Air-Induced Passive Intermodulation in FDD Networks: Modeling, Cancellation and Measurements

Lampu, Vesa; Anttila, Lauri; Turunen, Matias; Fleischer, Marko; Hellmann, Jan; Valkama, Mikko

doi:10.1109/ieeeconf53345.2021.9723205

Cited by 7 publications

(15 citation statements)

References 11 publications

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“…In CA, multiple component carriers (CCs) are adopted to increase throughput and capacity, while, in general, the CC allocation can be contiguous or noncontiguous in frequency. When such CA signals experience nonlinearity-especially in the case of noncontiguous allocation-severe intermodulation distortion can be generated, and if the source of the nonlinearity is a passive device, the distortion is called passive intermodulation (PIM) [2]- [8]. PIM can, in general, be generated by loose connection of cables, filters, switches, or even external metallic objects in the radiation field of the antennas, which we call air-induced PIM in this work.…”

Section: Introductionmentioning

confidence: 99%

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Air-Induced PIM Cancellation in FDD MIMO Transceivers

Lampu

Anttila

Turunen

et al. 2022

IEEE Microw. Wireless Compon. Lett.

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In this letter, air-induced passive intermodulation (PIM) modeling and cancellation schemes are presented in a multiple-input multiple-output (MIMO) frequency-division duplexing (FDD) transceiver context. PIM is distortion generated by nonlinear passive devices either within the transmitter chain or outside the transceiver system, as is the case in air-induced PIM. In FDD systems, the PIM products may lie on the receiver band, thus possibly desensitizing the receiver chain. Unlike previous PIM cancellation works, we consider a challenging rank-2 dual-carrier MIMO transceiver scenario, with two spatially multiplexed signals per component carrier (CC). Stemming from the PIM modeling, we first present a cancellation method based on a complete set of identified basis functions (BFs). Additionally, to relax the processing complexity, we propose an alternative canceller solution with a reduced number of BFs, inspired by the problem modeling. RF measurements conducted with real-life equipment indicate favorable PIM suppression levels of up to 20 dB using both introduced techniques.

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Section: Introductionmentioning

confidence: 99%

“…More recently, in [7], conducted PIM cancellers taking into account also the potentially co-existing PA nonlinearity with reduced complexity through decoupling the memory were introduced, focusing also on a two CC case. Our previous work [8] considered the modeling and digital cancellation of air-induced PIM in a simple two CC scenario.…”

Section: Introductionmentioning

confidence: 99%

Air-Induced PIM Cancellation in FDD MIMO Transceivers

Lampu

Anttila

Turunen

et al. 2022

IEEE Microw. Wireless Compon. Lett.

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“…This indicates that we only require a third-order instantaneous model of the received signal to determine the q coefficients. For improved accuracy in the implementation of the algorithm, the coefficients q 1 and q 2 can be defined as arithmetic means of the shown expressions in (15) and (16). We can then construct the BF matrix [t] of (10) using the BFs expressed in Table I Calculate c as per Eq.…”

Section: B Channel Coefficient Method: Single Pim Sourcementioning

confidence: 99%

“…The potential coexistence of nonlinear power amplifiers (PAs) and PIM distortion is considered in [12] and [18], where reduced complexity models through decoupling of the nonlinearity and memory were introduced. In [16], basic modeling and digital cancellation of air-induced PIM were pursued in a simple two-CC scenario. Finally, our preliminary work in [17] addresses the air-induced PIM cancellation in a multiple-input-multiple-output (MIMO) scenario with four simultaneous carriers.…”

Section: A Prior Artmentioning

confidence: 99%

“…If the source of the nonlinearity is a passive device, the distortion is called passive intermodulation (PIM) [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17]. Typically, loose connections of cables, filters, switches, antennas [12], [13], [14], [15], [18], [19], [20], [21], or even external metallic objects in the radiation field of the antennas [16], [17] can be the cause of PIM. The PIM caused by external sources is in focus in this work, and such distortion is referred to as airinduced PIM.…”

Section: Introductionmentioning

confidence: 99%

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Air-Induced Passive Intermodulation in FDD MIMO Systems: Algorithms and Measurements

Lampu

Anttila

Turunen

et al. 2023

IEEE Trans. Microwave Theory Techn.

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In this article, we model and develop effective cancellation schemes for passive intermodulation (PIM) distortion induced by external objects in the vicinity of the transmitterreferred to as air-induced PIM-in frequency-division duplex (FDD) multiple-input-multiple-output (MIMO) systems. PIM is interference generated from the transmitted signals undergoing nonlinear transformation, which, in FDD systems, may cause desensitization of the receiver chain. First, we present a general model of the received air-induced PIM signal, with an arbitrary number of dual-carrier TX chains active and an arbitrary number of PIM sources causing interference, on all the intermodulation frequencies. Then, the derived model is used to develop a cancellation scheme based on a complete set of basis functions (BFs) in a rank-2 dual-carrier MIMO system with four active carriers. To alleviate the high complexity of the aforementioned scheme, we then propose a novel alternative cancellation scheme with much reduced complexity, leveraging on the physical modeling of the system, which is capable of handling any number of PIM sources in the system. RF measurementbased experimentations carried out with real-life equipment evidence excellent cancellation capabilities of the complete BF model, which can be retained with much reduced complexity with the proposed alternative technique.

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Overview of Passive Intermodulation in Modern Wireless Networks: Concepts and Cancellation Techniques

Ahmmed,

Kiayani,

Shubair

et al. 2023

IEEE Access

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Passive Intermodulation (PIM) is a well-known phenomenon that poses a significant challenge to modern wireless communication systems. Although efforts have been made to reduce or mitigate the PIM through hardware design, frequency planning, and/or band separation techniques, the impact of PIM on radio performance remains significant. This is especially true for radio transceivers operating in the frequency division duplex mode, which are known to be susceptible to PIM interference. Moreover, with the adoption of carrier aggregation and advanced multi-antenna technology, PIM is increasingly becoming a major problem in multi-band multi-standard radio systems. Therefore, innovative approaches that exploit PIM detection, avoidance, and cancellation techniques are required to effectively mitigate or reduce its impact. In response to these challenges, this study highlights various PIM interference mechanisms and their interactions which cause potential receiver sensitivity degradation. The discussion further explores PIM mitigation strategies, and underscores the potential of digital PIM cancellation solutions to offer a hardware-independent resolution for reducing PIM impact in multi-band radios, in the 5G era and beyond in radio systems.

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Air-Induced Passive Intermodulation in FDD Networks: Modeling, Cancellation and Measurements

Cited by 7 publications

References 11 publications

Air-Induced PIM Cancellation in FDD MIMO Transceivers

Air-Induced PIM Cancellation in FDD MIMO Transceivers

Air-Induced Passive Intermodulation in FDD MIMO Systems: Algorithms and Measurements

Overview of Passive Intermodulation in Modern Wireless Networks: Concepts and Cancellation Techniques

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