|
Let’s engrave our thoughts in the history! |
|
Behrang Nosrat Makouei |
|
1- Yazdan-Panah, A.; Nosrat-Makouei, B. & Vaughan, R. Non-Uniform Pilot-Symbol Allocation for Closed-loop OFDM IEEE Trans. Wireless Commun., vol. 7, no. 7, pp. 2723–2731, Jul. 2008 [j1] [abstract] 1- Nosrat-Makouei, B.; Wang, L. & Beg, M. A Large Deformation Diffeomorphic Metric Mapping Solution For Automatic Functional Magnetic Resonance Imaging Brain Mapping to be submitted to NeuroImage [j2] 3- Nosrat-Makouei, B.; Wang, L. & Beg, M. Inferior Frontal Gyrus and Hippocampus For Cognitive Tasks in Schizophrenia Patients: A Functional Magnetic Resonance Imaging Study to be submitted to NeuroImage [j3] |
|
Medical Image Processing:
1- Nosrat-Makouei, B.; Wang, L.; Barch, D.M.& Beg M. F. Reducing Erroneous Influence from Neighboring Structures by Diffeomorphic Registration of fMRI Data Accepted for Human Brain Mapping (HBM) 2008 [c1]
2- Makouei, B.; Wang, L. & Beg, M.
2- Wang, L.; Nosrat-Makouei, B.; Barch, D.M.; Csernansky, J. G.; Miller, M. I. & Beg M. F. More Accurate Registration of Hippocampal Functional Data via Large-Deformation Differomorphic Maps Human Brain Mapping (HBM) 2006, Florence Italy. 2006 [c3] [abstract]
Wireless Communications:
1- Nosrat-Makouei, B.; Yazdan-Panah, A. & Vaughan, R.
2- Yazdan-Panah, Ali; Nosrat-Makouei, Behrang; Vaughan, Rodney G. OFDM with Cyclic-Pilot Time Diversity Vehicular Technology Conference, 2007. VTC-2007 Fall. 2007 IEEE 66th , vol., no., pp.1371-1375, Sept. 30 2007-Oct.3, 2007 [c5] [abstract]
3- Yazdan-Panah, A.; Makouei, B. & Vaughan, R.
4- Shariat, M.; Ferdosizadeh, M.; Abdoli, M.; Makouei, B.; Yazdanpanah, A. & Marvasti, F. |
|
—Journal Papers— |
|
—Conference Papers— |
|
Publications |
|
Talks |
|
1- Nosrat-Makouei, B. & Yazdan-Panah, A. OFDM with Cyclic-Pilot Time Diversity SFU webcasts in Communications. April 5, 2007 You can access the recording from here. Our talk starts at the 33rd minute of the recording. |
|
Paper abstracts |
|
1- Non-Uniform Pilot-Symbol Allocation for Closed-loop OFDM Abstract—We present a new perspective on the use of channel state information (CSI) at the transmitter of orthogonal frequency division multiplexing (OFDM) systems. While conventional closed-loop OFDM systems attempt to pre-equalize the channel through power loading, we propose an average signal-to- noise ratio (SNR) maximizing strategy based on the allocation of pilot locations. Our derivation for the average output SNR of OFDM systems with interpolated channel estimation reveals a combinatorial optimization problem in terms of the pilot-symbol locations. Using this framework, we arrive at the SNR gain achieved in using uniform and non-uniform pilot locations. Further, we present simple sub-optimum solutions based on decoupled optimization and show how minor adjustments of these solutions can also lead to very favorable error rate performances. The proposed simulations are simulated in a wide range of Doppler frequencies and compared to uniform pilot allocation in terms of average symbol error rate.
2- Pilot Feedback Equalization for Time Varying OFDM Systems Abstract—It is well known that feedback and power loading can enhance the error rate performance (or link quality) of orthogonal frequency-division multiplexing (OFDM) systems. Conventional power loading algorithms for OFDM are based on forward channel state information (CSI) knowledge in the transmitter provided by a dedicated feedback link from the receiver. In this paper we propose a feedback scheme where instead of providing the transmitter with forward-link CSI we directly send the received pilots back to the transmitter. The transmitter extracts the forward-link CSI, and compensates both the amplitude and the phase of the channel for each tone before transmitting the OFDM symbol, a process also known as pre-equalization. Although the proposed scheme is sub-optimum in terms of power loading, we show that our feedback technique converts the Rayleigh fading channel into a flat channel and also simplifies the receiver.
