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Current Projects
Power Efficient Scheduling for Multi-core Systems: More computational power is offered by current embedded systems to cope with CPU intensive applications, however, this facility comes at the price of more energy consumption and eventually higher heat dissipation. Massively multi-core processors are also prominently featured in the future product roadmaps of many industry leaders.
With the birth of multi-core systems, manufacturers on one side have introduced system with multiple cores to lead in cutting edge technology, while on the other front, this advancement presents research community with enormous challenges i.e., handling thermal issues and non uniform performance of cores, and lack of mature scheduling theory, to name a few. Maintaining performance symmetry among the cores is one of the vital issues researchers are dealing with currently both from hardware and software perspectives. So far, two possible solutions to non uniform frequencies of cores are explored (i) adding dynamic voltage circuitry per core (hardware), and (ii) schedule tasks among cores wisely to enable all cores run at optimal uniform frequency. The first compensation strategy exhibits leakage power at higher frequencies and undermine thermal throttling. Being the promising alternative, the latter is relatively unexplored from scheduling point of view as compared to uni-processor counter part. In particular, very little is known so far for applying power-efficient scheduling on multi-core systems. Considering this gap, we partition the given workload among cores with the intention that all cores run at the same uniform speed for maximum gain in energy savings.
Integration of DVS into Non-preemptive Real-time Systems: With explosive growth in embedded industry in general and handheld devices in particular, more and more complex applications are being built today to attract potential customers. The most promising scheduling strategy for such processor hungry applications is dynamic priority scheduling, which is optimal scheduling technique from utilization view point. Similarly, these devices are battery powered and energy is a scared resources which must be utilized intelligently. Owing these limitations, real-time system community is currently focusing on the dynamic voltage scaling (DVS), to extend the operational hours of such devices. Much of the work done on integrating DVS into real-time systems is targeting preemptive task systems mainly and very little attention is dedicated to the non-preemptive counterpart. Hence, the inherit drawback associated with preemptive systems is the high number of context switching, and represents a substantial cost to the system in terms of CPU time. In this work, we introduce a faster test to cope feasibility analysis at run time in non-preemptive case. Once this test is validated, the test will be extended to integrate the DVS component so that the timing constraints of the system remain intact, while running the CPU at minimum possible speed.
Performance-sensitive Power Aware Scheduling for Multiprocessor Systems: Traditionally, real-time systems are focused on periodic task models where tasks are released at regular time periods. The scheduling algorithms that are optimal on uniprocessor are not necessarily optimal in multiprocessor case. With maturity of multiprocessor architecture, real-time systems today operate in dynamic environment where human activities (aperiodic tasks) are inevitable. These tasks must be completed as soon as possible, therefore the priority of such tasks must be higher than that of periodic tasks. However, there is tradeoff involved between system responsiveness and system energy consumptions. We believe, both are the main aspects of a real-time systems, however, responsiveness becomes more important, especially when humans interact with the system. We schedule mixed tasks (periodic and aperiodic) on the multiprocessor platform, however, in contrast to its counter part (uni-processor systems), the field of scheduling mixed tasks at multiprocessor system still remains unexplored. In this work, we are going to accommodate mixed workload with earliest-deadline first (EDF) algorithm and proposed a restriction on the performance degradation of aperiodic tasks. For reducing overall energy consumptions, aperioidic tasks are assigned to processors, capable of executing tasks at lowest speed while ensuring system performance does not degrade beyond a threshold level.
Design and Verification of Asynchronous Circuits and Systems: Asynchronous circuits provide several alluring properties - over their synchronous counterparts, such as locally generated timing signals in the place of global clocks, potential performance speedups, robustness towards variability in the manufacturing process and operating conditions, and automatic shutdown of blocks that are not in use resulting in power savings. The goals of the project are to develop:
1. Design of energy-efficient asynchronous circuits and systems.
2. Formal Verification methods for asynchronous circuits and systems that are highly-automated, efficient, and scalable.
Complex relation discovery from distributed semantic web: This project aims to discover complex yet meaningful and obscured relationships between resource entities from the growing semantic web data. For example, our project will enable users to uncover previously unknown and potentially interesting correlations between two or more diseases, or associations between different persons. The challenges include heterogeneous data format, distributed data distribution, and large amount of data. We are trying to combine the P2P semantic indexing and graph search to address this problem.
Energy Efficient Green Radio: The ubiquitous wireless applications and information technology increasingly contribute to the overall energy consumption of the world. Reducing the energy requirement of radio access networks has become an urgent environmental need. In this green radio project, we consider both wide area networks (such as cellular) and local area networks (such as WLAN). The objective is to investigate and create innovative methods for the reduction of the total power needed to operate a radio access network and to identify appropriate radio architectures which enable such a power reduction. In particular, we focus on the following two networks:
1. Future Mobile Cellular Radio Networks: We will develop new energy efficient cellular deployment architectures by bringing BSs closer to mobile users. However, increasing the density of BSs/RSs causes more inter-cell interference (ICI). We will exploit cooperation between BSs/RSs on how to turn interference into useful signals by the appropriate use of radio resource management (RRM) techniques.
