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In this paper, we consider massive MIMO uplink using maximum ratio combining (MRC) and zero forcing (ZF) receivers with perfect and imperfect channel state information (CSI). We derive lower and upper bounds on the achievable rates with arbitrary power allocation. Analytical and simulation results illustrate the accuracy and characteristics of the rate bounds.
The successful implementation of dynamic spectrum access in cognitive radio networks requires that the secondary user has an autonomous knowledge of the true status of the licensed user activities. This paper investigates and proposes a robust blind spectrum sensing technique that is based on the variational Bayesian learning for Gaussian mixture model framework for use in multi-antenna cognitive...
In this paper, we study the non-integer degrees of freedoms (DoF) of the time-invariant multiple-input multiple-output (MIMO) interfering multiple access channel (IMAC) in the simple setting of two cells, K users per cell, and M antennas at all nodes. We apply the idea of channel diversity developed by Li, Jafarkhani, and Jafar to this setting to derive the exact characterization of the maximum achievable...
This paper proposes a high-sum-rate maximum signal-to-interference and noise ratio (Max-SINR) plus maximum signal-to-leakage and noise ratio (Max-SLNR) beamforming per user (Max-SINR plus Max-SLNR per user) at the relay station (RS) for multi-pair two-way relay system with multi-antenna users. The proposed beamformer applies Max-SINR and Max-SLNR to uplink and downlink channels, respectively. It beam-forms...
In this paper, we study the secrecy rate maximization problem with the group-sparse penalty in the form of a mixed £f/£i regularization to design beamformers in Amplify-and-Forward (AF) relay networks. Resorting to such group-sparse penalty, we can efficiently choose a small size of relays to join in the secure transmission and reduce the cooperation overhead. In our work, the proximal gradient algorithm...
The increasing scale of Multiple-Input Multiple-Output (MIMO) topologies employed in forthcoming wireless communications standards presents a substantial implementation challenge to designers of embedded baseband signal processing architectures for MIMO transceivers. Specifically the increased scale of such systems has a substantial impact on the perfor-mance/cost balance of detection algorithms for...
This paper addresses the problem of pilot power allocation between users in massive multiuser multiple-input-multiple-output (MU-MIMO) systems with heterogeneous users. By exploiting the fact that heterogeneous users can experience different path loss and shadowing degradations due to their distinct locations, this paper proposes an optimized pilot power allocation strategy for massive MIMO systems...
In this paper, we evaluate how much beamforming and noise injection can improve physical layer security by deriving the probability of non-zero secrecy capacity and the secrecy outage probability. Our model is a typical wiretap channel model, composed of three participants — the transmitter Alice, the legitimate receiver Bob and the eavesdropper Eve. A typical cellular scenario is considered where...
In this paper, we investigate low-complexity user scheduling schemes for the downlink (DL) massive multiuser multiple-input multiple-output (MU-MIMO) system, where an M-antenna (M is very large) base station (BS) serves K (K > 2) N-antenna (N > 1) users with linear transceivers. Establishing the theoretical foundation of our scheduling schemes, we first investigate the asymptotic sum-rates of...
We propose a differential space-time coded (STC) radio-frequency-identification (RFID) system where the tag has two antennas and the reader has a single or multiple antennas. In this system, the M-ary phase-shift keying constellation is used, and encoding at the tag and decoding at the reader are simple. Simulation results show that the proposed STC RFID system can achieve a performance improvement...
This paper investigates multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying networks with orthogonal space-time block codes (OSTBC) and M-ary frequency-shift-keying (FSK) modulation. A non-coherent detection scheme is proposed and analyzed in a situation where the fading channels undergo temporal correlation. Specifically, the destination employs the linear minimum mean square...
In recent years, the use of shore or buoy mounted forward scatter radar transceivers for the detection of small, low radar cross section, slow speed (otherwise termed low detectability) maritime targets has been proposed and investigated. Work has focused on the fundamental development of the single baseline link, which would form the basis of any netted system and has mostly been investigated at...
In this paper, we propose an enhanced strategy for jointly-optimized uncoordinated beamforming over cognitive radio network. We consider a transmission of a single information stream in both primary and secondary links where both primary and secondary users are equipped with multiple antennas and transmit concurrently over the same spectrum. Specifically, the optimum weights to maximize the individual...
In this paper, we consider the problem of secure communication in multiuser downlink wiretap networks where there exist a base-station (BS) equipped with multiple antennas, multiple legitimate receivers and a passive eavesdropper. The transmitter simultaneously transmits an information signal and artificial noise (AN) separately to the intended receivers and the eavesdropper, in which way, the secrecy...
Cooperative relay is considered as an efficient scheme to improve the physical layer security of a wireless relay system in the presence of eavesdroppers. In this paper, multiple-level relay scheme is proposed. We consider relay weight design for secrecy rate maximization subject to a power constraint. The results show that a higher achievable secrecy rate is achieved in the two-level relay channel...
This paper investigates the design of interference alignment (IA) for a three-cell constant cellular interfering network, where three base stations in the cellular network simultaneously transmit signals to a group of users in their own cells while causing interference to each other. While determining the existence of IA with reaching the degrees of freedom (DoF) outer bound is still a very challenging...
We investigate iterative detection and decoding, a.k.a. turbo detection, for multiple-input multiple-output (MIMO) transmission. This investigation is based on a low complexity softoutput MIMO detector with a priori information feedback. We show that maximum a posteriori performance (without turbo iteration) can be achieved, at a much lower computational cost, by using the proposed soft-output MIMO...
We propose a new transmission scheme for MEMO Y channel by combining the antenna selection algorithm with signal space alignment and network coding strategy. This strategy works with more relaxed constraint between M and N. The average symbol error rate of the transmission scheme is analyzed for the multiple-access phase and the broadcast phase respectively. We show that the proposed scheme can provide...
In this paper we propose an algorithm for 2D antenna array that can be used in ground surveillance systems. Due to the multipath propagation of signals robustness against imperfect knowledge about direction of arrival (DOA) is needed. We achieve the needed robustness by using two dimensional Slepian window functions. Although main interest of our research is surveillance, results of it may be also...
MIMO CDMA system with the calibration of OFDM method is proposed. To obtain the spatial diversity between the symbols, STBC block codes were used. Space time block coding (STBC) is the most efficient method due to its provision of full spatial diversity and simple linear decoder. The combination of space-time block coding (STBC) and Direct-Sequence CodeDivision Multiple Access (CDMA) has the potential...
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