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See detailHybrid Analog-Digital Transceiver Designs for Cognitive Radio Millimiter Wave Systems
Tsinos, Christos UL; Maleki, Sina UL; Chatzinotas, Symeon UL et al

in Hybrid Analog-Digital Transceiver Designs for Cognitive Radio Millimiter Wave Systems (in press)

Recent advances in Milimeter wave (mmWave) band mobile communications may provide solutions to the increasing traffic demand in modern wireless systems. Even though mmWave bands are scarcely occupied, the ... [more ▼]

Recent advances in Milimeter wave (mmWave) band mobile communications may provide solutions to the increasing traffic demand in modern wireless systems. Even though mmWave bands are scarcely occupied, the design of a prospect transceiver should guarantee the efficient coexistence with the incumbent services in these bands. To that end, in this paper, two underlay cognitive transceiver designs are proposed based on a hybrid Analog/Digital transceiver architecture that enables the mmWave spectrum access while controlling the interference to the incumbent users with low hardware complexity and power consumption. The first cognitive solution designs a codebook free cognitive hybrid pre-coder by maximizing the mutual information between its two ends subject to interference, power and hardware constraints related to the analog counterpart. The second solution is codebook based and exhibits less complexity than the first one at the cost of inferior spectral efficiency. A novel codebook free solution for the post-coder at the cognitive receiver part is further proposed, based on a hardware constrained Minimum Mean Square Error criterion. Simulations study the performance of both the proposed hybrid approaches and compare it to the one of a fully digital solution for typical wireless environments. [less ▲]

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See detailA Framework for Optimizing Multi-cell NOMA: Delivering Demand with Less Resource
You, Lei; Lei, Lei UL; Yuan, Di et al

in 2017 IEEE Global Communications Conference (GLOBECOM) (2017, December)

Non-orthogonal multiple access (NOMA) allows multiple users to simultaneously access the same time-frequency resource by using superposition coding and successive interference cancellation (SIC). Thus far ... [more ▼]

Non-orthogonal multiple access (NOMA) allows multiple users to simultaneously access the same time-frequency resource by using superposition coding and successive interference cancellation (SIC). Thus far, most papers on NOMA have focused on performance gain for one or sometimes two base stations. In this paper, we study multi-cell NOMA and provide a general framework for user clustering and power allocation, taking into account inter-cell interference, for optimizing resource allocation of NOMA in multi-cell networks of arbitrary topology. We provide a series of theoretical analysis, to algorithmically enable optimization approaches. The resulting algorithmic notion is very general. Namely, we prove that for any performance metric that monotonically increases in the cells’ resource consumption, we have convergence guarantee for global optimum. We apply the framework with its algorithmic concept to a multi-cell scenario to demonstrate the gain of NOMA in achieving significantly higher efficiency. [less ▲]

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See detailRelay Selection Strategies for SWIPT-Enabled Cooperative Wireless Systems
Gautam, Sumit UL; Lagunas, Eva UL; Sharma, Shree K. et al

in IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Montreal, Canada, Oct. 2017 (2017, October)

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See detailFacial Expression Recognition via Joint Deep Learning of RGB-Depth Map Latent Representations
Oyedotun, Oyebade UL; Demisse, Girum UL; Shabayek, Abd El Rahman UL et al

in 2017 IEEE International Conference on Computer Vision Workshop (ICCVW) (2017, August 21)

Humans use facial expressions successfully for conveying their emotional states. However, replicating such success in the human-computer interaction domain is an active research problem. In this paper, we ... [more ▼]

