Active Self-interference Cancellation Research Articles

Differential Active Self-Interference Cancellation for Asynchronous In-Band Full-Duplex GFSK

Differential Active Self-Interference Cancellation for Asynchronous In-Band Full-Duplex GFSK

Self-Interference Leakage Estimation ‘N’ Cancellation Element: Design of an Active Self-Interference Cancellation Coupler

Monostatic radar systems as well as radars with separated but nearby-placed transmit and receive antennas are beneficial in terms of cost-efficiency and miniaturization, which is necessary for their integration into compact radar systems or mobile devices <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> as well as for radar networks that demand reciprocal transmission channels between the nodes <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> . However, this lack of separation between the transmit (Tx) and receive (Rx) paths due to miniaturization implies only week isolation between Tx and Rx.

Wideband, Millimeter Wave Domain SI Canceling (&gt;50dB) In-Band Full-Duplex Circulator Receiver

This paper describes a 26-GHz fully integrated In-band Full-duplex Circulator (IBFD) Receiver (RX), which employs passive and active Self-interference Cancellation (SIC) techniques in the mm-wave domain. Coverage of wireless networks at mm-wave frequencies can be enhanced by deploying a large number of base stations economically based on Integrated Access and Backhaul (IAB) relays and repeaters. However, to retain the channel capacity, IAB needs to be implemented using full-duplex schemes that suffer from a strong Transmitter (TX) to RX SI. This SI leakage can significantly impact the receiver sensitivity and increase the baseband/ADC dynamic range requirements. Canceling SI at mm-wave applications is particularly challenging given the high frequency of operation, wide bandwidth, and antenna (ANT) impedance sensitivity to the surroundings. Proposed mm-wave RX with a shared ANT interface based on a circulator with active SI cancelers provide ~53 dB SIC over 400 MHz and ~40 dB SIC over 400 MHz in mm-wave domain to meet the link budget requirements. Proposed architecture achieves SIC by (i) introducing a shared ANT interface based on a hybrid-coupler and a non-reciprocal delay line that provides wideband SIC and additionally creates a SI replica (ii) subsequent active cancellation using SI replica processed with variable gain amplifiers and phase shifters. This system also accommodates SI channel variations due to surroundings. Proposed 26-GHz circulator RX has >100x better SIC at high TX power (>10dBm) levels in comparison to the state-of-the-art and it consumes ~111 mW power. The system is implemented in 45nm SOI CMOS and has an active area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.54\, mm^{2}$ </tex-math></inline-formula> . Stand-alone RX NF is ~5.8 dB and TX to ANT insertion loss (IL) is ~3.1 dB. Over-the-air measurements with modulated TX (128 QAM 2.1 Gb/s) and RX (128 QAM 4.2 Gb/s) signals show an EVM of 3.3%.

Impact of Self-Energy Recycling and Cooperative Jamming on SWIPT-Based FD Relay Networks With Secrecy Constraints

This paper investigates the secrecy performance of a power splitting-based simultaneous wireless information and power transfer cooperative relay network in the presence of an eavesdropper. The relay is considered to operate in full-duplex (FD) mode to perform both energy harvesting and information decoding simultaneously. To accomplish that, the relay is assumed to employ two rechargeable batteries, which switch between power supplying mode and charging mode at each transmission block. We also assume that the self-interference inherent of the FD mode is not completely suppressed. Therefore, it is assumed that, after some stages of passive and active self-interference cancellation, there is still a residual self-interference (RSI). A portion of this RSI (remaining after passive cancellation) is recycled for energy harvesting. In order to improve the system secrecy performance, it is considered that the relay can split its transmit power to send the information signal and to emit a jamming signal to degrade the eavesdropper&#x2019;s channel. The secrecy performance is evaluated in terms of the secrecy outage probability and the optimal secrecy throughput. Tight-approximate and asymptotic expressions are obtained for the secrecy outage probability, and the particle swarm optimization method is employed for addressing the secrecy throughput optimization problem. From numerical results, we show that the secrecy performance can be increased depending on the self-energy recycling channel condition. Finally, our derived expressions are validated via Monte Carlo simulations.

Millimeter-Wave Full Duplex Radios: New Challenges and Techniques

Equipping millimeter-wave (mmWave) systems with full duplex capability would accelerate and transform next-generation wireless applications and forge a path for new ones. Full duplex mmWave transceivers could capitalize on the already attractive features of mmWave communication by supplying spectral efficiency gains and latency improvements while also affording future networks deployment solutions in the form of interference management and wireless backhaul. Foreseeable challenges and obstacles in making mmWave full duplex a reality are presented in this article along with noteworthy unknowns warranting further investigation. With these novelties of mmWave full duplex in mind, we lay out potential solutions - beyond active self-interference cancellation - that harness the spatial degrees of freedom bestowed by dense antenna arrays to enable simultaneous transmission and reception in-band.

