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See detail2018 IEEE 23rd International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD)
Domouchtsidis, Stavros; Tsinos, Christos UL; Chatzinotas, Symeon UL et al

in 2018 IEEE 23rd International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD) (2018)

Large-Scale Antenna Array Systems may be used to serve multiple users in the same time-frequency resource block which results to harmful multi-user interference (MUI). In the literature precoding ... [more ▼]

Large-Scale Antenna Array Systems may be used to serve multiple users in the same time-frequency resource block which results to harmful multi-user interference (MUI). In the literature precoding techniques have been proposed as a way to mitigate the induced MUI, by designing the transmitted signals using the knowledge of the Channel State Information (CSI), in block-level precoding (BLP) or both the CSI and the information-bearing symbols, in symbol-level precoding (SLP). However, the proposed SLP techniques require fully digital baseband processing which is infeasible in large-scale antenna array systems because of the high cost and power consumption of radio frequency (RF) components. In order to reduce the number of y-RF chains, we address an Antenna Selection Symbol-Level Precoding (AS-SLP) scheme, which minimizes the MUI by activating only a subset of the available antennas. For this scheme we develop an efficient algorithm, based on Coordinate Descent. Simulations provide an insight on the efficiency of the proposed approach and its improvement with respect to the fully digitally approaches. [less ▲]

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See detailOFDM-based automotive joint radar-communication system
Dokhanchi, Sayed Hossein UL; Shankar, Bhavani UL; Stifter, Thomas et al

in 2018 IEEE Radar Conference (RadarConf18) (2018)

We propose a novel automotive joint radar-communication (JRC) system, where the system first transmits OFDM sub-carriers for radar processing followed by sub-carriers enabling radar and communication ... [more ▼]

We propose a novel automotive joint radar-communication (JRC) system, where the system first transmits OFDM sub-carriers for radar processing followed by sub-carriers enabling radar and communication functionalities. The receiver processing includes iterative estimation of parameters to alleviate the shortage of samples to estimate range. The receiver first estimates the target parameters from the sub-carriers dedicated to radar; these parameters then determine the channel for the communication link. The communication data is then extracted, thereby enabling the use of all the carriers for improving the range estimation. It is shown that the range estimation improves significantly after efficient use of all the sub-carriers. Furthermore, for radar parameter estimation, we propose an effective iterative method based on alternating least square (ALS) to recover the angle of arrival (AoA), Doppler and Range. Numerical results demonstrate the feasibility of our proposed system. [less ▲]

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See detailSDR Implementation of a Testbed for Real-Time Interference Detection with Signal Cancellation
Politis, Christos; Maleki, Sina UL; Merlano Duncan, Juan Carlos UL et al

in IEEE Access (2018)

Interference greatly affects the quality of service of wireless and satellite communications, having also a financial impact for the telecommunication operators. Therefore, as the interfering events ... [more ▼]

Interference greatly affects the quality of service of wireless and satellite communications, having also a financial impact for the telecommunication operators. Therefore, as the interfering events increase due to the deployment of new services, there is an increasing demand for the detection and mitigation of interference. There are several interference detectors in the literature, evaluated by using extensive simulations. However, this paper goes one step further, designing, implementing and evaluating the performance of the developed interference detection algorithms experimentally using a software defined radio, and particularly the universal software radio peripheral platform. A realistic communication system is implemented, consisting of a transmitter, a channel emulator and a receiver. Based on this system, we implement all the appropriate communications features such as pulse shaping, synchronization and demodulation. The real-time system implementation is validated and evaluated through signal and interference detection. We observe that the interference detection threshold is critical to the functioning of the system. Several existing interference detection techniques fail in practice due to this fact. In this paper, we propose a robust and practically implementable method the selection of threshold. Finally, we present real-time experimental results for the probabilities of false alarm and detection in order to verify the accuracy of our study and reinforce our theoretical analysis. [less ▲]

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See detailOn-Board Precoding in a Multiple Gateway Multibeam Satellite System
Joroughi, Vahid UL; Shankar, Bhavani UL; Maleki, Sina UL et al

in Proceedings of IEEE VTC Fall 2018 (2018)

This paper present On-Board Precoding (OBP) for a multiple gateway multibeam satellite system where full frequency reuse pattern is employed at both user and feeder links. By reducing the Channel State ... [more ▼]