Humans use facial expressions successfully for conveying their emotional states. However, replicating such success in the human-computer interaction domain is an active research problem. In this paper, we propose deep convolutional neural network (DCNN) for joint learning of robust facial expression features from fused RGB and depth map latent representations. We posit that learning jointly from both modalities result in a more robust classifier for facial expression recognition (FER) as opposed to learning from either of the modalities independently. Particularly, we construct a learning pipeline that allows us to learn several hierarchical levels of feature representations and then perform the fusion of RGB and depth map latent representations for joint learning of facial expressions. Our experimental results on the BU-3DFE dataset validate the proposed fusion approach, as a model learned from the joint modalities outperforms models learned from either of the modalities. [less ▲]

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See detailRandom Phase Center Motion Technique for Enhanced Angle-Doppler Discrimination Using MIMO Radars
Hammes, Christian UL; Shankar, Bhavani UL; Nijsure, Yogesh UL et al

Scientific Conference (2017, August)

A random Phase Center Motion (PCM) technique is presented in this paper, based on Frequency Modulated Continuous Wave (FMCW) radar, in order to suppress the angle- Doppler coupling in Time Division ... [more ▼]

A random Phase Center Motion (PCM) technique is presented in this paper, based on Frequency Modulated Continuous Wave (FMCW) radar, in order to suppress the angle- Doppler coupling in Time Division Multiplex (TDM) Multiple- Input-Multiple-Output (MIMO) radar when employing sparse array structures. The presented approach exploits an apparently moving transmit platform or PCM due to spatio-temporal transmit array modulation. In particular, the work considers a framework utilizing a random PCM trajectory. The statistical characterization of the random PCM trajectory is devised, such that the PCM and the target motion coupling is minimal, while the angular resolution is increased by enabling the virtual MIMO concept. In more details, this paper discusses sidelobe suppression approaches within the angle-Doppler Ambiguity Function (AF) by introducing a phase center probability density function within the array. This allows for enhanced discrimination of multiple targets. Simulation results demonstrate the suppression angle- Doppler coupling by more than 30 dB, even though spatiotemporal transmit array modulation is done across chirps which leads usually to strong angle-Doppler coupling. [less ▲]

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See detailTraining Very Deep Networks via Residual Learning with Stochastic Input Shortcut Connections
Oyedotun, Oyebade UL; Shabayek, Abd El Rahman UL; Aouada, Djamila UL et al

in 24th International Conference on Neural Information Processing, Guangzhou, China, November 14–18, 2017 (2017, July 31)

Many works have posited the benefit of depth in deep networks. However, one of the problems encountered in the training of very deep networks is feature reuse; that is, features are ’diluted’ as they are ... [more ▼]

Many works have posited the benefit of depth in deep networks. However, one of the problems encountered in the training of very deep networks is feature reuse; that is, features are ’diluted’ as they are forward propagated through the model. Hence, later network layers receive less informative signals about the input data, consequently making training less effective. In this work, we address the problem of feature reuse by taking inspiration from an earlier work which employed residual learning for alleviating the problem of feature reuse. We propose a modification of residual learning for training very deep networks to realize improved generalization performance; for this, we allow stochastic shortcut connections of identity mappings from the input to hidden layers.We perform extensive experiments using the USPS and MNIST datasets. On the USPS dataset, we achieve an error rate of 2.69% without employing any form of data augmentation (or manipulation). On the MNIST dataset, we reach a comparable state-of-the-art error rate of 0.52%. Particularly, these results are achieved without employing any explicit regularization technique. [less ▲]

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See detailEnergy-Efficient Design for Edge-caching Wireless Networks: When is Coded-caching beneficial?
Vu, Thang Xuan UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in Abstract book of IEEE 18th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) (2017, July)

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See detailInterference Constraint Active Learning with Uncertain Feedback for Cognitive Radio Networks
Tsakmalis, Anestis UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in IEEE Transactions on Wireless Communications (2017), 16(7), 4654-4668

In this paper, an intelligent probing method for interference constraint learning is proposed to allow a centralized cognitive radio network (CRN) to access the frequency band of a primary user (PU) in an ... [more ▼]

