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Next Generation Internet (NGI), 2012 8th EURO-NGI Conference on

Date 25-27 June 2012

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Displaying Results 1 - 25 of 30
  • [Front cover]

    Page(s): c1
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    Freely Available from IEEE
  • [Copyright notice]

    Page(s): 1
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  • Foreword

    Page(s): i
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  • [Blank page]

    Page(s): ii
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  • Contents

    Page(s): iii
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  • [Blank page]

    Page(s): iv
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  • Chairs and committees

    Page(s): v - vi
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  • Author index

    Page(s): vii - viii
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  • Program

    Page(s): ix - xii
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  • Keynotes

    Page(s): xiii - xiv
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    These keynotes discuss the following: Toward the future Internet - Remember the past; Horizon 2020: Networking and sustainability; Energy efficiency in the present and future Internet: An evolutionary approach. View full abstract»

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  • Combined contention and TDMA-based communication in wireless sensor networks

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1070 KB) |  | HTML iconHTML  

    Wireless sensor networks usually consist of a large number of very small, energy-constrained sensor nodes. The nodes capture information from their immediate environment to send it to a destination node (sink) in a timely manner. This work proposes a combined contention and TDMA-based approach for load balancing and a discrete-time Markov model that allows to study the trade-off between energy consumption and transfer delay in clustered wireless sensor networks. Our investigations show that the length of the TDMA frame needs to be configured close to the minimum that is capable of transferring the offered load for optimizing energy efficiency and minimizing the delay. View full abstract»

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  • Outage probability, average transmission time, and quality of experience for cognitive radio networks over general fading channels

    Page(s): 9 - 15
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (862 KB) |  | HTML iconHTML  

    In this paper, we examine the delay performance in cognitive radio networks (CRNs) over general fading channels where secondary users are allowed to simultaneously access the spectrum licensed by primary users. In particular, subject to the peak interference power constraint, we investigate the effect of general fading channels on the delivery delay of data packets and acknowledgements (ACKs). A lower bound of outage probability and an upper bound of average transmission time are derived by utilizing the concept of timeout. Specifically, we apply the above results to investigate the quality of experience (QoE) for various fading channels, such as one-sided Gaussian, Rayleigh, Nakagami-m and Weibull channels. The numerical results indicate that the delay of ACKs under severe fading leads to a degradation of system performance. View full abstract»

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  • Cognitive radio networks with elastic traffic

    Page(s): 17 - 24
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (650 KB) |  | HTML iconHTML  

    We model and evaluate an infrastructure based cognitive radio network where impatient unlicensed or secondary users (SUs) offer elastic traffic. The interference created by SUs to the licensed users is analyzed when the secondary network uses two different spectrum access schemes, the conventional random access scheme and a new scheme we refer to as access with preference. To further control the interference, a limit is set to the number of channels SUs have access to. With this new constraint, the abandonment probability, the mean delay and throughput of the SUs degrades significantly. To improve the QoS perceived by the active SUs, we define and evaluate an admission control scheme for the SUs. View full abstract»

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  • Optimal intercell coordination for multiple user classes with elastic traffic

    Page(s): 25 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (627 KB) |  | HTML iconHTML  

    We consider the intercell coordination problem between two neighboring cells, assuming that the traffic in the system consists of elastic downlink data flows. In this case, there is an option of completely switching off one base station at certain times, which reduces interference and enables a higher service rate in the neighboring base station. We use a flow level queueing model to describe the evolution of the system based on a symmetric capacity region. Recent results by Verloop and Núñez-Queija show that, assuming a single class of flows for each cell, the stochastically optimal dynamic policy is to have both stations switched on whenever there are users in both cells. In this paper, we consider a system where the two stations are able to provide services to two different classes of users - the near ones and the far ones. In this setting, the stochastic optimality of the Both Stations On policy does not necessarily hold, but it may still be a close-to-optimal policy, at least for minimizing the mean flow delay. We present a systematic method based on the policy improvement algorithm of the theory of the Markov Decision Processes to generate a near-optimal state-dependent resource allocation policy. Our numerical experiments with these two dynamic policies indicate that the Both Stations On policy is, indeed, close to optimal even when there are multiple user classes. View full abstract»

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  • Flow-level modeling and analysis of dynamic TDD in LTE

    Page(s): 33 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (634 KB) |  | HTML iconHTML  

