http://hdl.handle.net/10993/86 Search this channel search http://orbilu.uni.lu/simple-search http://hdl.handle.net/10993/41957 Title: Energy Efficient Bit Allocation and Hybrid Combining for Millimeter Wave MIMO Systems <br/> <br/>Author, co-author: Kaushik, Aryan; Tsinos, Christos; Vlachos, Evangelos; Thompson, John Thu, 23 Jan 2020 08:35:57 GMT http://hdl.handle.net/10993/41950 Title: Hybrid Analog-Digital Transceiver Designs for Multi-User MIMO mmWave Cognitive Radio Systems <br/> <br/>Author, co-author: Tsinos, Christos; Chatzinotas, Symeon; Ottersten, Björn Wed, 22 Jan 2020 22:44:35 GMT http://hdl.handle.net/10993/41949 Title: Symbol Level Precoding with Low Resolution DACs for Constant Envelope OFDM MU-MIMO Systems <br/> <br/>Author, co-author: Tsinos, Christos; Domouchtsidis, Stavros; Chatzinotas, Symeon; Ottersten, Björn Wed, 22 Jan 2020 22:36:55 GMT http://hdl.handle.net/10993/41948 Title: MM-Based Solution for Partially Connected Hybrid Transceivers with Large Scale Antenna Arrays <br/> <br/>Author, co-author: Arora, Aakash; Tsinos, Christos; Shankar, Bhavani; Chatzinotas, Symeon; Ottersten, Björn <br/> <br/>Abstract: In a mmWave multiple-input multiple-output (MIMO) communication system employing a large-scale antenna array (LSAA), the hybrid transceivers are used to reduce the power consumption and the hardware cost. In a hybrid analog-digital (A/D) transceiver, the pre/post-processing operation splits into a lower-dimensional baseband (BB) pre/postcoder, followed by a network of analog phase shifters. Primarily two kinds of hybrid architectures are proposed in the literature to implement hybrid transceivers namely, the fully-connected and the partially-connected. Implementation of fully-connected architecture has higher hardware complexity, cost and power consumption in comparison with partially-connected. In this paper, we focus on partially-connected hybrid architecture and develop a low-complexity algorithm for transceiver design for a single user point-to-point mmWave MIMO system. The proposed algorithm utilizes the variable elimination (projection) and the minorization-maximization (MM) frameworks and has convergence guarantees to a stationary point. Simulation results demonstrate that the proposed algorithm is easily scalable for LSAA systems and achieves significantly improved performance in terms of the spectral efficiency (SE) of the system compared to the state-of-the-art solution. Wed, 22 Jan 2020 22:15:02 GMT http://hdl.handle.net/10993/41947 Title: Majorization-Minimization Algorithms for Analog Beamforming with Large-Scale Antenna Arrays <br/> <br/>Author, co-author: Arora, Aakash; Tsinos, Christos; Shankar, Bhavani; Chatzinotas, Symeon; Ottersten, Björn <br/> <br/>Abstract: Beamforming with large-scale antenna arrays (LSAA) is one of the predominant operations in designing wireless communication systems. However, the implementation of a fully digital system significantly increases the number of required radio-frequency (RF) chains, which may be prohibitive. Thus, analog beamforming based on a phase-shifting network driven by a variable gain amplifier (VGA) is a potential alternative technology. In this paper, we cast the beamforming vector design problem as a beampattern matching problem, with an unknown power gain. This is formulated as a unit-modulus least-squares (ULS) problem where the optimal gain of the VGA is also designed in addition to the beamforming vector. We also consider a scenario where the receivers have the additional processing capability to adjust the phases of the incoming signals to mitigate specular multipath components. We propose efficient majorization-minimization (MM) based algorithms with convergence guarantees to a stationary point for solving both variants of the proposed ULS problem. Numerical results verify the effectiveness of the proposed solution in comparison with the existing state-of-the-art techniques. Wed, 22 Jan 2020 22:01:10 GMT http://hdl.handle.net/10993/41946 Title: Hybrid Analog-Digital Precoding Design for Satellite Systems <br/> <br/>Author, co-author: Arora, Aakash; Tsinos, Christos; Shankar, Bhavani; Chatzinotas, Symeon; Ottersten, Björn <br/> <br/>Abstract: The work investigates the feasibility of massive MIMO in SatCom. Towards this, the necessary channel models, system parameters and scenarios are identified and a basic simulator developed. The work then considers an efficient implementation of the massive MIMO transmission