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The scaling up of antennae and terminals in large-scale multiple-input multiple-output (MIMO) systems helps increase the spectral efficiency at the penalty of prohibitive computational complexity. In conventional linear detection such as the minimum mean square error (MMSE) signal detection, the high complexity is mainly caused by solving the inversion of random matrix, especially in large-scale MIMO...
This paper presents a vehicle positioning method based on joint estimation of time of arrival (TOA) and direction of arrival (DOA) with Vehicle-to-Roadside (V2R) communications. By analyzing the measured channel frequency response (CFR) between vehicles and the roadside unit (RU), the enhanced two-dimensional matrix pencil (2-D MP) algorithm is implemented to design the parameter estimator, which...
In this paper, an efficient channel estimation scheme is proposed for the point-to-point lens-antenna-array enabled millimeter wave (mmWave) multiple-input multiple-output (MIMO) system with limited number of radio frequency (RF) chains at both source and destination. By exploiting the energy focusing property of lens antenna arrays at both the transmitter and receiver, as well as the multi-path sparsity...
Wireless energy transfer (WET) is potentially a promising solution to provide convenient and reliable energy supplies for energy-constrained networks, and has drawn growing interests recently. To overcome the significant propagation loss over distance, employing multi-antennas at the energy transmitter (ET) to more efficiently direct wireless energy to desired energy receivers (ERs), termed energy...
Cross-VM covert channels leverage physical resources shared between co-resident virtual machines, like CPU cache, memory bus, and disk bus, to leak information. The capacity of cross-VM covert channels varies on different cloud platforms. Thus, it is hard for cloud service providers to estimate the risk of information leakage caused by cross-VM covert channels on their own platforms. In this paper,...
In this paper, we propose a solution to the carrier frequency offset (CFO) estimation based on data dependent superimposed training scheme for Orthogonal Frequency Division Multiplexing (OFDM) systems. The proposed CFO estimation can improve the bandwidth efficiency compared with traditional pilot assistant scheme because it consumes no extra bandwidth for the training sequence is superimposed to...
The performance of time-interleaved analog-to-digital converters (TIADCs) is seriously restricted by the mismatch of the timing skew between ADC channels. The concept of dual-ADC based calibration is that setting two ADC to sample the same input signal synchronously, and the differences of the two outputs are used in calibration algorithm to estimate and compensate the errors in each ADC. Based on...
This paper studies wireless spectrum sharing between a primary radio (PR) link and a secondary radio or so-called cognitive radio (CR) link. Assuming that the PR adapts its transmit power and/or rate upon receiving an interference signal from the CR, and such transmit adaptations are observable by the CR, this phenomenon leads to a new form of feedback from PR to CR, termed as hidden PR feedback,...
This paper studies the transmission strategy for a cognitive radio (CR) that operates under spectrum sharing with a primary radio (PR). It is assumed that the CR transmitter is equipped with multi-antennas and thereby transmit beamforming and power control are jointly deployed to balance between the interference avoidance at the PR terminals and the throughput maximization of the CR link. We name...
We consider a spectrum sharing based cognitive radio wireless communications system which consists of a secondary transmitter (ST) and a secondary receiver (SR), both equipped with multiple antennas, and a single-antenna primary user (PU). ST is composed of an orthogonal space-time block code (OSTBC) followed by a linear precoder which acts as a multimode beamformer. Given a fixed OSTBC, our goal...
We consider the channel estimation issues for two-way relay network (TWRN) that employs orthogonal frequency division multiplexing (OFDM) modulation. We propose a two-phase training protocol for channel estimation, which is compatible with two-phase data transmission scheme associated with TWRN. It will be seen that channel estimation in TWRN is quite different from that in the traditional point-to-point...
This paper presents a multi-antenna cognitive radio (CR) system that is capable of operating concurrently with the primary radio (PR) link. The operation of the CR system consists of three stages: environmental learning, CR channel training and CR data transmission. In environmental learning stage, partial channel information between PR and CR are obtained blindly, based on which the transmit beamforming...
In this paper, we study the channel estimation problem for the two-way wireless relay network (TWRN) where two terminals exchange their information through a relay node in a bi-directional manner. We derive the maximum likelihood (ML) channel estimator as well as a new estimator called the linear maximum signal-to-noise ratio (LMSNR) estimator. It is shown that our proposed methods give superior performance...
This paper studies the information-theoretic limits of a cognitive radio (CR) network under spectrum sharing with an existing primary radio (PR) network for wireless communications. In particular, the fading cognitive multiple-access channel (C-MAC) is studied, where multiple CR users transmit to the base station (BS) of the CR network under both individual transmit power constraints and a set of...
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