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Archibald R.,University of California at Davis | Liu Y.,ATandT Inc. | Corbett C.,Johns Hopkins University | Ghosal D.,University of California at Davis
IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference | Year: 2011

One of the key challenges facing network administrators in securing an enterprise network is the anonymity of the traffic on the network. Although current research has taken steps forward addressing the issue of identifying the application layer protocols (e.g., SSH, HTTP, or FTP) a more fine-grained identification is required for a variety of applications that run over these established application layer protocols. We are specifically interested in disambiguating traffic that is carried by the HTTP application layer protocol. In this paper, we investigate representatives of classes of applications, namely social networking (Facebook), web-mail (Gmail), and streaming video applications (YouTube), all of which communicate via the HTTP protocol. We use specific features derived from network traffic (i.e., the TCP/IP packet headers) that can be used to classify the flows as belonging to each application. An important aspect of our work is to classify the applications based on any segment of the traffic flow. We consider different signals that can be derived from the network flow such as the packet sizes and inter-arrival times and apply simple statistical and spectral analysis to identify distinguishing features of the applications. Our classification system yields a classification rate of 93% or better using only packet size statistics. We evaluate our system on network flows collected from the backbone of the UC Davis campus network. Furthermore, we consider two types of noise an adversary may inject to evade detection: packet padding and altering the inter-packet delays. Despite these two types of noise, using our classification method we are still able to achieve a reasonable classification rate. © 2011 IEEE. Source


Liu Q.,ATandT Inc.
Conference on Optical Fiber Communication, Technical Digest Series | Year: 2014

Changes in the telecommunication services are getting bigger and faster. To be agile to these changes, metro transport network architectures for the future need to support dynamic connectivity management with switching technologies at different levels that can be controlled via a programmable interface. The right combination of switching technologies depends on the level of transparency expected by the service layer through the transitions and the scale and extent of connectivity needed. © 2014 OSA. Source


Dalton M.J.,Air Force Research Lab | Dalton M.J.,General Dynamics Corporation | Kannan R.,Air Force Research Lab | Kannan R.,ATandT Inc. | And 7 more authors.
Macromolecules | Year: 2011

A new bis(4-aminophenoxy) monomer containing a two-photon absorbing (2PA) and fluorescent diphenylaminodiethylfluorene-benzothiazole chromophore (AF240) was synthesized and used as a comonomer in preparing a series of heat-resistant, 2PA-active polyimides. Highly organo-soluble, these polymers easily formed optically clear, but nonfluorescent, films that contained covalently bound, AF240-like dye in concentrations up to ∼1.0 M. For comparison purposes, a model compound (AF349) with phthalimido end-caps was also prepared. From the fluorescence data, the presence of phthalimido moieties in both the model compound and the polymers drastically quenched the fluorescence emission from the 2PA moieties of these materials in solution as well as in solid state. Their intrinsic (at 780 nm and with 160 fs pulses) and effective (at 800 nm and 8 ns pulses) two-photon properties in THF solutions (0.02 M), and film samples (40-65 μm thick) were determined by a direct nonlinear transmission technique. Thus, their intrinsic (σ(2) fs) and effective cross-section (σ(2) ns) values in solution are 7.7-37 and 1070-6000 GM per repeat unit, respectively. Surprisingly for the film samples, while the σ(2) fs values agree with those determined in solutions, the σ(2) ns values are 7-9 times larger, depending on the dye content. On the basis of the results of photophysical characterization of these polymers, we propose that on a nanosecond or slower time scale a stabilized/confined excited state complex is formed in an intrachain mode between an AF240-like moiety and a phthalimido unit to reasonably account for the fluorescence quenching and enhancement in the effective two-photon responses in film form. © 2011 American Chemical Society. Source


Huang J.S.,ATandT Inc. | Hsueh K.,IFOSSF | Reynolds A.,IFOSSF
IEEE International Conference on Digital Ecosystems and Technologies | Year: 2013

Traditional approaches to Social, Economic and Environmental Development (SEED) have historically employed a closed, top-down model in which problems are viewed narrowly and the input of local stakeholders is rarely sought. More recent efforts to address development from a holistic, multidisciplinary perspective-while a major step in the right direction-have been hindered by a lack of appropriate tools and well-defined processes to enable disparate resources to work effectively together towards common goals. The proposed SEED Framework leverages and expands the mandate of Digital Agenda set forth by several nations, and the resulting technology development with additional design patterns for the purpose of building a collaborative SEED Digital Ecosystem. The framework aims to effectively support self-organizing, multidisciplinary collaborations and, most importantly, to translate concepts and ideas into actions for holistic and sustained social, economic and environmental development with a deep awareness of the local culture. © 2013 IEEE. Source


Liu Y.,University of California at Davis | Huynh M.,ATandT Inc. | Ghosal D.,University of California at Davis
2015 International Conference on Computing, Networking and Communications, ICNC 2015 | Year: 2015

Long Term Evolution (LTE) is being widely deployed to support real-time applications, such as voice over IP and video games. These power consuming applications create new challenges for resource allocation. Therefore, providing efficient resource allocation as well as extending user equipment's (UE) battery lifetime are two important goals in LTE network. Maximum Largest Weighted Delay First (M-LWDF) algorithm is one of the primary downlink scheduling mechanisms currently used for real-time applications. The Discontinuous Reception (DRX) mechanism, which is widely adopted in LTE to conserve the mobile phone's battery resources, results in higher latency and higher packet loss rate due to its sleep mode. The impact of DRX mechanism on downlink scheduling by using M-LWDF algorithm was studied comprehensively for the first time. Then a novel scheme, utility based scheduling scheme (USS), was proposed to reduce packet loss which was caused by DRX sleep mode by considering the remaining DRX awake time at UE and adjusting the DRX parameters. The simulation results show that by using this proposed scheme, significant performance gain will be achieved when compared with traditional scheduling algorithms, such as Proportional Fairness (PF) and M-LWDF. Packet delay and packet drop rate will be decreased by 23.5% and 59.5% respectively. © 2015 IEEE. Source

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