Performance of a Shared Packet Wireless Network with Interactive Data Users

This paper studies the user-perceived performance of a shared packet wireless network for interactive data applications such as Web-browsing. We have defined a new measure: the Equivalent Circuit Rate (ECR) for a user in a shared access network is the dedicated access circuit rate that would be required by the user in order to have an equivalent user experience. The ECR measure is intuitive, useful and robust. We present a simple analytical model based on a closed queueing network with a finite population of interactive data users whose traffic can be modeled as ON/OFF traffic with feedback. The analytical results are consistent with our detailed simulations, where we study TCP-based Web traffic simulations for an EDGE (Enhanced Data Rates for GSM Evolution) TDMA system using realistic workload models. Our study incorporates constant bit-rate channels, variable bit-rate channels, as well as mixed user groups with different channel conditions. We show that a shared wireless network is well characterized by simple parameters that depend only on mean statistics, for a broad range of scenarios. ECR is well approximated by R×(1–U), where U is the utilization and R is the effective shared channel rate; this result holds even if different user groups have different rates or the channel rates are variable. These results will be useful in network dimensioning, admission control, and for defining quality of service targets for different user groups.     

An Agent-Based Smart Home System and Its Service-Scheduling Mechanism: Design and Implementation

This investigation presents an agent-based smart (ABS) home system that automates home-service operations. The ABS home system comprises three subsystems, namely user interface, home gateway, and home functionality. ABS home users can request services with handheld devices through an ABS user interface, and receive them through an agent cooperation mechanism. This investigation has designed three agents and implemented them in the agent platform: the manager agent schedules the service processes; the service agent manages service requests, and the task agent executes service operations. With home-functionality subsystems including location servers, message centers, and multimedia centers in ABS homes, services are conveniently provided, efficient, and comfortably manipulated. The Universal Plug and Play feature adopts IP network technology to control, manage, and transfer data among functionality devices in ABS homes. The proposed service-scheduling mechanism provides services that are conveniently provided, efficient, and comfortably manipulated. This study presents an implementation of the ABS home system to illustrate the feasibility of the proposed architecture. The study also presents a performance evaluation to demonstrate the effectiveness of the proposed mechanism.     

Behavioral network engineering: making intrusion detection become autonomic

In this paper we present an interesting case of what we callbehavioral network engineering, i.e. an approach to optimize network operation by exploiting information about user’s behavior. Behavioral information is needed both to characterize the overall usage context of the network and to describe the specific attitudes of single users. Indeed, in a network which is autonomically managed global knowledge of the current network “situation” is of paramount importance to optimally exploit available network resources. Furthermore, in case the behavior of single individuals can significantly impact network operation, it becomes mandatory to hold more fine-grained information. Distributed Denial of Service (DDoS) attacks represent an interesting example, since attack patterns can definitely be seen as particular (i.e. malicious) behaviors. To better illustrate the above concepts, we present an Intrusion Detection System (Ids) designed around the behavioral network engineering paradigm and relying on a flow monitoring system used for behavior summarization.     

基于SNMP的光纤放大器远程监控系统设计

为了管理光纤放大器的各项数据指标,基于简单网络管理协议(SNMP)设计了一种远程监控系统.该系统管理端采用SNMP<'++>开发包为用户提供了友好的管理界面,代理端使用MSP430单片机和CS8900A网卡驱动芯片作为网络通信的硬件支持.建立了光纤放大器的各项数据指标管理信息库文件的私有节点.结果表明,系统通过与实际光...     

