The diversity gain of a multiple-inputmultiple-output (MIMO) system adopting the Neyman-Pearson (NP) criterion is derived for a signal-present versus signal-absent scalar hypothesis test statistic and for a vector si...
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ISBN:
(纸本)9781457705397
The diversity gain of a multiple-inputmultiple-output (MIMO) system adopting the Neyman-Pearson (NP) criterion is derived for a signal-present versus signal-absent scalar hypothesis test statistic and for a vector signal-present versus signal-absent hypothesis testing problem. The results are applied to a MIMO radar system with M transmit and N receive antennas, used to detect a target composed of Q random scatterers with possibly non-Gaussian reflection coefficients in the presence of possibly non-Gaussian clutter-plus-noise. It is found that the diversity gain for the MIMO radar system is dependent on the cumulative distribution function (cdf) of the reflection coefficients while invariant to the cdf of the clutter-plus-noise under some reasonable conditions. If the noise-free received waveforms at each receiver span a space of dimension M' <= M, the largest possible diversity gain is controlled by min (N M', Q) and the cdf of the magnitude square of a linear transformed version of the reflection coefficient vector. It is shown that properly chosen nonorthogonal waveforms can achieve the same diversity gain as orthogonal waveforms.
This paper proposes a non-line-of-sight (NLOS) identification technique that exploits statistics of space-frequency correlation of multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) syst...
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ISBN:
(纸本)9781457713484
This paper proposes a non-line-of-sight (NLOS) identification technique that exploits statistics of space-frequency correlation of multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Here, space correlation refers to the correlation across antenna elements and frequency correlation refers to the correlation across subcarriers. In this technique, the mean value and standard deviation of space-frequency correlation over multiple transmit and receive antenna combinations are used to identify NLOS conditions. The technique requires minimal variation of spatial correlation across different multi-path components. The channel model satisfying this requirement is studied and the performance of the proposed technique is investigated.
In this paper, we propose a quantized predictive pre-coding scheme for spatial multiplexing multiple-inputmultiple-output (MIMO) systems with delayed feedback. A geodesic transmit subspace prediction algorithm is des...
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ISBN:
(纸本)9781424492688
In this paper, we propose a quantized predictive pre-coding scheme for spatial multiplexing multiple-inputmultiple-output (MIMO) systems with delayed feedback. A geodesic transmit subspace prediction algorithm is designed to predict the transmit subspace for the forthcoming transmission at the receiver. An infrequently updated codebook for transmit subspace quantization is developed to improve the quantization resolution. Numerical results show that in various time-varying channels with unit step feedback delay the performance of the proposed approach is better than previously proposed memoryless Grassmannian subspace packing scheme, the 1-bit geodesic feedback algorithm, and the Gaussian vector quantization algorithm, under the same or even lower feedback rate.
multiple-inputmultiple-output (MIMO) systems employing adaptive modulation have been widely used for their potential to optimize the spectral efficiency while keeping the bit error probability (BEP) under a certain t...
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ISBN:
(纸本)9781424493326
multiple-inputmultiple-output (MIMO) systems employing adaptive modulation have been widely used for their potential to optimize the spectral efficiency while keeping the bit error probability (BEP) under a certain target level. In this paper, we examine a MIMO system using square orthogonal space-time block codes (OSTBCs) with rate-adaptive M-QAM and operating over arbitrarily correlated Rayleigh fading channel with imperfect channel estimation. Assuming finite-rate feedback without delay, we derive accurate closed-form expressions for the average BEP, spectral efficiency and bit error outage of our system. The presented expressions allow to easily study the impact of channel estimation errors and fading correlation on the performance of rate-adaptive MIMO OSTBC systems.
The diversity gain of a multiple-inputmultiple-output (MIMO) system adopting the Neyman-Pearson (NP) criterion is derived for a signal-present versus signal-absent scalar hypothesis test statistic and for a vector si...
详细信息
ISBN:
(纸本)9781457705380
The diversity gain of a multiple-inputmultiple-output (MIMO) system adopting the Neyman-Pearson (NP) criterion is derived for a signal-present versus signal-absent scalar hypothesis test statistic and for a vector signal-present versus signal-absent hypothesis testing problem. The results are applied to a MIMO radar system with M transmit and N receive antennas, used to detect a target composed of Q random scatterers with possibly non-Gaussian reflection coefficients in the presence of possibly non-Gaussian clutter-plus-noise. It is found that the diversity gain for the MIMO radar system is dependent on the cumulative distribution function (cdf) of the reflection coefficients while invariant to the cdf of the clutter-plus-noise under some reasonable conditions. If the noise-free received waveforms at each receiver span a space of dimension M' <= M, the largest possible diversity gain is controlled by min (NM', Q) and the cdf of the magnitude square of a linear transformed version of the reflection coefficient vector. It is shown that properly chosen nonorthogonal waveforms can achieve the same diversity gain as orthogonal waveforms.
