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Articles 1 - 11 of 11
Full-Text Articles in Entire DC Network
Channel Estimation And Optimal Training Design For Correlated Mimo Two-Way Relay Systems In Colored Environment, Rui Wang, Meixia Tao, Hani Mehrpouyan, Yingbo Hua
Channel Estimation And Optimal Training Design For Correlated Mimo Two-Way Relay Systems In Colored Environment, Rui Wang, Meixia Tao, Hani Mehrpouyan, Yingbo Hua
Hani Mehrpouyan
In this paper, while considering the impact of the antenna correlation and the interference from neighboring users, we analyze channel estimation and training sequence design for multi-input multi-output (MIMO) two-way relay systems. To this end, we propose to decompose the bidirectional transmission links into two phases, i.e., the multiple access (MAC) phase and the broadcast (BC) phase. By considering the Kronecker-structured channel model, we derive the optimal linear minimum mean-square-error (LMMSE) channel estimators. The corresponding training designs for the MAC phase and the BC phase are then formulated and solved to improve channel estimation accuracy. For the general scenario of …
High Rate Space-Time Codes For Millimeter-Wave Systems With Reconfigurable Antennas, Vida Vakilian, Hani Mehrpouyan, Yingbo Hua
High Rate Space-Time Codes For Millimeter-Wave Systems With Reconfigurable Antennas, Vida Vakilian, Hani Mehrpouyan, Yingbo Hua
Hani Mehrpouyan
In this paper, we propose a high-rate space-time block code (STBC) for millimeter-wave wireless communication systems that are equipped with reconfigurable multiple-input multiple-output (MIMO) antennas. We assume that each reconfigurable antenna element has the capability of forming its beam and can independently change the characteristics of its radiation pattern1. We exploit this feature of the antenna elements to construct the proposed space-time block code where each coded symbol is sent over independent beams. As a result, the received coded symbols at different receive antennas will have different power levels, a desired property that can be used in data detection. We …
Hybrid Millimeter-Wave Systems: A Novel Paradigm For Hetnets, Hani Mehrpouyan, Michail Matthaiou, Rui Wang, George K. Karagiannidis, Yingbo Hua
Hybrid Millimeter-Wave Systems: A Novel Paradigm For Hetnets, Hani Mehrpouyan, Michail Matthaiou, Rui Wang, George K. Karagiannidis, Yingbo Hua
Hani Mehrpouyan
Heterogeneous Networks (HetNets) are known to enhance the bandwidth efficiency and throughput of wireless networks by more effectively utilizing the network resources. However, the higher density of users and access points in HetNets introduces significant inter-user interference that needs to be mitigated through complex and sophisticated interference cancellation schemes. Moreover, due to significant channel attenuation and presence of hardware impairments, e.g., phase noise and amplifier nonlinearities, the vast bandwidth in the millimeter-wave band has not been fully utilized to date. In order to enable the development of multi-Gigabit per second wireless networks, we introduce a novel millimeter-wave HetNet paradigm, termed …
Channel Estimation And Carrier Recovery In The Presence Of Phase Noise In Ofdm Relay Systems, Rui Wang, Hani Mehrpouyan, Meixia Tao, Yingbo Hua
Channel Estimation And Carrier Recovery In The Presence Of Phase Noise In Ofdm Relay Systems, Rui Wang, Hani Mehrpouyan, Meixia Tao, Yingbo Hua
Hani Mehrpouyan
In this paper, we analyze joint channel, carrier frequency offset (CFO), and phase noise estimation in orthogonal frequency division multiplexing (OFDM) relaying networks. To achieve this goal, a detailed transmission framework involving both training and data symbols is first presented. Next, a novel algorithm that applies the training symbols to jointly estimate the channel responses, CFO, and phase noise parameters based on the maximum a posteriori criterion is proposed. Additionally, to evaluate the performance of the proposed channel estimation and carrier recovery algorithms, we analyze the ambiguities among the estimated parameters. Based on this analysis, a new Hybrid Cramér-Rao Lower …
New Expression For The Functional Transformation Of The Vector Cramér-Rao Lower Bound, Ali A. Nasir, Hani Mehrpouyan, Rodney A. Kennedy
New Expression For The Functional Transformation Of The Vector Cramér-Rao Lower Bound, Ali A. Nasir, Hani Mehrpouyan, Rodney A. Kennedy
Hani Mehrpouyan
Assume that it is desired to estimate α = f(θ), where f(·) is an r-dimensional function. This paper derives the general expression for the functional transformation of the vector Cramér-Rao lower bound (CRLB). The derived bound is a tight lower bound on the estimation of uncoupled parameters, i.e., parameters that can be estimated separately. Unlike previous results in the literature, this new expression is not dependent on the inverse of the Fisher’s information matrix (FIM) of the untransformed parameters, θ. Thus, it can be applied to scenarios where the FIM for θ is ill-conditioned or singular. …
Phase Noise And Carrier Frequency Offset In Ofdm Systems: Joint Estimation And Hybrid Cramér-Rao Lower Bound, Omar Hazim Salim, Ali A. Nasir, Hani Mehrpouyan, Wei Xiang
Phase Noise And Carrier Frequency Offset In Ofdm Systems: Joint Estimation And Hybrid Cramér-Rao Lower Bound, Omar Hazim Salim, Ali A. Nasir, Hani Mehrpouyan, Wei Xiang
Hani Mehrpouyan
