certain conditions-or even better in the practical case where there are phase estimation errors in the path gain estimates employed at the transmitter.
In this paper, we first provide an alternative construction of full-diversity rate-one space-timeblock codes (STBCs) based on linear constellation precoding (LCP) and circular delay techniques. Through explicit unita...
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ISBN:
(纸本)0780393058
In this paper, we first provide an alternative construction of full-diversity rate-one space-timeblock codes (STBCs) based on linear constellation precoding (LCP) and circular delay techniques. Through explicit unitary diagonal precoding on symbol blocks, and implicit FFT precoding via circularly shifted transmissions over multiple antennas, the proposed design preserves the modulus property of the information symbols. We then demonstrate that existing quasi-orthogonal STBCs can be constructed by embedding modulus-preserving LCP designs into orthogonal structures, and interestingly, they are also equivalent to the space-time-frequency (STF) block codes, which have been developed for multi-antenna OFDM systems, up to unitary transformations.
Plenty of work have been done on space-time processing in which multiple transmit / receive antennas are used in conjunction with coding to exploit both spatial diversity and time diversity. Constant Mode Algorithm （...
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Plenty of work have been done on space-time processing in which multiple transmit / receive antennas are used in conjunction with coding to exploit both spatial diversity and time diversity. Constant Mode Algorithm （CMA） is an efficient blind adaptive Multi-User Detection （MUD） algorithm for CDMA systems. In this paper, we put forward a novel receiver, which combines CMA blind adaptive Multi-user Detection with STBC technique, and compare the performances of the system using different CM algorithms including SDCMA （ Steepest-Descent CMA）, Standard Linearity Confine CMA（SLCCMA） and Least Squares CMA（LSCMA）. Simulations have been done with multi-path Rayleigh channel.
OFDM (Orthogonal Frequency Division Multiplexing) can effectively eliminate the ISI between different symbols and has high frequency efficiency. OFDM is sensitive to the Doppler frequency offset caused by moving that ...
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OFDM (Orthogonal Frequency Division Multiplexing) can effectively eliminate the ISI between different symbols and has high frequency efficiency. OFDM is sensitive to the Doppler frequency offset caused by moving that can be overcome by space-timecoding. So the application the combination of the space-timecoding and OFDM in next generation wireless telecommunications has attracted more and more attention. In this article, the structure of DSTBC (Differential space-time block coding) combined with OFDM system is given first. Because of no need of channel estimation, the complexity of the receiver is simpler than STBC-OFDM system. Then, performance comparison is made by simulation among pure OFDM system, STBC-OFDM system and DSTBC-OFDM system under Rayleigh fading channel and SUI channel. It is concluded that the STBC-OFDM system can be replaced by DSTBC-OFDM system under stationary or low to moderate velocity conditions.
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