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The fifth-generation (5G) wireless communication systems envision the deployment of massive multiple-input multiple-output (MIMO) technology for enhanced network coverage and capacity. With frequency division duplex (FDD) being the prominent mode of operation, addressing the challenges for massive MIMO systems in FDD is extremely important. One such challenge is the downlink channel estimation, which...
In previous studies, it has been proven that by applying the co-array concept, we can detect the Direction of Arrival (DoA) of more sources with less antenna elements. This paper investigates two parameters that have a crucial influence on the co-arrays' DoA estimation performance in practical tests: near field conditions and a multipath environment.
In this paper the impact of exponential correlation model on massive multiple input multiple output (MIMO) channel estimation is analyzed using a large number of antennas in the base station (BS) and a user terminal. We consider pilot-based channel estimation in the UL channel. The Linear minimum mean square error (LMMSE) estimator is used to investigate the effect of correlation factor on the average...
Ground-based and shipborne Communications ESM systems operating in the VHF and UHF bands have been typically based on arrays designed accordingly to regular geometries. Prominent example are Uniform Circular Arrays (UCAs). Unfortunately, UCAs are not easily installable on small or narrow platforms, as it is in the case of UAVs; this is due also to the long wavelengths of the signals in the VHF band...
Recently, LTE Release 12 and IEEE 802.11ac adopted 256-quadrature amplitude modulation (QAM) as a tool to accommodate high demand of data throughput in wireless systems. Furthermore, currently developing IEEE 802.11ax considers 1024-QAM to further increase the Wi-Fi throughput. In this paper, we propose low complexity schemes in soft detection of high order QAM symbols in multiple input multiple output...
Shadowing from vehicles can degrade the performance of vehicle-to-vehicle (V2V) communication systems significantly. It is thus important to characterize and model the influence of common shadowing objects like cars properly. For multilink systems it is essential to model the joint effects on the different links. However, the multilink shadowing effects in V2V channels are not yet well understood...
This paper addresses the research question on how digital beamsteering algorithms can be combined with analog beamforming in the context of millimeter-wave communication for next generation (5G) cellular systems. Key is the use of coarse quantisation of the individual antenna signals next to the analog beamforming. The extreme case of single bit quantization is analyzed. Direction-of-Arrival (DoA)...
A multiuser MIMO (MU-MIMO) TDD system in which the base station (BS) uses a large scale antenna array to communicate with single-antenna mobile users is considered. We present novel schemes to estimate both large-scale and small-scale fading coefficients by uplink pilot sequences. The large-scale fading coefficients (LSFCs) are usually ignored or assumed perfectly known and almost all MIMO channel...
WLAN-based indoor location fingerprinting has been attractive owing to the advantages of open access and high accuracy. Most fingerprinting-based systems so far rely on the received signal strength (RSS), which can be easily measured at the receiver with commercial WLAN equipment. However, RSS is a coarse value which simply measures the received power for a whole channel. Thus, it fluctuates over...
The recent explosion of mobile Internet usage results in the need for higher data rate in future mobile communication systems. One of the key technologies to satisfy this requirement is the multilink transmission technique which utilizes the cooperative signal processing among spatially distributed multiple users and/or base stations, thus it is considered as more robust in ensuring the degree of...
Extensive analysis of channel measurement data for the investigation of new channel models plays a fundamental role in designing and evaluating todays wireless communication systems. Besides the knowledge of the parameters and their distribution functions, the cross correlation between them is of great interest and can be exploited for more sophisticated channel simulations. In this contribution the...
In this paper we study the phase estimation problem in the presence of white noise and phase distortions on the basis of the Markovian technique of nonlinear processing of random fields. The emphasis is on the processing error dependence of the number of receivers.
This paper addresses the problem of estimating the two-dimensional direction-of-arrival (2D DOA) of multiple narrowband signals impinging on an L-shaped array, which is structured by two uniform linear arrays (ULAs). A computationally efficient method without eigendecomposition is proposed, where the elevation angles are estimated from the cross-correlation matrices between the received data of two...
As a combination of OFDM with space-time coding technique, MIMO-OFDM has recently received considerable attentions, which can not only effectively enhance the transmission rate and capacity of the wireless communication system but also effectively combat multi-path fading and interfere. This paper discusses the two-dimensional pilot-based channel estimation method in MIMO-OFDM system, and the principle...
It is often crucial in most of today's Autonomous Underwater Vehicles (AUVs) missions that the vehicle position be known precisely. Navigation performance of an Aided Inertial Navigation System (AINS) is always limited by the accuracy of sensors. In this paper we focus on enhancing performance of the AINS via micronavigation, which exploits a so-called Displaced Phase Center Antenna (DPCA) technique...
To estimate speed of a moving user transmitting data over a single input single output (SISO) Rayleigh fading channels, many autocorrelation function (ACF) based schemes have been presented in literature. It was shown that in a multiple input multiple output (MIMO) channel with N antennas on each side, the velocity of a moving mobile can be obtained by applying the ACF based velocity estimation schemes...
A single-port adaptive DOA estimation based on temporally-correlated array signal samples is proposed. Temporal correlation is created by lowering the receiver bandwidth and/or increasing the weighing rate. The proposed technique can estimates the DOAs of multiple independent sources in very low SNR levels. The proposed technique is compared with MUSIC and single-port beam space MUSIC.
In this paper, a new method for AOA estimation, based on the synthetic ESPRIT algorithm is described and tested with actual CDMA signals. Physical size constraints of handheld devices typically exclude the possibility of using multiple antennas. To overcome this limitation, antenna array can be synthesized by physically moving a single antenna in an arbitrary trajectory while collecting a snapshot...
We propose a method to estimate the number of partial discharge sources in multipath environment using the multichannel blind deconvolution method called the super-exponential deflation method. Blind deconvolution is a method of recovering transmitted signals from only observed signals. The deflation approach can extract a source signal which is non-Gaussian from the observed signals one by one. The...
In this paper we consider the problem of the estimation of the digital elevation model (DEM) of a ground scene starting from dual baseline interferometric synthetic aperture radar (SAR) signals. classical maximum likelihood (ML) estimation techniques require the knowledge of the joint probability density function (PDF) of the two measured interferometric phases. Usually the joint PDF expression is...
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