Yingbo Hua - US grants

Blind identification of multivariate systems concerns with modelling, estimation and detection of multivariate systems driven by unknown sources. It is an emerging area of fundamental importance to applications such as wireless communications, human-computer interface, and video surveillance. It provides a foundation for, as well as a unification of many application-specific views arid techniques. In particular, it brings a bridge between the field of space-time coding for wireless communications and the field of speech recognition for human-computer interface.

This project continues a systematic study previously conducted by the P1 in the past a few years. A primary focus is to understand the limits of blind identification of convolutive multiple-input-multiple-output (MIMO) systems driven by nonwhite sources. This is known to be a challenging problem. Prior work in this area mainly concerns with single-input-multiple-output (SIMO) systems. instantaneous MIMO systems, MIMO systems driven by white sources, or MIMO systems driven by modulated sources. Preliminary discoveries on convolutive MIMO systems driven by nonwhite sources have been made recently by the P1. and more are yet to be discovered. Great efforts will be made to draw connections between the generic identifiability conditions associated with unknown sources and those associated with encoded and/or modulated sources. The results of this work will be a complete understanding of the identifiabilty of MIMO systems. a complete taxonomy of identification algorithms for various conditions of MIMO systems with various coding schemes, and a complete evaluation of performance bounds of MIMO systems driven by unknown sources.

This project will also explore a key application in speech enhancement. The acoustic channel in a common environment (such as offices) is known to have a convolutive distortion that severely hampers the performance of today's best speech recognition systems. Blind deconvolution is of great importance at the very front end of a speech recognition system. The flexibility or friendliness of future human-computer interface depends on how well blind deconvolution can be carried out and consequently how well speech recognition can be performed. To some degree, research has either neglected the structural model of acoustic channels or ignored the hidden models in speech signals. This project will cross-fertilize between the field of sensor arrays and the field of speech recognition. By exploiting multiple microphones, the structural details of acoustic channels as well as the hidden Markov model of speech signals, we are expecting a significantly improved speech recognition system by the end of this project.

0401310
Hua

This project investigates a novel concept of wireless communications, which is based on cooperative nature of multiple wireless mobile nodes within the framework of mobile ad hoc networks. But unlike the previously explored approaches that are mostly medium access control (MAC) protocols, this project aims at improving the capacity of the most fundamental physical link via multiple distributed wireless relays. These relays that are clustered and located anywhere between a source and a destination do not perform the conventional store-and-forward operations, but rather they are programmed to perform space-time modulation on their received baseband signals that are corrupted by both fading and noise. These relays do not need to exchange symbols with each other, and no feedback of channel state information is necessary. Hence, the burden on the MAC layer is reduced, and the ability to adapt to fast time-varying environment is improved. Such an array of relays performs like an array of wireless antennas, and reduces the negative effect of small scale fading on the signals received at the destination. With the space diversity achieved by the relays, the effective channel between the source and the destination becomes virtually free of small scale fading, which resembles wireline communications. The relays to be developed in this project are a function rather than a rigid device, and this function can be embedded in all mobile nodes, and more importantly can be embedded under the MAC based cooperative schemes. This project goes beyond the traditional mode of research, and the PIs of complementary strength have laid out a vertically integrated research plan to rapidly further develop the concept of distributed wireless relays, which is already proven to be promising based on a preliminary study.

Broader Impact:

Wireless communication technology will continue to evolve to meet the needs of future generations of mankind. One of the desired features of wireless communications is a fully mobile wireless network where neither base-station nor pre-existing infrastructure is required. Such a communication network is desired by people working and moving in remote areas and by the general public in the events of catastrophe. Distributed wireless relays may also be a useful solution to enhance the capacity of the cellular mobile systems, and the quality of future wireless communications may become seamless from that of wireline communications. A preliminary study by the PI shows that with distributed wireless relays, the total power consumption can be reduced by more than 10 dB from the baseline of the traditional single relay system. When fully proven and implemented, this power saving may imply that all batteries used in mobile nodes in a dense mobile network could last more than ten times longer. This project is not only likely to lead to technological breakthrough, but also will help the training of graduate students and undergraduate students (especially minority students) from two campuses of the University of California, who may become the first entrepreneurs to benefit the society by using distributed wireless relays in wireless communications.

Mobile ad hoc networks (MANETs) are highly desirable in areas/situations where base stations are unavailable or too expensive to establish. Lack of infrastructure, intermittent connectivity, and frequent changes in topology due to mobility present significant challenges in the research of MANETs. While most prior efforts were primarily focused on the networking layer, there are compelling reasons supported by recent information theory and signal processing studies which indicate that an integrated approach seeking cross-layer diversity exploitation can lead to more fruitful results. This project follows that path.

The objective of this project is to develop a framework of communication, networking, and signal processing techniques for MANETs by exploiting node cooperation at the physical, medium access, and networking layers. Three different but intertwined research directions are involved, Specifically, the first is to develop a distributive modulation theory over wireless relay channels, covering investigation of the characteristics of wireless relay channels, modulation and detection for coherent, differential and non-coherent communications for relay networks, power allocation and placement of relay nodes. The second direction is to develop bandwidth-efficient and delay-tolerant cooperative coding schemes to address several issues that are unique in coded cooperation, including bandwidth expansion caused by repetitive transmissions from relays, node asynchronism due to distributive locations of relays, and scalability (viz., the capability to degrade gracefully when some cooperating nodes that implement a distributive code fail because of fading). The third direction is to explore networking by parallel relays and develop networking protocols that take into account the realistic characteristics of radio signals and provide a flexible framework for diversity exploitation.

"This award is funded under the American Recovery and Reinvestment Act of 2009(Public Law 111-5)."


Lead Proposal#: 0902885
Title: Parameterized Architecture-Level Thermal Modeling and Characterization for Multi-Core Microprocessor Design
PI: Sheldon X.-D. Tan, Dept of Electrical Engineering, UC Riverside
co-PI: Yingbo Hua, Dept of Electrical Engineering, UC Riverside

Inst: Department of Electrical Engineering
CoPI Inst:University of California at Riverside


ABSTRACT
Multicore (also known as so-called chip-multiprocessors (CMP)) architectures are the trend for current and future microprocessor designs. They provide better performance via thread-level parallelism, better power/thermal scaling, and easy design by design reuse. However, power/thermal considerations are still the first-class constraints for multicore microprocessor designs. Thermal-aware design space explorations at core and architecture level for multicore microprocessors become critical design issues.

This research seeks to explore new techniques of building compact parameterized, transient thermal models for efficient thermal-aware design space explorations in multicore microprocessor designs.
The project consists of three thrusts: (1) Architecture-level behavioral transient thermal modeling and characterization; (2) Parameterized thermal modeling considering variable design parameters; (3) Thermal model optimization and reduction. The proposed method is a top-down, black-box approach, meaning that it does not require any knowledge of the internal structures of the systems; This approach makes the proposed method very general and flexible, which contrasts the existing approaches. The accuracy of the models is ensured by the measured or precisely computed thermal-power information from hardware. The parameterized models can accommodate different design variable parameters for efficient design space explorations.

The outcome of this research will add significantly to the core knowledge of thermal modeling multicore design. It will provide a new alternative way to complement existing architecture-level thermal models for the architecture community. Since the PIs will work closely with SRC, the proposed project will have immediate impacts on thermal-aware multicore microprocessor design in industry. This grant will enable the PI to hire more women and underrepresented minority students to contribute to the greater diversity in America's science and technology workforce.