This paper present On-Board Precoding (OBP) for a multiple gateway multibeam satellite system where full frequency reuse pattern is employed at both user and feeder links. By reducing the Channel State Information (CSI) roundtrip delay to half, OBP offers significant benefits in the emerging multiple gateway scenario in terms of lower gateways coordination. However, two critical issues need to be addressed: (a) interference in both user and feeder links is the bottleneck of the whole system and employing interference mitigation techniques is essential, (b) clear push towards non-adaptive (fixed) payload implementation, leading to low computationally complex satellite architectures. In order to fulfill requirements (a) and (b), this paper studies the impact of employing a fixed OBP technique at the payload which is sufficiently robust to the variations in both user and feeder link channels. In addition to (a) and (b), the provided simulation results depict the performance gain obtained by our proposed OBP with respect to the conventional interference mitigation techniques in multiple gateway multibeam systems. [less ▲]

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See detailLearning-based rainfall estimation via communication satellite links
Gharanjik, Ahmad UL; Mishra, Kumar Vijay; Shankar, Bhavani UL et al

in 2018 IEEE Statistical Signal Processing Workshop (SSP) (2018)

We present a method for estimating rainfall by opportunistic use of Ka-band satellite communication network. Our approach is based on the attenuation of the satellite link signal in the rain medium and ... [more ▼]

We present a method for estimating rainfall by opportunistic use of Ka-band satellite communication network. Our approach is based on the attenuation of the satellite link signal in the rain medium and exploits the nearly linear relation between the rain rate and the specific attenuation at Ka-band frequencies. Although our experimental setup is not intended to achieve high resolutions as millimeter wavelength weather radars, it is instructive because of easy availability of millions of satellite ground terminals throughout the world. The received signal is obtained over a passive link. Therefore, traditional weather radar signal processing to derive parameters for rainfall estimation algorithms is not feasible here. We overcome this disadvantage by employing neural network learning algorithms to extract relevant information. Initial results reveal that rainfall accumulations obtained through our method are 85% closer to the in situ rain gauge estimates than the nearest C-band German weather service Deutscher Wetterdienst (DWD) radar. [less ▲]

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See detailDeploying Joint Beamhopping and Precoding in Multibeam Satellite Networks
Joroughi, Vahid UL; Lagunas, Eva UL; Andrenacci, Stefano UL et al

in Global Conference on Signal and Information Processing (GlobalSIP) (2018)

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See detailGraph Similarity based on Graph Fourier Distances
Lagunas, Eva UL; Marques, Antonio G.; Chatzinotas, Symeon UL et al

in European Signal Processing Conference (EUSIPCO), Rome, Italy, 3-7 September 2018 (2018)

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See detailInterference Localization On-Board the Satellite Using Drift Induced Virtual Array
Arora, Aakash UL; Maleki, Sina; Shankar, Bhavani UL et al

in Proc. 2018 International Conference on Signal Processing and Communications (SPCOM) (2018)

Herein, we investigate the interference received from other wireless networks into a satellite communication (SATCOM) link, and review approaches to identify the interference location using on-board ... [more ▼]

Herein, we investigate the interference received from other wireless networks into a satellite communication (SATCOM) link, and review approaches to identify the interference location using on-board satellite processing. Interference is an increasing problem for satellite communication links, and while receiving signals from gateways or user terminals, the uplink is prone to disturbance by interference due to jammers or unintentional transmissions. In this paper, our aim is to localize unknown interference sources present on the ground by estimating direction of arrival (DOA) information using onboard processing (OBP) in the satellite, and the satellite drift inducing a virtual array. In this work, the signal sampled by the drifting single antenna feed is modeled as using an arbitrary array. Building on this model, we perform the 2-D DOA (azimuth and elevation) estimation. The key challenges in such a design include single snapshot based DOA estimation with low complexity and robustness, arising out of limited on-board computational complexity as well as uncertainty in parameters like the drift speed. Employing realistic satellite drift patterns, the paper illustrates the performance of the proposed technique highlighting the accuracy in localization under adverse environments. We provide numerical simulations to show the effectiveness of our methodology. [less ▲]

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See detail3DBodyTex: Textured 3D Body Dataset
Saint, Alexandre Fabian A UL; Ahmed, Eman UL; Shabayek, Abd El Rahman UL et al

in 2018 Sixth International Conference on 3D Vision (3DV 2018) (2018)

