The Experts below are selected from a list of 6607659 Experts worldwide ranked by ideXlab platform
Ashutosh Sabharwal - One of the best experts on this subject based on the ideXlab platform.
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softnull many antenna full duplex wireless via digital beamforming
IEEE Transactions on Wireless Communications, 2016Co-Authors: Evan Everett, Clayton Shepard, Lin Zhong, Ashutosh SabharwalAbstract:In this paper, we present and study a digital-controlled method, called SoftNull, to enable full-duplex in many-antenna systems. Unlike most designs that rely on analog cancelers to suppress Self-Interference, SoftNull relies on digital transmit beamforming to reduce Self-Interference. SoftNull does not attempt to perfectly null Self-Interference, but instead seeks to reduce Self-Interference sufficiently to prevent swamping the receiver’s dynamic range. Residual Self-Interference is then cancelled digitally by the receiver. We evaluate the performance of SoftNull using measurements from a 72-element antenna array in both indoor and outdoor environments. We find that SoftNull can significantly outperform half-duplex for small cells operating in the many-antenna regime, where the number of antennas is many more than the number of users served simultaneously.
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in band full duplex wireless challenges and opportunities
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Ashutosh Sabharwal, Philip Schniter, Dongning Guo, Daniel W Bliss, Sampath Rangarajan, Risto WichmanAbstract:In-band full-duplex (IBFD) operation has emerged as an attractive solution for increasing the throughput of wireless communication systems and networks. With IBFD, a wireless terminal is allowed to transmit and receive simultaneously in the same frequency band. This tutorial paper reviews the main concepts of IBFD wireless. One of the biggest practical impediments to IBFD operation is the presence of Self-Interference, i.e., the interference that the modem's transmitter causes to its own receiver. This tutorial surveys a wide range of IBFD Self-Interference mitigation techniques. Also discussed are numerous other research challenges and opportunities in the design and analysis of IBFD wireless systems.
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passive self interference suppression for full duplex infrastructure nodes
IEEE Transactions on Wireless Communications, 2014Co-Authors: Evan Everett, Achaleshwar Sahai, Ashutosh SabharwalAbstract:Recent research results have demonstrated the feasibility of full-duplex wireless communication for short-range links. Although the focus of the previous works has been active cancellation of the Self-Interference signal, a majority of the overall Self-Interference suppression is often due to passive suppression, i.e., isolation of the transmit and receive antennas. We present a measurement-based study of the capabilities and limitations of three key mechanisms for passive Self-Interference suppression: directional isolation, absorptive shielding, and cross-polarization. The study demonstrates that more than 70 dB of passive suppression can be achieved in certain environments, but also establishes two results on the limitations of passive suppression: (1) environmental reflections limit the amount of passive suppression that can be achieved, and (2) passive suppression, in general, increases the frequency selectivity of the residual Self-Interference signal. These results suggest two design implications: (1) deployments of full-duplex infrastructure nodes should minimize near-antenna reflectors, and (2) active cancellation in concatenation with passive suppression should employ higher-order filters or per-subcarrier cancellation.
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self interference cancellation with phase noise induced ici suppression for full duplex systems
Global Communications Conference, 2013Co-Authors: E Ahmed, Ahmed M Eltawil, Ashutosh SabharwalAbstract:One of the main bottlenecks in practical full-duplex systems is the oscillator phase noise, which bounds the possible cancellable Self-Interference power. In this paper, a digital-domain Self-Interference cancellation scheme for full-duplex orthogonal frequency division multiplexing systems is proposed. The proposed scheme increases the amount of cancellable Self-Interference power by suppressing the effect of both transmitter and receiver oscillator phase noise. The proposed scheme consists of two main phases, an estimation phase and a cancellation phase. In the estimation phase, the minimum mean square error estimator is used to jointly estimate the transmitter and receiver phase noise associated with the incoming Self-Interference signal. In the cancellation phase, the estimated phase noise is used to suppress the intercarrier interference caused by the phase noise associated with the incoming Self-Interference signal. The performance of the proposed scheme is numerically investigated under different operating conditions. It is demonstrated that the proposed scheme could achieve up to 9dB more Self-Interference cancellation than the existing digital-domain cancellation schemes that ignore the intercarrier interference suppression.