An architecture for a mobile OSI mail access system

An architecture and implementation which support an interface to the X.400 mail environment using the full open-systems communications protocols for a portable computer are described. The implementation is designed to be used over a cellular radio telephone network. The portable computer is used to implement the user agent interface of the CCITT X.413 (1988) message store. A full set of security facilities, designed for use with interpersonal messaging (IPM), is included in the architecture. A number of important issues are discussed regarding the placement and management of keys for the IPM security, as well as authentication between the user and the portable computer and between the user agent and the message store. To support the use of the CCITT message-store model, it was necessary to implement a full protocol stack for open systems interconnection on the portable computer. The design and the author's experiences are described     

Distributed resource management and connection control for a multi-access interface to a broadband ISDN (BISDN)

A customer premises network (CPN) provides a common communications fabric to efficiently integrate the traffic of multiple terminals on a common access interface to a BISDN. An important consideration in choosing a CPN architecture is to facilitate terminal portability and application transparency, so as to accommodate standard broadband terminals and applications, requiring only minor modification to adapt them from the standard BISDN interface to the multi-terminal environment. This paper explores the multi-faceted issues of CPN transparency with an emphasis on the evolving BISDN control and management architecture. We introduce a control architecture that conforms to a rigorous separation between ‘call control’ and ‘connection management’. This allows the CPN to be transparent to the user to network signalling exchange, and to participate only in the connection management via a remote resource management protocol. More generally, this scheme allows a call control entity located in a local exchange node (LEN) to manage a distributed set of resources such as switches and multiplexors (and CPNs). This is achieved through the definition of a standard interoperable interface between the central call control entity and the connection control entities which may be remotely located in various network elements. The features and functionality for such an interface, which we term the bearer connection control interface, are described within the framework of the OSI remote management architecture. A standard remote resource management protocol allows for the co-operative sharing of resources across administrative domains. Although the importance of such a scheme is particularly visible as applied to remote CPN management, it is useful in other application domains where it is advantageous to distribute management processes.     

Activity-Based User Modeling in Wireless Networks

Wireless network research still lacks methods to evaluate the performance that can be expected from application layer protocols. User behavior is the predominant factor affecting network performance on this layer. It has two aspects: user mobility and user network usage. These aspects are not orthogonal, but highly correlated: a user’s mobility pattern will influence her usage of the network. Existing approaches, however, reduce the modeling of user behavior to analytical mobility models and network traffic models, thereby separating these intertwined parameters. This paper demonstrates how the use of an integrated view based on the users’ real-world activity can explain network-relevant parameters both with respect to mobility and to network usage and thereby allows a more natural modeling of user behavior. The evaluation within a campus scenario shows that such an activity based model captures the motion and service usage much more realistically than existing models.     

Game based capacity allocation for utility computing environments

Utility computing has the potential to greatly increase the efficiency of IT operations by sharing resources across multiple users. This sharing, however, introduces complex problems with regards to pricing and allocating these resources in a way that is fair, easy to implement, and economically efficient. In this paper, we study a queue-based model that attempts to address these issues. Each client/user has a continuous flow of jobs that need to be processed. The service rate each receives, however, is proportional to a bid it submits to the system operator. Assuming that user costs are some function of their average backlogs plus their bid amounts, we use this allocation mechanism to construct an economic game. Much previous research has shown that these types of allocation games have desirable properties if the cost functions are well-defined and convex over the space of possible outcomes. Because of its queueing interface, however, our model induces functions that do not satisfy the latter, commonly assumed properties. In spite of these complications, we show that the game still has a unique equilibrium and that the system will converge to this point if users iteratively make ??best response?? updates to their bids. Finally, we explore the ??price of anarchy?? in our model, proving a bound on efficiency losses as a function of several fundamental system parameters. Thus, our scheme results in equilibria with a number of highly desirably properties.     

