The composite channel models of the generalized distributed antenna system （GDAS） such as Rayleigh-lognormal fading are studied. Then comparisons are performed between the GDAS and the traditional multiple-input mul...
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The composite channel models of the generalized distributed antenna system （GDAS） such as Rayleigh-lognormal fading are studied. Then comparisons are performed between the GDAS and the traditional multiple-input multiple-output （MIMO） system to analyze the ergodic capacity of the GDAS and make conclusions that it is impossible to achieve an analytical expression for the ergodic capacity of the GDAS. Moreover, in order to evaluate the performance of the ergodic capacity of the GDAS conveniently, the analytical lower bound and upper bound of the ergodic capacity of the GDAS are derived by using the results from multivariate statistics and matrix inequalities, under the scenarios of Rayleigh-lognormal fading and equal power allocation scheme at transmitter. Finally, the analytical bounds are verified by comparisons with the numerical results.
This paper presents a family of rate-one quasi-orthogonal space-time block codes (QO-STBCs) for any number of transmit antennas. Full diversity of the proposed QO-STBCs is achieved via the use of constellation rotatio...
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This paper presents a family of rate-one quasi-orthogonal space-time block codes (QO-STBCs) for any number of transmit antennas. Full diversity of the proposed QO-STBCs is achieved via the use of constellation rotation. When the number of transmit antennas is even, these codes are delay "optimal." this property along with the quasi-orthogonality one allows the codes to have low decoding complexity. Besides, by applying lookup tables into the detection methods presented in [1] and generalizing them, two low-complexity maximum-likelihood (ML) decoders for the proposed QO-STBCs and for other existing QO-STBCs, called PMLD and QMLD, are obtained. Simulation results are provided to verify the bit error rate (BER) performances and complexities of both the proposed QOSTBCs and the proposed decoders.
This paper proposes a space-time decision feedback equalization (ST-DFE) assisted multiuser detection (MUD) scheme for multiple receiver antenna aided space division multiple access systems. A minimum bit error rate (...
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This paper proposes a space-time decision feedback equalization (ST-DFE) assisted multiuser detection (MUD) scheme for multiple receiver antenna aided space division multiple access systems. A minimum bit error rate (MBER) design is invoked for the MUD, which is shown to be capable of improving the achievable bit-error rate performance and enhancing the attainable system capacity over that of the standard minimum mean square error (MMSE) design. An adaptive implementation of the MBER ST-DFE assisted MUD is proposed using a stochastic gradient-based least bit error rate algorithm, which is demonstrated to consistently outperform the classical least mean square (LMS) algorithm, while achieving a lower computational complexity than the LMS algorithm for the binary signalling scheme. Our simulation results demonstrate that the MBER ST-DFE assisted MUD is more robust to channel estimation errors as well as to potential error propagation imposed by decision feedback errors, compared to the MMSE ST-DFE assisted MUD.
In this paper, we develop some new automatic repeat request (ARQ) protocols for multiple-inputmultiple-out (MIMO) flat-fading channels which adapt the bit-to-symbol mapping of each ARQ retransmission. We begin by def...
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In this paper, we develop some new automatic repeat request (ARQ) protocols for multiple-inputmultiple-out (MIMO) flat-fading channels which adapt the bit-to-symbol mapping of each ARQ retransmission. We begin by defining a model for distinctly mapped transmissions through flat-fading MIMO channels. We characterize the effect that such a mapping diversity has on an integrated receiver utilizing sphere decoding. Varying the symbol mapping complicates the sphere decoding process, particularly for the enumeration of candidate solutions within the sphere. A technique that enables quick candidate enumeration is presented, utilizing concepts from existing closest point search schemes. The advantage of mapping diversity, in reducing bit error rate and reducing computational complexity, is presented along with simulation examples.
Multi-hop ad hoc networks suffer from hidden nodes and exposed nodes. The multiple antennas receiver initiated busy tone medium access (MARI-BTMA) with the MIMO-OFDM transceiver architecture is a promising technique t...
