36 results on '"Korpi, Dani"'
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2. Nonlinear self-interference cancellation in MIMO full-duplex transceivers under crosstalk
- Author
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Korpi, Dani, Anttila, Lauri, and Valkama, Mikko
- Published
- 2017
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3. Method for creating location-specific audio textures
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Heittola, Toni, Mesaros, Annamaria, Korpi, Dani, Eronen, Antti, and Virtanen, Tuomas
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- 2014
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4. Full-Duplexing with SDR Devices : Algorithms, FPGA Implementation and Real-Time Results
- Author
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Anttila, Lauri, Lampu, Vesa, Hassani, Seyed Ali, Campo, Pablo Pascual, Korpi, Dani, Turunen, Matias, Pollin, Sofie, Valkama, Mikko, Tampere University, and Electrical Engineering
- Subjects
SELF-INTERFERENCE CANCELLATION ,Technology ,Science & Technology ,213 Electronic, automation and communications engineering, electronics ,Adaptation models ,Field programmable gate arrays ,Engineering, Electrical & Electronic ,Computational modeling ,Radio transmitters ,COMPENSATION ,Engineering ,Splines (mathematics) ,FPGA implementation ,Telecommunications ,Full-duplex ,Real-time systems ,software-defined radio ,OFDM - Abstract
In this paper, we present a novel nonlinear digital self-interference canceller algorithm, its implementation details on a software-defined radio (SDR) platform, and performance results of real-time full-duplex experiments on both device and link level. The canceller algorithm is based on an augmented Hammerstein model, with a nonlinear part modeling the transmitter non-idealities followed by a linear filter to model the self-interference (SI) channel. The nonlinear part includes a spline-based model for the nonlinear power amplifier, a polynomial model for baseband nonlinearities, as well as models for I/Q mismatch and LO leakage. The canceller is implemented on an FPGA as a part of an OFDM transceiver testbed for real-time measurements. Extensive real-time measurements show excellent performance: (1) the digital canceller, together with an RF isolator, can suppress the SI to within 1-2 dB’s of the receiver noise floor, with total SI suppression of up to 103 dB; (2) digital cancellation of up to 46 dB is evidenced, which is among the highest real-time cancellations in literature; (3) system-level measurements with OFDM signals demonstrate the benefit of utilizing the proposed canceller in a two-way communication scenario, showing up to 90% increase in sum-rate compared to half-duplex communication. publishedVersion
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- 2021
5. On the human ability to discriminate audio ambiances from similar locations of an urban environment
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Korpi, Dani, Heittola, Toni, Partala, Timo, Eronen, Antti, Mesaros, Annamaria, and Virtanen, Tuomas
- Published
- 2013
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6. Communications Survival Strategies for Industrial Wireless Control.
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Khosravirad, Saeed R., Tirkkonen, Olav, Parts, Ulo, Zhou, Liang, Korpi, Dani, Baracca, Paolo, and Uusitalo, Mikko A.
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COMMUNICATION strategies ,INDUSTRIAL controls manufacturing ,PRODUCTION scheduling ,QUALITY of service ,ERROR rates - Abstract
Industrial wireless control systems are mainly designed on the premise of time-sensitive ultra-reliable low-latency communications (URLLC). With the introduction of survival time to the quality of service requirements of such systems, the design paradigm has evolved from typical link reliability (i.e., minimizing packet error rate), to service availability, that is, minimizing the chance of burst errors, which can cause loss of communication for longer than survival time. In this article, we address the implications of this evolution and present a set of survival time strategies that are designed to guarantee end-to-end dependable industrial wireless control. To ensure service availability, transmissions are divided into normal and survival modes. The presented strategies include scheduling and link adaptation that are designed to target the differences between these modes of operation, traffic prioritization to enhance service availability for users in survival mode, and more efficient multi-node, multi-path, and multi-carrier communications techniques. [ABSTRACT FROM AUTHOR]
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- 2022
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7. Downlink Coverage and Rate Analysis of Low Earth Orbit Satellite Constellations Using Stochastic Geometry
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Okati, Niloofar, Riihonen, Taneli, Korpi, Dani, Angervuori, Ilari, Wichman, Risto, Tampere University, Electrical Engineering, and Research group: Wireless Communications and Positioning
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Computer Science - Networking and Internet Architecture ,Networking and Internet Architecture (cs.NI) ,Signal Processing (eess.SP) ,FOS: Computer and information sciences ,213 Electronic, automation and communications engineering, electronics ,Physics::Space Physics ,FOS: Electrical engineering, electronic engineering, information engineering ,Systems and Control (eess.SY) ,Electrical Engineering and Systems Science - Signal Processing ,Electrical Engineering and Systems Science - Systems and Control - Abstract
