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This paper considers a multiuser massive multiple-input multiple-output (MIMO) uplink transmission with the help of an Nr-antenna amplify-and-forward (AF) relay. Assume that the base station (BS) is equipped with a large array of Nd antennas but supported by a far smaller number, K, of radio-frequency (RF) chains, which greatly reduce hardware complexity and cost. A hybrid processing is proposed to...
In this paper, we aim to minimize the total transmission power in uplink LTE networks where mutual interference exists among cells. We use the signal-to-interference-noise-ratio (SINR) coupling model to characterize the mutual relation. By analyzing the SINR coupling model, we prove that operating at minimal rate and maximal load is optimal in minimizing the total transmission power. To solve the...
This paper investigates performance of a mixed radio frequency (RF)/free space optical (FSO) two-way relaying system. A half-duplex two-way relay is adopted to establish the communication between both RF and FSO links. Under this scenario, the associated end-to-end statistical features of the system are derived. They are then used for calculating outage and average symbol error rate (ASER) of M-ary...
This paper considers the optimal energy efficient association for HetNets by applying almost blank subframes (ABSs) techniques. Aiming at maximizing energy efficiency (EE) without the quality of service (QoS) constraints, we obtain a closed-form optimal solution, which indicates that the optimal choice of blank resource block (RB) fraction for EE maximization is binary without individual user QoS...
This paper focuses on decode-and-forward (DF) OFDM full duplex relaying (FDR) systems with multiple relays, where residual loop interference is taken into account. Closed-form and high-SNR approximate expressions for the outage probability are derived. Simulations are carried out to validate the derived outage performance and compare the performance of OFDM FDR with that of OFDM half duplex relaying...
We investigate device-to-device (D2D) communication underlaying cellular networks with M-antenna base stations. We consider both beamforming (BF) and interference cancellation (IC) strategies under quantized channel state information (CSI), as well as, perfect CSI. We derive tight closed-form approximations of the ergodic achievable rate which hold for arbitrary transmit power, location of users and...
This paper investigates robust energy efficient beam-forming for multi-cell downlink transmissions. A bounded uncertainty region is considered to model the impairments of channel state information (CSI) available at the base station (BS). We formulate the problem of beamforming optimization by maximizing the worst case energy efficiency (EE) under CSI uncertainties. Due to the non-convex nature of...
Relaying has been regarded as an effective technique to meet the challenge of network coverage extension. Although relaying can improve cell-edge user performance, cell-center users may suffer serious interference from relay stations. Therefore, intra-cell interference and inter-cell interference have been two major problems which degrade the entire network performance under improper relay deployments...
This paper studies adaptive coordinated control of device-to-device (D2D) communications underlaying a cellular network with a multi-antenna base station (BS). We analyze the performance of cellular and D2D users under the channel imperfections including both quantization error and feedback delay. More specifically, we derive the received signal-to-interference-and-noise ratio (SINR) distributions...
Identifying exons in eukaryotes is an important topic in computational biology. In this paper, according to the three-base periodicity of eukaryotic exons, a model-independent method based on the empirical mode decomposition and the modified Gabor-wavelet transform has been developed for identifying exons in DNA sequences of eukaryotes. This novel technique is aimed particularly at detecting the significant...
Pilot contamination has become a main constraint for large-scale multi-input multi-output (MIMO) systems. In this paper, we consider a large-scale multi-cell MIMO where the number of users per cell K is proportional to that of base station antennas M. Both performances with and without pilot contamination are analyzed in a quantitative way with closed-form expressions. Unlike some existing works,...
This paper studies the capacity performance of coordinated multi-point (CoMP) downlink transmissions based on limited feedback. We consider both path loss effects and channel imperfections including feedback delay and quantization error. Closed-form expressions are derived to characterize ergodic achievable rates for joint processing (JP) and coordinated beamforming (CBF) techniques, respectively...
In this paper, we develop a novel joint transmit and receive design for multiuser MIMO (MU-MIMO) systems. The proposed scheme exploits the channel temporal correlation and incorporates the matched filter (MF) combining vector into the beamforming design. Considering the beamforming is optimized with the outdated channel state information (CSI) feedback, we design the beamformer by maximizing the conditional...
This paper investigates the beamforming design for multiuser downlink with limited feedback, where a practical channel state information (CSI) feedback model consisting both feedback delay and CSI quantization error is considered. Under this circumstance, we derive a closed-form multiuser beamforming scheme via minimizing the expected mean square error (MSE) with respect to the feedback imperfection...
In this paper, we investigate the beamforming optimization for the downlink of multiuser MISO (MU-MISO) system with finite-rate feedback, where the transmitter is only aware of a delayed and quantized version of the channel state information (CSI). By taking into consideration both CSI quantization error and feedback delay, we propose an improved beamforming optimization criterion by maximizing the...
Physical layer secret key can be extracted from wireless fading channels based on channel quantization with guardband (CQG). In this paper, we analyze the key generation efficiency of the CQG protocol. Analytical closed-form expressions of bit error rate (BER) and key generation efficiency are derived for the CQG protocol. In order to further improve the key generation efficiency, we concatenate the...
We consider a MIMO relay downlink system using precoding and limited feedback from two-hop channels. Since the conventional precoding matrices are directly obtained by treating the quantized channel state information (CSI) feedback as the real CSI, we propose an improved relay precoding strategy by taking the effect of channel quantization error into account. The proposed relaying technique is designed...
Owing to its spectral efficiency, bidirectional relaying is a promising candidate for information exchange in multiple-user cooperative networks. When the network is limited by resource constraints, amplify-and-forward (AaF) relay protocol is often the choice due to its simplicity and ease of use. Power allocation for AaF protocol has being extensively studied in unidirectional relay networks but...
This paper investigates the user selection strategy in multiuser downlinks using zero-forcing beamforming (ZFBF) and finite-rate feedback (FRF). In order to mitigate the interference-limited effect, we propose an efficient user scheduling scheme combined with adaptive transmission mode selection to achieve a better diversity and multiplexing tradeoff in terms of the sum rate performance. In this scheme,...
Iterative reconstruction algorithms augmented with regularization can produce high-quality reconstructions from few views and even in the presence of significant noise. In this paper we focus on the particularities associated with the GPU acceleration of these. First, we introduce the idea of using exhaustive benchmark tests to determine the optimal settings of various parameters in iterative algorithm,...
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