The Experts below are selected from a list of 15588 Experts worldwide ranked by ideXlab platform
Risto Wichman - One of the best experts on this subject based on the ideXlab platform.
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Recent advances in antenna design and interference cancellation algorithms for in-band Full Duplex relays
IEEE Communications Magazine, 2015Co-Authors: Mikko Heino, Emilio Antonio-rodr??guez, Sathya N. Venkatasubramanian, Sathya Venkatasubramanian, Taneli Riihonen, Timo Huusari, Dani Korpi, Clemens Icheln, Katsuyuki Haneda, Lauri Anttila, Risto WichmanAbstract: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 Full-Duplex 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.
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energy detection in Full Duplex cognitive radios under residual self interference
International Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2014Co-Authors: Taneli Riihonen, Risto WichmanAbstract:This paper investigates the possibility to exploit inband Full-Duplex wireless technology for simultaneous spectrum sensing and data transmission in cognitive radio terminals. The focus is especially on the receiver operating characteristics of basic energy detection. Full-Duplex operation suffers from self-interference, even after cancellation since it is imperfect in prac-tice. The effect on the probability of missed detection is analyzed, and increasing sensing time is proposed as a countermeasure for residual distortion which, unlike in half-Duplex operation, does not cause large overhead due to lost transmission opportunities. The study also compares the two- and single-antenna implementations of Full-Duplex radios and elicits a channel imbalance problem in the former due to which sensing provides different information than the transmitting antenna would observe.
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Full Duplex transceiver system calculations analysis of adc and linearity challenges
IEEE Transactions on Wireless Communications, 2014Co-Authors: Dani Korpi, Taneli Riihonen, Lauri Anttila, Mikko Valkama, Ville Syrjala, Risto WichmanAbstract: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.
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Full Duplex transceiver system calculations analysis of adc and linearity challenges
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Taneli Riihonen, Lauri Anttila, Mikko Valkama, Ville Syrjala, Risto WichmanAbstract: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, alongside with 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.
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hybrid Full Duplex half Duplex relaying with transmit power adaptation
IEEE Transactions on Wireless Communications, 2011Co-Authors: Taneli Riihonen, Stefan Werner, Risto WichmanAbstract:Focusing on two-antenna infrastructure relays employed for coverage extension, we develop hybrid techniques that switch opportunistically between Full-Duplex and half-Duplex relaying modes. To rationalize the system design, the classic three-node Full-Duplex relay link is first amended by explicitly modeling residual relay self-interference, i.e., a loopback signal from the transmit antenna to the receive antenna remaining after cancellation. The motivation for opportunistic mode selection stems then from the fundamental trade-off determining the spectral efficiency: The half-Duplex mode avoids inherently the self-interference at the cost of halving the end-to-end symbol rate while the Full-Duplex mode achieves Full symbol rate but, in practice, suffers from residual interference even after cancellation. We propose the combination of opportunistic mode selection and transmit power adaptation for maximizing instantaneous and average spectral efficiency after noting that the trade-off favors alternately the modes during operation. The analysis covers both common relaying protocols (amplify-and-forward and decode-and-forward) as well as reflects the difference of downlink and uplink systems. The results show that opportunistic mode selection offers significant performance gain over system design that is confined to either mode without rationalization.
Ashutosh Sabharwal - One of the best experts on this subject based on the ideXlab platform.
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power controlled medium access control protocol for Full Duplex wifi networks
IEEE Transactions on Wireless Communications, 2015Co-Authors: Wooyeol Choi, Hyuk Lim, Ashutosh SabharwalAbstract:Recent advances in signal processing have demonstrated in-band Full-Duplex capability at WiFi ranges. In addition to simultaneous two-way exchange between two nodes, Full-Duplex access points can potentially support simultaneous uplink and downlink flows. However, the atomic three-node topology, which allows simultaneous uplink and downlink, leads to inter-client interference. In this paper, we propose a random-access medium access control protocol using distributed power control to manage inter-client interference in wireless networks with Full-Duplex-capable access points that serve half-Duplex clients. Our key contributions are two-fold. First, we identify the regimes in which power control provides sum throughput gains for the three-node atomic topology, with one uplink flow and one downlink flow. Second, we develop and benchmark PoCMAC, a Full 802.11-based protocol that allows distributed selection of a three-node topology. The proposed MAC protocol is shown to achieve higher capacity as compared to an equivalent half-Duplex counterpart, while maintaining similar fairness characteristics in single contention domain networks. We carried out extensive simulations and software-defined radio-based experiments to evaluate the performance of the proposed MAC protocol, which is shown to achieve a significant improvement over its half-Duplex counterpart in terms of throughput performance.