through the use of hybrid analog/digital precoder. Efficient algorithmic solutions are proposed for the partially connected precoder architecture which enables efficiency in power/ hardware complexity and its performance evaluated. Wed, 22 Jan 2020 21:49:20 GMT http://hdl.handle.net/10993/41866 Title: Localization Performance of 1-Bit Passive Radars in NB-IoT Applications <br/> <br/>Author, co-author: Sedighi, Saeid; Mishra, Kumar Vijay; Shankar, Bhavani; Ottersten, Björn <br/> <br/>Abstract: Location-based services form an important use-case in emerging narrowband Internet-of-Things (NB-IoT) networks. Critical to this offering is an accurate estimation of the location without overlaying the network with additional active sensors. The massive number of devices, low power requirement, and low bandwidths restrict the sampling rates of NB-IoT receivers. In this paper, we propose a novel low-complexity approach for NB-IoT target delay estimation in cases where one-bit analog-to-digital-converters (ADCs) are employed to sample the received radar signal instead of high-resolution ADCs. This problem has potential applications in the design of inexpensive NB-IoT radar and sensing devices. We formulate the target estimation as a multivariate fractional optimization problem and solve it via Lasserre's semi-definite program relaxation. Numerical experiments suggest feasibility of the proposed approach yielding high localization accuracy with a very low number of 1-bit samples. Wed, 22 Jan 2020 04:30:04 GMT http://hdl.handle.net/10993/41865 Title: Optimum Design for Sparse FDA-MIMO Automotive Radar <br/> <br/>Author, co-author: Sedighi, Saeid; Shankar, Bhavani; Mishra, Kumar Vijay; Ottersten, Björn <br/> <br/>Abstract: Automotive radars usually employ multiple-input multiple-output (MIMO) antenna arrays to achieve high azimuthal resolution with fewer elements than a phased array. Despite this advantage, hardware costs and desired radar size limits the usage of more antennas in the array. Similar trade-off is encountered while attempting to achieve high range resolution which is limited by the signal bandwidth. However, nowadays given the demand for spectrum from communications services, wide bandwidth is not readily available. To address these issues, we propose a sparse variant of Frequency Diverse Array MIMO (FDA-MIMO) radar which enjoys the benefits of both FDA and MIMO techniques, including fewer elements, decoupling, and efficient joint estimation of target parameters. We then employ the Cram\'{e}r-Rao bound for angle and range estimation as a performance metric to design the optimal antenna placement and carrier frequency offsets for the transmit waveforms. Numerical experiments suggest that the performance of sparse FDA-MIMO radar is very close to the conventional FDA-MIMO despite 50\% reduction in the bandwidth and antenna elements. Wed, 22 Jan 2020 04:30:02 GMT http://hdl.handle.net/10993/41697 Title: Carrier Aggregation in Multi-Beam High Throughput Satellite Systems <br/> <br/>Author, co-author: Kibria, Mirza; Lagunas, Eva; Maturo, Nicola; Spano, Danilo; Al-Hraishawi, Hayder; Chatzinotas, Symeon <br/> <br/>Abstract: Carrier Aggregation (CA) is an integral part of current terrestrial networks. Its ability to enhance the peak data rate, to efficiently utilize the limited available spectrum resources and to satisfy the demand for data-hungry applications has drawn large attention from different wireless network communities. Given the benefits of CA in the terrestrial wireless environment, it is of great interest to analyze and evaluate the potential impact of CA in the satellite domain. In this paper, we study CA in multi-beam high throughput satellite systems. We consider both inter-transponder and intra-transponder CA at the satellite payload level of the communication stack, and we address the problem of carrier-user assignment assuming that multiple users can be multiplexed in each carrier. The transmission parameters of different carriers are generated considering the transmission characteristics of carriers in different transponders. In particular, we propose a flexible carrier allocation approach for a CA enabled multi-beam satellite system targeting a proportionally fair user demand satisfaction. Simulation results and analysis shed some light on this rather unexplored scenario and demonstrate the feasibility of the CA in satellite communication systems. Mon, 20 Jan 2020 08:48:50 GMT http://hdl.handle.net/10993/41695 