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Two novel numerically efficient approaches are proposed for maximum capacity designs in multiple-input multiple-output (MIMO) systems under the practical per-antenna power constraint. One is an explicit solution (ES) when the rank of the channel matrix is equal to the number of transmit antennas. And the other is an efficient iterative approach (EIA). The ES is optimum and the EIA is nearly optimum...
In this paper, we present a method which jointly performs robust channel estimation and signal detection over rank-deficient MIMO links. This technique achieves an excellent estimation of the channel matrix by using all detected symbols within a data frame. Symbol detection is achieved by means of a sphere decoding algorithm. The proposed scheme is equivalent to having the training preamble occupy...
We consider the uplink of a wireless sensor network with single-antenna sensors, an access point (AP) equipped with multiple antennas, and a common radio channel. To reduce the number of outages resulting from the noise amplification by the zero-forcing (ZF) within the successive interference cancellation (SIC) procedure, the AP is given the possibility to request a selected number of sensors to retransmit...
The main concern in slow fading channels is that the coded symbols can not be sent over multiple fades of the channel, because when they are transmitted across all strong and weak subchannels of a multiple-input multiple-output (MIMO) channel, the weak subchannels play the major role in the degradation of the total performance of the channel. In this paper, we propose a 2-dimensional transmit beamforming...
Coherent space-time codes perform not so excellent in high moving speed case due to the inaccurate channel estimation. However, differential space-time code is appealing in this case because no channel estimation is needed. While in low and middle signal-to-noise ratio regions differential space-time codes are inferior to the coherent ones. To achieve an excellent performance in a various moving speed...
In order to improve the reliability of VBLAST in block fading channel, phase rotation precoding is proposed. Through phase rotation of the modulated signals at the transmitter, the burst decoding error is changed into random error at the receiver, which can be corrected easily. So the system performance is enhanced. Simulation results demonstrate the validity of the proposed scheme.
Recently, a new paradigm for cognitive radio networks has been advocated, where primary users (PUs) recruit some secondary users (SUs) to cooperatively relay the primary traffic. However, all existing work on such cooperative cognitive radio networks (CCRNs) operate in the temporal domain. The PU needs to give out a dedicated portion of channel access time to the SUs for transmitting the secondary...
A novel iterative (turbo) receiver is introduced, suitable for orthogonal frequency division multiplexing (OFDM) employing quadrature amplitude modulation (QAM) and receiver diversity. The system operates over a double-selective channel and includes a carrier frequency offset (CFO). We propose a maximum a posteriori probability expectation-maximization (MAP-EM) receiver with a different EM parameter...
Firstly, this paper gives a simple introduction of the encoding/decoding theory of LDPC and Space-time coding. And it carries out a detailed research and analysis on LDPC coding system and the space-time block coding system. Then, LDPC and space-time coding are combined. The performance of LDPC-STBC under AWGN channel is given through computer simulation. The simulation results show that this method...
Motivated by the recent development of Spatial Modulation (SM) and Differential Space-Time Shift Keying (DSTSK), we propose a reduced-complexity Conventional Differential Detector (CDD) as well as a reduced-complexity Multiple-Symbol Differential Sphere Detector (MSDSD) for DSTSK. Both schemes operate on a symbol-by-symbol basis in order to reduce the complexity of the classic block-by-block-based...
Cooperative detection involving neighboring base stations is a promising means to increase spectral efficiency in the uplink of cellular systems. To fully utilize the new degrees of freedom that come with base station cooperation, it is essential that a joint scheduler is aware of the interference conditions in all participating cells in order to perform efficient resource and rate allocation. However,...
In a distributed MIMO system (D-MIMO), multiple base stations work in cooperation manner to enhance system throughput by suppressing inter-cell and inter-user interference. In this paper, we propose two practical distributed algorithms that are based on block diagonalization technique. The proposed schemes eliminate the need of iterative computations, and hence can be implemented without information...
We present a new space-time encoder based on packet-level redundancy which can increase the space-time encoder rate beyond unity without compromising diversity gains. A complementary low-complexity decoding algorithm based on maximum ratio combining and successive interference cancelation is further proposed. A major merit of the decoding algorithm is that it allows to adaptively tradeoff between...
In this paper, we are concerned with low-complexity detection in large multiple-input multiple-output (MIMO) systems with tens of transmit/receive antennas. Our new contributions in this paper are two-fold. First, we propose a low-complexity algorithm for large-MIMO detection based on a layered low-complexity local neighborhood search. Second, we obtain a lower bound on the maximum-likelihood (ML)...
In this paper, we propose a systematic design of space-time block codes (STBC) which can achieve high rate and full diversity when the partial interference cancellation (PIC) group decoding is used at receivers. The proposed codes can be applied to any number of transmit antennas and admit a low decoding complexity while achieving full diversity. For M transmit antennas, in each codeword real and...
In this paper a novel detection algorithm for spatial modulation (SM) based on sphere decoder (SD) tree search idea is proposed. The aim is to reduce the receiver complexity of the existing optimal decoder while maintaining an optimum performance. The algorithm performs a maximum likelihood (ML) search, only over those points that lie inside a sphere, centered at the received signal, of given radius...
For a family/sequence of Space-Time Block Codes (STBCs) C1, C2, ..., with increasing number of transmit antennas Ni, with rates Ri complex symbols per channel use, i = 1, 2,..., the asymptotic normalized rate is defined as limi→∞ Ri/Ni. A family of STBCs is said to be asymptotically-good if the asymptotic normalized rate is non-zero, i.e., when the rate scales as a nonzero fraction of the number of...
In this paper, we present new constructions of quasi-orthogonal space-time block codes for 4 and 6 transmit antennas. The proposed codes possess the following properties: full-rate, full transmit diversity, even power distribution and low decoding complexity, which make these two codes very practical spacetime coding schemes. For the case of 4 transmit antennas, the code can be decoded pair-by-pair,...
In this paper, we propose an iteration scheme for the virtual layered space frequency communication architecture. The architecture enables the decoding of the transmitted orthogonal frequency division multiplexing (OFDM)-QPSK signals even if the number of spatial multiplexed layers is twice that of receiving antennas over multipath fading channels. In the proposed iteration scheme, the MAP decoder...
Two numerical approaches, the Robust-Generalized Iterative Approach (R-GIA) and the Robust-Transmit Covariance Optimization Approach (R-TCOA), are proposed for jointly designing the minimum mean square error (MMSE) precoders and decoders of uplink multiuser multiple-input-multiple-output (MIMO) systems with arbitrary linear equality power constraints and possibly imperfect channel state information...
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