As low Earth orbit (LEO) satellite communication systems are gaining increasing popularity, new theoretical methodologies are required to investigate such networks' performance at large. This is because deterministic and location-based models that have previously been applied to analyze satellite systems are typically restricted to support simulations only. In this paper, we derive analytical expressions for the downlink coverage probability and average data rate of generic LEO networks, regardless of the actual satellites' locality and their service area geometry. Our solution stems from stochastic geometry, which abstracts the generic networks into uniform binomial point processes. Applying the proposed model, we then study the performance of the networks as a function of key constellation design parameters. Finally, to fit the theoretical modeling more precisely to real deterministic constellations, we introduce the effective number of satellites as a parameter to compensate for the practical uneven distribution of satellites on different latitudes. In addition to deriving exact network performance metrics, the study reveals several guidelines for selecting the design parameters for future massive LEO constellations, e.g., the number of frequency channels and altitude., Comment: Accepted for publication in the IEEE Transactions on Communications in April 2020
- Published
- 2020
8. 5G-Xcast D3.2 Air Interface
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Garro, Eduardo, Carcel, Jose Luis, Gimenez, Jordi J., Fuentes, Manuel, Vargas, David, Gomez-Barquero, David, Korpi, Dani, Mi, De, Hongzhi Chen, and Hemadeh, Ibrahim
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- 2019
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9. Cascaded Spline-Based Models for Complex Nonlinear Systems: Methods and Applications.
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Pascual Campo, Pablo, Anttila, Lauri, Korpi, Dani, and Valkama, Mikko
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NONLINEAR systems ,FINITE impulse response filters ,ANTENNA arrays ,RADIO technology ,SYSTEM identification - Abstract
In this paper, we present a class of cascaded nonlinear models for complex-valued system identification, aimed at baseband modeling of nonlinear radio systems. The proposed models consist of serially connected elementary linear and nonlinear blocks, with the nonlinear blocks implemented as uniform spline-interpolated look-up tables (LUT) and the linear blocks as FIR filters. Wiener, Hammerstein, and Wiener-Hammerstein models are built, and simple but efficient gradient based adaptive learning rules are derived for all the models. This approach leads to remarkably simple solutions in terms of computational complexity, making the techniques suitable for real-time implementation. The proposed methods are then applied to full-duplex self-interference cancellation and digital predistortion in various real-life scenarios. First, evaluations with measured data from an in-band full-duplex prototype working at 2.4 GHz ISM band show that the algorithms are capable of obtaining similar cancellation performance as existing state-of-the-art solutions, regardless of the clearly reduced complexity. Second, a mmW active antenna array working at 28 GHz center frequency is digitally predistorted with the proposed solutions. The unwanted emissions and nonlinear distortion are suppressed to similar levels as with other state-of-the art solutions, and the corresponding linearity specifications are fulfilled in all cases, while the processing complexity is again drastically reduced. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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10. Gradient-Adaptive Spline-Interpolated LUT Methods for Low-Complexity Digital Predistortion.
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Campo, Pablo Pascual, Brihuega, Alberto, Anttila, Lauri, Turunen, Matias, Korpi, Dani, Allen, Markus, and Valkama, Mikko
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POWER amplifiers ,RADIO technology ,IMPULSE response ,ANTENNA arrays ,MACHINE learning - Abstract
In this paper, new digital predistortion (DPD) solutions for power amplifier (PA) linearization are proposed, with particular emphasis on reduced processing complexity in future 5G and beyond wideband radio systems. The first proposed method, referred to as the spline-based Hammerstein (SPH) approach, builds on complex spline-interpolated lookup table (LUT) followed by a linear finite impulse response (FIR) filter. The second proposed method, the spline-based memory polynomial (SMP) approach, contains multiple parallel complex spline-interpolated LUTs together with an input delay line such that more versatile memory modeling can be achieved. For both structures, gradient-based learning algorithms are derived to efficiently estimate the LUT control points and other related DPD parameters. Large set of experimental results are provided, with specific focus on 5G New Radio (NR) systems, showing successful linearization of multiple PA samples as well as a 28 GHz active antenna array, incorporating channel bandwidths up to 200 MHz. Explicit performance-complexity comparisons are also reported between the SPH and SMP DPD systems and the widely-applied ordinary memory-polynomial (MP) DPD solution. The results show that the linearization capabilities of the proposed methods are very close to that of the ordinary MP DPD, particularly with the proposed SMP approach, while having substantially lower processing complexity. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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11. Sum-Rate Analysis and Optimization of Self-Backhauling Based Full-Duplex Radio Access System
