Adaptive RF Front-Ends Using Electrical-Balance Duplexers and Tuned SAW Resonators

Liempd, Barend van; Visweswaran, Akshay; Ariumi, Saneaki; Hitomi, Shinya; Wambacq, Piet; Craninckx, Jan

doi:10.1109/tmtt.2017.2728039

Cited by 40 publications

(26 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fact that the receiver must be operating simultaneously while transmitting, and at the same carrier frequency, leads to large implementation challenges particularly in facilitating sufficient transmitter-receiver isolation [12], [19], [23], [28], [37]- [40]. This calls for new hardware, to replace the TDD RF switching with more elaborate circulator [20], [23]- [25] or EBD [12], [26], [27] type of circuitries, and has been studied actively over the recent years, under the inband full-duplex radio terminology, with primarily communications applications in mind, see, e.g., [19], [23], [37]- [45]. In the radar context, the self-interference (SI) stemming from the direct coupling of the transmit signal to the receiver can be interpreted as a strong static target at a very short distance [11], [12], [33], [46].…”

Section: Self-interference Problem and Cancellation Solutions Amentioning

confidence: 99%

Full-Duplex OFDM Radar With LTE and 5G NR Waveforms: Challenges, Solutions, and Measurements

Barneto

Riihonen

Turunen

et al. 2019

IEEE Trans. Microwave Theory Techn.

226

View full text Add to dashboard Cite

This paper studies the processing principles, implementation challenges, and performance of OFDM-based radars, with particular focus on the fourth-generation Long-Term Evolution (LTE) and fifth-generation (5G) New Radio (NR) mobile networks' base stations and their utilization for radar/sensing purposes. First, we address the problem stemming from the unused subcarriers within the LTE and NR transmit signal passbands, and their impact on frequency-domain radar processing. Particularly, we formulate and adopt a computationally efficient interpolation approach to mitigate the effects of such empty subcarriers in the radar processing. We evaluate the target detection and the corresponding range and velocity estimation performance through computer simulations, and show that highquality target detection as well as high-precision range and velocity estimation can be achieved. Especially 5G NR waveforms, through their impressive channel bandwidths and configurable subcarrier spacing, are shown to provide very good radar/sensing performance. Then, a fundamental implementation challenge of transmitter-receiver (TX-RX) isolation in OFDM radars is addressed, with specific emphasis on shared-antenna cases, where the TX-RX isolation challenges are the largest. It is confirmed that from the OFDM radar processing perspective, limited TX-RX isolation is primarily a concern in detection of static targets while moving targets are inherently more robust to transmitter self-interference. Properly tailored analog/RF and digital selfinterference cancellation solutions for OFDM radars are also described and implemented, and shown through RF measurements to be key technical ingredients for practical deployments, particularly from static and slowly moving targets' point of view.

show abstract

Section: Self-interference Problem and Cancellation Solutions Amentioning

confidence: 99%

Full-Duplex OFDM Radar With LTE and 5G NR Waveforms: Challenges, Solutions, and Measurements

Barneto

Riihonen

Turunen

et al. 2019

IEEE Trans. Microwave Theory Techn.

226

View full text Add to dashboard Cite

show abstract

“…These cancellation techniques have previously been combined for in-band full-duplex (IBFD) applications [6], and thus this architecture supports both FDD and IBFD. This work also characterises the desensitisation in the presence of a +27 dBm Tx blocker, going beyond previous works which either did not characterise desensitisation noise [4], [5], or did not achieve full power operation [3]. Section II introduces the design and operation of the novel duplexing architecture, and Section III describes the hardware prototype.…”

Section: Introductionmentioning

confidence: 98%

“…In [3], active cancellation (AC) only is used to cancel SI at the Rx input, however the Rx is desensitised to a noise figure of 15.4 dB at a Tx power of just +17 dBm, suggesting AC alone may be insufficient. Electrical balance duplexers (EBDs) implement a form of passive selfinterference cancellation, and CMOS EBD prototypes have demonstrated the required power handling, insertion loss, and linearity for cellular handset applications [4], [5]. But, to date no EBD prototypes have demonstrated sufficiently wideband (>20 MHz) transmit-to-receive (Tx-Rx) isolation concurrently in the Tx and Rx bands [4].…”

