Adaptive self-interference cancelation in LTE-A carrier aggregation FDD direct-conversion transceivers

Gebhard, Andreas; Kanumalli, Ram Sunil; Neurauter, B.; Huemer, Mario

doi:10.1109/sam.2016.7569758

Cited by 20 publications

(13 citation statements)

References 9 publications

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“…The other category of blind concepts applies blind source separation (BSS) techniques, which however suffer from high computational effort [19]. In the context of interference cancellation [20], [21], I/Q imbalance calibration plays a role, too. Mixed signal solutions employ an auxiliary receiver with less stringent requirements than a normal receiver, which often leads to designs, where low IRR is even more an issue [22], [23].…”

Section: A Prior Approaches For I/q Imbalance Compensationmentioning

confidence: 99%

Ultra-Low Complex Blind I/Q-Imbalance Compensation

Paireder¹,

Kanumalli²,

Sadjina³

et al. 2019

IEEE Trans. Circuits Syst. I

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Direct-conversion transceivers are the predominating architecture in current mobile communication systems. Despite many advantages, this topology suffers from unavoidable mismatches in the analog part, which causes imbalance between the in-phase and quadrature (I/Q) component. In this paper, we present a novel fully digital, blind I/Q imbalance compensation algorithm that features extremely low computational complexity and high compensation performance for a wide range of input signal types. Different to many state-of-the-art compensation schemes, the approach is not based on a gradient descent optimization and does not require any global feedback. This simplifies the implementation at high data rates and reduces the configuration effort to a minimum. For comparison, we examine an existing method of moment-based estimator with similar properties, for which we also provide the detailed insights beyond available literature. For both algorithms, we provide a rigorous mathematical analysis, which is supported by simulations with a focus on various long-term evolution (LTE) signal types. In addition, hardware architectures, including field-programmable gate array (FPGA) verification, are presented for both algorithms.

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Section: A Prior Approaches For I/q Imbalance Compensationmentioning

confidence: 99%

Ultra-Low Complex Blind I/Q-Imbalance Compensation

Paireder¹,

Kanumalli²,

Sadjina³

et al. 2019

IEEE Trans. Circuits Syst. I

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“…Another critical issue that appears is the Tx modulated spur interference problem that occurs in LTE-CA frequency division duplex (FDD) transceivers [22,23]. In addition, due to the non-linearities in the receiver Tx-induced second order intermodulation distortion (IMD2) interference can appear [24,25].…”

Section: Fig 2 Tx Induced Modulated Spurs and Imd2 Interference Illmentioning

confidence: 99%

Digitally-intensive transceivers for future mobile communications—emerging trends and challenges

Kanumalli

Buckel

Preissl

et al. 2018

Elektrotech. Inftech.

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This article presents an overview of the major trends and challenges involved with the design of multi-band, multi-standard digitallyintensive radio frequency transceivers for next generation mobile communications. In addition, we discuss in detail one aspect of the implementation challenges, namely the occurrence and cancellation of self-interference especially in carrier aggregation modes. For that, we present a novel digital cancellation technique to jointly compensate the self-interference caused by transmit (Tx) modulated spurs and Tx second order intermodulation distortion products (IMD2) in the receiver. This architecture exploits the underlying relation between both types of interference and offers a low-complexity solution to mitigate the Tx-IMD2 interference. Simulation results show, that the proposed technique significantly suppresses both types of interference and restores the signal-to-noise ratio of the wanted signal within 0.3 dB from its value in the absence of interference, thereby achieving 30 dB of cancellation.Keywords: RF; mobile communications; wireless communications; signal processing; interference cancellation; carrier aggregation Digital unterstützte Hochfrequenz-Transceiver für den Mobilfunk der Zukunft -Trends und Herausforderungen. Dieser Artikel gibt zunächst einen Überblick über aktuellen Trends und Herausforderungen bei der Entwicklung von Multi-Band, Multi-Standard HF-Transceivern für die nächste Mobilfunk-Generation, die einen hohen Anteil an digitaler Elektronik aufweisen. Im Anschluss wird im Detail auf ein spezielles Problem solcher Transceiver eingegangen, nämlich der Selbst-Interferenz, die durch den eigenen Sender verursacht wird und die vor allem im Carrier Aggregation-Modus auftritt. Die Problematik wird nicht nur detailliert erklärt, diese Arbeit präsentiert auch eine Methode zur Unterdrückung von Selbst-Interferenz mit den Mitteln der digitalen

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“…simultaneously in time. Due to the limited duplexer isolation, transceivers operating in FDD mode suffer from the leakage of the high power transmit signal that appears in the RX chain [2]. To target this problem, state-of-the-art cellular handsets use duplexers providing a high TX-RX isolation of around 55 dBm [3] in combination with RX architectures being able to handle large blocker levels up to 0 dBm without excessive gain compression [4].…”

mentioning

confidence: 99%

“…Due to device nonlinearities and cross-talk between LO paths resulting from unavoidable layout imperfections, LO-LO spurs can appear at various locations in the receiver, potentially down-converting a blocker into the receiver baseband. This interference present in the baseband is referred to as modulated spur and can cause a severe degradation of the signal-to-noise ratio (SNR) of the desired signal [2], [5]. As shown in Fig.…”

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confidence: 99%

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A Mixed-Signal Circuit Technique for Cancellation of Interferers Modulated by LO Phase-Noise in 4G/5G CA Transceivers

Sadjina¹,

Kanumalli²,

Gebhard

et al. 2018

IEEE Trans. Circuits Syst. I

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In RF transceivers operating in carrier-aggregation, spurs are generated on the transceiver chip which may downconvert any blocker signal located at the spur frequency into the receiver baseband. The blocker signal could either be the transceiver's own transmit signal when operating in frequencydivision duplex, or a WiFi-related signal received by the antenna. This so-called modulated spur interference contains the phasenoise (PN) of the involved local oscillator harmonics which created the spur and leads to a degradation of the wanted RX signal. The presented mixed-signal circuit mimics the spur building law including the PN of the harmonics and is, therefore, able to provide a replica of the spur interference including PN modulated components. This replica is then used as a reference signal for the digital cancellation of the main and image modulated spur interference using a widely-linear (WL) cancellation structure. The proposed circuit technique is implemented in 28 nm LP CMOS technology, and measurement results show that the mixed-signal solution outperforms a digital-only WL cancellation with respect to PN cancellation even with high blocker power levels of −15 dBm at the input of the low-noise amplifier.

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Adaptive self-interference cancelation in LTE-A carrier aggregation FDD direct-conversion transceivers

Cited by 20 publications

References 9 publications

Ultra-Low Complex Blind I/Q-Imbalance Compensation

Ultra-Low Complex Blind I/Q-Imbalance Compensation

Digitally-intensive transceivers for future mobile communications—emerging trends and challenges

A Mixed-Signal Circuit Technique for Cancellation of Interferers Modulated by LO Phase-Noise in 4G/5G CA Transceivers

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