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Korpi, Dani, Riihonen, Taneli, Sabharwal, Ashutosh, and Valkama, Mikko
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FOS: Computer and information sciences ,Information Theory (cs.IT) ,Computer Science - Information Theory ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Data_CODINGANDINFORMATIONTHEORY - Abstract
In this article, a radio access system with a self-backhauling full-duplex access node serving legacy half-duplex mobile devices is studied and analyzed. In particular, it is assumed that the access node is using the same center frequency for all the transmissions, meaning that also the backhauling is done using the same frequency resources as the uplink and downlink transmissions. It is further assumed that the access node has a massive array to facilitate efficient beamforming and self-interference nulling in its own receiver. As a starting point, the signal model for the considered access node is first derived, including all the transmitted and received signals within the cell. This is then used as a basis for obtaining the sum-rate expressions, which depict the overall rates experienced by the mobile users that are served by the access node. In addition, the data rate for the bi-directional backhaul link is also derived, since the access node must be able to backhaul itself wirelessly. The maximum achievable sum-rate is then determined by numerically solving an optimization problem constructed from the data rate expressions. The full-duplex scheme is also compared to two alternative transmission schemes, which perform all or some of the transmissions in half-duplex mode. The results show that the full-duplex capability of the access node is beneficial for maximizing the sum-rate, meaning that a simple half-duplex transmission scheme is typically not optimal. In particular, the highest sum-rate is usually provided by a relay type solution, where the access node acts as a full-duplex relay between the mobiles and the backhaul node., 30 pages, submitted for review
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- 2016
12. Analog Imperfections in Wireless Full-Duplex Transceivers
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Korpi, Dani, Elektroniikan ja tietoliikennetekniikan laitos - Department of Electronics and Communications Engineering, Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering, Tampere University of Technology, Valkama, Mikko, Riihonen, Taneli, and Anttila, Lauri
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Signaalinkäsittelyn ja tietoliikennetekniikan koulutusohjelma - Abstract
Käytössä olevien taajuusalueiden ruuhkautumisen vuoksi langattoman tiedonsiirron spektritehokkuuden lisääminen on tullut yhä tärkeämmäksi. Vastauksena tähän, useat viimeaikaiset tutkimukset osoittavat, että on itse asiassa mahdollista lähettää ja vastaanottaa radiosignaaleja langattomasti käyttäen vain yhtä keskitaajuutta. Nämä niinkutsutut full-duplex lähetin/vastaanottimet voivat teoriassa jopa kaksinkertaistaa spektritehokkuuden, koska ne eivät tarvitse erillisiä taajuuskaistoja lähetetyille ja vastaanotetuille signaaleille. Haasteena tällaisessa tiedonsiirrossa on kuitenkin se, että lähetetty signaali on vastaanottimen näkökulmasta voimakas häiriölähde, sillä se kytkeytyy lähettimestä suoraan vastaanottimeen. Tämä itse-interferenssi on suurin käytännön este full-duplex lähetin/vastaanottimen toteutukselle, joten on erittäin tärkeää pystyä jollakin keinolla vaimentamaan sitä. Tässä työssä tutkitaan itse-interferenssin vaikutusta tyypilliseen full-duplex lähetin/vastaanottimeen, kun itse-interferenssiä vaimennetaan sekä analogisesti että digitaalisesti. Lisäksi työssä esitetään analogiselle vaimennukselle kaksi vaihtoehtoista toteutustapaa. Kaiken kaikkiaan, työn tuloksena saadaan tietoa full-duplex lähetin/ vastaanottimessa esiintyvien eri epäideaalisuuksien voimakkuuksista. Varsinainen analyysi perustuu yksinkertaistettuihin malleihin, joilla pyritään mallintamaan yksittäisten komponenttien synnyttämiä analogisia häiriöitä. Näiden mallien avulla johdetaan lausekkeet eri signaalikomponenttien tehoille, joilla saadaan laskettua lopullinen signaali-kohina-interferenssi suhde. Tämän lisäksi johdetuilla lausekkeilla lasketaan lukuisia esimerkkituloksia käyttäen todenmukaisia parametreja. Saadut tulokset osoittavat, että analogia-digitaalimuunnoksessa vaaditaan runsaasti bittejä, tai vaihtoehtoisesti, että itse-interferenssiä täytyy vaimentaa analogisesti huomattava määrä. Lisäksi havaittiin, että tietyt analogiset häiriöt, etenkin tehovahvistimen aiheuttama epälineaarinen vääristymä, sekä mahdollisesti myös vastaanottimen epälineaarisuus, täytyy ottaa huomioon vaimennettaessa itse-interferenssiä digitaalisesti. Saadut tulokset ovat yhtäpitäviä aaltomuotosimulaatioilla saatujen tulosten kanssa, mikä vahvistaa niiden luotettavuuden.
