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In this paper, a solution to determine the optimum number of base station antennas in an energy efficient downlink massive multiple-input multiple-output (MIMO) system using the zero-forcing (ZF) precoding scheme with imperfect channel state information is provided. In the case where an arbitrary number of base station antennas are used, a recent study has shown that, as the reliability of the channel...
In this letter, we present the mode combinations needed to achieve orthogonal sub-channels in an ideal wireless orbital angular momentum based multiple-input multiple-output (OAM-MIMO) multiplexing system with $N$ OAM transmitters and $M$ receive antennas. The results show that, orthogonality is achieved if the absolute difference between any two transmitted modes $|v_k|\mod M\ne 0$. The modes...
The use of multiple-input multiple-output (MIMO) techniques is one of the proposed methods for detecting message signals multiplexed on a single frequency using multiple wireless orbital angular momentum (OAM) states. In a recent study, the use of a uniform circular array (UCA) of conventional antennas at the receive side was used in an ideal wireless OAM communication system. In this paper, we show...
A wireless multiple-input multiple-output (MIMO) multiplexing system consists of multiple transmit and receive antennas. The channel capacity of such systems does not merely depend on the number of degrees of freedom (DoF) it can support, but also on their gains, represented by the singular values of the channel matrix. A radio frequency based orbital angular momentum (OAM) communication system can...
A wireless orbital angular momentum (OAM) communication system is modeled using multiple-input multiple-output (MIMO) techniques. The channel matrix is derived using the azimuthal phase profile of the OAM modes. A simulation of an ideal line of sight (LOS) infrastructure, based on the model is also presented. It consists of concentric circular array OAM generators at the transmitting side and a uniform...
In this paper the performances of zero-forcing (ZF) and maximum ratio transmission (MRT) are analyzed and compared in a downlink massive multiple-input multiple-output system. The system employs a large number of base station antennas serving multiple user terminals within the same cell. The achievable sum rate and the required downlink transmit power using each of the precoding schemes are derived,...
A large scale MIMO (multiple-input multiple-output) system with cloud base-station (BS) architecture is proposed to address the lack of spectrum resource. Potential transmission schemes including uplink training and downlink precoding are described and analyzed in this paper. The novel system is designed to mitigate interferences among users and make full use of spatial multiplexing gain. Simulation...
A physical-layer feedback space (PFS) based relay selection (PFS/RS) for Virtual MIMO Systems is proposed in this paper. Relay selection along the multi-hop relay chain is performed on a two-hop segment basis. For each two-hop segment, cluster head of the first cluster (CH1) initiates relay selection by sending an invitation message to the second and third cluster. Each candidate relay in the second...
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