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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 nonlinear distortion suppression for Full Duplex systems
Asilomar Conference on Signals Systems and Computers, 2013Co-Authors: E Ahmed, Ahmed M Eltawil, Ashutosh SabharwalAbstract:In Full-Duplex systems, due to the strong self-interference signal, system nonlinearities become a significant limiting factor that bounds the possible cancellable self-interference power. In this paper, a 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 distortion caused by the transmitter and receiver nonlinearities. An iterative technique is used to jointly estimate the self-interference channel and the nonlinearity coefficients required to suppress the distortion signal. The performance is numerically investigated showing that the proposed scheme achieves a performance that is less than 0.5dB off the performance of a linear Full-Duplex system.
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on the impact of phase noise on active cancelation in wireless Full Duplex
IEEE Transactions on Vehicular Technology, 2013Co-Authors: Achaleshwar Sahai, Christopher H Dick, Gaurav Patel, Ashutosh SabharwalAbstract:Recent experimental results have shown that Full-Duplex communication is possible for short-range communications. However, extending Full-Duplex to long-range communication remains a challenge, primarily due to residual self-interference, even with a combination of passive suppression and active cancelation methods. In this paper, we investigate the root cause of performance bottlenecks in current Full-Duplex systems. We first classify all known Full-Duplex architectures based on how they compute their canceling signal and where the canceling signal is injected to cancel self-interference. Based on the classification, we analytically explain several published experimental results. The key bottleneck in current systems turns out to be the phase noise in the local oscillators in the transmit-and-receive chain of the Full-Duplex node. As a key by-product of our analysis, we propose signal models for wideband and multiple-input-multiple-output (MIMO) Full-Duplex systems, capturing all the salient design parameters, thus allowing future analytical development of advanced coding and signal design for Full-Duplex systems.
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rate gain region and design tradeoffs for Full Duplex wireless communications
arXiv: Information Theory, 2013Co-Authors: E Ahmed, Ahmed M Eltawil, Ashutosh SabharwalAbstract:In this paper, we analytically study the regime in which practical Full-Duplex systems can achieve larger rates than an equivalent half-Duplex systems. The key challenge in practical Full-Duplex systems is uncancelled self-interference signal, which is caused by a combination of hardware and implementation imperfections. Thus, we first present a signal model which captures the effect of significant impairments such as oscillator phase noise, low-noise amplifier noise figure, mixer noise, and analog-to-digital converter quantization noise. Using the detailed signal model, we study the rate gain region, which is defined as the region of received signal-of-interest strength where Full-Duplex systems outperform half-Duplex systems in terms of achievable rate. The rate gain region is derived as a piece-wise linear approximation in log-domain, and numerical results show that the approximation closely matches the exact region. Our analysis shows that when phase noise dominates mixer and quantization noise, Full-Duplex systems can use either active analog cancellation or base-band digital cancellation to achieve near-identical rate gain regions. Finally, as a design example, we numerically investigate the Full-Duplex system performance and rate gain region in typical indoor environments for practical wireless applications.
Sachin Katti - One of the best experts on this subject based on the ideXlab platform.