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- 2014
13. Transmit Power Optimization and Feasibility Analysis of Self-Backhauling Full-Duplex Radio Access Systems.
- Author
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Korpi, Dani, Riihonen, Taneli, Sabharwal, Ashutosh, and Valkama, Mikko
- Abstract
We analyze an inband full-duplex access node that is serving mobile users while simultaneously connecting to a core network over a wireless backhaul link, utilizing the same frequency band for all communication tasks. Such wireless self-backhauling is an intriguing option for the next generation wireless systems since a wired backhaul connection might not be economically viable if the access nodes are deployed densely. In particular, we derive the optimal transmit power allocation for such a system in closed form under quality-of-service (QoS) requirements, which are defined in terms of the minimum data rates for each mobile user. For comparison, the optimal transmit power allocation is solved also for two reference scenarios: a purely half-duplex access node, and a relay-type full-duplex access node. Based on the obtained expressions for the optimal transmit powers, we then show that the systems utilizing a full-duplex capable access node have a fundamental feasibility boundary, meaning that there are circumstances under which the QoS requirements cannot be fulfilled using finite transmit powers. This fundamental feasibility boundary is also derived in closed form. The feasibility boundaries and optimal transmit powers are then numerically evaluated in order to compare the different communication schemes. In general, utilizing the purely full-duplex access node results in the lowest transmit powers for all the communicating parties, although there are some network geometries under which such a system is not capable of reaching the required minimum data rates. In addition, the numerical results indicate that a full-duplex capable access node is best suited for relatively small cells. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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14. Adaptive Nonlinear RF Cancellation for Improved Isolation in Simultaneous Transmit–Receive Systems.
- Author
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Kiayani, Adnan, Waheed, Muhammad Zeeshan, Anttila, Lauri, Abdelaziz, Mahmoud, Korpi, Dani, Syrjala, Ville, Valkama, Mikko, Kosunen, Marko, Stadius, Kari, and Ryynanen, Jussi
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5G networks ,ADAPTIVE radar ,RADIO frequency ,RADIO transmitter-receivers ,LOW noise amplifiers - Abstract
This paper proposes an active radio frequency (RF) cancellation solution to suppress the transmitter (TX) passband leakage signal in radio transceivers supporting simultaneous transmission and reception. The proposed technique is based on creating an opposite-phase baseband equivalent replica of the TX leakage signal in the transceiver digital front-end through adaptive nonlinear filtering of the known transmit data, to facilitate highly accurate cancellation under a nonlinear power amplifier (PA). The active RF cancellation is then accomplished by employing an auxiliary TX chain to generate the actual RF cancellation signal, and combining it with the received signal at the receiver (RX) low-noise amplifier (LNA) input. A closed-loop parameter learning approach, based on the decorrelation learning rule, is also developed to efficiently estimate the coefficients of the nonlinear cancellation filter in the presence of a nonlinear PA with memory, finite passive isolation, and a nonlinear LNA. The performance of the proposed cancellation technique is evaluated through comprehensive RF measurements adopting commercial LTE-Advanced transceiver hardware components. The results show that the proposed technique can provide an additional suppression of up to 54 dB for the TX passband leakage signal at the LNA input, even at very high transmit power levels and with wide transmission bandwidths. Such a novel cancellation solution can, therefore, substantially improve the TX–RX isolation, hence reducing the requirements on passive isolation and RF component linearity, as well as increasing the efficiency and flexibility of the RF spectrum use in the emerging 5G radio networks. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
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15. Inband Full-Duplex Radio Transceivers: A Paradigm Shift in Tactical Communications and Electronic Warfare?
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Riihonen, Taneli, Korpi, Dani, Rantula, Olli, Rantanen, Heikki, Saarelainen, Tapio, and Valkama, Mikko
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MILITARY electronics , *WIRELESS communications , *RADIO frequency , *TECHNOLOGICAL innovations , *DIGITAL communications , *RADIO transmitters & transmission - Abstract
Inband FD operation has great potential in civilian/commercial wireless communications, because it can as much as double transmission links? spectral efficiency by exploiting the newfound capability for STAR that is facilitated by advanced SIC techniques. This article surveys the prospects of exploiting the emerging FD radio technology in military communication applications as well. In addition to enabling high-rate twoway tactical communications, the STAR capability could give a major technical advantage to armed forces by allowing their radio transceivers to conduct electronic warfare at the same time that they are also receiving or transmitting other signals at the same frequency bands. After comprehensively introducing FD transceiver architectures and SIC requirements in military communications, this article outlines and analyzes all the most promising defensive and offensive applications of the STAR capability. It is not out of the question that this disruptive technology could even bring about a paradigm shift in operations at the cyber-electromagnetic battleground. At least, forward-looking innovators in the military communications community would right now have a window of opportunity to engage in original, potentially high-impact scientific research on FD military radio systems, which we would like to spur on by this speculative tutorial article. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
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16. Self-backhauling full-duplex access node with massive antenna arrays: Power allocation and achievable sum-rate.