3- OFDM with Cyclic-Pilot Time Diversity Abstract—We present a novel transceiver design for orthogonal frequency-division multiplexing (OFDM) wireless systems employing pilot symbol aided channel estimation (PSACE). The design is based on the insertion of known pilots into the time-frequency OFDM grid in a controlled cyclic fashion to exploit time diversity in the pilot tones without consuming additional bandwidth resource. Semi-blind iterative detection based on the expectation maximization algorithm along with optimum combining is employed at the receiver. Despite moderately increased transceiver complexity, simulations show that the proposed design has superior error rate performance compared to conventional PSACE methods for the same pilot overhead.
4- An Expectation-Maximization Solution to Interpolated OFDM Systems Abstract—We propose a hybrid channel estimation process for orthogonal frequency division multiplexing (OFDM) systems. We show that the OFDM channel estimation process can be substantially improved by using a blind estimation module, namely the expectation-maximization (EM) algorithm, in addition to a conventional non-blind estimation module such as pilot symbol aided channel estimation (PSAC). We provide a mathematical framework for the EM module and present computer simulations on its performance for an OFDM system operating in a frequency dispersive mobile channel. An additional benefit is revealed by our simulations which show that the proposed method is particularly powerful when the pilot insertion rate, i.e. overhead, is low.
5- Comparison Between Several Methods of PPM Demodulation Based on Iterative Techniques Abstract – In this paper we examine demodulation methods for non- uniform pulse position modulation (PPM), which is generated by the crossings of a modulating signal with a sawtooth wave. At high sampling rates (several times the Nyquist), demodulation can be achieved by an appropriate low pass filter of the PPM pulses. However, at sampling rates near the Nyquist rate, this approach creates unacceptable distortion. Here, we are interested in PPM at the Nyquist rate and illustrate the efficiency of iterative methods. Lowering the sampling rate we essentially reduce the bandwidth requirement of the transmitted PPM pulses. Several iterative methods such as Wiley/Marvasti, Time-varying, adaptive weight, Zero-order-hold, Voronoi, linear interpolation algorithms are discussed, where the PPM demodulation is converted as a non-uniform sampling reconstruction problem. Also another approach called the inverse system approach is introduced and the performance of the two algorithms is assessed.
6- Enhanced Accuracy in Registration of Cortex Functional Data via Large-Deformation Differomorphic Maps Abstract—The complex folding pattern of the cerebral cortex has presented a major obstacle for functional MRI studies. The considerable variability in the folding structure of the cortex virtually prevents all low-dimensional registration methods from giving accurate normalization in this area. On the other hand, growing research on localizing the human neurological behavior on cortex, and the need for mapping the subjects into a standard coordinate space before performing statistical analysis, calls for more accurate mapping and registration methods. In this paper we present our approach of using the FreeSurfer software package together with the large deformation Differomorphic metric maps (LDDMM) to first automatically segment the Cortex using the former and then compute accurate Differomorphic mappings between each subject and the selected template’s brain using the latter. We present a comparison of the accuracy of our approach with the mapping algorithm implemented in the SPM software package using a synthetic fMRI data-set.
7- More Accurate Registration of Hippocampal Functional Data via Large-Deformation Differomorphic Maps Abstract—The variability of medial temporal lobe structures (1)present challenges to functional imaging studies in this region. Under the traditional low-dimensional alignment to Talairach space, this variability is both global and local, resulting in poor overlap across individuals, and thus reduced confidence in the location of any observed activity in the standard space. In recent work (2) it was demonstrated that high-dimensional Diffeomorphic maps of the MTL structures drastically improved fidelity of functional signal overlaps in this region. In this work we investigate the improvement in observing hippocampal functional activities by comparing these mapping methods in the hippocampus. |
