Optimal and Suboptimal Minimum-Variance Filtering in Networked Systems with Mixed Uncertainties of Random Sensor Delays, Packet Dropouts and Missing Measurements

Maryam Moayedi,Yeng Chai Soh,Yung Kuan Foo 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.6

In this paper the Kalman filtering problem for networked stochastic linear discrete-time systems with random measurement delays, packet dropouts and missing measurements is studied. Based on a quasi Markov-chain approach, a unified/combined model is developed to accommodate random delay, packet dropout and missing measurement. Two approaches for constructing a filter via the linear matrix inequality approach are proposed. Simulation studies are then conducted to evaluate the effec-tiveness of the constructed estimators.

Performance analysis of WPM‐based transmission with equalization‐aware bit loading

Sarbagya Buddhacharya,Poompat Saengudomlert 한국전자통신연구원 2019 ETRI Journal Vol.41 No.2

Wavelet packet modulation (WPM) is a multicarrier modulation (MCM) technique that has emerged as a potential alternative to the widely used orthogonal frequency‐division multiplexing (OFDM) method. Because WPM has overlapped symbols, equalization cannot rely on the use of the cyclic prefix (CP), which is used in OFDM. This study applies linear minimum mean‐square error (MMSE) equalization in the time domain instead of in the frequency domain to achieve low computational complexity. With a modest equalizer filter length, the imperfection of MMSE equalization results in subcarrier attenuation and noise amplification, which are considered in the development of a bit‐loading algorithm. Analytical expressions for the bit error rate (BER) performance are derived and validated using simulation results. A performance evaluation is carried out in different test scenarios as per Recommendation ITU‐R M.1225. Numerical results show that WPM with equalization‐aware bit loading outperforms OFDM with bit loading. Because previous comparisons between WPM and OFDM did not include bit loading, the results obtained provide additional evidence of the benefits of WPM over OFDM.

에너지 효율적 반복 SIC-MMSE MIMO 검출

클라우파브리스,아흐메드살림,김수영 통신위성ㆍ우주산업연구회 2015 한국위성정보통신학회논문지 Vol.10 No.1

본 논문에서는 연판정 간섭 소거 최소 자승-오류(soft interference cancellation and minimum mean squared-error; SIC-MMSE)방법을 이용한 새로운 에너지 효율적 다중안테나(multi-input multi-output; MIMO) 검출 기법을 소개한다. SIC-MMSE 방법의 가장 큰 계산 복잡도는 복소 행렬에 대하여 안테나 개수 만큼의 여러 번 역행렬 계산을 해야 하는데 있다. 본 논문에서는 행렬에 대한테일러 시리즈 확장(Taylor series expansion) 기법을 이용하여 안테나 개수에 상관없이 단 한번의 역행렬 계산만을 필요로 하는방법을 제안하며, 이와 같은 방법을 이용하여 계산의 복잡도를 감소시킬 수 있다. 본 논문에서 제안한 기법의 복잡도 감소 효과는안테나 개수가 증가함에 따라 더 크게 나타난다. 본 논문에서 제시한 시뮬레이션 결과를 통하여 제안한 기법이 기존의 SIC-MMSE기법에 비하여 더 적은 복잡도로 거의 동일한 성능을 도출할 수 있음을 알 수 있다. In this paper, we propose a new computationally efficient joint iterative multi-input multi-output (MIMO) detection schemeusing a soft interference cancellation and minimum mean squared-error (SIC-MMSE) method. The critical computationalburden of the SIC-MMSE scheme lies in the multiple inverse operations of the complex matrices. We find a new way whichrequires only a single matrix inversion by utilizing the Taylor series expansion of the matrix, and thus the computationalcomplexity can be reduced. The computational complexity reduction increases as the number of antennas is increased. Thesimulation results show that our method produces almost the same performances as the conventional SIC-MMSE withreduced computational complexity.

