In this contribution we first derive a transmitter multiuser preprocessing (TMP) scheme for a general multiuser multiple-input-multiple-output (MIMO) system based on the minimum power distortionless response (MPDR) cr...
详细信息
In this contribution we first derive a transmitter multiuser preprocessing (TMP) scheme for a general multiuser multiple-input-multiple-output (MIMO) system based on the minimum power distortionless response (MPDR) criterion, which minimizes the power in the context of a given downlink mobile terminal (MT) under the distortionless condition. This optimization problem results in a solution, which has the same form as the minimum mean-square error (MMSE) multiuser detection (MUD). Hence, we then extend the well-known rank-reduction techniques in MMSE-MUD to the MPDR-TMP in order to mitigate the possible implementation problems of the MPDR-TMP. In our study three classes of rank-reduction algorithms are considered, which are derived, respectively, based on the eigen-analysis methods of principal components (PC) and cross-spectral metrics (CSMs) as well as on the Taylor polynomial approximation (TPA) approach, which does not depend on the eigen-analysis. In this contribution both the capacity and error performance of a downlink space-division multiple-access (SDMA) system is investigated, when either the full-rank or reduced-rank MPDR-TMP is invoked. From our study and simulation results, it can be shown that the MPDR-TMP scheme is highly efficient for achieving the capacity and for suppressing the multiuser interference (MUI). The reduced-rank techniques can be employed by the MPDR-TMP, so as to reduce its implementation complexity while achieving the near full-rank performance of the full-rank MPDR-TMP.
This paper analyzes bit error rate (BER) and outage probability of singular value decomposition-based multiple-input multiple-output systems with channel estimation error and feedback delay over uncorrelated Ricean fa...
详细信息
This paper analyzes bit error rate (BER) and outage probability of singular value decomposition-based multiple-input multiple-output systems with channel estimation error and feedback delay over uncorrelated Ricean fading channels. By utilizing marginal unordered and ordered eigenvalue distributions of complex noncentral Wishart. matrices, we derive exact closed-form expressions on the average system performance and high signal-to-interference-plus-noise ratio (SINR) approximations on the individual eigen-subehannels, respectively, under the assumption of equal power allocation. Our expressions apply for various modulation formats and arbitrary numbers of transmit and receive antennas. Our results show that in low-to-moderate SINR regimes, both the BER and the outage probability increase with channel estimation error, feedback delay and the Ricean K-factor at a polynomial rate that is inversely proportional to the difference between the numbers of transmit and receive antennas. We also show that, with channel estimation, error and feedback delay, the diversity orders of the BER and outage probability are zero and an irreducible error floor exists at high SINR.
In this letter a multiuser transmitter preprocessing (MUTP) approach is proposed for downlink wireless communications, such as in spatial-division multiple-access (SDMA) or direct-sequence code-division multiple-acces...
详细信息
In this letter a multiuser transmitter preprocessing (MUTP) approach is proposed for downlink wireless communications, such as in spatial-division multiple-access (SDMA) or direct-sequence code-division multiple-access (DS-CDMA) system. In the proposed MUTP the preprocessing matrix is obtained by constructing a subspace that is orthogonal to the interference subspace without relying on eigen-analysis. The proposed MUTP fully removes the downlink multiuser interference, resulting in the zero-forcing (ZF) solution. It is capable of achieving the same bit error rate (BER) performance as the conventional ZF-based MUTP (ZF-MUTP).
Semi-blind joint maximum likelihood (ML) channel estimation and data detection is proposed for multiple-input multiple-output (MIMO) systems. The joint ML optimization over channel and data is decomposed into an itera...
详细信息
Semi-blind joint maximum likelihood (ML) channel estimation and data detection is proposed for multiple-input multiple-output (MIMO) systems. The joint ML optimization over channel and data is decomposed into an iterative two-level optimization loop. An efficient optimization search algorithm referred to as the repeated weighted boosting search (RWBS) is employed at the upper level to identify the unknown MIMO channel while an enhanced ML sphere detector termed as the optimized hierarchy reduced search algorithm is used at the lower level to perform ML detection of the transmitted data. Only a minimum pilot overhead is required to aid the RWBS channel estimator's initial operation, which not only speeds up convergence but also avoids ambiguities inherent in blind joint estimation of both the channel and data.
A new space-time block code family for two transmitters, called the space-time error correcting codes (STECCs), is presented. As it is built from any linear forward error correcting code (FEC), a STECC is able to corr...
详细信息
A new space-time block code family for two transmitters, called the space-time error correcting codes (STECCs), is presented. As it is built from any linear forward error correcting code (FEC), a STECC is able to correct errors while achieving high spectral efficiencies. The key principle is the FEC linearity which is exploited to transmit linear combinations of FEC codewords to create a space-time redundancy. The proposed code exhibits interesting performance on an ISI-free block fading channel. This result is all the more true as the number of FEC codewords considered in the combination is high.
In practical wireless multiple-input multiple-output (MIMO) communication systems, the channel estimation must be imperfect. Unfortunately, the channel estimation errors have not been taken into account by existing so...