2. Future Enterprise and Home Networks: We will design and evaluate adaptive resource management schemes in order to minimize energy consumption while satisfying users’ QoS requirements. We will focus on adaptive frequency assignment and network topology control for wireless mesh networks and Femtocell networks to reduce energy consumption under dynamic traffic loads. We will also consider dynamic spectrum access and resource management to improve the coexistence and cooperation of heterogeneous wireless networks.
Exploiting social collaboration for sharing over distributed communities: In this project, we study how social network and social collaborations can facilitate sharing over social communities. We propose a novel scheme that exploits the social property of humans, such as natural grouping, trust formation, and peer recommendation between people, to facilitate sharing and collaborating in large-scale distributed community. In this framework, network nodes perform local dynamic topology adaptations to spontaneously create communities according to users’ social-closeness and trust. The basic premise of such semantic communities is that sharing requests have a high probability of being fulfilled within the community. Members in the same community share similar social patterns hence are able to make recommendations to each other. We propose a fully decentralized a trust-enabled recommendation system intended to overcome the scalability barriers of centralized approaches. At the same time, social trust is constructed between users according to their experiences and recommendations from “friends”.
Semantics-based publish-subscribe for mobile ad-hoc networks (MANET): MANETs are composed of autonomous, wireless devices which are connected in a self-organized way without the need for fixed infrastructure. These opportunistic and dynamic characteristics of MANETs make communications in them complex. This publish/subscribe model decouples time, space, and flow between publishers and subscribers, allowing for greater scalability and a more dynamic network topology as required by MANETs. However, the use of publish/subscribe paradigm in mobile ad hoc networks brings many new challenges, mainly due to the highly dynamic topology and the scarce resources. Most of the research on publish/subscribe systems so far has concentrated on fixed network. Our project proposes an effective semantics-based pub/sub communication scheme for large MANETs. The main idea is to cluster users into zones. Efficient semantics-based intra- and inter- zone communication is proposed to match subscriptions and notifies the interested subscribers.
Cellular and Ad-hoc Hybrid Wireless Network: A hybrid wireless network (HWN) consists of an infrastructure based network (such as WiMAX) and several ad hoc components (such as MANETs). By using an HWN, one can achieve the benefits offered by both infrastructure wireless networks (e.g., good reliability and QoS support) and ad hoc networks (e.g., larger coverage, low cost deployment, and flexibility). In this particular project, we propose to investigate network design, Quality of Service provisioning, and effective communications in HWNs. We will adopt a systematic, joint-layer design approach for the proposed research. So far, we’ve modeled the joint OFDMA resource allocation (in cellular) and QoS routing (in ad-hoc) problem and proposed some good heuristic solutions.
Mobile social network: Mobile ad hoc social networks are self-configuring social networks that connect users using mobile devices, such as laptops, PDAs, and cellular phones. These social networks facilitate users to form virtual communities of similar interests or commonalities. This project aims to propose a concrete, generalized, and novel framework to develop a fully functional mobile ad hoc social network. The proposed framework provides effective and efficient solutions to social network construction, semantics-based user profile matching, and multi-hop semantics-based routing. Moreover, the proposed framework because of its generality is applicable in applications of critical importance, such as disaster-recovery, homeland security, and personnel control.
Efficient query evaluation over distributed data sites: The broad availability of data coupled with increased capabilities and decreased costs of both storage and computing technologies enable us to sharing data in an unprecedented scale. This compels us to rethink how we will manage - store, retrieve, explore, analyze, and communicate - this abundance of data. In this project, we propose novel techniques that can greatly reduce bandwidth cost of distributed query processing while allowing efficient processing of complex queries, over large-scale, fully decentralized, and semantically heterogeneous data sets. In particular, our solution integrates topology adaptation, semantic query routing, and view-based caching techniques to reduce bandwidth cost of distributed query processing while allowing efficient evaluation of complex semantic queries over large-scale, fully decentralized, and semantically heterogeneous networks.
Cellular and Ad-hoc Hybrid Wireless Network: A hybrid wireless network (HWN) consists of an infrastructure based network (such as WiMAX) and several ad hoc components (such as MANETs). By using an HWN, one can achieve the benefits offered by both infrastructure wireless networks (e.g., good reliability and QoS support) and ad hoc networks (e.g., larger coverage, low cost deployment, and flexibility). In this particular project, we propose to investigate network design, Quality of Service provisioning, and effective communications in HWNs. We will adopt a systematic, joint-layer design approach for the proposed research. So far, we’ve modeled the joint OFDMA resource allocation (in cellular) and QoS routing (in ad-hoc) problem and proposed some good heuristic solutions.
Distributed search/discovery: Locating desirable resources and information from a large-scale distributed system such as P2P system and grid is a very important issue. However, resource discovery in such systems is challenging due to the considerable diversity, large number, dynamic behavior, and geographical distribution of the resources. The resource discovery technology required to achieve the ambitious global vision is still in its infancy, and existing applications have difficulties in achieving both rich searchability and good scalability. In this project, we investigate the resource discovery problem for open-networked global-scale networks. In particular, we propose a distributed semantics-based discovery framework. We try to improve three aspects of performance: expressiveness, scalability, and efficiency.