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This paper presents a new approach to solving the rank constrained beamforming problem. Instead of relaxing the problem to a feasible set of the positive semidefinite matrices, we restrict the problem to a space of polynomials whose dimension is equal to the desired rank. The solution to the resulting optimization is then required to be full rank, allowing a simple matrix decomposition to recover...
Massive MIMO is one of the most promising technologies for the fifth generation (5G) mobile communication systems. In order to better assess the system performance, it is essential to build a corresponding channel model accurately. In this paper, a three-dimension (3D) two-cylinder regular-shaped geometry-based stochastic model (GBSM) for non-isotropic scattering massive MIMO channels is proposed...
This paper presents a new technique for efficient system level analysis of joint nonlinear thermal and RF effects in active antenna array transmitters. The technique is based on the integration of an electro-thermal simulation with comprehensive electro-magnetic (EM) and nonlinear temperature-dependent behavioral models for the active circuits. Simulation results for a 64 (8×8) element GaN-based antenna...
In the research project, a design concept of the mm-wave antenna array operating at 38 GHz is proposed by using a 64-element micorstrip patch antenna array. Theoretical and experimental study validates the design approach for the use of the Fifth generation (5G) wireless communication system.
The paper presents results of an investigation of a MU-MIMO system suitable for providing broadband services. The base station has a circular array and each user has a single high gain antenna. Two optimum zero forcing beamformers are considered and semi-orthogonal user selection is used to schedule users in the downlink. A key point of the investigation is to determine the maximum number of users...
In this paper, the capacity of a communication system based on orbital angular momentum (OAM) multiplexing is thoroughly studied and compared with the conventional multiple input multiple output (MIMO) system under different settings. In our studied OAM multiplexing communication system, both the transmitter side and the receiver side use uniform circular array (UCA) with identical or different settings...
It is well known that most wireless channels are sparse. The channel impulse responses (CIRs) of certain size antenna array have a partially shared support due to the spatial correlation. Moreover, the CIRs during adjacent symbols have a common support due to the temporal correlation. In this paper, we propose a novel compressed channel estimation scheme for the uplink massive multi-input multi-out...
Hardware impairments effects on Massive MIMO system's capacity were investigated and seem to vanish asymptotically at the base station when equipped with a larger array. Surprisingly, the effect of the local oscillator (LO) phase noise does not strictly obey the same law as the additive noise when a common LO is utilized. Having a close look at large array base station utilizing OFDM signaling, one...
Full dimension multiple input multiple output (FD-MIMO) employs 2-dimensional (2D) active antenna array configurations at the transmitter along with advanced digital processing to improve capacity for next generation wireless networks and services. This technology can achieve multi user MIMO (MU-MIMO) of high magnitude via the provision of simultaneous data transmission to large number of user equipments...
Herein is proposed a novel high-steep rock slope landslide monitoring system based on the configuration of multi-static multiple-input multiple-output synthetic aperture radar (MIMO-SAR). In this system, three spastically distributed radars are employed. Each is a Ku-band MIMO-SAR, transmitting mutually orthogonal waveforms and sensing the slope movement from different view angles. The three radars...
Advanced communication systems utilizing multiple transmitting antennas working in a same frequency, such as phased array antennas or MIMO (Multi-Input Multi-Output) antennas, recently receive more and more research attentions. One of technical issues, which certainly need to take into account, is the electromagnetic compatibility. In particular, the evaluation of Specific Absorption Rate (SAR), in...
It is well known that waveforms can be designed to maximize the SNR of objects with specific desired features. In some cases, it may be desirable to tune a waveform for different features at different angles. A MIMO radar can transmit multiple waveforms across a large span of angles. It is possible to design a MIMO radar waveform transmitted from individual elements to achieve the desired waveform...
Through two different applications (a MIMO system and a superdirective antenna array), we will show in this paper that a complete surface current optimization on an antenna allows the design of an optimal antenna system. For example, this surface current optimization can be applied to a MIMO system through a minimization of the cross-correlation coefficient or a superdirective antenna array with a...
In this study a sparse MIMO system with difference co-array processing is presented. It consists of two dense transmitter arrays in split configuration and a symmetrical hybrid receiver array. A combination of a periodically thinned array and two non-uniform sub-arrays is proposed to synthesize the receiver structure with low optimization effort. High angular resolution is achieved in the MUSIC spectrum...
Direction-of-arrival (DOA) is a research direction in array signal processing. This paper estimates the DOA for Multiple-Input Multiple-Output (MIMO) radar system. The algorithms of multiple signal classification and approximated maximum likelihood (MUSIC-AML) based on linear array are deduced. The number of target sources is also valued in this paper. The results show the feasibility and validity...
In this paper, a radar system implementation is addressed to detect a point target, that is a Multiple-Input Multiple-Output (MIMO) Radar. It is an emergent concept in radar field and has reached a substantial considerations. The advantages of MIMO radars is presented in comparison of SIMO and SAR radars. The simulation and measurement results show that the MIMO Radars can reach a better angular resolution...
Massive multiple input and multiple output (MIMO) systems can increase the spectrum and energy efficiency of existing cells, and because of this, massive MIMO has been considered as a potential technique for next generation wireless communication networks. Since a thorough knowledge of the propagation channel is a prerequisite of reliable communication systems, massive MIMO channels are of great current...
With massive MIMO and/or millimeter wave technologies, the system has large numbers of antennas and/or frequency bands to increase the capacity and the number of the accessed users. In this case, conventional precoding method performed at the baseband becomes impractical, since the processing complexity is large and the cost of the hardware is high. Therefore, hybrid radio frequency (RF) and baseband...
A compact dual-polarized antenna with four radiating square patches is presented and arranged to establish an array for massive MIMO systems operating at 3.7GHz. There are three stack levels of orthohexagonal rings in the array and each ring contains six sub-arrays with a gain of 16.6dBi and half-power beam width of 12.5° in azimuth. Within a volume of 8λ×8λ×3λ, the maximum mutual coupling level between...
This paper investigates the dominant propagation mechanisms in indoor line-of-sight (LOS) environments from channel measurement and ray tracing simulation. Double-directional channel sounding was performed using 24×24 multiple-input multiple-output (MIMO) channel sounder at 11 GHz with 400 MHz bandwidth to get the MIMO channel transfer function. Path parameters from ray tracing simulation and antenna...
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