    We present a queueing analysis of elastic traffic performance in LTE systems using the dynamic TDD scheme. Both fair resource sharing and performance optimization using different approaches are considered. We first analyze the system without any restrictions in the resource allocation between the uplink and downlink and demonstrate that a simple dynamic scheduling scheme (called here dynamic-PS), where the allocation for a single flow is always inversely proportional to the total number of active flows, shows good performance and fairness properties compared with any optimized static allocation scheme. We also consider the achievable gains with more detailed traffic statistics, including the application of the Gittins index policy and SRPT. However, the actual LTE TDD system only supports a discrete set of possible allocations in the capacity region. We then investigate how these allocation constraints impact the performance of the discretized variant of the dynamic-PS policy by using different approaches. To optimize the performance we apply MDP for exponential service times and, for example, derive a structural result that the optimal policy always selects among two corner points of the capacity region. Also, an SRPT-like heuristic scheduling algorithm is given. The analytical and simulated results suggest that the discrete dynamic-PS policy is robust against impact of different service time distributions, fair and performs reasonably well. View full abstract»

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  • Cognitive Radio spectrum decision based on channel usage prediction

    Page(s): 41 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1417 KB) |  | HTML iconHTML  

    The paper is about a new strategy suggested for spectrum decision in Cognitive Radio (CR) networks. By jointly considering sensing error, Secondary Users (SUs) competition and SUs transmission collision, a new parameter called Channel Usage State (CUS) is introduced. For a particular channel, we predict the respective probabilities of occurrence of CUS states by using the LeZi-update scheme. We also adopt a fuzzy comparison algorithm to combine the prediction results as a joint value. The largest joint value is associated with the most available channel for access by SUs in the near future. By comparing with random channel access, the suggested strategy can improve SUs transmission throughput. This is demonstrated by the simulation evaluations. View full abstract»

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  • Beacon-enabled cognitive access for dynamic spectrum access

    Page(s): 49 - 56
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (735 KB) |  | HTML iconHTML  

    In dynamic spectrum access networks, the unused licensed spectrum used by primary users (PU) is opened to unlicensed secondary users (SU) for improving spectrum efficiency. We design a simple time-based threshold policy for collective protection of PUs, enabled by an out-of-band channel. In particular, multiple SUs may be widely distributed in a geographic location. The interference that collocated SUs cause to each other, termed self-interference, becomes a major source that may degrade the SUs communication performance. We establish an analytical framework for carrier sense multiple access (CSMA) based coexistence mechanisms when integrated into a family of time based threshold policies, and study its performance though theoretical analysis. View full abstract»

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  • Pricing and regulating Quality of Experience

    Page(s): 57 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1163 KB) |  | HTML iconHTML  

    Counteracting economic challenges in the network industry partially resulting from enormous traffic growth rates and the absence of successful Quality of Service (QoS) mechanisms in practice, we propose a novel concept centering price and quality differentiation on customers' quality perceptions, i.e., Quality of Experience (QoE). By fundamentally building on the known Paris Metro Pricing (PMP) concept we iteratively integrate pricing mechanisms with QoE aspects. Our concept also cardinally incorporates the interests of users, Internet Service Providers (ISPs) offering Internet access, and regulatory bodies-e.g., controlling the fraction of premium service class capacity. Our findings demonstrate the economic desirability for ISPs to apply price discrimination based on QoE considerations. The inclusion of QoE aspects in the traffic classification process, moreover, yields a significant increase of user utilities, while further stimulating the overall demand. This may also prepare the scene for involvements in the Net Neutrality (NN) debate. View full abstract»

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  • Content dependency of the traffic control in the darwin streaming server

    Page(s): 65 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (755 KB) |  | HTML iconHTML  

    The Darwin Streaming Server employs stream thinning and transmission rate adaptation for traffic and congestion control. We investigate the relation of video content with the stream thinning and transmission rate adaptation process under 3GPP-adaptation. We observe that stream thinning is not only initiated upon fluctuation of network properties or the jitter buffer, but sometimes also upon the content of the streamed video. Moreover, we show that in extreme situations the video transmission is halted based merely on content dependent properties reflected in the RTSP feedback. This may have adverse consequences for the user experience. We put forward alterations to the 3GPP-adaptation traffic control of the Darwin Streaming Server that controls the stream thinning process. The alterations aim to avoid video freezes as a result of video content dependent properties. The results show that the probability of an interrupt-free playback is higher for the alterations than for the default streaming server algorithms. View full abstract»

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  • A Wireless Sensor and Actuator Network for improving the electrical power grid dependability

    Page(s): 71 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (973 KB) |  | HTML iconHTML  

    This paper presents an overview of a Wireless Sensor and Actuator Network (WSAN) used to monitor an electrical power grid distribution infrastructure. The WSAN employs appropriate sensors to monitor key grid components, integrating both safety and security services, which improve the grid distribution dependability. The supported applications include, among others, video surveillance of remote secondary substations, which imposes special requirements from the point of view of quality of service and reliability. The paper presents the hardware and software architecture of the system together with performance results. View full abstract»

