In-Band Full-Duplex Wireless Systems Research Articles

Exploring the Past, Present, and Future of In-Band Full-Duplex Wireless Systems [Book/Software Reviews

Kenneth Kolodziej is a technical staff member in the RF Technology Group at the Massachusetts Institute of Technology (MIT) Lincoln Laboratory, where he is a principal investigator on wideband electronics and in-band full-duplex (IBFD), commonly known as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">simultaneous transmit and receive</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">STAR</i> ) systems. He has conducted research on RF, microwave, and photonic circuits, including antenna, radar, and communications systems. He received his B.E. and M.E. degrees in electrical engineering from the Stevens Institute of Technology in Hoboken, NJ. He has published numerous journal articles and conference papers and holds several patents in the field of antennas and RF systems. He is also an IEEE Member and is very actively serving the IEEE Society.

Cyclic Prefix Noise Reduction for Digital Self Interference Cancellation in OFDM-Based In-Band Full-Duplex Wireless Systems

Orthogonal frequency division multiplexing (OFDM) is the pertinent waveform for current and next generation wireless systems, whose spectral efficiency can be potentially doubled by in-band full-duplex (IBFD) communication. However, in OFDM based IBFD systems, digital self-interference cancellation (DSIC) employed at baseband does not provide sufficient cancellation in the cyclic prefix (CP) region. When the propagation delay between two communicating radios is non-zero, the CP noise affects the data region of the desired signal. In this work, we propose CP noise reduction (CPNR) technique for OFDM based IBFD radios. We have evaluated CPNR with time and frequency domain DSIC schemes via both simulations and MATLAB and FPGA implementations on our Software Defined Radio based IBFD radio. In the laboratory tests, the total suppression of the IBFD radio is improved by 6 dB by employing CPNR in frequency-domain DSIC and EVM for bidirectional communication is improved by up to 5%, allowing realistic propagation delays. In addition to improving the total suppression and EVM performance, CPNR is also shown to enhance the multi-path resiliency of DSIC techniques.

Photonic-Enabled RF Canceller for Wideband In-Band Full-Duplex Wireless Systems

In-band full-duplex (IBFD) wireless systems offer the ability to revolutionize frequency spectrum utilization for future networks. This is only possible if the self-interference generated by each wireless node is sufficiently mitigated, and becomes more challenging as the bandwidth increases. RF cancellation is one of the critical components that enables this interference reduction, but has previously been limited to narrowband operation or restricted to distinctive environments. This paper presents a novel RF canceller that utilizes photonic components to create a wideband vector modulator architecture with tunable time-delay taps. A prototype system with 20 canceller taps has been demonstrated to provide 25 and 20 dB of cancellation over 500-MHz and 1-GHz instantaneous bandwidths, respectively, and is tunable between 0.5 and 5.5 GHz. This unique photonic-enabled RF canceller design provides a path forward to achieve the wideband operation and high tap counts that will be required to successfully deploy future wireless systems with IBFD technology.

Distribution of the Residual Self-Interference Power in In-Band Full-Duplex Wireless Systems

This paper derives the distribution of the residual self-interference (SI) power in an analog post-mixer canceler adopted in a wireless in-band full-duplex communication system. We focus on the amount of uncanceled SI power due to SI channel estimation errors. Closed form expressions are provided for the distribution of the residual SI power when Rician and Rayleigh fading SI channels are considered. Moreover, the distribution of the residual SI power is derived for low and high channel gain dynamics, by considering the cases when the SI channel gain is time-invariant and time-variant. While for time-invariant channels the residual SI power is exponentially distributed, for time-variant channels the exponential distribution is not a valid assumption. Instead, the distribution of the residual SI power can be approximated by a product distribution. Several Monte Carlo simulation results show the influence of the channel dynamics on the distribution of the residual SI power. Finally, the accuracy of the theoretical approach is assessed through the comparison of numerical and simulated results, which confirm its effectiveness.

In-Band Full-Duplex Relaying: A Survey, Research Issues and Challenges

Recent advances in self-interference cancellation techniques enable in-band full-duplex wireless systems, which transmit and receive simultaneously in the same frequency band with high spectrum efficiency. As a typical application of in-band full-duplex wireless, in-band full-duplex relaying (FDR) is a promising technology to integrate the merits of in-band full-duplex wireless and relaying technology. However, several significant research challenges remain to be addressed before its widespread deployment, including small-size full-duplex device design, channel modeling and estimation, cross-layer/joint resource management, interference management, security, etc. In this paper, we provide a brief survey on some of the works that have already been done for in-band FDR, and discuss the related research issues and challenges. We identify several important aspects of in-band FDR: basics, enabling technologies, information-theoretical performance analysis, key design issues and challenges. Finally, we also explore some broader perspectives for in-band FDR.