In this paper, an intelligent probing method for interference constraint learning is proposed to allow a centralized cognitive radio network (CRN) to access the frequency band of a primary user (PU) in an underlay cognitive communication scenario. The main idea is that the CRN probes the PU and subsequently eavesdrops the reverse PU link to acquire the binary ACK/NACK packet. This feedback is implicit channel state information of the PU link, indicating whether the probinginduced interference is harmful or not. The intelligence of this sequential probing process lies in the selection of the power levels of the secondary users, which aims to minimize the number of probing attempts, a clearly active learning (AL) procedure, and expectantly the overall PU QoS degradation. The enhancement introduced in this paper is that we incorporate the probability of each feedback being correct into this intelligent probing mechanism by using a multivariate Bayesian AL method. This technique is inspired by the probabilistic bisection algorithm and the deterministic cutting plane methods (CPMs). The optimality of this multivariate Bayesian AL method is proven and its effectiveness is demonstrated through numerical simulations. Computationally cheap CPM adaptations are also presented, which outperform existing AL methods. [less ▲]

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See detailPower Allocation for In-Band Full-Duplex Self-Backhauling
Lagunas, Eva UL; Lei, Lei UL; Maleki, Sina UL et al

in International Conference on Telecommunications and Signal Processing (TSP), Barcelona, Spain, July 2017 (2017, July)

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See detailSpatial PAPR Reduction in Symbol-level Precoding for the Multi-beam Satellite Downlink
Spano, Danilo UL; Alodeh, Maha UL; Chatzinotas, Symeon UL et al

in IEEE SPAWC 2017 (2017, July)

In this work, a novel symbol-level precoding scheme is proposed, for managing the multi-user interference in the forward downlink channel of a multi-beam satellite system. Besides exploiting the ... [more ▼]

In this work, a novel symbol-level precoding scheme is proposed, for managing the multi-user interference in the forward downlink channel of a multi-beam satellite system. Besides exploiting the constructive interference effect, the proposed scheme aims at improving the robustness of the transmitted signals to the non-linear distortions of practical satellite systems. This is done by reducing the imbalances between the instantaneous power transmitted by the multiple antennas, which are detrimental in non-linear systems. More specifically, this work proposes a symbol-level precoding scheme performing the minimization of the spatial peak-to-average power ratio, under Quality-of-Service constraints. An iterative algorithm is proposed to solve the related optimization problem. Numerical results are presented to assess the performance of the proposed scheme, which outperforms the state of the art symbol-level precoding techniques in terms of spatial peak-to-average power ratio across the transmitting antennas. [less ▲]

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See detailLow Complexity Symbol-Level Design for Linear Precoding Systems
Krivochiza, Jevgenij UL; Kalantari, Ashkan UL; Chatzinotas, Symeon UL et al

in Heusdens, Richard; Weber, Jos H. (Eds.) PROCEEDINGS of the 2017 Symposium on Information Theory and Signal Processing in the Benelux (2017, May 11)

The practical utilization of the symbol-level precoding in MIMO systems is challenging since the implementation of the sophisticated optimization algorithms must be done with reasonable computational ... [more ▼]

The practical utilization of the symbol-level precoding in MIMO systems is challenging since the implementation of the sophisticated optimization algorithms must be done with reasonable computational resources. In the real implementation of MIMO precoding systems, the processing time for each set of symbols is a crucial parameter, especially in the high-throughput mode. In this work, a symbol-level optimization algorithm with reduced complexity is devised. Performance of a symbol-level precoder is shown to improve in terms of the processing times per set of symbols. [less ▲]

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See detailOn the Diversity of Partial Relaying Cooperation with Relay Selection in Finite-SNR Regime
Vu, Thang Xuan UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in IEEE International Conference on Communications (2017, May)

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See detailFinite-SNR analysis for partial relaying cooperation with channel coding and opportunistic relay selection
Vu, Thang Xuan UL; Duhamel, Pierre; Chatzinotas, Symeon UL et al

in EURASIP Journal on Advances in Signal Processing (2017)

