A Survey of Self-Interference in LTE-Advanced and 5G New Radio Wireless Transceivers

Sadjina, Silvester; Paireder, Thomas; Huemer, Mario; Pretl, Harald

doi:10.1109/tmtt.2019.2951166

Cited by 53 publications

(26 citation statements)

References 79 publications

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“…Some terms are redundant, thus, the number of real-valued operations can be reduced slightly. Depending on the available hardware, the frequency shift by f ∆ might be implemented using a multiplication with precomputed complex exponentials or the CORDIC 5 algorithm [49]. The specification of the CSF is provided in Table II, too.…”

Section: A Implementation Of Reference Signal Generationmentioning

confidence: 99%

“…J K is the reversal matrix of size K × K [50]. Similarly to the analysis in [41], the samples of the reference 5 Coordinate Rotation Digital Computer signal are highly correlated and, thus, the Eigenvalue spread of the auto-covariance matrix of x[n] is high for narrow allocations. The TD-LMS is a standard concept to improve the performance of the N-LMS algorithm in such cases [42] by transforming the reference sequence.…”

Section: B Transform-domain Lms Algorithmmentioning

confidence: 99%

“…In FDD carrier aggregation (CA) operation, which is enabled by the Long-Term Evolution Advanced (LTE-A) and 5G standards [3], [4], PA harmonics are critical. A harmonic emission close to an Rx carrier might be down-converted to the baseband (BB) and overlay the wanted Rx signal [5]. The spectral separation provided by the front-end filters, especially the duplexers, is typically insufficient to avoid a deterioration of the Rx signal.…”

Section: Introductionmentioning

confidence: 99%

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Low-Complex Digital Cancellation of Transmitter Harmonics in LTE-A/5G Transceivers

Paireder

Huemer

2021

IEEE Open J. Commun. Soc.

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Nowadays, mobile communication radio frequency transceivers for LTE-A/5G usually operate in frequency-division duplex mode and support carrier aggregation. The resulting complexity requires compromises in the analog front-end. One consequence is a limited stop-band attenuation of the duplex filters that separate the transmit and the receive paths. The resulting transmit leakage signal combined with other non-idealities, like power amplifier (PA) harmonics, can create self-interference problems that desensitize the receivers. In this work, we propose an optimized digital self-interference cancellation scheme to mitigate the unacceptable performance degradation caused by PA induced harmonics. We derive an appropriate interference model and quantify the interference power levels for a specific PA. Based on these results, our low-complex cancellation approach solely targets the dominating components. Our algorithm relies on the auto-covariance matrix for the second and third power of LTE signals, which we derive for the first time in an analytic form. This statistical information can be combined with the transform-domain concept to noticeably improve the performance of a least-mean squares based cancellation algorithm. The capabilities of the approach are demonstrated by means of simulations and are validated on measurement data.

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Section: A Implementation Of Reference Signal Generationmentioning

confidence: 99%

Section: B Transform-domain Lms Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low-Complex Digital Cancellation of Transmitter Harmonics in LTE-A/5G Transceivers

Paireder

Huemer

2021

IEEE Open J. Commun. Soc.

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“…However, recent studies suggested that the second-order intermodulation (IM) distortion may be significant in wideband transceivers widely used in long-term evolution advanced (LTE-A) and fifth-generation new radio (5G NR) systems [2][3][4][5][6][7]. In direct conversion receivers, also known as homodyne or zero-IF receivers, the second-order IM dominates in degrading the performance of the receiver by causing a severe signalto-interference-plus-noise ratio degradation of the received signal [6,7] because the regenerated second-order distortion is hard to discriminate from the desired signal [8]. Further, the second-order intercept point (IP2), which is used to quantify the second-order distortion regenerated by non-linear sys-tems and devices, appears more frequently in recent amplifier datasheets [9].…”

Section: Introductionmentioning

confidence: 99%

On IP2 impact to nonlinear distortion of RF amplifiers

Yang

Yan

et al. 2021

J. eng.

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The second-order distortion, often using second-order intercept point (IP2) as an indicator, has been considered easy to be filtered in narrowband radio frequency (RF) communications because it is located far away from the passband of transmitted signals. However, with rapidly increased applications in wideband RF communications, the secondorder intermodulation (IM) might become important, partially evidenced by the increased appearances of IP2 in the amplifier datasheets in recent years. In this article, a power spectrum model of the second-order IM is derived to quantify the second-order distortion using the IP2. This model could be used to determine under what conditions, in terms of the relation between the carrier frequency and bandwidth, the second-order IM will affect the passband or the adjacent bands or other applications, using three types of frequency scenarios. These discussions are beneficial for RF engineers and spectrum planners to predict interferences from second-order IM. The experimental measurement at the end of the article validates the spectrum model. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…In potential applications, as the frequency of the 5G band n78 is approximately twice that of the LTE band B3, when an MS in the dual-connectivity mode transmits signals in the LTE band B3 while receiving in the 5G band n78, its receiver will be severely interfered by the nonlinear interference due to the distortion of the power amplifier (PA) [4]. Specifically, as the transmitted signal in the uplink frequency band comprises the desired transmitted signal (DTS) and mirror frequency interference (MFI) due to the in-phase/quadrature (I/Q) imbalance of the transmitter, the received nonlinear interference in the downlink frequency band includes not only the secondorder harmonics of the DTS and MFI, but also the evenorder intermodulation products (IMP) of the DTS and MFI.…”

Section: Introductionmentioning

confidence: 99%

Neural-Network-Based Nonlinear Self- Interference Cancelation Scheme for Mobile Stations With Dual-Connectivity

Wang

Qin

2021

IEEE Access

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Dual-connectivity technology enables a base station to assign multiple carriers from various bands to a mobile station (MS), thus increasing its bandwidth and data rate. However, when the downlink frequency assigned to the MS is approximately twice its uplink frequency, the MS's receiver will be seriously interfered by the nonlinear self-interference from its own transmitter. This paper addresses the problem of nonlinear self-interference cancelation for MSs operating in the dual-connectivity mode. Compared with conventional systems, this scenario faces some new challenges because of the wide variety of nonlinear interference components, including not only harmonics but also intermodulation products, and the more complicated interference channels, including both nonlinear and linear devices. In addition, the frequency, bandwidth and frequency-selective channel parameters of the interference are influenced by the uplink resource block allocation. To solve these problems, a two-part nonlinear self-interference canceler is proposed, where one part is designed as a neural network to capture the nonlinear characteristics, and the other part is designed as a linear filter to capture the linear characteristics. Furthermore, a low-complexity two-step training scheme is proposed to approximate the interference channel in the entire system bandwidth. Finally, a hardware prototype is implemented to verify the effectiveness of the proposed scheme. The experimental results show that the proposed scheme achieves more than 20 dB interference cancelation, and significantly outperforms the conventional polynomial-based and pure neural-network cancelation schemes.

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A Survey of Self-Interference in LTE-Advanced and 5G New Radio Wireless Transceivers

Cited by 53 publications

References 79 publications

Low-Complex Digital Cancellation of Transmitter Harmonics in LTE-A/5G Transceivers

Low-Complex Digital Cancellation of Transmitter Harmonics in LTE-A/5G Transceivers

On IP2 impact to nonlinear distortion of RF amplifiers

Neural-Network-Based Nonlinear Self- Interference Cancelation Scheme for Mobile Stations With Dual-Connectivity

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