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in band full duplex wireless challenges and opportunities
arXiv: Information Theory, 2013Co-Authors: Ashutosh Sabharwal, Philip Schniter, Dongning Guo, Daniel W Bliss, Sampath Rangarajan, Risto WichmanAbstract:In-band full-duplex (IBFD) operation has emerged as an attractive solution for increasing the throughput of wireless communication systems and networks. With IBFD, a wireless terminal is allowed to transmit and receive simultaneously in the same frequency band. This tutorial paper reviews the main concepts of IBFD wireless. Because one the biggest practical impediments to IBFD operation is the presence of Self-Interference, i.e., the interference caused by an IBFD node's own transmissions to its desired receptions, this tutorial surveys a wide range of IBFD Self-Interference mitigation techniques. Also discussed are numerous other research challenges and opportunities in the design and analysis of IBFD wireless systems.
Mikko Valkama - One of the best experts on this subject based on the ideXlab platform.
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Full-duplex mobile device: Pushing the limits
IEEE Communications Magazine, 2016Co-Authors: Dani Korpi, Joose Tamminen, Matias Turunen, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract: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.
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adaptive nonlinear digital self interference cancellation for mobile inband full duplex radio algorithms and rf measurements
Global Communications Conference, 2014Co-Authors: Dani Korpi, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract:This article investigates novel adaptive Self-Interference cancellation solutions and the total integrated cancellation performance of a mobile single-antenna inband full-duplex transceiver. First, novel self-adaptive digital Self-Interference cancellation algorithms are described, with an emphasis on tracking of time-varying Self-Interference coupling channel in a mobile device as well as on structural ability to suppress also nonlinear Self-Interference with highly nonlinear mobile power amplifiers. This leads to an advanced self-adaptive nonlinear digital canceller which utilizes a novel orthogonalization procedure for nonlinear basis functions, together with low-cost LMS-based parameter learning. The achievable Self-Interference cancellation performance is then evaluated with actual RF measurements using mobile device scale RF components, in particular a highly nonlinear PA. The measurements also incorporate a novel self-adaptive RF cancellation circuit in order to realistically assess the total integrated cancellation performance. The reported results show that highly efficient Self-Interference cancellation can be achieved also in a mobile device, despite a heavily nonlinear PA and limited computing and hardware resources. The proposed cancellation solutions, when integrated together, show that 100 dB of Self-Interference can be cancelled using a 20 MHz LTE waveform, while the SI can be attenuated by over 110 dB with a narrower bandwidth of 1.4 MHz, all measured at 2.4 GHz ISM band. Furthermore, these results are achieved using a highly nonlinear transmitter power amplifier and fully adaptive canceller structures which can track a rapidly changing coupling channel in a mobile full-duplex device.
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full duplex mobile device pushing the limits
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Joose Tamminen, Matias Turunen, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract:In this article, we address the challenges of transmitter-receiver isolation in \emph{mobile full-duplex devices}, building on shared-antenna based transceiver architecture. Firstly, self-adaptive analog RF cancellation circuitry is required, since the capability 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 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 with 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 be feasible also in mobile devices, and thus be one potential technology in, e.g., 5G and beyond radio systems.
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widely linear digital self interference cancellation in direct conversion full duplex transceiver
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Dani Korpi, Lauri Anttila, Ville Syrjala, Mikko ValkamaAbstract: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.
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widely linear digital self interference cancellation in direct conversion full duplex transceiver
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Lauri Anttila, Ville Syrjala, Mikko ValkamaAbstract:This article addresses the modeling and cancellation of Self-Interference in full-duplex direct-conversion radio transceivers, operating under practical imperfect radio frequency (RF) components. Firstly, 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 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.
Dani Korpi - One of the best experts on this subject based on the ideXlab platform.