Title: Hardware Precoding Demonstration in Multi-Beam UHTS Communications under Realistic Payload Characteristics <br/> <br/>Author, co-author: Merlano Duncan, Juan Carlos; Querol Borras, Jorge; Maturo, Nicola; Krivochiza, Jevgenij; Spano, Danilo; Norshahida, Saba; Martinez Marrero, Liz; Chatzinotas, Symeon; Ottersten, Björn <br/> <br/>Abstract: In this paper, we present a new hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in multi-beam ultra high throughput satellite systems under realistic payload and channel impairments. We build the test-bed to demonstrate a real-time channel aided precoded transmission under realistic conditions such as the power constraints and satellite-payload non-linearities. We develop a scalable architecture of an SDR platform with the DVB-S2X piloting. The SDR platform consists of two parts: analog-to-digital (ADC) and digital-to-analog (DAC) converters preceded by radio frequency (RF) front-end and Field-Programmable Gate Array (FPGA) backend. The former introduces realistic impairments in the transmission chain such as carrier frequency and phase misalignments, quantization noise of multichannel ADC and DAC and non-linearities of RF components. It allows evaluating the performance of the precoded transmission in a more realistic environment rather than using only numerical simulations. We benchmark the performance of the communication standard in realistic channel scenarios, evaluate received signal SNR, and measure the actual channel throughput using LDPC codes. Mon, 20 Jan 2020 04:30:04 GMT http://hdl.handle.net/10993/41598 Title: Precoded Cluster Hopping in Multi-Beam High Throughput Satellite Systems <br/> <br/>Author, co-author: Kibria, Mirza; Lagunas, Eva; Maturo, Nicola; Spano, Danilo; Chatzinotas, Symeon <br/> <br/>Abstract: Beam-Hopping (BH) and precoding are two trending technologies for the satellite community. While BH enables flexibility to adapt the offered capacity to the heterogeneous demand, precoding aims at boosting the spectral efficiency. In this paper, we consider a high throughput satellite (HTS) system that employs BH in conjunction with precoding. In particular, we propose the concept of Cluster-Hopping (CH) that seamlessly combines the BH and precoding paradigms and utilizes their individual competencies. The cluster is defined as a set of adjacent beams that are simultaneously illuminated. In addition, we propose an efficient time-space illumination pattern design, where we determine the set of clusters that can be illuminated simultaneously at each hopping event along with the illumination duration. We model the CH time-space illumination pattern design as an integer programming problem which can be efficiently solved. Supporting results based on numerical simulations are provided which validate the effectiveness of the proposed CH concept and time-space illumination pattern design. Tue, 14 Jan 2020 14:51:57 GMT http://hdl.handle.net/10993/41550 Title: Deploying Dynamic On-Board Signal Processing Schemes for Multibeam Satellite Systems <br/> <br/>Author, co-author: Joroughi, Vahid; Kibria, Mirza; Lagunas, Eva; Shankar, Bhavani; Chatzinotas, Symeon; Grotz, Joel; Maleki, Sina; Ottersten, Björn Mon, 13 Jan 2020 17:15:31 GMT http://hdl.handle.net/10993/41503 Title: Modeling and Implementation of 5G Edge Caching over Satellite <br/> <br/>Author, co-author: Vu, Thang Xuan; Poirier, Yannick; Chatzinotas, Symeon; Maturo, Nicola; Grotz, Joel; Roelens, Frederic <br/> <br/>Abstract: The fifth generation (5G) wireless networks have to deal with the high data rate and stringent latency requirements due to the massive invasion of connected devices and data-hungry applications. Edge caching is a promising technique to overcome these challenges by prefetching the content closer to the end users at the edge node’s local storage. In this paper, we analyze the performance of edge caching 5G networks with the aid of satellite communication systems. Firstly, we investigate the satellite-aided edge caching systems in two promising use cases: a) in dense urban areas, and b) in sparsely populated regions, e.g., rural areas. Secondly, we study the effectiveness of satellite systems via the proposed satellite-aided caching algorithm, which can be used in three configurations: i) mono-beam satellite, ii) multi-beam satellite, and iii) hybrid mode. Thirdly, the proposed caching algorithm is evaluated by using both empirical Zipf-distribution data and the