Centralized Two-Way AF MIMO Multiple Dispersed Relay Network

Kanghee Lee,Jie Yang,Kwon, Hyuck M.,Hyuncheol Park,Lee, Yong H. IEEE 2015 IEEE Transactions on Vehicular Technology VT Vol.64 No.5

<P>This paper considers a two-way amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay network consisting of two sources (each with multiple antennas) and multiple physically dispersed single-antenna relays. A central station finds the optimum relay amplifying matrices and transmit/receive beamforming vectors explicitly and iteratively under the transmit power constraints at the sources and the relays. The minimum-mean-square-error criterion is used. Numerical results show that the proposed scheme outperforms the existing two-way AF MIMO network schemes proposed by Arti et al. and Wang et al.</P>

Energy efficient joint iterative SIC-MMSE MIMO detection

클라우파브리스,아흐메드살림,김수영,Ngayahala, F.C. Kamaha,Ahmed, Saleem,Kim, Sooyoung Korea Society of Satellite Technology 2015 한국위성정보통신학회논문지 Vol.11 No.3

본 논문에서는 연판정 간섭 소거 최소 자승-오류(soft interference cancellation and minimum mean squared-error; SIC-MMSE) 방법을 이용한 새로운 에너지 효율적 다중안테나(multi-input multi-output; MIMO) 검출 기법을 소개한다. SIC-MMSE 방법의 가장 큰 계산 복잡도는 복소 행렬에 대하여 안테나 개수 만큼의 여러 번 역행렬 계산을 해야 하는데 있다. 본 논문에서는 행렬에 대한 테일러 시리즈 확장(Taylor series expansion) 기법을 이용하여 안테나 개수에 상관없이 단 한번의 역행렬 계산만을 필요로 하는 방법을 제안하며, 이와 같은 방법을 이용하여 계산의 복잡도를 감소시킬 수 있다. 본 논문에서 제안한 기법의 복잡도 감소 효과는 안테나 개수가 증가함에 따라 더 크게 나타난다. 본 논문에서 제시한 시뮬레이션 결과를 통하여 제안한 기법이 기존의 SIC-MMSE 기법에 비하여 더 적은 복잡도로 거의 동일한 성능을 도출할 수 있음을 알 수 있다. In this paper, we propose a new computationally efficient joint iterative multi-input multi-output (MIMO) detection scheme using a soft interference cancellation and minimum mean squared-error (SIC-MMSE) method. The critical computational burden of the SIC-MMSE scheme lies in the multiple inverse operations of the complex matrices. We find a new way which requires only a single matrix inversion by utilizing the Taylor series expansion of the matrix, and thus the computational complexity can be reduced. The computational complexity reduction increases as the number of antennas is increased. The simulation results show that our method produces almost the same performances as the conventional SIC-MMSE with reduced computational complexity.

Cooperative Distributed Beamforming With Outdated CSI and Channel Estimation Errors

Jung-Bin Kim,Ji-Woong Choi,Cioffi, John M. IEEE 2014 IEEE TRANSACTIONS ON COMMUNICATIONS Vol.62 No.12

<P>This paper investigates the effect of imperfect channel state information (CSI) on the outage performance of cooperative distributed beamforming (DBF). The acquisition of perfect CSI is disturbed by outdated CSI and channel estimation errors. Decode-and-forward relays are considered with individual power constraints at each relay. Considering a training-and-feedback strategy to acquire CSI, a closed-form approximate expression for outage probability and the achievable diversity gain are first provided under Rayleigh fading channels. Numerical observations verify that the approximation is very tight. It is shown that outdated CSI seriously degrades the performance, and therefore, the outage probability is bounded and no diversity is achieved. Conversely, channel estimation errors cause slight performance degradation, and full diversity order is still achievable. However, even when CSI is outdated, it is shown that the asymptotic outage decreases as the number of relays K increases, where the logarithm of the outage probability decreases at the rate of K log K. This paper shows that, when the destination re-estimates the current CSI for decoding, the effect of outdated CSI is greatly mitigated and consequently achieves a diversity gain of one. To re-estimate the current CSI with small overhead, the beamformed training sequence (BFTS) strategy is proposed, in which a new closed-form formula for minimum-mean-square-error estimation is presented using Gaussian approximation. Numerical results verify that the outage performance with the proposed BFTS scheme is close to that of a perfect estimation. A closed-form outage expression of DBF with the proposed BFTS scheme is also presented under an assumption of high-signal-to-noise ratio (SNR), but the expression is very tight even in low-to-moderate SNR regimes.</P>