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See detailCarrier Allocation for Hybrid Satellite-Terrestrial Backhaul Networks
Lagunas, Eva UL; Maleki, Sina UL; Lei, Lei UL et al

in ICC Workshop on Satellite Communications: Challenges and Integration in the 5G ecosystem, Paris, France, May 2017 (2017, May)

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See detailDiscrimination of Angle-Doppler Signatures using Arbitrary Phase Center Motion for MIMO Radars
Hammes, Christian UL; Nijsure, Yogesh UL; Shankar, Bhavani UL et al

Scientific Conference (2017, May)

A novel Phase Center Motion (PCM) based technique for discriminating angle-Doppler signatures within Multiple-Input-Multiple-Output (MIMO) radars using Frequency Modulated Continuous Wave (FMCW) has been ... [more ▼]

A novel Phase Center Motion (PCM) based technique for discriminating angle-Doppler signatures within Multiple-Input-Multiple-Output (MIMO) radars using Frequency Modulated Continuous Wave (FMCW) has been explored in this work. The PCM technique induces angle dependent Doppler shifts in the back-scattered signal, wherein a modified Doppler post processing for FMCW leads to joint angle-Doppler processing. Specifically, we intend to design unique spatialtemporal motion of the phase center on each individual MIMO radar channel in an effort to synthesize nearly orthogonal angle- Doppler signatures. Subsequently, we also develop a MIMO radar receiver design, which would be capable of discriminating between these induced angle-Doppler signatures. The asymptotic investigation provides a Bessel function characteristic. Simulation results demonstrate a significant side-lobe suppression of 8:5 dB for an individual PCM trajectory and 7 dB over distinct PCM trajectories, in an attempt towards realization of nearly orthogonal MIMO radar channels. [less ▲]

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See detailSpectral-Efficient Model for Multiuser Massive MIMO: Exploiting User Velocity
Vu, Thang Xuan UL; Trinh, Anh Vu; Chatzinotas, Symeon UL et al

in IEEE international Conference on Communications (2017, May)

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See detailFaster-than-Nyquist Spatiotemporal Symbol-level Precoding in the Downlink of Multiuser MISO Channels
Alodeh, Maha UL; Spano, Danilo UL; Chatzinotas, Symeon UL et al

in The 42nd IEEE International Conference on Acoustics, Speech and Signal Processing (2017, March)

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See detailVideo-Based Feedback for Assisting Physical Activity
Baptista, Renato UL; Goncalves Almeida Antunes, Michel UL; Aouada, Djamila UL et al

in 12th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISAPP) (2017)

In this paper, we explore the concept of providing feedback to a user moving in front of a depth camera so that he is able to replicate a specific template action. This can be used as a home based ... [more ▼]

In this paper, we explore the concept of providing feedback to a user moving in front of a depth camera so that he is able to replicate a specific template action. This can be used as a home based rehabilitation system for stroke survivors, where the objective is for patients to practice and improve their daily life activities. Patients are guided in how to correctly perform an action by following feedback proposals. These proposals are presented in a human interpretable way. In order to align an action that was performed with the template action, we explore two different approaches, namely, Subsequence Dynamic Time Warping and Temporal Commonality Discovery. The first method aims to find the temporal alignment and the second one discovers the interval of the subsequence that shares similar content, after which standard Dynamic Time Warping can be used for the temporal alignment. Then, feedback proposals can be provided in order to correct the user with respect to the template action. Experimental results show that both methods have similar accuracy rate and the computational time is a decisive factor, where Subsequence Dynamic Time Warping achieves faster results. [less ▲]

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See detailCoded Caching and Storage Planning in Heterogeneous Networks
Vu, Thang Xuan UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in 2017 IEEE Wireless Communications and Networking Conference (WCNC) (2017)

Detailed reference viewed: 16 (2 UL)