Passive Self-Interference Suppression for Full-Duplex Infrastructure Nodes

By Evan Everett, Achaleshwar Sahai, Ashutosh Sabharwal. IEEE Transactions on Wireless Communications, 2013

872 citations recorded by the source corpus.

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.

View Paper: https://www.semanticscholar.org/paper/640d951af6c1bd5b8838746bec29fd0774f16cd2

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Citations in the corpus

In-Band Full-Duplex Relaying: A Survey, Research Issues and Challenges (2015, methodology): “Moreover, propagation-domain self-interference suppression is very important and contributes to a large portion of self-interference cancellation in existing full-duplex designs [42].”
Widely Linear Digital Self-Interference Cancellation in Direct-Conversion Full-Duplex Transceiver (2014, background): “To suppress such SI inside the transceiver, various antenna-based solutions [2], [4], [12], [13], active analog/RF cancellation methods [2]– [4], [8], [14]–[16] and digital baseband cancellation techniques [3], [14], [17], [18] have been proposed in the literature.”
Full-Duplex OFDM Radar With LTE and 5G NR Waveforms: Challenges, Solutions, and Measurements (2019, background): “Then, we address a fundamental implementation challenge stemming from the limited TX–RX isolation [11], [19]–[22] in real base stations and the corresponding transmitter selfinterference (SI) at the radar.”
In-Band Full-Duplex Technology: Techniques and Systems Survey (2019, methodology): “While some amount of this separation effect has been incorporated into all multiantenna IBFD systems, it has independently been studied with variable distances for both directional and omnidirectional antenna elements [18].”
All-Digital Self-Interference Cancellation Technique for Full-Duplex Systems (2014, methodology): “For instance, the experimental results in [14] show that, the self-interference channel Rician factor is inversely proportional to the achieved passive suppression amount which determines the received self-interference signal power.”
A Survey of In-Band Full-Duplex Transmission: From the Perspective of PHY and MAC Layers (2015, background): “The authors in [13], [14], [30], [33], [38], [41], [51], [53], [54] implemented IBFD systems with WARP platforms to verify the feasibility of IBFD systems in smallsized devices such as laptop computers.”
BackFi: High Throughput WiFi Backscatter (2015, methodology): “We leverage recent work on self-interference can-celation for full-duplex radios to enable the backscatter signal to be received while the WiFi device is transmitting [17, 20, 43, 12, 8, 11, 9, 8, 26, 16, 39, 10].”