详细信息
ISBN:
(纸本)9781424423736
In practical wireless multiple-input multiple-output (MIMO) communication systems, the channel estimation must be imperfect. Unfortunately, the channel estimation errors have not been taken into account by existing soft-output MIMO minimum mean square error (MMSE) ordering successive interference cancellation (OSIC) detectors when calculating the log-likelihood ratio of each coded bit, i.e., the soft information. As a result, the system performance can be degraded. In this paper, we propose a novel soft-output MIMO MMSE OSIC detector when MMSE MIMO channel estimation is applied. Based on the basic statistic properties of MMSE MIMO channel estimation, this proposed detector takes the channel estimation error into account in the computation of the MMSE filter and LLR of each coded bit. When compared with existing MIMO MMSE OSIC detectors, our simulation results show that the proposed novel detector can obtain considerable performance gain at the cost of negligible increase of complexity.
Orthogonal space-time block coding (STBC) offers linear-complexity one-shot maximum-likelihood (ML) reception when the channel coefficients are known to the receiver. However, when the channel coefficients are unknown...
详细信息
ISBN:
(纸本)9781424429257
Orthogonal space-time block coding (STBC) offers linear-complexity one-shot maximum-likelihood (ML) reception when the channel coefficients are known to the receiver. However, when the channel coefficients are unknown, the optimal receiver takes the form of sequence detection. In this work, we prove that ML noncoherent sequence detection can always be performed in polynomial time with respect to the block length for orthogonal STBC and Rayleigh distributed channel coefficients. Using recent results on efficient maximization of reduced-rank quadratic forms over finite alphabets, we develop a novel algorithm that performs ML noncoherent orthogonal STBC detection with polynomial complexity in the block length. The order of the polynomial complexity of the proposed receiver is determined by the number of transmit and receive antennas.
This paper presents an experimental evaluation of open-loop precoding MIMO (multipleinputmultipleoutput) using a testbed targeted at IMT-Advanced systems. Open-loop MIMO is realized by applying Rotational OFDM (R-O...
详细信息
ISBN:
(纸本)9781424426430
This paper presents an experimental evaluation of open-loop precoding MIMO (multipleinputmultipleoutput) using a testbed targeted at IMT-Advanced systems. Open-loop MIMO is realized by applying Rotational OFDM (R-OFDM), that is previously proposed by authors, to MIMO transmission. MIMO R-OFDM is more robust with respect to correlated channels than conventional open-loop MIMO-OFDM, because it optimizes the distances between the constellation points using simple phase rotation. The angle of phase rotation depends on the modulation orders and coding rate, hence the receiver does not need to feed the CSI (Channel State Information) back to the transmitter. In this paper, MIMO R-OFDM is implemented in a testbed targeted at IMT-Advanced systems, it is then evaluated experimentally and by computer simulations. The results of the evaluation reveal that MIMO R-OFDM is effective in correlated channels, and the gain in terms of the CIR (Carrier to Interference Ratio) with respect to conventional MIMO OFDM to achieve PER (Packet Error Rate) = 0.01 is about 1.5 dB when MIMO R-OFDM is used in correlated channels.
This paper presents a system model and method for the two-dimensional (2-D) imaging application via a narrowband multiple-input multiple-output (MIMO) radar system with two perpendicular linear arrays. The proposed me...
详细信息
ISBN:
(纸本)9781424421787
This paper presents a system model and method for the two-dimensional (2-D) imaging application via a narrowband multiple-input multiple-output (MIMO) radar system with two perpendicular linear arrays. The proposed method utilities the spatial parallel procedure sampling the scattered echoes during a single snapshot illumination, instead of the spatial sequential one sampling the scattered echoes during multiple snapshot illuminations in inverse synthetic aperture radar (ISAR) imaging. Consequently, the complex motion compensation in ISAR imaging can be avoided. Furthermore, in our array configuration, multiple narrowband shared-spectrum waveforms coded with orthogonal ployphase sequences are employed to illuminate a target. The mainlobe of the compressed echoes front the different filter band for all scatterers could be located in the same range bin, and thus, complex range alignment in classical ISAR imaging is not necessary. Numerical simulations based on synthetic data are provided for testing our proposed method.
To combat the effect of intersymbol interference caused by frequency selectivity of fading channel in space time coding schemes, two main methods are employed, i.e. multichannel equalization and orthogonal frequency d...
详细信息
ISBN:
(纸本)9781424416325
To combat the effect of intersymbol interference caused by frequency selectivity of fading channel in space time coding schemes, two main methods are employed, i.e. multichannel equalization and orthogonal frequency division multiplexing. The complexity of the multichannel equalization method restricts its use widely. Orthogonal frequency division multiplexing (OFDM) converts the frequency selective channel into parallel non-frequency selective subchannel and eliminates the intersymbol interference. This paper investigates using Monte Carlo simulations, the performance of known space time coding schemes in an OFDM environment with different channel delay spreads. Simulation results (i.e. frame error rate) show that Super-Orthogonal Space Time Code in an OFDM environment outperform other schemes (i.e. STTC-OFM and STBC-OFDM) with delay spreads incorporated.
暂无评论