In this paper, a new iterative pilot-aided algorithm based on expectation conditional maximization (ECM) for joint estimation of Wiener phase noise (PHN) and carrier frequency offset (CFO) in orthogonal frequency division multiplexing (OFDM) systems is proposed. Next, a new expression for the hybrid Cramér-Rao lower bound (HCRB) for joint estimation of PHN and CFO in OFDM systems is derived. Numerical results show that the proposed estimator outperforms existing algorithms in terms of mean square error while performing close to the derived HCRB at moderate PHN variances. Moreover, the proposed estimator is found to be computationally more efficient than existing algorithms …
Joint Estimation Of Channel And Oscillator Phase Noise In Mimo Systems, Hani Mehrpouyan, Ali A. Nasir, Steven D. Blostein, Thomas Eriksson, George K. Karagiannidis, Tommy Svensson
Joint Estimation Of Channel And Oscillator Phase Noise In Mimo Systems, Hani Mehrpouyan, Ali A. Nasir, Steven D. Blostein, Thomas Eriksson, George K. Karagiannidis, Tommy Svensson
Hani Mehrpouyan
Oscillator phase noise limits the performance of high speed communication systems since it results in time varying channels and rotation of the signal constellation from symbol to symbol. In this paper, joint estimation of channel gains and Wiener phase noise in multi-input multi-output (MIMO) systems is analyzed. The signal model for the estimation problem is outlined in detail and new expressions for the Cramér-Rao lower bounds (CRLBs) for the multi-parameter estimation problem are derived. A data-aided least-squares (LS) estimator for jointly obtaining the channel gains and phase noise parameters is derived. Next, a decision-directed weighted least-squares (WLS) estimator is proposed, …
Performance Of Circular Qam Constellations With Time Varying Phase Noise, M. Assad Tariq, Hani Mehrpouyan, Tommy Svensson
Performance Of Circular Qam Constellations With Time Varying Phase Noise, M. Assad Tariq, Hani Mehrpouyan, Tommy Svensson
Hani Mehrpouyan
Time varying phase noise is a limiting factor in high-speed wireless communication systems, e.g., microwave backhaul links in cellular networks. This paper seeks to investigate the performance of circular M-ary quadrature amplitude modulations (M-QAMs) in the presence of time varying phase noise. A new approximate union bound expression for the symbol-error probability (SEP) of a specific circular M-QAM constellation is derived. Numerical results show that this expression is accurate at medium-to-high signal-to-noise ratios (SNRs) for different constellation orders, M. Next, exact closed-form expressions for the SEP of binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) …
Optimal And Approximate Methods For Detection Of Uncoded Data With Carrier Phase Noise, Rajet Krishnan, Hani Mehrpouyan, Thomas Eriksson, Tommy Svensson
Optimal And Approximate Methods For Detection Of Uncoded Data With Carrier Phase Noise, Rajet Krishnan, Hani Mehrpouyan, Thomas Eriksson, Tommy Svensson
Hani Mehrpouyan
Previous results in the literature have shown that derivation of the optimum maximum-likelihood (ML) receiver for symbol-by-symbol (SBS) detection of an uncoded data sequence in the presence of random phase noise is an intractable problem, since it involves the computation of the conditional probability distribution function (PDF) of the phase noise process. In this paper, we seek to minimize symbol error probability (SEP), which is achieved by SBS detection of the sequence based on all received signals. We show that the ML detector for this problem can be formulated as a weighted sum of central moments of the conditional PDF …
Estimation, Training, And Effect Of Timing Offsets In Distributed Cooperative Networks, Hani Mehrpouyan, Steven D. Blostein
Estimation, Training, And Effect Of Timing Offsets In Distributed Cooperative Networks, Hani Mehrpouyan, Steven D. Blostein
Hani Mehrpouyan
Successful collaboration in cooperative networks requires accurate estimation of multiple timing offsets. When combined with signal processing algorithms, the estimated timing offsets can be applied to mitigate the resulting inter-symbol interference (ISI). This paper seeks to address timing synchronization in distributed multi-relay amplify-and-forward (AF) and decode-andforward (DF) relaying networks, where timing offset estimation using a training sequence is analyzed. First, training sequence design guidelines are presented that are shown to result in improved estimation performance. Next, two iterative estimators are derived that can determine multiple timing offsets at the destination. The proposed estimators have a considerably lower computational complexity while …
Synchronization In Cooperative Networks: Estimation Of Multiple Carrier Frequency Offsets, Hani Mehrpouyan, Steven Blostein
Synchronization In Cooperative Networks: Estimation Of Multiple Carrier Frequency Offsets, Hani Mehrpouyan, Steven Blostein
Hani Mehrpouyan
The distributed nature of cooperative networks may result in multiple carrier frequency offsets (CFOs), which make the channel time-varying and overshadow the performance gainspromised by collaborative communications. However, much of the analysis in the area of cooperative communications assumes perfect synchronization. This paper seeks to address frequency synchronization in cooperative communication systems, where CFO estimation using a training sequence is analyzed. The Cramer-Rao lower bound (CRLB) for various cooperative protocols is derived. In the next step, we propose two computationally efficient iterative estimators based on the MUltiple SIgnal Characterization (MUSIC) algorithm, that can estimate the CFOs from all the relays …