Speech and Language Processing for Multimodal Human-Computer Interaction

In this paper, we describe our recent work at Microsoft Research, in the project codenamed Dr. Who, aimed at the development of enabling technologies for speech-centric multimodal human-computer interaction. In particular, we present in detail MiPad as the first Dr. Who's application that addresses specifically the mobile user interaction scenario. MiPad is a wireless mobile PDA prototype that enables users to accomplish many common tasks using a multimodal spoken language interface and wireless-data technologies. It fully integrates continuous speech recognition and spoken language understanding, and provides a novel solution to the current prevailing problem of pecking with tiny styluses or typing on minuscule keyboards in today's PDAs or smart phones. Despite its current incomplete implementation, we have observed that speech and pen have the potential to significantly improve user experience in our user study reported in this paper. We describe in this system-oriented paper the main components of MiPad, with a focus on the robust speech processing and spoken language understanding aspects. The detailed MiPad components discussed include: distributed speech recognition considerations for the speech processing algorithm design; a stereo-based speech feature enhancement algorithm used for noise-robust front-end speech processing; Aurora2 evaluation results for this front-end processing; speech feature compression (source coding) and error protection (channel coding) for distributed speech recognition in MiPad; HMM-based acoustic modeling for continuous speech recognition decoding; a unified language model integrating context-free grammar and N-gram model for the speech decoding; schema-based knowledge representation for the MiPad's personal information management task; a unified statistical framework that integrates speech recognition, spoken language understanding and dialogue management; the robust natural language parser used in MiPad to process the speech recognizer's output; a machine-aided grammar learning and development used for spoken language understanding for the MiPad task; Tap & Talk multimodal interaction and user interface design; back channel communication and MiPad's error repair strategy; and finally, user study results that demonstrate the superior throughput achieved by the Tap & Talk multimodal interaction over the existing pen-only PDA interface. These user study results highlight the crucial role played by speech in enhancing the overall user experience in MiPad-like human-computer interaction devices.     

Offiine traffic analysis system based on Hadoop

Offiine network traffic analysis is very important for an in-depth study upon the understanding of network conditions and characteristics, such as user behavior and abnormal traffic. With the rapid growth of the amount of information on the Intemet, the traditional stand-alone analysis tools face great challenges in storage capacity and computing efficiency, but which is the advantages for Hadoop cluster. In this paper, we designed an offiine traffic analysis system based on Hadoop （OTASH）, and proposed a MapReduce-based algorithm for TopN user statistics. In addition, we studied the computing performance and failure tolerance in OTASH. From the experiments we drew the conclusion that OTASH is suitable for handling large amounts of flow data, and are competent to calculate in the case of single node failure.     

Weight Pick: an efficient packet selection algorithm for network coding based multicast retransmission in mobile communication networks

This paper proposes an efficient packet selection algorithm, called Weight Pick, for improving the efficiency of a network coding based multicast retransmission protocol in mobile communication networks. Unlike existing packet selection algorithms, Weight Pick introduces the concept of a dynamic combination number in performing network coding. Based on this concept, a base station dynamically determines the number of packets combined or encoded in a retransmission packet based on the current packet receiving status of users and the combination number for each retransmission packet can be different. In packet selection, Weight Pick attempts to find an encoding combination whose weight is not less than (C ? 1) for every user, where C is the combination number of that retransmission packet. Simulation results show that Weight Pick can significantly improve the retransmission performance as compared with existing packet selection algorithms in terms of both packet loss ratio and packet transmission delay.     

Pricing under information asymmetry for?a?large population of?users

In this paper, we study optimal nonlinear pricing policy design for a monopolistic network service provider in the face of a large population of users of different types described by a given probability distribution. In an earlier work (Shen and Ba?ar in IEEE J. Sel. Areas Commun. 25(6):1216?C1223, 2007), we had considered games with symmetric information, in the sense that either users?? true types are public information available to all parties, or each user??s true type is private information known only to that user. In this paper, we study the intermediate case with information asymmetry; that is, users?? true types are shared information among the users themselves, but are not disclosed to the service provider. The problem can be formulated as an incentive-design problem, for which an ??-team optimal incentive (pricing) policy has been obtained, which almost achieves Pareto optimality for the service provider. A comparative study between games with information symmetry and asymmetry are conducted as well to evaluate the service provider??s game preferences.     