more realistic Movielens dataset. Last but not least, the proposed caching scheme is implemented and tested by our developed demonstrators which allow real-time analysis of the cache hit ratio and cost analysis. Fri, 10 Jan 2020 17:11:34 GMT http://hdl.handle.net/10993/41493 Title: The Potential Short- and Long-Term Disruptions and Transformative Impacts of 5G and Beyond Wireless Networks: Lessons Learnt from the Development of a 5G Testbed Environment <br/> <br/>Author, co-author: PATWARY, MOHMAMMAD; NAWAZ, SYED JUNAID; RAHMAN, MD. ABDUR; Sharma, Shree Krishna; RASHID, MD MAMUNUR; BARNES, STUART <br/> <br/>Abstract: The capacity and coverage requirements for 5th generation (5G) and beyond wireless connectivity will be significantly different from the predecessor networks. To meet these requirements, the anticipated deployment cost in the United Kingdom (UK) is predicted to be between £30bn and £50bn, whereas the current annual capital expenditure (CapEX) of the mobile network operators (MNOs) is £2.5bn. This prospect has vastly impacted and has become one of the major delaying factors for building the 5G physical infrastructure, whereas other areas of 5G are progressing at their speed. Due to the expensive and complicated nature of the network infrastructure and spectrum, the second-tier operators, widely known as mobile virtual network operators (MVNO), are entirely dependent on the MNOs. In this paper, an extensive study is conducted to explore the possibilities of reducing the 5G deployment cost and developing viable business models. In this regard, the potential of infrastructure, data, and spectrum sharing is thoroughly investigated. It is established that the use of existing public infrastructure (e.g., streetlights, telephone poles, etc.) has a potential to reduce the anticipated cost by about 40% to 60%. This paper also reviews the recent Ofcom initiatives to release location-based licenses of the 5G-compatible radio spectrum. Our study suggests that simplification of infrastructure and spectrum will encourage the exponential growth of scenario-specific cellular networks (e.g., private networks, community networks, micro-operators) and will potentially disrupt the current business models of telecommunication business stakeholders – specifically MNOs and TowerCos. Furthermore, the anticipated dense device connectivity in 5G will increase the resolution of traditional and non-traditional data availability significantly. This will encourage extensive data harvesting as a business opportunity and function within small and medium-sized enterprises (SMEs) as well as large social networks. Consequently, the rise of new infrastructures and spectrum stakeholders is anticipated. This will fuel the development of a 5G data exchange ecosystem where data transactions are deemed to be high-value business commodities. The privacy and security of such data, as well as definitions of the associated revenue models and ownership, are challenging areas – and these have yet to emerge and mature fully. In this direction, this paper proposes the development of a unified data hub with layered structured privacy and security along with blockchain and encrypted off-chain based ownership/royalty tracking. Also, a data economy-oriented business model is proposed. The study found that with the potential commodification of data and data transactions along with the low-cost physical infrastructure and spectrum, the 5G network will introduce significant disruption in the Telco business ecosystem. Thu, 09 Jan 2020 18:33:54 GMT http://hdl.handle.net/10993/41410 Title: Optimization of Rate Fairness in Multi-Pair Wireless-Powered Relaying System <br/> <br/>Author, co-author: Bui, Van-Phuc; Nguyen, van Dinh; Nguyen, Hieu; Dobre, Octavia; Shin, Oh Soon <br/> <br/>Abstract: This letter considers a multi-pair decode-andforward relay network where a power-splitting (PS) protocol is adopted at the energy-constrained relay to provide simultaneous wireless information and energy harvesting (EH). To achieve higher efficiency of EH, we propose a new PS-based EH architecture at the relay by incorporating an alternating current (AC) computing logic, which is employed to directly use the wirelessly harvestedACenergyforcomputationalblocks.Underanonlinear EHcircuit,ourgoalistomaximizethefairnessofend-to-endrate amonguserpairssubjecttopowerconstraints,resultinginanonconvex problem. We propose an iterative algorithm to achieve a suboptimal and efficient