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A new indoor calibration method is proposed to estimate and compensate mutual coupling and channel gain/phase inconsistency parameters for a uniform linear array (ULA). This calibration method employs only one assistant source in near-field and is unnecessary to conduct complex feed circuits behind the antennas. Firstly, accurate channel gain/phase deviation is estimated via an inside testing structure...
This paper studies a specific sequential decision making problem: joint optimization of power and communication decisions of a remote estimation problem over an additive noise channel. At each time, the sensor observes a sample from a one-dimensional stochastic process, and then decides whether to transmit its observation to the remote estimator or not, which takes place over an additive noise channel...
Spatial channel covariance information can replace full channel state information for designing analog precoders in millimeter wave (mmWave) hybrid MIMO systems. Hybrid MIMO architectures, however, make it challenging to estimate the spatial channel covariance matrix because the estimator in baseband can only see the low-dimensional projections of the original channel. In this paper, we propose two...
FSO technology is useful where physical connections are impractical due to high cost or other considerations. Atmospheric turbulence is small scale, irregular air motions characterized by winds that vary in speed and direction. Turbulence is important because it mixes and churns the atmosphere and causes the water vapour , smoke , and other substances. Turbulence near the Earth's surface differ from...
This paper studies the mean square quadratic (MSQ) detectability for multi-output networked systems over finite-state fading channels. The unreliability from the plant output to the estimator input is described by multiplicative noises. A finite-state random process is introduced to model time-varying fading channels. Necessary and sufficient conditions for MSQ detectability are given in the form...
Network diversity multiple access or NDMA is the family of algorithms with the highest potential throughput in the literature of signal-processing-assisted random access. NDMA uses the concept of protocol-induced retransmissions to create an adaptive source of physical (PHY) layer diversity. This adaptive diversity is used to resolve packet collisions (via signal separation) without the explicit need...
Network diversity multiple access (NDMA) is the family of algorithms with the highest potential throughput in the literature of signal-processing assisted random access protocols. NDMA uses the concept of protocol-induced retransmissions to create an adaptive source of diversity. This diversity is used to resolve packet collisions employing signal separation tools without the explicit need (or as...
In this paper produced effect investigation of thermal and phase noise of frequency synthesizer complex on error of MIMO channel coefficients estimation. Dependence of channel coefficients estimation errors on time mismatch when channel coefficients testing is analyzed. Employment of technique time-division multiplexing is justified. Calculated to dependencies of error estimation on accepted signal...
In high mobility environment, the carrier frequency offset (CFO) introduced by Doppler shifts can severely degrade the system performance. On the other hand, orthogonal pilot sequence which is utilized in conventional frame structure for CFO and channel estimation induces large pilot resource consumption as the number of users increases, resulting in low achievable throughput. In this paper, we propose...
In this paper we propose a compressive channel estimation for fast fading channel in orthogonal frequency division multiplexing (OFDM) systems. We formulate the sparse compressive sensing (CS) problem by exploiting the delay-Doppler sparse structure of the doubly dispersive channel. To combat the severe inter-carrier interference (ICI) caused by the Doppler shift, this estimator is based on the banded...
Spectrum Sensing (SS) techniques play an important role in the Cognitive Radio (CR) systems. In recent years, many spectrum sensing techniques have been proposed in the literature to identify the state of the Primary Users (PUs) in the temporal domain. However, these techniques are usually interested in the current state of channel without consideration to their status in the past. In this paper,...
The combination of MIMO techniques with OFDM, MIMO-OFDM, is a promising way of achieving high spectral efficiency in wireless communication systems. However, the performance of MIMO-ODFM systems is highly degraded by RF impairments such as phase noise. Similar to the SISO case, phase noise in MIMO-OFDM systems results in a common phase error (CPE) and inter carrier interference (ICI). In this paper...
In millimeter wave (mmWave) systems adopting large number of antennas at both the transmitter and the receiver, channel estimation is challenging due to the large number of antennas and low signal-to-noise ratio (SNR) before beamforming. Due to the sparse nature of mmWave channels, the channel estimation can be solved by beam search. While conventional beam search schemes rely on exhaustive training,...
This paper is concerned with the joint estimation of phase noise and time-varying channel responses in full-duplex multiple-input multiple-output (MEMO) orthogonal frequency division multiplexing (OFDM) systems. The time-variation of phase noise and multipath MIMO channel responses gives rise to the identiflability problem of estimating a large number of unknowns which is much greater than the number...
Millimeter wave (mmWave) communication is favored for its abundant bandwidth. However, the sampling rate scales up with the large bandwidth, thus making it difficult to implement high-resolution analog-to-digital converters (ADCs). In addition, a large-scale array is employed to overcome the high path loss of the mmWave channels. Due to the large number of antennas and the directional feature of the...
In this paper, a channel estimation method based on the superimposed pilots with the first-order statistics is proposed for massive MIMO systems. In the proposed method, no time slots are cost on training. Hence, transmission rate of the system is higher than the traditional method. Further, a decoder is designed based on MMSE decoder. Finally, simulations show that the performance of the system with...
In this study, two techniques for compensating in-phase/quadrature-phase imbalance (IQI), which are joint estimation and compensation (JEC) and separated estimation and compensation (SEC), have been investigated in the uplink quantized massive MIMO systems. Taking the impacts of both quantization and IQI into consideration, we have expressed the details of the channel estimation and IQI compensation...
In amplify-and forward (AF) cooperative systems, accurate channel state information (CSI) for both the cascaded and individual links is essential for coherent combining to achieve spatial diversity. The combined superimposed training strategy(TM+ST) is proposed, where the time-multiplexed (TM) training scheme is employed at source node (SN) to estimate the cascaded channel(S-R-D) while relay-assisted...
Modern wireless systems and standards increasingly rely on OFDM for high-throughput communications. However, these systems are often highly vulnerable to selective jamming attacks, particularly when a jammer targets (part of) the known frame preamble. In this paper, we consider one of the most disruptive jamming attacks against the preamble-based frequency offset (FO) estimation in IEEE 802.11a/n/ac/ax...
In this paper, we consider bandwidth efficient design and channel estimation over time-varying frequency-selective environments, where the basis expansion model (BEM) is used to describe the time-varying channel. Superimposed training based channel estimation based affine precoding model is designed, where the data interference is eliminated from received data prior to performing channel estimation,...
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