In this paper, a dataset, named 3DBodyTex, of static 3D body scans with high-quality texture information is presented along with a fully automatic method for body model fitting to a 3D scan. 3D shape ... [more ▼]

In this paper, a dataset, named 3DBodyTex, of static 3D body scans with high-quality texture information is presented along with a fully automatic method for body model fitting to a 3D scan. 3D shape modelling is a fundamental area of computer vision that has a wide range of applications in the industry. It is becoming even more important as 3D sensing technologies are entering consumer devices such as smartphones. As the main output of these sensors is the 3D shape, many methods rely on this information alone. The 3D shape information is, however, very high dimensional and leads to models that must handle many degrees of freedom from limited information. Coupling texture and 3D shape alleviates this burden, as the texture of 3D objects is complementary to their shape. Unfortunately, high-quality texture content is lacking from commonly available datasets, and in particular in datasets of 3D body scans. The proposed 3DBodyTex dataset aims to fill this gap with hundreds of high-quality 3D body scans with high-resolution texture. Moreover, a novel fully automatic pipeline to fit a body model to a 3D scan is proposed. It includes a robust 3D landmark estimator that takes advantage of the high-resolution texture of 3DBodyTex. The pipeline is applied to the scans, and the results are reported and discussed, showcasing the diversity of the features in the dataset. [less ▲]

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See detailMulticarrier phase modulated continuous waveform for automotive joint radar-communication system
Dokhanchi, Sayed Hossein; Shankar, Bhavani UL; Stifter, Thomas Stifter et al

in 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) (2018)

Automotive radar implementation in the mm Wave band (79 G Hz) is being increasingly considered for the high bandwidths offered. While the radar systems and technology is maturing in mm Wave bands, the ... [more ▼]

Automotive radar implementation in the mm Wave band (79 G Hz) is being increasingly considered for the high bandwidths offered. While the radar systems and technology is maturing in mm Wave bands, the reuse of radar spectrum for low latency, limited throughput and safety critical communication has started to receive attention of late. Towards this, a joint radar-communication (JRC) system is proposed where the platform performs sensing and communication operations. The major challenge in JRC waveform design is the lack of degrees of freedom (DoF), due to need to estimate communication symbols in addition to the radar parameters. In this work, we propose a novel automotive JRC system based on multicarrier phase-modulated continuous waveform (MC-PMCW). MC-PMCW provides sufficient DoF to confine desired parameters, i.e., angles of arrival, Doppler shifts, ranges, and communication symbols in different dimensions. It can overcome the limitations of conventional PMCW and OFDM waveforms by leveraging the multicarrier feature of OFDM and the code sequence of PMCW to embed radar and communication. Further, the separation of parameters into different domains reduces complexity and enhances robustness; this is desirable in automotive scenarios characterized by dynamic scenes. Numerical results demonstrate the effectiveness of the proposed system. [less ▲]

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See detailMultigroup Multicast Beamforming and Antenna Selection with Rate-Splitting in Multicell Systems
Tervo, Oskari; Trant, Le-Nam; Chatzinotas, Symeon UL et al

in 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) (2018)

This paper studies energy-efficient joint coordinated beamforming and antenna selection in multi-cell multi-user multigroup multicast multiple-input single-output systems. We focus on interference-limited ... [more ▼]

This paper studies energy-efficient joint coordinated beamforming and antenna selection in multi-cell multi-user multigroup multicast multiple-input single-output systems. We focus on interference-limited scenarios, e.g., when the number of radio frequency (RF) chains is of the same order as the number of multicasting groups. To tackle the interference, we exploit rate-splitting to divide the group messages into common and group-specific sub-messages. We propose a per-cell rate-splitting approach, where the common message is locally designed to be decoded by the in-cell users, while treated as noise by the out-cell users. We consider the case where the number of RF chains is smaller than that of antennas, and consider a switching architecture, that is, the antenna selection is employed to choose the best antennas for transmission. Numerical results illustrate the potential of the proposed approach to significantly improve the energy efficiency in the interference-limited regime. [less ▲]

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See detailEnergy-Efficient Multicell Multigroup Multicasting With Joint Beamforming and Antenna Selection
Tervo, Oskari; Tran, Le-Nam; Pennanen, Harri et al

in IEEE Transactions on Signal Processing (2018)