solution to this challenging problem by leveraging the inner approximation framework. Numerical results demonstrate that the proposed algorithm outperforms the traditional direct current computing and other baseline schemes. Wed, 25 Dec 2019 15:14:44 GMT http://hdl.handle.net/10993/41408 Title: Oversampled DFT-Modulated Biorthogonal Filter Banks: Perfect Reconstruction Designs and Multiplierless Approximations <br/> <br/>Author, co-author: Alves Martins, Wallace; Shankar, Bhavani; Ottersten, Björn <br/> <br/>Abstract: We propose a novel methodology for designing oversampled discrete Fourier transform-modulated uniform filter banks. The analysis prototype is designed as a Nyquist filter, whereas the synthesis prototype is designed to guarantee perfect reconstruction (PR) considering oversampling. The resulting optimization problem fits into the disciplined convex programming framework, as long as some convex objective function is employed, as the minimization of either the stop-band energy or the maximum deviation from a desired response. The methodology also accounts for near-PR multiplierless approximations of the prototype analysis and synthesis filters, whose coefficients are obtained in the sum-of-power-of-two (SOPOT) space. The quantized coefficients are computed using successive approximation of vectors, which is able to yield filters with a reduced number of SOPOT coefficients in a computationally efficient manner. The proposed methodology is especially appealing for supporting actual hardware deployments, such as modern digital transparent processors to be used in next-generation satellite payloads. Tue, 24 Dec 2019 09:07:02 GMT http://hdl.handle.net/10993/41379 Title: Real-time Radio Frequency Interference Detection and Mitigation with the Front-End GNSS Interference eXcisor (FENIX) <br/> <br/>Author, co-author: Querol Borras, Jorge; Perez, Adrian; Munoz-Martin, Joan Francesc; Camps, Adriano <br/> <br/>Abstract: The number of applications based on Global Navigation Satellite Systems (GNSS) has been increasing in the last years. With its proliferation, Radio-Frequency Interference (RFI) has become one of the most concerning topics on GNSS-based devices for navigation, positioning and timing, but also for Earth Observation purposes such as GNSS-Reflectometry (GNSS-R) and GNSS-Radio Occultations (GNSS-RO) due to the corruption of the received signal and the corresponding geophysical measurements. The Front-End GNSS Interference eXcisor (FENIX) mitigates the problem of RFI by providing a plug-and-play solution which, placed between the antenna and the receiver, excises virtually any kind of interference signal, as its mitigation algorithm is agnostic on the particular type of RFI. The new version of FENIX is also capable of operating with large signal bandwidths ($\sim$50 MHz) and dual-band applications (e.g. L1 + L2 or L1/E1 + L5/E5). This paper shows the performance of the system for commercial GNSS receivers and GNSS-R applications. The use of FENIX in Microwave Radiometers is also possible, but it is out of the scope of this paper. Fri, 20 Dec 2019 13:09:05 GMT http://hdl.handle.net/10993/41375 Title: A Review of RFI Mitigation Techniques in Microwave Radiometry <br/> <br/>Author, co-author: Querol Borras, Jorge; Perez, Adrian; Camps, Adriano <br/> <br/>Abstract: Radio frequency interference (RFI) is a well-known problem in microwave radiometry (MWR). Any undesired signal overlapping the MWR protected frequency bands introduces a bias in the measurements, which can corrupt the retrieved geophysical parameters. This paper presents a literature review of RFI detection and mitigation techniques for microwave radiometry from space. The reviewed techniques are divided between real aperture and aperture synthesis. A discussion and assessment of the application of RFI mitigation techniques is presented for each type of radiometer. Fri, 20 Dec 2019 12:50:06 GMT http://hdl.handle.net/10993/41189 Title: Characterization of the MSE Region under a Total Power Budget for Asynchronous Two-Way Relay Networks <br/> <br/>Author, co-author: Rahimi, Razgar; Shahbazpanahi, Shahram; Ottersten, Björn Wed, 04 Dec 2019 14:08:16 GMT http://hdl.handle.net/10993/41186 Title: Joint Power Allocation and Distributed Beamforming Design for Multi-Carrier Asynchronous Two-Way Relay Networks <br/> <br/>Author, co-author: KianiHarchehgani, Sharareh; Shahbazpanahi, Shahram; Dong, Min; Boudeau, Gary Wed, 04 Dec 2019 13:40:42 GMT