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  • Real-time multimedia monitoring in large-scale wireless multimedia sensor networks: Research challenges

    Page(s): 79 - 86
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB) |  | HTML iconHTML  

    Wireless Sensor Networks (WSNs) have enjoyed dramatic developments over the last decade. The availability of CMOS cameras and microphones enlarged the scope of WSNs paving the way to the development of Wireless Multimedia Sensor Networks (WMSN). Among the envisaged WMSN applications, Real-time Multimedia Monitoring constitutes one of the most promising. However, the resource requirements of these applications place difficult challenges in terms of network lifetime and scalability. This paper starts by identifying the main characteristics and requirements of Real-time Multimedia Monitoring applications and then highlights key research directions that may help to overcome those challenges. View full abstract»

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  • Fast but economical: A simulative comparison of structured peer-to-peer systems

    Page(s): 87 - 94
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (861 KB) |  | HTML iconHTML  

    In the past many proposals for structured peer-to-peer protocols have been published. They differ in properties like overlay topology and routing table maintenance. Furthermore, each protocol exhibits various parameters e.g. to adjust the size of the routing table or stabilization intervals, making it difficult to choose an optimal protocol and parameter set for a given scenario (e.g. churn rate, number of nodes). For this purpose, we developed the overlay simulation framework OverSim and implemented six well known structured overlay protocols. In this paper we first compare these protocols among each other. Furthermore, we study several recursive and iterative routing variants and show the effect of routing table redundancy and lookup parallelism on routing latency and bandwidth costs. For each overlay protocol we identify an optimal parameter set for a typical peer-to-peer scenario. Finally, we show how overlay protocols adapt to variations in churn rate and network size. Our results show considerable advantages of the protocols Kademlia and Bamboo, while De Bruijn based protocols reveal a lack of stability under churn. View full abstract»

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  • Simulated annealing algorithm for virtual network reconfiguration

    Page(s): 95 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (791 KB) |  | HTML iconHTML  

    Network virtualization has evoked interest among researchers as a promising solution for developing flexible and manageable architectures for future Internet. One of the major challenges in network virtualization is the efficient allocation of substrate resources to the Virtual Networks (VNs) - a problem known as Virtual Network Embedding (VNE). Most of the past research on VNE has been focused on algorithms to allocate resources to VNs. The problem of reconfiguration, however, is relatively less explored. In this paper, we propose a simulated annealing algorithm for reconfiguring the VNs in order to balance the load across the substrate network, thereby reducing the peak node and link load on the substrate network. Through extensive simulations we evaluate the proposed reconfiguration algorithm and show that after reconfiguration there is a 20% reduction in maximum link load and 5% reduction in maximum node load. The average link load is reduced by 50% and the fraction of links having a load above 50% is reduced from 66% to 14%. We also show that periodic reconfiguration leads to a significant improvement in the acceptance ratio of VN requests. View full abstract»

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  • Reliable multicast on a WDM Optical Packet Ring

    Page(s): 103 - 110
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1492 KB) |  | HTML iconHTML  

    The present paper addresses multicast protection in WDM Optical Packet Rings that are currently considered for future metro network architectures. The considered architecture is optically transparent for transit traffic, which drastically limits the number of OEO conversions compared to e.g. Ethernet Packet Rings. WDM Optical Packet Rings offer huge capacity while still retaining a packet based granularity, which is not the case for ROADM based networks. Metro networks now support multicast, as IPTV services are largely deployed. Two alternate methods for implementing the traditional 1+1 and 1:1 protection mechanisms are proposed. Both rely on using the time slotted control channel to deliver failure and recovery information. The performance of the two methods are thoroughly assessed and it is shown that the transient degradation durations are always bounded by the Ring Round Trip Time, which is at least an order of magnitude less than the usual 50ms target time for protection. Moreover, using a Multicast Drop-off Point is shown to provide an almost loss free transport in case of single failure. Lastly the single ring protection schemes are extended to multi-ring architectures, relying on an MPLS-TP compatible operation mode of the WDM optical packet rings. View full abstract»

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  • Impact on retail prices of non-neutral wholesale prices for content providers

    Page(s): 111 - 117
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    The impact of wholesale prices is examined in a context where the end customer access both free content and pay-per-use content, delivered by two different providers through a common network provider. We formulate and solve the game between the network provider and the pay-per-use content provider, where both use the price they separately charge the end customer with as a leverage to maximize their profits. In the neutral case (the network provider charges equal wholesale prices to the two content providers), the benefits coming from wholesale price reductions are largely retained by the pay-per-use content provider. When the free content provider is charged more than its pay-per-use competitor, both the network provider and the pay-per-use content provider see their profit increase, while the end customer experiences a negligible reduction in the retail price. View full abstract»

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