On the Interaction Between Joint Tx/Rx IQI and Channel Estimation Errors in DVB-T Systems

Mohajeran, Seyed Ali; Sadough, Seyed Mohammad Sajad

doi:10.1109/jsyst.2017.2717968

Cited by 5 publications

(7 citation statements)

References 16 publications

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“…In [27], a method of a non-iterative blind compensator to mitigate IQI was introduced and investigated by using inactive subcarriers in orthogonal frequency division multiplexing with index modulation (OFDM-IM) data transmission. To investigate the effect of different IQI on the channel estimation and sum rate, Kolomvakis et al [33] derived the linear minimum mean square error estimator on a MIMO system with large antenna arrays. Furthermore, the expressions of the outage probability were derived by assuming that all the destinations and relay nodes were IQI impaired in [34].…”

mentioning

confidence: 99%

I/Q Imbalance and Imperfect SIC on Two-Way Relay NOMA Systems

Tian

et al. 2020

Electronics

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Non-orthogonal multiple access (NOMA) system can meet the demands of ultra-high data rate, ultra-low latency, ultra-high reliability and massive connectivity of user devices (UE). However, the performance of the NOMA system may be deteriorated by the hardware impairments. In this paper, the joint effects of in-phase and quadrature-phase imbalance (IQI) and imperfect successive interference cancellation (ipSIC) on the performance of two-way relay cooperative NOMA (TWR C-NOMA) networks over the Rician fading channels are studied, where two users exchange information via a decode-and-forward (DF) relay. In order to evaluate the performance of the considered network, analytical expressions for the outage probability of the two users, as well as the overall system throughput are derived. To obtain more insights, the asymptotic outage performance in the high signal-to-noise ratio (SNR) region and the diversity order are analysed and discussed. Throughout the paper, Monte Carlo simulations are provided to verify the accuracy of our analysis. The results show that IQI and ipSIC have significant deleterious effects on the outage performance. It is also demonstrated that the outage behaviours of the conventional OMA approach are worse than those of NOMA. In addition, it is found that residual interference signals (IS) can result in error floors for the outage probability and zero diversity orders. Finally, the system throughput can be limited by IQI and ipSIC, and the system throughput converges to a fixed constant in the high SNR region.Electronics 2020, 9, 249 2 of 16 signals of other users with lower channel gains before decoding their own signals based on the SIC technique [7]. Hence, NOMA can support multiple users with limited resources and improve spectral efficiency, which has attracted considerable attention from academia and industry. For instance, in [8,9], the authors discussed power allocation under various criteria for a downlink NOMA system. In order to improve the system throughput, a network NOMA technique was proposed and analysed for the uplink coordinated multi-point transmission (CoMP) in [10].Cooperative communications is another solution to mitigate the fading effects of wireless environments [11]. NOMA in cooperative communication systems is commonly referred to as cooperative-NOMA (C-NOMA), which is able to enhance the system reliability [12]. The authors analysed the effect of the power allocation coefficient on the error performance under a one-way relay C-NOMA system in [13]. The authors in [14] presented a new system detection scheme for a one-way relay C-NOMA system, which used the maximal ratio combining (MRC) and SIC to decode signals. Sheng Luo et al. in [15] proposed an adaptive transmission scheme based on a one-way relay C-NOMA network with a dedicated relay, which could temporarily store the received information. Recently, two-way relaying (TWR) has attracted a great deal of research attention because of its ability to achieve higher spectral efficiency in comparison to one-way relayin...

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confidence: 99%

I/Q Imbalance and Imperfect SIC on Two-Way Relay NOMA Systems

Tian

et al. 2020

Electronics

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“…However, these works [9]- [13] only presented linear-minimum-mean-squareerror (LMMSE) [14] based CE, that requires strong prior CSI. On another front, there are also some works on least-squares (LS) based CE under IQI [15]- [17]. A special structured pilot was used in [15] to obtain LS estimator (LSE) for both actual and IQI-based virtual signal terms.…”

Section: A State-of-the-artmentioning

confidence: 99%

“…All existing works [9]- [17], investigating the impact of IQI on CE, considered the underlying additional virtual signal term as interference, and simply ignored the information content in it. Likewise, the current precoder designs for multiantenna TX serving single-antenna RX are based on suboptimal maximum ratio transmission (MRT) scheme, ignoring the impairment that signal undergoes due to IQI.…”

Section: B Motivation and Scopementioning

confidence: 99%

“…Current works [9]- [17] considered h B s * +n J as the effective noise signal under IQI, and thus, applied conventional pseudoinverse method [20]…”

Section: A Existing Lse H a For Iqi-impaired Channelsmentioning

confidence: 99%

“…Therefore, LS and LMMSE estimates using conventional methods were presented in [16] to quantify EB gains during MISO wireless power transfer under joint-TX-RX IQI and CE errors over Rician fading. Lately, an LSE using additional pilots to exploit the interference among symmetric subcarriers for mitigating effect of IQI was designed in [17].…”

Section: A State-of-the-artmentioning

confidence: 99%

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Optimal Least Squares Estimator and Precoder for Energy Beamforming Over IQ-Impaired Channels

Mishra

Johansson

2019

IEEE Signal Process. Lett.

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Usage of low-cost hardware in large antenna arrays and low-power wireless devices in Internet-of-Things (IoT) has led to the degradation of practical beamforming gains due to the underlying hardware impairments like in-phase-and-quadraturephase imbalance (IQI). To address this timely concern, we present a new nontrivial closed-form expression for the globally-optimal least-squares estimator (LSE) for the IQI-influenced channel between a multiantenna transmitter and single-antenna IoT device. Thereafter, to maximize the realistic transmit beamforming gains, a novel precoder design is derived that accounts for the underlying IQI for maximizing received power in both single and multiuser settings. Lastly, the simulation results, demonstrating a significant −8dB improvement in the mean-squared error of the proposed LSE over existing benchmarks, show that the optimal precoder designing is more critical than accurately estimating IQI-impaired channels. Also, the proposed jointly-optimal LSE and beamformer outperforms the existing designs by providing 24% enhancement in the mean signal power received under IQI.

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