High accuracy phase‐matching delay estimation method based on phase correction

In the integrated system of underwater single-node detection and communication, active self-interference cancellation requires high accuracy of time delay estimation. To solve this problem, this Letter proposes a high accuracy delay estimation method based on phase correction. Initially, the normalised frequency correction is calculated according to the phase difference and time delay of the signal. Then, the discrete spectrum is reconstructed, and the phase is obtained by the least square method. Finally, the time delay is estimated by the phase difference between the received signal and the reference signal. This method corrects the phase and frequency errors caused by the Fourier transform and improves the accuracy of time delay estimation. Simulation results confirm the efficacy of the proposed method and achieve the accuracy requirement of the active self-interference cancellation.

Semi-Blind Data Detection and Non-Linear Equalization in Full-Duplex TWR-OFDM Systems With High Mobility

Full-duplex two-way relay (FD-TWR) system has potential to increase the spectral efficiency in the future 5G wireless system. Full-duplex transceiver suffers from inevitable self-interference (SI) which can be alleviated by active self-interference cancellation (SIC) method. However, the mitigation capability of SIC mechanism is limited specifically due to inherent non-linearities of transmitter and receiver front end. As a consequence, residual self-interference (RSI) will degrade the system’s signal-to-noise ratio (SNR) and throughput. Non-linearity in RF power amplifier in collusion with time-variant channel results is a great challenge in efficient signal detection and successful SI suppression. In contrast to classical schemes, which consider non-linear distortion at the transmitter, we present a semi-blind data detection and non-linear channel estimation in the presence of RSI at the receiver. Attributed to non-linearity, the target posterior probability density function is mathematically intractable. In this paper, a sequential importance sampling based particle filtering is used for joint data detection and estimation. Intractable distribution is approximated by using weighted random measures. A Taylor’s series expansion is used to locally linearize the non-analytic form of distribution. Numerical results validate the joint detection and channel estimation scheme. The robustness of the scheme is verified in presence of RSI under high mobility.

Simultaneous Transmission and Reception Transponder for Nano-satellite

The feasibility of simultaneous transmission and reception (STAR) in the same frequency for space transponder in nano-satellite is discussed. The demand of the self-interference cancellation for the transponder is analysed by space-ground link budget, and a STAR superheterodyne architecturebased transponder is also presented. Based on the conventional space TT&C frequency scheme, a feasible frequency scheme and digital signal processing process for the STAR transponder are expatiated. A FFT based carrier acquisition method is modified to adapt to such STAR transponder.The implementation of the STAR transponder is simulated. The simulation results show that with properly deployingthe passive and active self-interference cancellation modules, the self-interference can be cancelled to meet with the demand of demodulation which also implies that the STAR transponder presented in this paper is feasible.The simulation results also show that the radio frequency self-interference cancellation(RFSIC) does matter in such STAR transponder by realizing 29dB self-interference cancellation, and a total self-interference cancellation of about 68dB can be realized by the combination of passive suppression and RFSIC. The numerical results show that the digital self-interference cancellation is not necessary for the transponder when the transmission power of ground-satellite uplink is high enough, and the phase noise power is increased by the digital self-interference module.

Tunable Frequency-Division Duplex RF Front End Using Electrical Balance and Active Cancellation

This paper presents a novel, tunable, frequency-division duplexing radio frequency (RF) front end that combines passive and active self-interference (SI) cancellation. An electrical-balance duplexer is used to passively cancel transmitter noise in the receive band, and an active canceller is employed to suppress SI in the transmit (Tx)-band. Subsystem specifications are developed, and a system-level analysis of noise and SI powers in this novel architecture is provided, thereby illustrating its operation. A proof-of-concept demonstrator, built from a software-defined radio and discrete RF components, has been characterized across a range of duplex configurations in the 700–950-MHz range and also at 1900 (Long-Term Evolution (LTE) band 3) and 2600 MHz (LTE band 7). The prototype achieves an impressive 6.0–7.4-dB noise figure in the presence of a +27-dBm LTE uplink Tx blocker for duplex separations of 47.5 MHz and above. The duplexer has also been tested against reference sensitivity test cases defined in the 3GPP LTE specification, demonstrating specification compliant sensitivity in LTE bands 28 (700 MHz), 3, and 7.

Adaptive Self-Interference Cancellation for Full Duplex Radio: Analytical Model and Experimental Validation

Recent experimental results show that full-duplex (FD) communication is feasible provided that the residual self-interference after cancellation is close to the noise floor. In this paper, we present a low-complexity active self-interference cancellation technique for FD orthogonal frequency division multiplexing (OFDM) systems, which accounts for the inherent cyclostationarity of the OFDM signal in order to effectively cancel the self-interference. The method here proposed estimates the self-interference cancellation path by using a time-averaged mean-square error criterion, combined with a filtered least mean squares adaptive algorithm. Then, its performance is experimentally validated using a self-developed FD radio testbed implemented with off-the-shelf components. When combined with passive cancellation, applying the proposed technique provides enough self-interference suppression as to reach close (less than 2 dB) to the receiver noise floor.

