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This paper explores optimal array beamforming for secure communication in static multipath propagation environments. The problem is cast as a convex optimization of the average secure key rate achieved in the presence of a passive eavesdropper, and the optimization is performed using semidefinite programming. While representative results are presented for a uniform linear array, the optimization procedure...
This paper considers a downlink massive MIMO frequency division duplexing (FDD) system. Due to the large number of antennas, the required length of training sequence for downlink training significantly increases in FDD mode, which leads to prohibitive overhead in real system. Thus, in this work we investigate how the length of training sequence affects the system performance. For this purpose, we...
This paper presents outdoor field experimental results showing the achievement of 3-Gbps throughput performance based on 400-MHz bandwidth transmission when applying carrier aggregation with 4 component carriers and 4-by-4 single-user multiple-in multiple-out multiplexing in the 15-GHz frequency band in the downlink of 5G cellular radio access. A new radio interface with time division duplexing and...
In multiuser MIMO systems, the required feedback rate per user increases linearly with the number of transmit antennas in order to achieve full multiplexing gain. When it comes to massive MIMO systems, the feedback overhead grows unacceptable. This motivates us to explore a novel feedback reduction scheme based on principal component analysis (PCA). The proposed PCA based feedback scheme exploits...
Eigen-beamforming is an optimal beamforming scheme for full-dimension multi-input multi-output (FD-MIMO). However, it suffers from high complexity of the singular value decomposition (SVD) of the 3D channel matrix. In this paper, we propose a low complexity dual layer beamforming scheme to exploit both the horizontal and vertical degrees of freedom. The proposed scheme first segments the channel matrix...
We propose a new type of UE feedback report for future frequency division duplex (FDD) systems that relaxes the acquisition problem of downlink channel state information (CSI) at eNB with massive antenna arrays. The CSI acquisition is based on estimating the reciprocal characteristics of the multipath propagation channel at eNB during uplink transmission, whereas the non-reciprocal fast-fading characteristics...
In this paper, the on-body performance of three quasi-static channels was evaluated, when the human body undergoes certain typical movements. The main contribution of this work is the analysis of the impact of body movements on the performance of the on-body system in a mine environment. The quasi-static channels parameters were determined and compared to those of a corresponding static channel.
Designing antennas for diversity/MIMO requires a hybrid simulation/measurement approach for real-world situations where the idealized modeling can becomes dubious. Simulations can be accurate for well-defined configurations, but for elements mounted on a complex platform, a typical, simplified numerical configuration behaves differently to the real-world situation. A comparison is presented here for...
Diversity antennas are for improving the communications performance for a given signal power. The uptake of multiple-input multiple-output (MIMO) includes updating existing products, and this typically means modifying a printed circuit board (PCB) to house the updated radio chip(s), and the antennas. Modification for updated chips is relatively straightforward but adding an antenna to an already-packed...
Long Term Evolution (LTE) standard supports MU-MIMO as a new technology to take advantage of the inherent properties of MIMO technology in improving the spectral efficiency and to support multiple users simultaneously. This paper studies the performance of the SC-OFDMA-based LTE system in the uplink correlated Rayleigh fading channel in terms of bit error rate (BER). To the best of author knowledge,...
This paper presents a bilateral fading emulator for MIMO-OTA testing with a function of controlling the correlation of base station. On the basis of the Jakes theory, a methodology for achieving the spatial correlation of a base station antenna by setting the initial phases of scatterers in the two-dimensional channel model is introduced. The experimental results show that the designed correlation...
We consider the downlink of Cell-Free Massive MIMO systems, where a very large number of distributed access points (APs) simultaneously serve a much smaller number of users. Each AP uses local channel estimates obtained from received uplink pilots and applies conjugate beamforming to transmit data to the users. We derive a closed-form expression for the achievable rate. This expression enables us...
Personal location technologies are becoming important with the rapid development of Mobile Internet services. In Long Term Evolution (LTE) networks, the key problem of user location technology is that different base stations need be synchronized. However, high precision synchronization among different base stations is difficult, especially in indoor environment. In this paper, a new wireless location...
The performance of open-loop MIMO precoders is evaluated in the presence of a line-of-sight (LOS) component. Furthermore, the performance for the effect of the use of cross-polarized antennas is presented. The simulation results show that the proposed open-loop precoder works well even in the presence of the LOS with cross-polarized antennas.
In this paper, we investigate the performance of a dual-hop amplify-and-forward (AF) relay system with beamforming (BF), where the source and destination are both equipped with multi-antenna, which are correlated in space, while the relay has a single antenna corrupted by multiple co-channel interferences (CCIs). We first derive the closed-form expression for the outage probability (OP) of the output...
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)...
In this paper, we study the multiple-input multiple-output (MIMO) wiretap channel performing simultaneous wireless information and power transfer (SWIPT), where there are a multiple-antenna base station (BS), a multiple-antenna information decoding (ID) user, and a multiple-antenna energy harvesting (EH) user. The messages intended to the ID user need to be kept confidential to the EH user. The channels...
Major digital signal processing tasks that take place at the site of the Square Kilometre Array (SKA) telescopes are beamforming and correlation. The additional task of searching for pulsars is not discussed in detail in this paper. The combined processing, for correlation, exceeds 10 Pops/s. Input data rates are up to 66 Tb/s (SURVEY array) and output data rates are up to 34 Tb/s (LOW array). The...
Channel state information (CSI) at the base station (BS) is required to fully exploit the advantages of massive MIMO. However, due to massive BS antennas, the estimation and feedback of downlink CSI are very challenging in frequency division duplexing (FDD) massive MIMO. This paper proposes a block compressive channel estimation and feedback scheme for FDD massive MIMO, which can reduce the overhead...
The Square Kilometre Array (SKA) will form the largest radio telescope ever built and such a huge instrument in the desert poses enormous engineering and logistic challenges. Algorithmic and architectural breakthroughs are needed.
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