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ISBN:
(纸本)9781424406173
Multi-hop ad hoc networks suffer from hidden nodes and exposed nodes. The multiple antennas receiver initiated busy tone medium access (MARI-BTMA) with the MIMO-OFDM transceiver architecture is a promising technique to exploit diversity in the physical layer of broadband wireless communications to achieve better performance in the ad-hoc network. If the channel is asynchronous then this scheme suffers from frequency offset, which results in unfairness and lowers throughput. In this paper, the power leakage from multiple carriers due to the frequency offset is calculated. Varying the carrier sensing threshold level on the busy tone channels is proposed as a way to overcome this problem. The carrier sensing threshold level chosen is a trade-off between the exposed area and the hidden area. The optimal threshold level is derived which minimizes the sum of the exposed node area and the hidden node area. Numerical results show how the total area changes with respect to the frequency offset. The effect of frequency offset, path loss exponent and distance between the transmitter and the receiver on the optimal threshold level and the carrier sensing range are also analyzed.
We consider a terrestrial free-space optical communication link affected by atmospheric turbulence. By means of numerical simulations we estimate the reduction in scintillation achieved by the combined effect of apert...
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ISBN:
(纸本)0819463833
We consider a terrestrial free-space optical communication link affected by atmospheric turbulence. By means of numerical simulations we estimate the reduction in scintillation achieved by the combined effect of aperture averaging and four transmitters when mutually-incoherent sources and a realistic detector size are used. We evaluate two space-time coding schemes: the first scheme uses a repetition code operating on four transmitters, and the second scheme uses a size-four rate-one space-time block code, originally proposed for wireless radio-frequency links. Both schemes deliver large signal-to-noise ratio gains compare to a single-beam system. The first scheme gives the best performance in all cases because of the natural incoherence found among optical sources.
In the following, we present a novel wideband multiple-input, multiple-output (MIMO) channel model. The model is based on the Eigenvalue Decomposition (EVD) of the wideband channel correlation matrix. It does not assu...
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ISBN:
(纸本)9781424405169
In the following, we present a novel wideband multiple-input, multiple-output (MIMO) channel model. The model is based on the Eigenvalue Decomposition (EVD) of the wideband channel correlation matrix. It does not assume the scatterers at the receiver fade independently of those at the transmitter. It also models correlation between delay bins in the Power Delay Profile (PDP). With preliminary data gathered using the Wideband MIMO Software Defined Radio (WMSDR) in fixed outdoor locations, we show good agreement between modeled and measured data.
This paper presents a systematic derivation of the channel capacity of MIMO-OFDM systems. In addition, we model a new MIMO channel to help in understanding the effect of spatial multiplexing on the MlMO channel, such ...
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ISBN:
(纸本)9789077381281
This paper presents a systematic derivation of the channel capacity of MIMO-OFDM systems. In addition, we model a new MIMO channel to help in understanding the effect of spatial multiplexing on the MlMO channel, such as reducing the capacity and the BER, if spatial correlation is high. This effect will be found for some of the Space Division multiplexing (SDM) algorithms, namely, Zero Forcing (ZF) and Minimum Mean-Square Error (MMSE).
Metrics obtained from a set of channel measurement data are used to predict performance of different MIMO techniques, such as spatial multiplexing and space-time block coding. For a given channel realisation, metries ...
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ISBN:
(纸本)9781424400379
Metrics obtained from a set of channel measurement data are used to predict performance of different MIMO techniques, such as spatial multiplexing and space-time block coding. For a given channel realisation, metries such as mutual information, eigenvalues, etc. can be extracted and the BER performance simulated for different MIMO techniques. By correlating the simulated BER performances to the metrics, it can be determined which metrics are useful BER performance predictors for a given MIMO technique. It is shown that mutual information and the eigenvalues of the spatial correlation matrix are useful BER predictors for V-BLAST and STBC techniques.
A theory for jointly optimizing transmitter and receiver finite impulse response (FIR) multiple-input multiple-output (MIMO) filters is developed in the presence of near-end crosstalk and additive channel noise indepe...
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A theory for jointly optimizing transmitter and receiver finite impulse response (FIR) multiple-input multiple-output (MIMO) filters is developed in the presence of near-end crosstalk and additive channel noise independent of the original signal. The transfer function of the channel is a known MIMO transfer function with finite memory. Near-end crosstalk is included through another MIMO transfer function. The channel input signal is assumed to be power constrained. For a given channel with a maximum allowable average input power, the transmitter and receiver FIR MIMO filters are jointly optimized such that the mean square error (MSE) between the desired and reconstructed signal is minimized. An iterative numerical optimization algorithm is proposed. When compared to the methods available in the literature, the proposed method yields better results due to the joint optimization of the transmitter-receiver pair and is applicable to a more general scenario that may include correlated sources and near-end crosstalk.
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