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Korpi, Dani, Riihonen, Taneli, and Valkama, Mikko
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- 2016
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17. Digitally-controlled RF self-interference canceller for full-duplex radios.
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Tamminen, Joose, Turunen, Matias, Korpi, Dani, Huusari, Timo, Choi, Yang-Seok, Talwar, Shilpa, and Valkama, Mikko
- Published
- 2016
- Full Text
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18. Compact Inband Full-Duplex Relays With Beyond 100 dB Self-Interference Suppression: Enabling Techniques and Field Measurements.
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Korpi, Dani, Valkama, Mikko, Heino, Mikko, Icheln, Clemens, and Haneda, Katsuyuki
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ANTENNA design , *WIRELESS communications , *FREQUENCY division multiple access , *TIME division multiple access , *MIMO systems - Abstract
In this communication, the self-interference (SI) channel and the novel enabling techniques for a compact inband full-duplex relay are described and characterized in different operating environments. The full-duplex operation is based on a novel antenna design that uses wavetraps to provide passive isolation of up to 70 dB between the transmit and receive antenna ports. The passive isolation is complemented with novel active RF and digital cancellation stages that further suppress the residual SI to the receiver noise floor. Measurement results of a complete prototype implementation show that the proposed design can achieve an overall SI cancellation performance of over 100 dB even with an ambitious instantaneous bandwidth of 80 MHz. Similar results are obtained both in an anechoic chamber as well as in realistic multipath indoor environments. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
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19. Full-duplex mobile device: pushing the limits.
- Author
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Korpi, Dani, Tamminen, Joose, Turunen, Matias, Huusari, Timo, Choi, Yang-Seok, Anttila, Lauri, Talwar, Shilpa, and Valkama, Mikko
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- *
RADIO transmitter-receivers , *CELL phone systems , *ANTENNAS (Electronics) , *INTERFERENCE (Telecommunication) , *RADIO frequency ,DESIGN & construction - Abstract
In this article, we address the challenges of transmitter-receiver isolation in mobile full-duplex devices, building on shared-antenna-based transceiver architecture. First, self-adaptive analog RF cancellation circuitry is required, since the ability to track time-varying self-interference coupling characteristics is of utmost importance in mobile devices. In addition, novel adaptive nonlinear DSP methods are also required for final self-interference suppression at digital baseband, since mobile-scale devices typically operate under highly nonlinear low-cost RF components. In addition to describing the above kind of advanced circuit and signal processing solutions, comprehensive RF measurement results from a complete demonstrator implementation are also provided, evidencing beyond 40 dB of active RF cancellation over an 80 MHz waveform bandwidth with a highly nonlinear transmitter power amplifier. Measured examples also demonstrate the good self-healing characteristics of the developed control loop against fast changes in the coupling channel. Furthermore, when complemented by nonlinear digital cancellation processing, the residual self-interference level is pushed down to the noise floor of the demonstration system, despite the harsh nonlinear nature of the self-interference. These findings indicate that deploying the full-duplex principle can indeed also be feasible in mobile devices, and thus be one potential technology in, for example, 5G and beyond radio systems. [ABSTRACT FROM PUBLISHER]
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- 2016
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20. Adaptive Nonlinear Digital Self-Interference Cancellation for Mobile Inband Full-Duplex Radio: Algorithms and RF Measurements.
- Author
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Korpi, Dani, Choi, Yang-Seok, Huusari, Timo, Anttila, Lauri, Talwar, Shilpa, and Valkama, Mikko
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- 2015
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21. Digital self-interference cancellation under nonideal RF components: Advanced algorithms and measured performance.
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Korpi, Dani, Huusari, Timo, Choi, Yang-Seok, Anttila, Lauri, Talwar, Shilpa, and Valkama, Mikko
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- 2015
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22. Achievable rate regions and self-interference channel estimation in hybrid full-duplex/half-duplex radio links.
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Korpi, Dani, Riihonen, Taneli, and Valkama, Mikko
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- 2015
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23. Achievable Transmission Rates and Self-Interference Channel Estimation in Hybrid Full-Duplex/Half-Duplex MIMO Relaying.