In order to comply with the demand on increasing available data rates in particular in wireless technologies, systems with multiple transmit and receive antennas, also called MIMO (multiple-inputmultiple-output) syst...
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ISBN:
(纸本)9789898425737
In order to comply with the demand on increasing available data rates in particular in wireless technologies, systems with multiple transmit and receive antennas, also called MIMO (multiple-inputmultiple-output) systems, have become indispensable for future generations of wireless systems. Due to the strongly increasing demand in high-data rate transmission systems, frequency non-selective MIMO links have reached a state of maturity and frequency selective MIMO links are in the focus of interest. In this field, the combination of MIMO transmission and OFDM (orthogonal frequency division multiplexing) can be considered as an essential part of fulfilling the requirements of future generations of wireless systems. However, single-user scenarios have reached a state of maturity. By contrast multiple users' scenarios require substantial further research, where in comparison to ZF (zero-forcing) multiuser transmission techniques, the individual user's channel characteristics are taken into consideration in this contribution. The performed joint optimization of the number of activated MIMO layers and the number of transmitted bits per subcarrier along with the appropriate allocation of the transmit power shows that not necessarily all user-specific MIMO layers per subcarrier have to be activated in order to minimize the overall BER under the constraint of a given fixed data throughput.
A semi-definite relaxation decoder is proposed for a multiple-inputmultiple-output (MIMO) system based on 256-QAM constellation. Simulation results indicate that it is computationally efficient and can provide better...
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A semi-definite relaxation decoder is proposed for a multiple-inputmultiple-output (MIMO) system based on 256-QAM constellation. Simulation results indicate that it is computationally efficient and can provide better block-error-rate performance than a sub-optimal decoder.
Wireless communication is nowadays one of the areas attracting a lot of research activity due to the strongly increasing demand in high-data rate transmission systems. The use of multiple antennas at both the transmit...
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ISBN:
(纸本)9781467302029
Wireless communication is nowadays one of the areas attracting a lot of research activity due to the strongly increasing demand in high-data rate transmission systems. The use of multiple antennas at both the transmitter and receiver side has stimulated one of the most important technical breakthroughs in recent communications allowing increasing the capacity and dropping the bit-error rate. However, multiple-inputmultiple-output (MIMO) systems are not limited to wireless MIMO systems and can be observed in a huge variety of transmission links and network parts and have attracted a lot of attention since the mid 90's. In the field of optical MIMO transmission systems, multi-mode (MM) fibre offers the possibility to transmit different signals by different mode groups. The perspective of the MIMO philosophy within the field of optical transmission systems is elaborated in this contribution based on channel measurements within a (2 x 2) MIMO system. For the channel measurements the second optical window and a fibre length of 1,4 km was chosen. Computer simulations on an overall data rate of 10,24 Gbps underline the potential of multi-mode fibres in optical high-data rate MIMO communication systems and show that in order to achieve the best bit-error rate, not necessarily all MIMO layers have to be activated.
The IEEE802.11ac task group has started to establish a next-generation WLAN standard. The wider channel of more than 80 MHz achieving over a 1-Gbps data rate is discussed. We have developed an experimental platform co...
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ISBN:
(纸本)9781424480166
The IEEE802.11ac task group has started to establish a next-generation WLAN standard. The wider channel of more than 80 MHz achieving over a 1-Gbps data rate is discussed. We have developed an experimental platform consisting of baseband and RF units in a 2x2 MIMO-OFDM system for the wider channel and evaluated its system performance in a field experiment. A MIMO-OFDM transceiver in the baseband unit is designed to realize real-time MIMO detection and provide a maximum data rate of 600 Mbps. In the field experiment, we evaluated outdoor propagation characteristics at farm and between buildings for outdoor usage in WLAN systems.
Layered Steered Space-Time Codes (LSSTC) is a recently proposed multiple-inputmultiple-output (MIMO) system that combines the benefits of vertical Bell Labs space-time (VBLAST) scheme, space-time block codes (STBC) a...
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ISBN:
(纸本)9781424480166
Layered Steered Space-Time Codes (LSSTC) is a recently proposed multiple-inputmultiple-output (MIMO) system that combines the benefits of vertical Bell Labs space-time (VBLAST) scheme, space-time block codes (STBC) and beamforming. We suggest a new downlink scheme employing LSSTC with optimal power allocation, by assuming that the user feeds the BS with the average SNR per VBLAST layer through the uplink feedback channel. The motivation behind proposing such a system is to enhance the error performance by assigning power to the layers in an optimum manner. We refer to the system proposed as the optimum power allocation LSSTC (OPA-LSSTC). We will show that the OPA-LSSTC can provide about a 3 dB gain compared to the equal power allocation case.
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