Impacts of user-selfishness on cooperative content caching in social wireless networks

Cooperative caching can be an effective mechanism for reducing electronic content provisioning cost in Social Wireless Networks (SWNETs). These networks are formed by a collection of mobile data enabled devices physically gathering in settings such as university campus, malls, airport and other public places. In this paper, we first propose an optimal collaborative object caching policy in order to minimize the object provisioning cost in SWNETs with homogenous user requests and a peer-rebate model for promoting collaboration. Then using an analytical model we study the impacts of user selfishness on the provisioning cost and the earned rebate when certain nodes in an SWNET selfishly deviate from the optimal policy. User selfishness is motivated in order to either increase individually earned rebate or to reduce content provisioning cost. The analytical model is validated by experimental results from simulated SWNETs using the network simulator ns2.     

A low-complexity psychometric curve-fitting approach for the objective quality assessment of streamed game videos

The increasing popularity of video gaming competitions, the so called eSports, has contributed to the rise of a new type of end-user: the passive game video streaming (GVS) user. This user acts as a passive spectator of the gameplay rather than actively interacting with the content. This content, which is streamed over the Internet, can suffer from disturbing network and encoding impairments. Therefore, assessing the user’s perceived quality, i.e the Quality of Experience (QoE), in real-time becomes fundamental. For the case of natural video content, several approaches already exist that tackle the client-side real-time QoE evaluation. The intrinsically different expectations of the passive GVS user, however, call for new real-time quality models for these streaming services. Therefore, this paper presents a real-time Reduced-Reference (RR) quality assessment framework based on a low-complexity psychometric curve-fitting approach. The proposed solution selects the most relevant, low-complexity objective feature. Afterwards, the relationship between this feature and the ground-truth quality is modelled based on the psychometric perception of the human visual system (HVS). This approach is validated on a publicly available dataset of streamed game videos and is benchmarked against both subjective scores and objective models. As a side contribution, a thorough accuracy analysis of existing Objective Video Quality Metrics (OVQMs) applied to passive GVS is provided. Furthermore, this analysis has led to interesting insights on the accuracy of low-complexity client-based metrics as well as to the creation of a new Full-Reference (FR) objective metric for GVS, i.e. the Game Video Streaming Quality Metric (GVSQM).     

Capacity maximizing in massive MIMO with linear precoding for SSF and LSF channel with perfect CSI

The capacity of a massive MIMO cellular network depends on user and antenna selection algorithms, and also on the acquisition of perfect Channel State Information (CSI). Low computational cost algorithms for user and antenna selection significantly may enhance the system capacity, as it would consume a smaller bandwidth out of the total bandwidth for downlink transmission. The objective of this paper is to maximize the system sum-rate capacity with efficient user and antenna selection algorithms and linear precoding. We consider in this paper, a slowly fading Rayleigh channel with perfect acquisition of CSI to explore the system sum-rate capacity of a massive MIMO network. For user selection, we apply three algorithms, namely Semi-orthogonal user selection (SUS), Descending Order of SNR-based User Scheduling (DOSUS), and Random User Selection (RUS) algorithm. In all the user selection algorithms, the selection of Base Station (BS) antenna is based on the maximum Signal-to-Noise Ratio (SNR) to the selected users. Hence users are characterized by having both Small Scale Fading (SSF) due to slowly fading Rayleigh channel and Large-Scale Fading (LSF) due to distances from the base station. Further, we use linear precoding techniques, such as Zero Forcing (ZF), Minimum Mean Square Error (MMSE), and Maximum Ratio Transmission (MRT) to reduce interferences, thereby improving average system sum-rate capacity. Results using SUS, DOSUS, and RUS user selection algorithms with ZF, MMSE, and MRT precoding techniques are compared. We also analyzed and compared the computational complexity of all the three user selection algorithms. The computational complexities of the three algorithms that we achieved in this paper are O(1) for RUS and DOSUS, and O(M²N) for SUS which are less than the other conventional user selection methods.     