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Korpi, Dani, Riihonen, Taneli, Haneda, Katsuyuki, Yamamoto, Koji, and Valkama, Mikko
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- 2015
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24. Feasibility of in-band full-duplex radio transceivers with imperfect RF components: Analysis and enhanced cancellation algorithms.
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Korpi, Dani, Anttila, Lauri, and Valkama, Mikko
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- 2014
25. Reference receiver based digital self-interference cancellation in MIMO full-duplex transceivers.
- Author
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Korpi, Dani, Anttila, Lauri, and Valkama, Mikko
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- 2014
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26. Modeling and efficient cancellation of nonlinear self-interference in MIMO full-duplex transceivers.
- Author
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Anttila, Lauri, Korpi, Dani, Antonio-Rodriguez, Emilio, Wichman, Risto, and Valkama, Mikko
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- 2014
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27. Impact of received signal on self-interference channel estimation and achievable rates in in-band full-duplex transceivers.
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Korpi, Dani, Anttila, Lauri, and Valkama, Mikko
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- 2014
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28. Recent advances in antenna design and interference cancellation algorithms for in-band full duplex relays.
- Author
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Heino, Mikko, Korpi, Dani, Huusari, Timo, Antonio-Rodriguez, Emilio, Venkatasubramanian, Sathya, Riihonen, Taneli, Anttila, Lauri, Icheln, Clemens, Haneda, Katsuyuki, Wichman, Risto, and Valkama, Mikko
- Subjects
- *
SPECTRUM analysis , *ANTENNAS (Electronics) , *RADIO transmitter-receivers , *INTERFERENCE (Telecommunication) , *MIMO systems - Abstract
In-band full-duplex relays transmit and receive simultaneously at the same center frequency, hence offering enhanced spectral efficiency for relay deployment. In order to deploy such full-duplex relays, it is necessary to efficiently mitigate the inherent self-interference stemming from the strong transmit signal coupling to the sensitive receive chain. In this article, we present novel state-of-the-art antenna solutions as well as digital self-interference cancellation algorithms for compact MIMO fullduplex relays, specifically targeted for reduced-cost deployments in local area networks. The presented antenna design builds on resonant wavetraps and is shown to provide passive isolations on the order of 60?70 dB. We also discuss and present advanced digital cancellation solutions, beyond classical linear processing, specifically tailored against nonlinear distortion of the power amplifier when operating close to saturation. Measured results from a complete demonstrator system, integrating antennas, RF cancellation, and nonlinear digital cancellation, are also presented, evidencing close to 100 dB of overall self-interference suppression. The reported results indicate that building and deploying compact full-duplex MIMO relays is already technologically feasible. [ABSTRACT FROM PUBLISHER]
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- 2015
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29. Widely Linear Digital Self-Interference Cancellation in Direct-Conversion Full-Duplex Transceiver.
- Author
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Korpi, Dani, Anttila, Lauri, Syrjala, Ville, and Valkama, Mikko
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DIGITAL filters (Mathematics) ,DIRECT conversion receivers ,RADIOS ,DIGITAL electronics ,FUNCTIONAL analysis ,RADIO transmitter-receivers ,RADIO frequency - Abstract
This paper addresses the modeling and cancellation of self-interference in full-duplex direct-conversion radio transceivers, operating under practical imperfect radio frequency (RF) components. First, detailed self-interference signal modeling is carried out, taking into account the most important RF imperfections, namely, transmitter power amplifier nonlinear distortion as well as transmitter and receiver IQ mixer amplitude and phase imbalances. The analysis shows that after realistic antenna isolation and RF cancellation, the dominant self-interference waveform at the receiver digital baseband can be modeled through a widely linear transformation of the original transmit data, opposed to classical purely linear models. Such widely linear self-interference waveform is physically stemming from the transmitter and receiver IQ imaging and cannot be efficiently suppressed by classical linear digital cancellation. Motivated by this, novel widely linear digital self-interference cancellation processing is then proposed and formulated, combined with efficient parameter estimation methods. Extensive simulation results demonstrate that the proposed widely linear cancellation processing clearly outperforms the existing linear solutions, hence enabling the use of practical low-cost RF front ends utilizing IQ mixing in full-duplex transceivers. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
30. Cancellation of power amplifier induced nonlinear self-interference in full-duplex transceivers.
- Author
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Anttila, Lauri, Korpi, Dani, Syrjala, Ville, and Valkama, Mikko
- Published
- 2013
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31. Advanced self-interference cancellation and multiantenna techniques for full-duplex radios.