Section: Introductionmentioning

confidence: 99%

“…But, to date no EBD prototypes have demonstrated sufficiently wideband (>20 MHz) transmit-to-receive (Tx-Rx) isolation concurrently in the Tx and Rx bands [4]. However EBDs may be combined with additional filters to enhance isolation, e.g., [5], where an EBD provides Rx band isolation and is combined with a tunable SAW filter in the Rx path for Tx blocker rejection. Whilst achieving >50 dB isolation in both bands, this suffers from high complexity in the EBD balancing circuit, increases the Rx insertion loss, and still relies on off-chip components.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A 700–950 MHz Tunable Frequency Division Duplex Transceiver Combining Passive and Active Self-interference Cancellation

Laughlin

Zhang

Beach

et al. 2018

2018 IEEE/MTT-S International Microwave Symposium - IMS

View full text Add to dashboard Cite

This paper presents a novel tunable FDD transceiver architecture which uses an electrical balance duplexer (EBD) to isolate Tx noise in the Rx band, and combines this with active self-interference cancellation to suppress the Tx blocker. This overcomes the limited isolation bandwidth of EBDs, shifting complexity from the RF domain to the digital baseband domain in order to provide isolation in both bands. A discrete hardware prototype has shown promising results and demonstrated the viability of this architecture, achieving 6.0-7.4 dB antenna referred noise figure in a 20 MHz downlink bandwidth, in the presence of a +27 dBm Tx blocker, across a range of duplex configurations in the 700-950 MHz range.

show abstract

“…However, the SAW devices used in commercial LTE user equipment (UEs) often exceed this by a substantial margin; state-of-the-art acoustic resonator duplexers can provide 60-70 dB of isolation [5]. Electrical balance duplexers (EBDs) implement a form of feedforward RF self-interference cancellation based on the balancing of signals within a hybrid junction, and have received substantial interest as a potential alternative to SAW duplexers [1], [2], [4]. EBDs can be implemented within the radio frequency integrated circuit (RFIC), can be tuned over wide frequency ranges [1].…”

Section: Introductionmentioning

confidence: 99%

Tunable Duplexers: Downlink Band Isolation Requirements for LTE User Equipment

Laughlin

Zhang

Beach

et al. 2019

IEEE Wireless Commun. Lett.

View full text Add to dashboard Cite

Tunable duplexers based on self-interference cancellation present a promising alternative to fixed-frequency duplexers (e.g. surface acoustic wave devices), however the level of transmit-to-receive (Tx-Rx) isolation they provide is typically lower compared to acoustic devices. This paper quantifies the impact of reduced isolation on receiver (Rx) noise figure (NF), and determines minimum isolation requirements for Tx-Rx isolation in cellular handset transceivers. Measurements of Tx noise power spectral density from a cellular handset power amplifier are combined with theoretical analysis and long term evolution (LTE) downlink throughput simulations to assess the impact of isolation on the noise figure and sensitivity. Although lower duplexer isolation can lead to substantial desensitization for some duplex separation/bandwidth combinations, achieving LTE compliant sensitivity requires only 38 dB of isolation in the Rx band. LTE sensitivity specification compliance is therefore readily achievable with current tunable duplexing technologies.

show abstract

Adaptive RF Front-Ends Using Electrical-Balance Duplexers and Tuned SAW Resonators

Cited by 40 publications

References 13 publications

Full-Duplex OFDM Radar With LTE and 5G NR Waveforms: Challenges, Solutions, and Measurements

Full-Duplex OFDM Radar With LTE and 5G NR Waveforms: Challenges, Solutions, and Measurements

A 700–950 MHz Tunable Frequency Division Duplex Transceiver Combining Passive and Active Self-interference Cancellation

Tunable Duplexers: Downlink Band Isolation Requirements for LTE User Equipment

Contact Info

Product

Resources

About