A Low-Power Active Self-Interference Cancellation Technique for SAW-Less FDD and Full-Duplex Receivers

An active self-interference (SI) cancellation technique for SAW-less receiver linearity improvement is proposed. The active canceler combines programmable gain and phase in a single stage and is co-designed with a highly-linear LNA, achieving low noise and low power. A cross-modulation mechanism of the SI canceler is identified and strongly suppressed thanks to the introduction of an internal resistive feedback, enabling high effective receiver IIP3. TX leakage of up to −4 dBm of power is suppressed by over 30 dB at the input of the LNA, with benefits for the entire receiver in terms of IIP3, IIP2, and reciprocal mixing. The design was done in a 40 nm CMOS technology. The system, including receiver and active SI canceler, consumes less than 25 mW of power. When the canceler is enabled, it has an NF of 3.9–4.6 dB between 1.7 and 2.4 GHz and an effective IIP3 greater than 35 dBm.

Achievable Rates of Full-Duplex Massive MIMO Relay Systems Over Rician Fading Channels

We analytically study the achievable rates of full-duplex massive multiple-input multiple-output (MIMO) relay systems over Rician fading channels. The decode-and-forward protocol is adopted at the relay station, where the channel state information (CSI) is assumed to be imperfect. We demonstrate that the system bottleneck, self-interference (SI), can be significantly canceled by zero-forcing (ZF) processing at the relay station, which is equipped with massive receive and transmit arrays. Because no active SI cancellation is deployed at the relay station, there is no need for SI channel estimation. We derive an approximate closed-form achievable rate expression for ZF processing with statistical CSI. When the number of antennas of the transmit and receive arrays at the relay station is sufficiently large, the transmit powers of each source and the relay station can be significantly scaled down proportionally to the number of antennas. Since Rayleigh fading is a special case of Rician fading, the results in this paper hold for Rayleigh fading channels. The theoretical analysis is verified by the numerical results.

Low-Noise Active Cancellation of Transmitter Leakage and Transmitter Noise in Broadband Wireless Receivers for FDD/Co-Existence

A technique for active cancellation of transmitter self-interference in wideband receivers is presented. The active TX leakage cancellation circuitry is embedded within a noise-cancelling low-noise transconductance amplifier (LNTA) so that the noise and the distortion of the cancellation circuitry are cancelled, resulting in a noise-cancelling, self-interference cancelling receiver (NC-SIC RX). A second-point cancellation of TX noise in the RX band is performed after the LNTA so that the noise impact of the second canceller is reduced. Theoretical analyses related to the benefits and limits of active self-interference cancellation as well as the simultaneous cancellation of the noise and distortion of the cancellation circuitry are presented. A 0.3-1.7 GHz receiver with the proposed active cancellation is implemented in 65 nm CMOS. The proposed scheme can cancel up to +2 dBm peak TX leakage at the receiver input. The triple beat at +2 dBm peak TX leakage is 68 dB and the effective IIP3 is +33 dBm, representing increases of 38 and 19 dB, respectively, over the receiver without cancellation. The associated increase in receiver NF is less than 0.8 dB. In addition, the scheme effectively suppresses TX noise in RX band by up to 13 dB. The technique can be more generally viewed as an active combining structure that has ideally no noise penalty and is able to handle large signals without generating distortion and can be applied to any scenario where a replica of an interference signal can be generated.

全双工通信关键技术研究

Traditional half-duplex (HD) wireless systems transmit and receive signals adopting orthogonal time-slots, resulting in a great waste of frequency resources. And full-duplex (FD) wireless communication techniques have drawn extensive attention from academia and industry for the attractive abilities of doubling the channel capacity and promoting the utilization of spectrum resources. We frame the paper by rst comparing the per-formance of HD and FD modes and addressing the advantages and disadvantages of the existing FD techniques. As the core problem of FD systems, self-interference (SI) cancellation will be realized by two main techniques: passive self-interference suppression and active self-interference cancellation. In this paper, we also present the advantages and disadvantages of respective techniques. Besides, the design of FD media access control (FD-MAC) layer is carried out based on the complex time-varying wireless spectrum environment and the dynamic wireless network structure. Furthermore, the design and implement of FD algorithms are presented in this paper, including relay network coding, relay selection and dynamic resource allocation. Finally, we summarize the future research directions and conclude the whole paper.

Experiment-Driven Characterization of Full-Duplex Wireless Systems

We present an experiment-based characterization of passive suppression and active self-interference cancellation mechanisms in full-duplex wireless communication systems. In particular, we consider passive suppression due to antenna separation at the same node, and active cancellation in analog and/or digital domain. First, we show that the average amount of cancellation increases for active cancellation techniques as the received self-interference power increases. Our characterization of the average cancellation as a function of the self-interference power allows us to show that for a constant signal-to-interference ratio at the receiver antenna (before any active cancellation is applied), the rate of a full-duplex link increases as the self-interference power increases. Second, we show that applying digital cancellation after analog cancellation can sometimes increase the self-interference, and thus digital cancellation is more effective when applied selectively based on measured suppression values. Third, we complete our study of the impact of self-interference cancellation mechanisms by characterizing the probability distribution of the self-interference channel before and after cancellation.