Joint Channel Estimation and Equalization for MIMO-SCFDE Systems over Doubly Selective Channels

Zedong Xie,Xihong Chen,Xiaopeng Liu 한국통신학회 2017 Journal of communications and networks Vol.19 No.6

This paper considers a novel joint channel estimationand equalization (JCEE) algorithm for multiple-input-multipleoutputsingle-carrier frequency-domain-equalization (MIMOSCFDE)system over doubly selective channels for the first time. Given that the doubly selective channels can no longer support theassumption that the channel frequency-domain response remainsinvariant for the duration of one block, most of the channel estimationmethods cannot be applied directly in it. And the lack of theinformation interaction between channel estimation and channelequalization degrades the overall performance. We put forward anoise-eliminated minimum-mean-square-error channel estimation(MMSE-CE) algorithm for the initialization, which is then utilizedfor iterative processing using the ordered successive interferencecancellation (OSIC) technique. Analysis and simulation results validatethe improved performance of the proposed JCEE algorithmfor MIMO-SCFDE systems over doubly selective channels.

Linear versus Non-linear Interference Cancellation

Buehrer, R.Michael,Nicoloso, Steven P.,Gollamudi, Sridhar The Korean Institute of Communications and Informa 1999 Journal of communications and networks Vol.1 No.2

In this paper we compare linear and non-linear inter-ference cancellation for systems employing code division multi-ple access (CDMA) techniques. Specifically, we examine linear and non-linear parallel interference cancellation(also called multi-stage cancellation) in relationship to other multiuser detection al-gorithms. We show the explicit relationship between parallel inter-ference cancellation and the decorrelator (or direct matrix inver-sion). This comparison gives insight into the performance of paral-lel interference cancellation (PIC) and leads to vetter approaches. We also show that non-linear PIC approaches with explicit chan-nel setimation can provide performance improvement over linear PIC, especially when using soft non-linear symbol estimates. The application of interference cancellation to non-linear modulation techniques is also presented along with a discussion on minimum mean-squared error(MMSE) symbol estimation techniques. These are shown to further improve the performance of parallel cancella-tion.

Iterative Interstream Interference Cancellation for MIMO HSPA+ System

Hyougyoul Yu,Byonghyo Shim,오태원 한국통신학회 2012 Journal of communications and networks Vol.14 No.3

In this paper, we propose an iterative interstream interference cancellation technique for system with frequency selective multiple-input multiple-output (MIMO) channel. Our method is inspired by the fact that the cancellation of the interstream interference can be regarded as a reduction in the magnitude of the interfering channel. We show that, as iteration goes on, the channel experienced by the equalizer gets close to the single input multiple output (SIMO) channel and, therefore, the proposed SIMO-like equalizer achieves improved equalization performance in terms of normalized mean square error. From simulations on downlink communications of 2 × 2 MIMO systems in high speed packet access universal mobile telecommunications system standard, we show that the proposed method provides substantial performance gain over the conventional receiver algorithms.

Iterative Interstream Interference Cancellation for MIMO HSPA+ System

Yu, Hyoug-Youl,Shim, Byong-Hyo,Oh, Tae-Won The Korea Institute of Information and Commucation 2012 Journal of communications and networks Vol.14 No.3

In this paper, we propose an iterative interstream interference cancellation technique for system with frequency selective multiple-input multiple-output (MIMO) channel. Our method is inspired by the fact that the cancellation of the interstream interference can be regarded as a reduction in the magnitude of the interfering channel. We show that, as iteration goes on, the channel experienced by the equalizer gets close to the single input multiple output (SIMO) channel and, therefore, the proposed SIMO-like equalizer achieves improved equalization performance in terms of normalized mean square error. From simulations on downlink communications of $2{\times}2$ MIMO systems in high speed packet access universal mobile telecommunications system standard, we show that the proposed method provides substantial performance gain over the conventional receiver algorithms.