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Full-duplex mobile device: Pushing the limits
IEEE Communications Magazine, 2016Co-Authors: Dani Korpi, Joose Tamminen, Matias Turunen, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract: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.
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adaptive nonlinear digital self interference cancellation for mobile inband full duplex radio algorithms and rf measurements
Global Communications Conference, 2014Co-Authors: Dani Korpi, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract:This article investigates novel adaptive Self-Interference cancellation solutions and the total integrated cancellation performance of a mobile single-antenna inband full-duplex transceiver. First, novel self-adaptive digital Self-Interference cancellation algorithms are described, with an emphasis on tracking of time-varying Self-Interference coupling channel in a mobile device as well as on structural ability to suppress also nonlinear Self-Interference with highly nonlinear mobile power amplifiers. This leads to an advanced self-adaptive nonlinear digital canceller which utilizes a novel orthogonalization procedure for nonlinear basis functions, together with low-cost LMS-based parameter learning. The achievable Self-Interference cancellation performance is then evaluated with actual RF measurements using mobile device scale RF components, in particular a highly nonlinear PA. The measurements also incorporate a novel self-adaptive RF cancellation circuit in order to realistically assess the total integrated cancellation performance. The reported results show that highly efficient Self-Interference cancellation can be achieved also in a mobile device, despite a heavily nonlinear PA and limited computing and hardware resources. The proposed cancellation solutions, when integrated together, show that 100 dB of Self-Interference can be cancelled using a 20 MHz LTE waveform, while the SI can be attenuated by over 110 dB with a narrower bandwidth of 1.4 MHz, all measured at 2.4 GHz ISM band. Furthermore, these results are achieved using a highly nonlinear transmitter power amplifier and fully adaptive canceller structures which can track a rapidly changing coupling channel in a mobile full-duplex device.
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full duplex mobile device pushing the limits
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Joose Tamminen, Matias Turunen, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract:In this article, we address the challenges of transmitter-receiver isolation in \emph{mobile full-duplex devices}, building on shared-antenna based transceiver architecture. Firstly, self-adaptive analog RF cancellation circuitry is required, since the capability 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 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 with 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 be feasible also in mobile devices, and thus be one potential technology in, e.g., 5G and beyond radio systems.
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widely linear digital self interference cancellation in direct conversion full duplex transceiver
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Dani Korpi, Lauri Anttila, Ville Syrjala, Mikko ValkamaAbstract: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.
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widely linear digital self interference cancellation in direct conversion full duplex transceiver
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Lauri Anttila, Ville Syrjala, Mikko ValkamaAbstract:This article addresses the modeling and cancellation of Self-Interference in full-duplex direct-conversion radio transceivers, operating under practical imperfect radio frequency (RF) components. Firstly, 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 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.
Sachin Katti - One of the best experts on this subject based on the ideXlab platform.
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applications of self interference cancellation in 5g and beyond
IEEE Communications Magazine, 2014Co-Authors: Steven Siying Hong, Johannes Brand, Jeffrey Mehlman, Joel Brand, Steven Hong, Jung Choi, Jung-il Choi, Mayank Jain, Sachin Katti, Philip LevisAbstract:Self-Interference cancellation invalidates a long-held fundamental assumption in wireless network design that radios can only operate in half duplex mode on the same channel. Beyond enabling true in-band full duplex, which effectively doubles spectral efficiency, Self-Interference cancellation tremendously simplifies spectrum management. Not only does it render entire ecosystems like TD-LTE obsolete, it enables future networks to leverage fragmented spectrum, a pressing global issue that will continue to worsen in 5G networks. Self-Interference cancellation offers the potential to complement and sustain the evolution of 5G technologies toward denser heterogeneous networks and can be utilized in wireless communication systems in multiple ways, including increased link capacity, spectrum virtualization, any-division duplexing (ADD), novel relay solutions, and enhanced interference coordination. By virtue of its fundamental nature, Self-Interference cancellation will have a tremendous impact on 5G networks and beyond.