Lower hole-injection barrier between pentacene and a 1-hexadecanethiol-modified gold substrate with a lowered work function

We used ultraviolet photoemission spectroscopy (UPS) to study the hole injection barrier at the interface between pentacene and a gold surface treated with 1-hexadecanethiol (HDT). Through these UPS in-situ experiments, we found that the energy barrier between HDT-modified gold and pentacene was 0.74 eV. This energy barrier was 0.11 eV smaller than that between bare gold and pentacene, despite the work function of HDT-modified gold being 1.08 eV lower than that of bare gold. This result does not follow the typical trend, whereby decreasing the work function of a metal increases the energy barrier. The observed behavior can be explained by two factors. First, the bare gold substrate exhibited a large interface dipole, whereas the HDT-modified gold did not. And second, pentacene on the HDT-modified gold substrate had a lower ionization energy than pentacene on bare gold. This finding can be explained in terms of the polarization energy related to the more crystalline structure of pentacene on the HDT-modified gold substrate, which was established by X-ray diffraction analysis. For comparison, we also measured the injection barrier between the amorphous organic semiconductor, N,N′-diphenyl-N,N′bis(1-naphthyl-1,1′-biphenyl-4,4′-diamine (α-NPD)), and HDT-modified gold.     

A terminal-assisted route optimized NEMO management

The NEMO basic support protocol enhances mobile IPv6 (MIPv6) to enable mobile router (MR) to move together with mobile network node (MNN) as a unit. This protocol suffers from pinball routing effect which has triggered research works to enable direct routing between MNNs in the presence of network mobility. Instead of relying on MIPv6, this paper describes network mobility using a novel terminal-assisted IP mobility protocol on MNNs that work cooperatively with MRs and access routers to provide seamless connectivity. This protocol is superior as it neither suffers from pinball routing effect nor requires dedicated infrastructure support such as home agent. It also eliminates the need to dynamically increase the size of IP header in IP tunneling. Through quantitative comparisons with existing protocol, we show that this protocol performs better than existing protocols in terms of average packet delivery overhead and packet generation.     

BeWell: Sensing Sleep,Physical Activities and Social Interactions to Promote Wellbeing

Smartphone sensing and persuasive feedback design is enabling a new generation of wellbeing apps capable of automatically monitoring multiple aspects of physical and mental health. In this article, we present BeWell+ the next generation of the BeWell smartphone wellbeing app, which monitors user behavior along three health dimensions, namely sleep, physical activity, and social interaction. BeWell promotes improved behavioral patterns via feedback rendered as an ambient display on the smartphone’s wallpaper. With BeWell+, we introduce new mechanisms to address key limitations of the original BeWell app; specifically, (1) community adaptive wellbeing feedback, which generalizes to diverse user communities (e.g., elderly, children) by promoting better behavior yet remains realistic to the user’s lifestyle; and, (2) wellbeing adaptive energy allocation, which prioritizes monitoring fidelity and feedback responsiveness on specific health dimensions (e.g., sleep) where the user needs additional help. We evaluate BeWell+ with a 27 person, 19 day field trial. Our findings show that not only can BeWell+ operate successfully on consumer smartphones; but also users understand feedback and respond by taking steps towards leading healthier lifestyles.     

Cooperative spectrum sensing for cognitive radio networks in the presence of smart malicious users

Cognitive radio (CR) signaling imposes some threats to the network. One of these common threats is commonly referred to as primary user emulation attack, where some malicious users try to mimic the primary signal and deceive secondary users to prevent them from accessing vacant frequency bands. In this paper, we introduce a smart primary user emulation attacker (PUEA) that sends fake signals similar to the primary signal. We assume a smart attacker, in the sense that it is aware of its radio environment and may choose different transmission strategies and then, we compare it to an always present attacker. In the proposed smart attacker strategy, the occurrence of fake signal is adjusted according to the primary user activity. First, we investigate the received signal at the CR users under such attackers. Then, we formulate and derive cooperative spectrum sensing (CSS) rules for a cognitive network operating in the presence of a PUEA and propose a new spectrum sensing scheme based on energy detection. Simulation results show that our proposed method can mitigate the destructive effect of PUEA in spectrum sensing, compared to conventional energy detection spectrum sensing.