A Frequency-Selective I/Q Imbalance Analysis Technique

Rodriguez-Avila, R.; Nunez-Vega, G.; Parra-Michel, R.; Guzmán, Martha Elva Ramírez; Torres-Roman, D.

doi:10.1109/twc.2014.022014.130414

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…ZF/EZF is the basic operation in ZF-OSIC/EZF-OSIC, therefore EZF-OSIC with true M N T has superior performance to ZF-OSIC. Because the solution given by WLSD is equivalent to the solution obtained by EZF-OSIC for model (9), WLSD has a significantly improved performance with respect to the traditional ZF-OSIC. If C is an EMMSE receiver, we have [17]:…”

Section: B Mean Square Error Distance/snr Improvementmentioning

confidence: 99%

See 1 more Smart Citation

Widely Linear Sphere Decoder in MIMO Systems by Exploiting the Conjugate Symmetry of Linearly Modulated Signals

Ding

Wang

et al. 2016

IEEE Trans. Signal Process.

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International audienceThis paper investigates the widely linear processing(WLP) for the detection of circular signals such as M-aryphase shift keying (MPSK) signals, M-ary quadrature amplitudemodulation (MQAM) signals. Firstly, a unified mathematicalmodel is derived to describe the conjugate symmetry of generalMPSK/MQAM signals. In the unified model, a phase-rotation matrix(PRM) is introduced to partition the constellation of multipleinputmultiple-output (MIMO) signals into subsets. Signals in asubset share the same PRM. Secondly, a widely linear receiver isproposed in each subset for MIMO detection. To avoid repetitiveWLP in each subset, a widely linear sphere decoder (WLSD)is further proposed for MIMO systems. WLSD transforms thetraditional SD searching for a true transmitted vector into ashrunk one by searching for the corresponding phase-rotationvector

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Section: B Mean Square Error Distance/snr Improvementmentioning

confidence: 99%

“…would be, in wide sense, a left pseudo inverse of the extended channel matrix in the extended MIMO model (9). This is because…”

mentioning

confidence: 99%

Widely Linear Sphere Decoder in MIMO Systems by Exploiting the Conjugate Symmetry of Linearly Modulated Signals

Ding

Wang

et al. 2016

IEEE Trans. Signal Process.

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“…Because WLP can expand the "observation space" by considering both the observation data and their complex conjugates, so that the statistical information contained in both the covariance matrix and conjugate covariance matrix of the received signal can be fully exploited. That is why WLP has been attracting increasing attention in beamforming [19]- [22], direction-of-arrival (DoA) finding [23], wireless communications [24]- [26], [28]- [34], parameter estimation [35], [36], speech enhancement [37], image processing [38] etc. However, to the best of the authors' knowledge, few research considers WLP in NOMA.…”

Section: Introductionmentioning

confidence: 99%

A MIMO-NOMA Framework With Complex-Valued Power Coefficients

Tong

Ding

Liu

et al. 2019

IEEE Trans. Veh. Technol.

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This paper proposes a widely linear processing framework for multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) downlink systems. In the framework, a widely linear MIMO-NOMA (WL-MIMO-NOMA) model is derived by assuming that the base station transmits real-valued downlink signals. WL-MIMO-NOMA adopts complex-valued power allocation coefficients to stagger the user signals in phase. The main features of WL-MIMO-NOMA are the following: first, in general case, WL-MIMO-NOMA can remove all the inter-cluster interference and at least half of the intra-cluster interference; and second, in user pairing case, both interferences can be completely eliminated. This is distinct from the existing work where real power coefficients are used, which cannot guarantee the complete separation of the paired user signals because the signals transmitted to the paired users are overlapped in phase. In addition, the closed-form expressions of outage probabilities are derived. The phase difference of the complex power coefficients is optimized to minimize the outage probability. It is proven that, with the optimal phase difference, successive interference cancellation is unnecessary in user pairing case. Finally, the framework is extended to the mixed case of real/complex circular signals. Simulation results show that the proposed framework outperforms the existing work, and the numerical results agree well with the analytical analysis.

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“…However, these preambles usually serve for the purpose of frame synchronization and channel estimation, and are not designed for I/Q imbalance estimation. Therefore, rather than using these existing preambles, most pilot-aided I/Q imbalance estimation methods in literature were based on pilot signals with a dedicated structure [3], [4], and these pilot designs were usually incompatible with the existing preambles in common communication systems. These methods required exclusive pilot signals for I/Q imbalances estimation, and consequently resulted in an additional overhead.…”

Section: Introductionmentioning

confidence: 99%

I/Q Imbalance Estimation for Direct Conversion Receivers by Jointly Using the Existing Preambles and Blind Estimation

Wu¹,

Shamain²,

Choudhury³

et al. 2014

2015 IEEE Global Communications Conference (GLOBECOM)

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In this paper, we study the baseband estimation of the frequency-dependent imbalance between the in-phase and quadrature branches (I/Q imbalance) of a direct-conversion receiver, by exploiting the preambles which is not specially designed for I/Q imbalance estimation. We propose an in-service estimation method which consists of two stages: the first stage utilizes the existing preambles in a standard-compliant system to estimate the frequency-independent component of the I/Q imbalances on only a subset of subcarriers; in the second stage, a blind estimation method is proposed to estimate the frequencydependent component of I/Q imbalances on all subcarriers, based on the result of the first stage and the second-order statistics of the received signal. The proposed estimation method is applicable to commonly used multi-carrier systems.

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A Frequency-Selective I/Q Imbalance Analysis Technique

Cited by 10 publications

References 17 publications

Widely Linear Sphere Decoder in MIMO Systems by Exploiting the Conjugate Symmetry of Linearly Modulated Signals

Widely Linear Sphere Decoder in MIMO Systems by Exploiting the Conjugate Symmetry of Linearly Modulated Signals

A MIMO-NOMA Framework With Complex-Valued Power Coefficients

I/Q Imbalance Estimation for Direct Conversion Receivers by Jointly Using the Existing Preambles and Blind Estimation

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