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achieving single channel full duplex wireless communication
ACM IEEE International Conference on Mobile Computing and Networking, 2010Co-Authors: Jung-il Choi, Kannan Srinivasan, Mayank Jain, Phil Levis, Sachin KattiAbstract:This paper discusses the design of a single channel full-duplex wireless transceiver. The design uses a combination of RF and baseband techniques to achieve full-duplexing with minimal effect on link reliability. Experiments on real nodes show the full-duplex prototype achieves median performance that is within 8% of an ideal full-duplexing system. This paper presents Antenna Cancellation, a novel technique for Self-Interference cancellation. In conjunction with existing RF interference cancellation and digital baseband interference cancellation, antenna cancellation achieves the amount of Self-Interference cancellation required for full-duplex operation. The paper also discusses potential MAC and network gains with full-duplexing. It suggests ways in which a full-duplex system can solve some important problems with existing wireless systems including hidden terminals, loss of throughput due to congestion, and large end-to-end delays.
Lauri Anttila - One of the best experts on this subject based on the ideXlab platform.
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Full-duplex mobile device: Pushing the limits
IEEE Communications Magazine, 2016Co-Authors: Dani Korpi, Joose Tamminen, Matias Turunen, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract: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.
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adaptive nonlinear digital self interference cancellation for mobile inband full duplex radio algorithms and rf measurements
Global Communications Conference, 2014Co-Authors: Dani Korpi, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract:This article investigates novel adaptive Self-Interference cancellation solutions and the total integrated cancellation performance of a mobile single-antenna inband full-duplex transceiver. First, novel self-adaptive digital Self-Interference cancellation algorithms are described, with an emphasis on tracking of time-varying Self-Interference coupling channel in a mobile device as well as on structural ability to suppress also nonlinear Self-Interference with highly nonlinear mobile power amplifiers. This leads to an advanced self-adaptive nonlinear digital canceller which utilizes a novel orthogonalization procedure for nonlinear basis functions, together with low-cost LMS-based parameter learning. The achievable Self-Interference cancellation performance is then evaluated with actual RF measurements using mobile device scale RF components, in particular a highly nonlinear PA. The measurements also incorporate a novel self-adaptive RF cancellation circuit in order to realistically assess the total integrated cancellation performance. The reported results show that highly efficient Self-Interference cancellation can be achieved also in a mobile device, despite a heavily nonlinear PA and limited computing and hardware resources. The proposed cancellation solutions, when integrated together, show that 100 dB of Self-Interference can be cancelled using a 20 MHz LTE waveform, while the SI can be attenuated by over 110 dB with a narrower bandwidth of 1.4 MHz, all measured at 2.4 GHz ISM band. Furthermore, these results are achieved using a highly nonlinear transmitter power amplifier and fully adaptive canceller structures which can track a rapidly changing coupling channel in a mobile full-duplex device.
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full duplex mobile device pushing the limits
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Joose Tamminen, Matias Turunen, Timo Huusari, Yang-seok Choi, Shilpa Talwar, Lauri Anttila, Mikko ValkamaAbstract:In this article, we address the challenges of transmitter-receiver isolation in \emph{mobile full-duplex devices}, building on shared-antenna based transceiver architecture. Firstly, self-adaptive analog RF cancellation circuitry is required, since the capability 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 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 with 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 be feasible also in mobile devices, and thus be one potential technology in, e.g., 5G and beyond radio systems.
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widely linear digital self interference cancellation in direct conversion full duplex transceiver
IEEE Journal on Selected Areas in Communications, 2014Co-Authors: Dani Korpi, Lauri Anttila, Ville Syrjala, Mikko ValkamaAbstract: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.
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widely linear digital self interference cancellation in direct conversion full duplex transceiver
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Lauri Anttila, Ville Syrjala, Mikko ValkamaAbstract:This article addresses the modeling and cancellation of Self-Interference in full-duplex direct-conversion radio transceivers, operating under practical imperfect radio frequency (RF) components. Firstly, 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 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.