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fastforward fast and constructive Full Duplex relays
ACM Special Interest Group on Data Communication, 2014Co-Authors: Dinesh Bharadia, Sachin KattiAbstract:This paper presents, FastForward (FF), a novel Full Duplex relay that constructively forwards signals such that wireless network throughput and coverage is significantly enhanced. FF is a Layer 1 in-band Full Duplex device, it receives and transmits signals directly and simultaneously on the same frequency. It cleanly integrates into existing networks (both WiFi and LTE) as a separate device and does not require changes to the clients. FF's key invention is a constructive filtering algorithm that transforms the signal at the relay such that when it reaches the destination, it constructively combines with the direct signals from the source and provides a significant throughput gain. We prototype FF using off-the-shelf software radios running a stock WiFi PHY and show experimentally that it provides a 3× median throughput increase and nearly a 4× gain at the edge of the coverage area.
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Full Duplex MIMO radios
Proceedings of the 11th USENIX Syposium on Networked Systems Design and Implementation, 2014Co-Authors: Dinesh Bharadia, Sachin KattiAbstract:This paper presents the design and implementation of the first in-band Full Duplex WiFi-PHY based MIMO ra-dios that practically achieve the theoretical doubling of throughput. Our design solves two fundamental chal-lenges associated with MIMO Full Duplex: complexity and performance. Our design achieves Full Duplex with a cancellation design whose complexity scales linearly with the number of antennas, this complexity is close to the optimal possible. Further we also design novel digital estimation and cancellation algorithms that eliminate al-most all interference and achieves the same performance as a single antenna Full Duplex SISO system, which is again the best possible performance. We prototype our design by building our own analog circuit boards and integrating them with a WiFi-PHY compatible standard WARP software radio implementation. We show exper-imentally that our design works robustly in noisy indoor environments, and provides close to the expected theo-retical doubling of throughput in practice.
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Full Duplex radios
ACM Special Interest Group on Data Communication, 2013Co-Authors: Dinesh Bharadia, Emily Mcmilin, Sachin KattiAbstract:This paper presents the design and implementation of the first in-band Full Duplex WiFi radios that can simultaneously transmit and receive on the same channel using standard WiFi 802.11ac PHYs and achieves close to the theoretical doubling of throughput in all practical deployment scenarios. Our design uses a single antenna for simultaneous TX/RX (i.e., the same resources as a standard half Duplex system). We also propose novel analog and digital cancellation techniques that cancel the self interference to the receiver noise floor, and therefore ensure that there is no degradation to the received signal. We prototype our design by building our own analog circuit boards and integrating them with a Fully WiFi-PHY compatible software radio implementation. We show experimentally that our design works robustly in noisy indoor environments, and provides close to the expected theoretical doubling of throughput in practice.
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Practical, real-time, Full Duplex wireless
Proceedings of the 17th annual international conference on Mobile computing and networking - MobiCom '11, 2011Co-Authors: Mayank Jain, Siddharth Seth, Taemin Kim, Dinesh Bharadia, Philip Levis, Kannan Srinivasan, Jung-il Choi, Sachin Katti, Prasun SinhaAbstract:This paper presents a Full Duplex radio design using signal inversion and adaptive cancellation. Signal inversion uses a simple design based on a balanced/unbalanced (Balun) transformer. This new design, unlike prior work, supports wideband and high power systems. In theory, this new design has no limitation on bandwidth or power. In practice, we find that the signal inversion technique alone can cancel at least 45dB across a 40MHz bandwidth. Further, com- bining signal inversion cancellation with cancellation in the digital domain can reduce self-interference by up to 73dB for a 10MHz OFDM signal. This paper also presents a Full Duplex medium access control (MAC) design and evaluates it using a testbed of 5 prototype Full Duplex nodes. Full Duplex reduces packet losses due to hidden terminals by up to 88%. Full Duplex also mitigates unfair channel allocation in AP-based networks, increasing fairness from 0.85 to 0.98 while improving downlink throughput by 110% and uplink throughput by 15%. These experimental results show that a re-design of the wireless network stack to exploit Full Duplex capability can result in significant improvements in network performance.
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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.