- Author
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Korpi, Dani, Venkatasubramanian, Sathya, Riihonen, Taneli, Anttila, Lauri, Otewa, Strasdosky, Icheln, Clemens, Haneda, Katsuyuki, Tretyakov, Sergei, Valkama, Mikko, and Wichman, Risto
- Published
- 2013
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32. Full-Duplex Transceiver System Calculations: Analysis of ADC and Linearity Challenges.
- Author
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Korpi, Dani, Riihonen, Taneli, Syrjala, Ville, Anttila, Lauri, Valkama, Mikko, and Wichman, Risto
- Abstract
Despite the intensive recent research on wireless single-channel full-duplex communications, relatively little is known about the transceiver chain nonidealities of full-duplex devices. In this paper, the effect of nonlinear distortion occurring in the transmitter power amplifier (PA) and the receiver chain is analyzed, beside the dynamic range requirements of analog-to-digital converters (ADCs). This is done with detailed system calculations, which combine the properties of the individual electronics components to jointly model the complete transceiver chain, including self-interference cancellation. They also quantify the decrease in the dynamic range for the signal of interest caused by self-interference at the analog-to-digital interface. Using these system calculations, we provide comprehensive numerical results for typical transceiver parameters. The analytical results are also confirmed with full waveform simulations. We observe that the nonlinear distortion produced by the transmitter PA is a significant issue in a full-duplex transceiver and, when using cheaper and less linear components, also the receiver chain nonlinearities become considerable. It is also shown that, with digitally intensive self-interference cancellation, the quantization noise of the ADCs is another significant problem. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
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33. Analysis of Oscillator Phase-Noise Effects on Self-Interference Cancellation in Full-Duplex OFDM Radio Transceivers.
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Syrjala, Ville, Valkama, Mikko, Anttila, Lauri, Riihonen, Taneli, and Korpi, Dani
- Abstract
This paper addresses the analysis of oscillator phase-noise effects on the self-interference cancellation capability of full-duplex direct-conversion radio transceivers. Closed-form solutions are derived for the power of the residual self-interference stemming from phase noise in two alternative cases of having either independent oscillators or the same oscillator at the transmitter and receiver chains of the full-duplex transceiver. The results show that phase noise has a severe effect on self-interference cancellation in both of the considered cases, and that by using the common oscillator in upconversion and downconversion results in clearly lower residual self-interference levels. The results also show that it is in general vital to use high quality oscillators in full-duplex transceivers, or have some means for phase noise estimation and mitigation in order to suppress its effects. One of the main findings is that in practical scenarios the subcarrier-wise phase-noise spread of the multipath components of the self-interference channel causes most of the residual phase-noise effect when high amounts of self-interference cancellation is desired. [ABSTRACT FROM PUBLISHER]
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- 2014
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34. Kaistansisäinen full-duplex-tekniikka monitoimintoisissa ja monitilaisissa radioissa: sovelluskohteet ja järjestelmätestaukset
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Saikanmäki, Joni, Elektroniikka ja tietoliikennetekniikka – Electronics and Communications Engineering, Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering, Tampere University of Technology, Korpi, Dani, and Riihonen, Taneli
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Sähkötekniikka - Abstract
Radio transceivers are devices which send or receive electromagnetic waves for certain purpose. These devices are crucial in military domain for tactical communication and electronic warfare operations, and new types of technologies are continually being developed. Especially, inband full-duplex technology has potential as many military-related requirements can be covered by using this technology. This thesis discusses the emerging concept of a multi-functional radio with inband full-duplex capability that allows simultaneous use of multiple functionalities for tactical communication and electronic warfare. This is in contrast with legacy tactical radios that mostly make use of half-duplex technology, where only one functionality at the time can be enabled. Furthermore, this area has not been yet sufficiently explored in scientific literature. Full-duplex multi-functional radios are capable of manually or automatically modifying their functionalities to match the situation experienced in the battlefield. The full-duplex multi-functional radio may, for example, jam an opponent while receiving successfully tactical data from allied transmitters. On the other hand, the full-duplex multi-functional radio is capable of creating so-called radio shield which is "jamming bubble" where several different jamming strategies, such as tune and barrage jammer are exploited. The radio shield is capable of preventing an opponent's interception while receiving tactical information from allied transmitters. Furthermore, the radio shield can prevent activation of radio-controlled explosives that opponents may have, or the full-duplex multi-functional radio can be used for signal surveillance or signal detection purposes. Both defensive and offensive proof-of-concept experiments are performed to show the advantages of using a multi-functional radio that has inband full-duplex capability. In the offensive experiments, an inband full-duplex radio is used for jamming and intercepting an opponent on the same frequency band. The results show that the opponent's tactical signal quality decreases radically when jamming power is increased. However, increasing jamming power does not affect the full-duplex radio's own signal quality. In the experiments, several different jamming strategies, such as tune and barrage jammer are used. The same phenomenon can be seen in defensive experiments where the opponent tries to intercept tactical transmission between the full-duplex radio and its team's members. Due to this, the multi-functional radio with inband full-duplex capability can be exploited successfully in military environment.
