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This work deals with a joint design of radio access and fronthaul links for the uplink of cloud radio access network (C-RAN) equipped with wireless fronthaul link. A conventional uplink system based on per-cell decode-and-forward (DF) relaying, in which the message sent by each user equipment (UE) is decoded by the closest remote radio head (RRH) and forwarded to a baseband processing unit (BBU) via...
In millimeter-wave communication systems with large-scale antenna arrays, conventional digital beamforming may not be cost-effective. A promising solution is the implementation of hybrid beamforming techniques, which consist of low-dimensional digital beamforming followed by analog radio frequency (RF) beamforming. This work studies the optimization of hybrid beamforming in the context of a cloud...
When implementing single radio frequency (RF) chain multi-user (MU) millimeter-wave (mmWave) systems, an RF beamforming algorithm with a short beam training overhead is essential. In this paper, we propose a new MU RF beamforming algorithm based on the conventional RF beam training method in IEEE 802.11ad. Then, we investigate its asymptotic behavior for a large number of users scenario. We show that...
In this paper, we study a wireless powered communication network (WPCN) in a two-user interference channel, where two hybrid access-points (H-APs) support a user in each cell. In this two cell scenario, the H-APs first transmit the energy signal to charge both users in the downlink (DL) phase. Then, in the subsequent uplink (UL) phase, each user sends its information signal to the corresponding H-AP...
In this paper, we study self energy recycling techniques for point-to-point multiple-input multiple-output systems where a full-duplex transmitter with multiple antennas communicates with a multi-antenna receiver. Due to the full-duplex nature, the transmitter receives a signal transmitted by itself through a loop-back channel. Then, the energy of the signal is harvested and stored in an energy storage...
This paper investigates multi-user multi-input multi- output cognitive wireless powered communication networks (WPCN), in which a secondary WPCN shares spectrum with a primary wireless information transfer system. A typical WPCN consists of two different phases. In the first downlink phase, a hybrid access point (H-AP) transfers energy to charge users, and then in the subsequent uplink phase, the...
In this work, we consider a wireless powered communication network (WPCN) with an energy harvesting (EH) jammer where an eavesdropper tries to wiretap the communication between a user and a hybrid access-point (H-AP). In our system, the H-AP first transmits an energy signal to recharge the batteries of the EH user and the EH jammer in the energy transfer (ET) phase. Then, in the subsequent information...
In this paper, we propose a new user selection algorithm for full-duplex (FD) multiuser multiple-input single-output (MU-MISO) systems where a FD base station (BS) communicates with multiple half-duplex (HD) users in both downlink and uplink channels simultaneously. Due to self-interference at the BS and co-channel interference among users, a joint downlink and uplink user selection to maximize system...
In simultaneous wireless information and power transfer (SWIPT) systems, dedicated energy signals only convey wireless energy, but not information. For this reason, the energy-carring signals in the SWIPT can be pre- determined in advance and is shared among communication nodes. By exploiting this nature, this paper designs the optimal transmit beamforming vectors for the multiple-input single-output...
In this paper, we study a joint spatial division multiplexing (JSDM) beamforming scheme which enables large-scale spatial multiplexing gains for massive MIMO downlink systems. In contrast to the conventional JSDM which employs a block diagonalization (BD) method as a pre-beamformer, we aim to maximize sum-rate by applying minimum-mean-squared error (MMSE) approaches when designing a pre-beamformer...
In this paper, we study simultaneous wireless information and power transfer (SWIPT) for multiuser multipleinput- single-output (MISO) secrecy multicasting channels with imperfect channel state information. First, a robust secure beamfoming design is considered, where the transmit power is minimized subject to the secrecy rate outage probability constraint for legitimate users and the harvested energy...
In this paper, we present a new beamforming design at the relay in AF two-way relaying systems where a relay node with Nr antennas serves two source nodes equipped with a single antenna. In this system, we design low complexity relay beamforming which minimizes the mean squared error (MSE). To this end, unlike conventional designs based on perfect self-interference cancelation at each source whose...
This paper studies multi-user wireless powered communication networks, where energy constrained users scavenge energy of the radio frequency signals radiated from a hybrid access point (H-AP). The energy is then utilized for the users' uplink information transmission to the H-AP in time division multiple access mode. In this system, we aim to maximize the uplink sum rate performance by jointly optimizing...
In this paper, we study an energy harvesting scheme for a multiple-input-single-output secrecy channel under imperfect channel state information case with either deterministic and statistical channel uncertainties. The system consists of one multi-antenna transmitter, several multi-antenna energy receivers (ERs) and one single-antenna co-located receiver (CR) who adopts a power splitter to decode...
In this paper, we propose a new beamforming design to maximize energy efficiency (EE) for multiple input single output interfering broadcast channels (IFBC). Under this model, the EE problem is non-convex due to the coupled interference and its fractional form, and thus it is difficult to solve the problem. Conventional algorithms which address this problem have adopted an iterative method for each...
We address a new robust optimization problem in a multiuser multiple-input single-output broadcasting system with simultaneous wireless information and power transmission. Assuming that perfect channel- state information (CSI) for all channels is not available at the BS, the uncertainty of the CSI is modeled by an norm-bounded uncertainty set. To optimally design transmit beamforming weights and receive...
In this paper, we investigate an energy efficiency (EE) maximization problem in multi-user multiple input single output downlink channels. In this system model, the optimization problem is difficult to solve since it is in a non-convex fractional form. Hence, conventional algorithms have addressed the problem in an iterative manner for each channel realization that leads to high computational complexity...
In this paper, we focus on maximizing weighted sum energy efficiency (EE) for a multi-cell multi-user channel. In order to solve this non-convex problem, we first decompose the original problem into a sequence of parallel subproblems which can be optimized separately. For each subproblem, a base station employs dirty paper coding to maximize the EE for users within the cell while regulating interference...
In this paper, we study a transmit beamforming technique for multiple input single output downlink multi-user systems with directional antennas where a transmit antenna gain is determined in three dimensional coordinates. For a multiuser active antenna system, beamforming designs to maximize the weighted sum rate are proposed by optimizing the transmit antenna gain and power allocation. Since finding...
In this paper, we investigate a multiuser downlink distributed antenna system with simultaneous wireless information and power transmission under the assumption of imperfect channel state information at the distributed antenna (DA) port. To optimally design robust transmit beamforming vectors and receive power splitting factors, our design objective is to maximize the average worst-case signal-to-interference-plus-noise...
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