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See detailDynamic Spectrum Sharing in 5G Wireless Networks With Full-Duplex Technology: Recent Advances and Research Challenges
Sharma, Shree Krishna UL; Bogale, Tadilo Endeshaw; le, Long Bao et al

in IEEE Communications Surveys and Tutorials (2018), 20(1), 674-707

Full-duplex (FD) wireless technology enables a radio to transmit and receive on the same frequency band at the same time, and it is considered to be one of the candidate technologies for the fifth ... [more ▼]

Full-duplex (FD) wireless technology enables a radio to transmit and receive on the same frequency band at the same time, and it is considered to be one of the candidate technologies for the fifth generation (5G) and beyond wireless communication systems due to its advantages, including potential doubling of the capacity and increased spectrum utilization efficiency. However, one of the main challenges of FD technology is the mitigation of strong self-interference (SI). Recent advances in different SI cancellation techniques, such as antenna cancellation, analog cancellation, and digital cancellation methods, have led to the feasibility of using FD technology in different wireless applications. Among potential applications, one important application area is dynamic spectrum sharing (DSS) in wireless systems particularly 5G networks, where FD can provide several benefits and possibilities such as concurrent sensing and transmission (CST), concurrent transmission and reception, improved sensing efficiency and secondary throughput, and the mitigation of the hidden terminal problem. In this direction, first, starting with a detailed overview of FD-enabled DSS, we provide a comprehensive survey of recent advances in this domain. We then highlight several potential techniques for enabling FD operation in DSS wireless systems. Subsequently, we propose a novel communication framework to enable CST in DSS systems by employing a power control-based SI mitigation scheme and carry out the throughput performance analysis of this proposed framework. Finally, we discuss some open research issues and future directions with the objective of stimulating future research efforts in the emerging FD-enabled DSS wireless systems. [less ▲]

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See detailBinary Sequences set with small ISL for MIMO radar systems
Alaee-Kerahroodi, Mohammad; Modarres-Hashemi, Mahmoud; Naghsh, Mohammad Mahdi Naghsh et al

in 2018 26th European Signal Processing Conference (EUSIPCO) (2018)

In this paper, we aim at designing a set of binary sequences with good aperiodic auto- and crosscorrelation properties for Multiple-Input-Multiple-Output (MIMO) radar systems. We show such a set of ... [more ▼]

In this paper, we aim at designing a set of binary sequences with good aperiodic auto- and crosscorrelation properties for Multiple-Input-Multiple-Output (MIMO) radar systems. We show such a set of sequences can be obtained by minimizing the Integrated Side Lobe (ISL) with the binary requirement imposed as a design constraint. By using the block coordinate descent (BCD) framework, we propose an efficient monotonic algorithm based on Fast Fourier Transform (FFT), to minimize the objective function which is non-convex and NP-hard in general. Simulation results illustrate that the ISL of designed binary set of sequences is the neighborhood of the Welch bound, Indicating its superior performance. [less ▲]

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See detailEnergy-Efficient and Secure Resource Allocation for Multiple-Antenna NOMA with Wireless Power Transfer
Chang, Zheng; Lei, Lei UL; Zhang, Huaqing et al

in IEEE Transactions on Green Communications and Networking (2018)

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See detailConstrained Bayesian Active Learning of Interference Channels in Cognitive Radio Networks
Tsakmalis, Anestis UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in IEEE Journal of Selected Topics in Signal Processing (2017)

In this paper, a sequential probing method for interference constraint learning is proposed to allow a centralized Cognitive Radio Network (CRN) accessing the frequency band of a Primary User (PU) in an ... [more ▼]

In this paper, a sequential probing method for interference constraint learning is proposed to allow a centralized Cognitive Radio Network (CRN) accessing the frequency band of a Primary User (PU) in an underlay cognitive scenario with a designed PU protection specification. 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 indicates whether the probing-induced interference is harmful or not and can be used to learn the PU interference constraint. The cognitive part of this sequential probing process is the selection of the power levels of the Secondary Users (SUs) which aims to learn the PU interference constraint with a minimum number of probing attempts while setting a limit on the number of harmful probing-induced interference events or equivalently of NACK packet observations over a time window. This constrained design problem is studied within the Active Learning (AL) framework and an optimal solution is derived and implemented with a sophisticated, accurate and fast Bayesian Learning method, the Expectation Propagation (EP). The performance of this solution is also demonstrated through numerical simulations and compared with modified versions of AL techniques we developed in earlier work. [less ▲]