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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Recent advances in antenna design and interference cancellation algorithms for in-band Full Duplex relays
IEEE Communications Magazine, 2015Co-Authors: Mikko Heino, Emilio Antonio-rodr??guez, Sathya N. Venkatasubramanian, Sathya Venkatasubramanian, Taneli Riihonen, Timo Huusari, Dani Korpi, Clemens Icheln, Katsuyuki Haneda, Lauri Anttila, Risto WichmanAbstract: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 Full-Duplex 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.
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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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Full Duplex transceiver system calculations analysis of adc and linearity challenges
IEEE Transactions on Wireless Communications, 2014Co-Authors: Dani Korpi, Taneli Riihonen, Lauri Anttila, Mikko Valkama, Ville Syrjala, Risto WichmanAbstract: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.
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Full Duplex transceiver system calculations analysis of adc and linearity challenges
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Taneli Riihonen, Lauri Anttila, Mikko Valkama, Ville Syrjala, Risto WichmanAbstract: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, alongside with 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.
Taneli Riihonen - One of the best experts on this subject based on the ideXlab platform.
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Recent advances in antenna design and interference cancellation algorithms for in-band Full Duplex relays
IEEE Communications Magazine, 2015Co-Authors: Mikko Heino, Emilio Antonio-rodr??guez, Sathya N. Venkatasubramanian, Sathya Venkatasubramanian, Taneli Riihonen, Timo Huusari, Dani Korpi, Clemens Icheln, Katsuyuki Haneda, Lauri Anttila, Risto WichmanAbstract: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 Full-Duplex 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.
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energy detection in Full Duplex cognitive radios under residual self interference
International Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2014Co-Authors: Taneli Riihonen, Risto WichmanAbstract:This paper investigates the possibility to exploit inband Full-Duplex wireless technology for simultaneous spectrum sensing and data transmission in cognitive radio terminals. The focus is especially on the receiver operating characteristics of basic energy detection. Full-Duplex operation suffers from self-interference, even after cancellation since it is imperfect in prac-tice. The effect on the probability of missed detection is analyzed, and increasing sensing time is proposed as a countermeasure for residual distortion which, unlike in half-Duplex operation, does not cause large overhead due to lost transmission opportunities. The study also compares the two- and single-antenna implementations of Full-Duplex radios and elicits a channel imbalance problem in the former due to which sensing provides different information than the transmitting antenna would observe.
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Full Duplex transceiver system calculations analysis of adc and linearity challenges
IEEE Transactions on Wireless Communications, 2014Co-Authors: Dani Korpi, Taneli Riihonen, Lauri Anttila, Mikko Valkama, Ville Syrjala, Risto WichmanAbstract: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.
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Full Duplex transceiver system calculations analysis of adc and linearity challenges
arXiv: Information Theory, 2014Co-Authors: Dani Korpi, Taneli Riihonen, Lauri Anttila, Mikko Valkama, Ville Syrjala, Risto WichmanAbstract: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, alongside with 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.
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hybrid Full Duplex half Duplex relaying with transmit power adaptation
IEEE Transactions on Wireless Communications, 2011Co-Authors: Taneli Riihonen, Stefan Werner, Risto WichmanAbstract:Focusing on two-antenna infrastructure relays employed for coverage extension, we develop hybrid techniques that switch opportunistically between Full-Duplex and half-Duplex relaying modes. To rationalize the system design, the classic three-node Full-Duplex relay link is first amended by explicitly modeling residual relay self-interference, i.e., a loopback signal from the transmit antenna to the receive antenna remaining after cancellation. The motivation for opportunistic mode selection stems then from the fundamental trade-off determining the spectral efficiency: The half-Duplex mode avoids inherently the self-interference at the cost of halving the end-to-end symbol rate while the Full-Duplex mode achieves Full symbol rate but, in practice, suffers from residual interference even after cancellation. We propose the combination of opportunistic mode selection and transmit power adaptation for maximizing instantaneous and average spectral efficiency after noting that the trade-off favors alternately the modes during operation. The analysis covers both common relaying protocols (amplify-and-forward and decode-and-forward) as well as reflects the difference of downlink and uplink systems. The results show that opportunistic mode selection offers significant performance gain over system design that is confined to either mode without rationalization.
