1. History 2. Notational and mathematical preliminaries 3. Probability and statistics 4. Wireless communications fundamentals 5. Simple channels 6. Antenna arrays 7. Angle-of-arrival estimation 8. MIMO channel 9. Spatially adaptive receivers 10. Dispersive and doubly dispersive channels 11. Space-time coding 12. 2x2 network 13. Cellular networks 14. Ad-hoc networks 15. Medium access control protocols 16. Cognitive radios 17. Multiple antenna acquisition and synchronisation 18. Practical issues.

Adaptive Wireless Communications: MIMO Channels and Networks

This paper develops implementation strategy and method to accelerate the propagation and backpropagation (PBP) tomographic imaging algorithm using Graphic Processing Units (GPUs). The Compute Unified Device Architecture (CUDA) programming model is used to develop our parallelized algorithm since the CUDA model allows the user to interact with the GPU resources more efficiently than traditional shader methods. The results show an improvement of more than 80x when compared to the C/C++ version of the algorithm, and 515x when compared to the MATLAB version while achieving high quality imaging for both cases. We test different CUDA kernel configurations in order to measure changes in the processing-time of our algorithm. By examining the acceleration rate and the image quality, we develop an optimal kernel configuration that maximizes the throughput of CUDA implementation for the PBP method.

Abstract: GPU Accelerated Ultrasonic Tomography Using Propagation and Backpropagation Method

The blend of Multiple-Input–Multiple-Output (MIMO) and Orthogonal Frequency-Division Multiplexing (OFDM) provides a formidable air interface for fourth-generation (4G) technology. In beyond 4G standards, the derivative technologies of OFDM along with MIMO are poised to function as the air interface. The task of optimizing the performance metrics for resource allocation in MIMO-OFDM is a crucial aspect in 4G systems like Long Term Evolution (LTE) or LTE Advanced (LTE-A). As the evolution of LTE-Advanced continues and opens the vistas to fifth-generation (5G) standard, several performance metrics need to be optimized. The prime metrics which characterize a wireless system are the ergodic capacity and Spectral Efficiency (SE) of the system. There exists a precarious trade-off between SE and Energy Efficiency (EE) which needs to be judiciously balanced. Other aspects of resource optimization include enhancement of the throughput at the user end, reduction of cost per bit. This paper explores the critical aspects of potential enhancement and discusses ways to optimize resource allocation. Specific attention is given to the provisioning of the Cyclic Prefix (CP) in OFDM and use of Multiuser MIMO (MU-MIMO). Although CP is an overhead, but it is required to overcome the effects of Inter-Symbol Interference (ISI). However, adaptive CP length adjustment can improve the spectral efficiency. It is demonstrated that MU-MIMO yields a higher energy efficiency as compared to point-to-point MIMO. Therefore, MU-MIMO is ideally suited to yield a higher throughput in 4G and beyond systems.

Optimizing Resource Allocation of MIMO-OFDM in 4G and Beyond Systems

The combined use of orthogonal frequency-division multiplexing (OFDM) and wireless multiple-input multiple-output (MIMO) links is becoming common. For many applications, such as ad hoc wireless networks, interference is a significant issue. MIMO links allow for the spatial mitigation of interference; however, spatial interference mitigation when using OFDM modulation performs somewhat poorly because of the relatively limited interference spectral confinement of the Discrete Fourier Transform. Traditional windowing approaches that minimize leakage of the interference into neighboring carriers induce intercarrier interference. In this paper, a technique is developed for determining optimal windows that trade off interference suppression with intercarrier and interframe interference. This technique assumes channel statistics are known. Optimized windows for various levels of interference, delay spreads, frame length, and cyclic prefix lengths can be produced.

/pdf/optimal-windowing-in-mimo-ofdm-for-network-interference-1sur3pkeq3.pdf

Optimal windowing in MIMO OFDM for network interference suppression

Time sequences of 3D images of cerebral and other vasculature blood flow during surgery and other medical procedures allow enhanced visual feedback. The visual feedback constitutes an enhancement over the existing 2D time series of Xray projections as it facilitates the detection and observation of pathological abnormalities such as stenoses, aneurysms, and blood clots. An algorithm that outputs 3D+T sequences by fusing a single static 3D model of the vasculature with two time sequences of 2D projections was presented in [1]. Practical clinical use demands that the reconstruction be completed within a 5 minute time frame. When compared to CPU implementations, past GPU-based CT (computational tomography) implementations typically achieved one order-of-magnitude speed improvement, still insufficient speed for this application. To obtain further needed GPU speedup, we exploit the sparse structure of blood vasculature in order to achieve a total of two orders-of-magnitude performance increase. Our GPU implementation generates a 3D+T time series reconstruction in 2 minutes, enabling real time clinical use and safer, shorter procedures. Included in our approach is an architecture-aware partitioning method that accelerates the solution to a wide class of variational problems.

GPU-based real-time implementation of 3D+T image reconstruction with application to cerebral angiography

A noise adaptive Cusum-based algorithm for determining the arrival times of contrast at each spatial location in a 2D time sequence of angiographic images is presented. We employ a new group-wise registration algorithm to remove the effect of patient motions during the acquisition process. By using the registered image the proposed arrival time provides accurate results without relying on a priori knowledge of the shape of the time series at each location or even on the time series at each location having the same shape under translation.

Andrew D. Copeland

Papers

Optimal windowing in MIMO OFDM for network interference suppression

GPU-based real-time implementation of 3D+T image reconstruction with application to cerebral angiography

Enhancing the surgeons reality : Smart visualization of bolus time of arrival and blood flow anomalies from time lapse series for safety and speed of