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See detailSymbol-level Precoding for the Non-linear Multiuser MISO Downlink Channel
Spano, Danilo UL; Alodeh, Maha; Chatzinotas, Symeon UL et al

in IEEE Transactions on Signal Processing (2017)

This paper investigates the problem of the interference among multiple simultaneous transmissions in the downlink channel of a multi-antenna wireless system. A symbol-level precoding scheme is considered ... [more ▼]

This paper investigates the problem of the interference among multiple simultaneous transmissions in the downlink channel of a multi-antenna wireless system. A symbol-level precoding scheme is considered, in order to exploit the multi-user interference and transform it into useful power at the receiver side, through a joint utilization of the data information and the channel state information. In this context, this paper presents novel strategies which exploit the potential of symbol-level precoding to control the per-antenna instantaneous transmit power. In particular, the power peaks amongst the transmitting antennas and the instantaneous power imbalances across the different transmitted streams are minimized. These objectives are particularly relevant with respect to the non-linear amplitude and phase distortions induced by the per-antenna amplifiers, which are important sources of performance degradation in practical systems. More specifically, this work proposes two different symbol-level precoding approaches. A first approach performs a weighted per-antenna power minimization, under Quality-of-Service constraints and under a lower bound constraint on the per-antenna transmit power. A second strategy performs a minimization of the spatial peak-to-average power ratio, evaluated amongst the transmitting antennas. Numerical results are presented in a comparative fashion to show the effectiveness of the proposed techniques, which outperform the state of the art symbol-level precoding schemes in terms of spatial peak-to-average power ratio, spatial dynamic range, and symbol-error-rate over non-linear channels. [less ▲]

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See detailCache-Assisted Hybrid Satellite-Terrestrial Backhauling for 5G Cellular Networks
Kalantari, Ashkan; Fittipaldi, Marilena; Chatzinotas, Symeon UL et al

in Proceedings of IEEE Global Communications Conference (2017, December)

Fast growth of Internet content and availability of electronic devices such as smart phones and laptops has created an explosive content demand. As one of the 5G technology enablers, caching is a ... [more ▼]

Fast growth of Internet content and availability of electronic devices such as smart phones and laptops has created an explosive content demand. As one of the 5G technology enablers, caching is a promising technique to off-load the network backhaul and reduce the content delivery delay. Satellite communications provides immense area coverage and high data rate, hence, it can be used for large-scale content placement in the caches. In this work, we propose using hybrid mono/multi-beam satellite-terrestrial backhaul network for off-line edge caching of cellular base stations in order to reduce the traffic of terrestrial network. The off-line caching approach is comprised of content placement and content delivery phases. The content placement phase is performed based on local and global content popularities assuming that the content popularity follows Zipf-like distribution. In addition, we propose an approach to generate local content popularities based on a reference Zipf-like distribution to keep the correlation of content popularity. Simulation results show that the hybrid satellite-terrestrial architecture considerably reduces the content placement time while sustaining the cache hit ratio quite close to the upper-bound compared to the satellite-only method. [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 detailEnergy Minimization for Cache-assisted Content Delivery Networks with Wireless Backhaul
Vu, Thang Xuan UL; Chatzinotas, Symeon UL; Ottersten, Björn UL et al

in IEEE Wireless Communications Letters (2017)

Content caching is an efficient technique to reduce delivery latency and system congestion during peak-traffic time by bringing data closer to end users. In this paper, we investigate energy-efficiency ... [more ▼]

Content caching is an efficient technique to reduce delivery latency and system congestion during peak-traffic time by bringing data closer to end users. In this paper, we investigate energy-efficiency performance of cache-assisted content delivery networks with wireless backhaul by taking into account cache capability when designing the signal transmission. We consider multi-layer caching and the performance in cases when both base station (BS) and users are capable of storing content data in their local cache. Specifically, we analyse energy consumption in both backhaul and access links under two uncoded and coded caching strategies. Then two optimization problems are formulated to minimize total energy cost for the two caching strategies while satisfying some given quality of service constraint. We demonstrate via numerical results that the uncoded caching achieves higher energy efficiency than the coded caching in the small user cache size regime. [less ▲]

Detailed reference viewed: 135 (5 UL)