- Published
- 2018
35. Self-Interference Cancellation in Interband Carrier Aggregation Transceivers
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Waheed, Muhammad Zeeshan, Elektroniikka ja tietoliikennetekniikka – Electronics and Communications Engineering, Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering, Tampere University of Technology, Valkama, Mikko, and Korpi, Dani
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Electrical Engineering - Abstract
The increasing amount of data usage by mobile phone users requires higher data rates which, in turn, calls for employing larger bandwidths and flexible transmission schemes. To meet these demands, advanced solutions such as higher-order modulation techniques, multiantenna and multicarrier transmission shemes, among others, have been developed with time. Carrier aggregation (CA) is also one of the techniques that has been proposed, where multiple component carriers (CCs) are aggregated together to form larger transmission bandwidth in order to support high data rate requirements, while also enabling efficient spectrum utilization. In this thesis, the problem of self-interference in radio transceivers supporting interband CA, where separate transmitter (TX) and receiver (RX) chains are used for each CC, is studied and analyzed. At the transmitter the nonlinear behavior of the radio front-end components generates spurious intermodulation distortion components of the transmit CCs which, in some cases, may appear in one of the configured RX operating bands, causing self-interference. Moreover, the CCs are also distorted in a nonlinear fashion by each of the individual power amplifiers (PAs) in the transmitter chain, which means that the self-interference is actually produced by a cascade of two nonlinearities. The resulting self-interference may lead to the blockage of desired received signal, thus causing own receiver desensitization. In order to investigate and formulate a solution to this problem, in this thesis, a signal model for self-interference is first derived incorporating the nonlinearities of the TX PAs and passive front-end components. Then, a digital cancellation solution, utilizing the original transmit data and estimated parameters, is proposed to efficiently suppress the self-interference at the receiver band. The performance of the suggested method is first tested through waveform simulations, and then through practical radio frequency (RF) measurements adopting LTE-Advanced mobile transceiver components. It is observed that the self-interference is efficiently suppressed close to the receiver thermal noise floor by the proposed digital cancellation solution and sufficient cancellation of about 18.2 dB is achieved. All the results based on the waveform simulations and practical RF measurements are presented in this thesis work. The obtained results suggest that the digital cancellation is one potential approach for improving the receiver sensitivity in interband CA transceivers while also relaxing the RF components' linearity requirements.
- Published
- 2017
36. Real-time FPGA implementation of nonlinear self-interference cancellation in full-duplex radio transceiver
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Piililä, Mauno, Elektroniikka ja tietoliikennetekniikka – Electronics and Communications Engineering, Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering, Tampere University of Technology, Valkama, Mikko, and Korpi, Dani
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ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Tietotekniikka - Abstract
In full-duplex wireless communications, transmission and reception of signals occur simultaneously on the same center carrier frequency. It is one technique to increase limited wireless capacity, and particularly the spectral efficiency. The challenge of full-duplex tehnique is to separate the weak received signal from the transmitted signal, which can be even 120 dB stronger signal. This is called self-interference. Current duplexing techniques used in existing two-way communication systems are either time or frequency division duplexing, where signals received and transmitted utilizes different carrier frequencies, or transmission and reception are done in different time slots. The usage of full-duplex communications may, in theory, double the spectral efficiency of a wireless link and thereon the corresponding wireless system. To cancel the self-interference, and to recover the received signal, the self-interference has to be modelled accurately. Particularly important is the ability to model the nonlinear nature of the self-interference, that is caused by power amplifiers. In this Master’s Thesis work, one recenty developed nonlinear self-interference model and corresponding nonlinear digital self-interference cancellation technique is explored. Specifically, a real-time FPGA implementation is pursued and developed for 20 MHz LTE-like channel bandwidth. This real-time Labview FPGA solution of digital self-interference canceller can, of the overall three-phase self-interference suppression solution, provide measured cancellation at maximum of about 34 dB. The other self-interference cancellation or isolation methods used in measurements are a passive circulator with 20 dB attenuation, and an active RF-canceller, that at measurements provided about 43 dB cancellation. Thus the total real-time cancellation of the self-interference in the overall demonstration system is maximally nearly 100 dB. The developed real-time FPGA implementation could possibly be used as a base for an ASIC circuit development. The resources available in the FPGA used, affected essentially into the structure of the canceller and to the performance of the cancellation.
- Published
- 2017
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