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Graduate Student Seminar: Multipair Massive MIMO Relaying with Pilot-Data Transmission Overlay - 2017-04-25

Description:

Speaker: Leyuan Pan
Supervisor: Dr. Xiaodai Dong

ABSTRACT:

This seminar presents a pilot-data transmission overlay scheme for multipair massive multiple-input multiple-output (MIMO) relaying systems employing either half- or full-duplex (HD or FD)communications at the relay station (RS). In the proposed scheme, pilots are transmitted in partial overlap with data to decrease the channel estimation overhead. The RS can detect the source datawith minimal destination pilot interference by exploiting the asymptotic orthogonality of massive MIMO channels. Then pilot-data interference can be effectively suppressed with assistance of thedetected source data in the destination channel estimation. Due to the transmission overlay, the effective data period is extended, hence improving system throughput. Both theoretical and simulationresults confirm that the proposed pilot-data overlay scheme outperforms the conventional separate pilot-data design in the limited coherence interval scenario. Moreover, at asymptotically high andlow SNR regions, the proposed scheme is superior regardless of the coherence interval length. Because of simultaneous transmission, the proper power allocation of source data transmission and relaydata forwarding can further improve the system performance. Hence a power allocation problem is formulated and a successive convex approximation approach is proposed to solve the non-convexoptimization problem with the FD pilot-data transmission overlay.


Location: ENGINEERING OFFICE WING- 430
Times:14:00 - 15:00
Pricing:
URL:

Graduate Student Seminar: Framework of Channel Estimation for Hybrid Analog-and-Digital Processing Enabled Massive MIMO Communications - 2017-04-26

Description:

Speaker: Leyuan Pan
Supervisor: Dr. Xiaodai Dong

ABSTRACT:

This seminar presents a general channel estimation problem in the massive multiple-input multiple-output (MIMO) system which employs the hybrid analog/digital precoding structure with limitedradio-frequency (RF) chains. By properly designing RF combiners and performing multiple trainings, the proposed channel estimation can approach the performance of full-chain estimations depending onthe degree of channel spatial correlation and the number of RF chains. Dealing with the hybrid channel estimation, the optimal combiner is theoretically derived by relaxing the constant-magnitudeconstraint in a specific single-training scenario, which is then extended to the design of combiners for multiple trainings by Sequential and Alternating methods. Further, we develop a technique togenerate the phase-only RF combiners based on the corresponding unconstrained ones to satisfy the constant-magnitude constraints. The performance of the proposed hybrid channel estimation scheme isexamined by simulations under both nonparametric and parametric channel models. The simulation results verify that the estimated CSI can approach the performance of full-chain estimations in terms ofboth mean square error (MSE) and achieved spectral efficiency. Moreover, a covariance matching method is proposed to obtain channel correlation in practice and the simulation verifies itseffectiveness by evaluating the spectral efficiency performance in parametric channel models.


Location: ENGINEERING OFFICE WING- 430
Times:14:00 - 15:00
Pricing:
URL:

Graduate Student Seminar: Efficient Two-pass Beamforming applied to Ultrasound Imaging - 2017-04-27

Description:

Speaker: Hichem Rehouma
Supervisor: Dr. Daler Rakhmatov

Abstract:

In the past decade, the application of adaptive beamforming methods to medical ultrasound imaging has become a field of increased interest, due to their ability to achieve superior ultrasoundimage quality. Such enhancements, however, come at a high computational cost. This thesis attempts to address the following simple question: Can we maintain a superior image quality while reducingthe computational cost of adaptive beamforming? Our goal is to effectively combine low-complexity nonadaptive beamforming, such as the Delay-and-Sum (DAS) technique, with high-complexity adaptivebeamforming, such as the Minimum variance Distortionless Response (MVDR) technique, implemented using the Generalized Sidelobe Canceller (GSC), to obtain high-quality images at low computationalcost. We propose a simple two-pass beamforming scheme for that purpose. During the first pass, our scheme processes buffered input vectors using the inexpensive DAS method and computes thecorresponding envelope. Based on that envelope information, selected outputs may be recomputed during the second pass (to improve beamforming performance) using the expensive GSC beamforming method.The purpose of the first pass is to identify which nonadaptively beamformed outputs can be spared from a heavy computational load of adaptive beamforming taking place in the second pass. We haveevaluated our scheme using simulated ultrasound images of a 12-point phantom and a point-scatterer-cyst phantom, achieving substantial threshold-dependent computational savings without significantdegradation in image resolution and contrast, compared to pure GSC beamforming.


Location: ENGINEERING OFFICE WING- 430
Times:10:00 - 11:00
Pricing:
URL:

PhD Oral Examination: Leyuan Pan - 2017-04-27

Description:

Candidate: Leyuan Pan
Dissertation: Efficient Pilot-Data Transmission and Channel Estimation in Next Generation Wireless Communications
Supervisor(s): Dr. Xiaodai Dong


Location: ENGINEERING OFFICE WING- 430
Times:12:30 - 14:30
Pricing:
URL:http://www.uvic.ca/graduatestudies/assets/docs/oral-announcements/PAN_PhD%20oral%20announcement.pdf

M.Eng. Oral Examination: Haiying Chen - 2017-05-01

Description:

Candidate:Haiying Chen
Dissertatio n:Optimum Design of Frequency-Response-Masking Filters Using Convex-Concave Procedure
Supervisor:Dr. Wu-Sheng Lu


Location: ENGINEERING OFFICE WING- 230
Times:10:30 - 12:30
Pricing:
URL:

Masters Oral Examination: Hichem Rehouma - 2017-05-01

Description:

Candidate:Hichem Rehouma
Thesis:Efficient Two-Pass Beamforming Applied to Ultrasound Imaging
Supervisor (s):Dr. Daler Rakhmatov


Location: ENGINEERING OFFICE WING- 230
Times:14:00 - 16:00
Pricing:
URL:http://www.uvic.ca/graduatestudies/assets/docs/oral-announcements/REHOUMA_oral%20announcement.pdf

Graduate Student Seminar: Accelerating cn.MOPS with GPU - 2017-05-05

Description:

Speaker: Mohammad Alkhamis
Supervisor: Dr. Amirali Baniasadi

ABSTRACT:

cn.MOPS is a model-based algorithm used to quantitatively detect copy-number variations in next-generation, DNA-sequencing data. The algorithm is implemented as an R package and canaccelerate processing with multi-CPU parallelism. For very large data sets, however, cn.MOPS requires many CPU cores and a large memory space to significantly reduce execution time. In this thesis,an alternative mechanism of parallelism is proposed. Using one CPU core and a GPU device, the proposed solution, gcn.MOPS, delivered the equivalent performance of cn.MOPS running on 237× CPU coresand decreased memory usage by more than half.


Location: ENGINEERING OFFICE WING- 430
Times:11:15 - 12:15
Pricing:
URL: