| 1. |
- Amani, Payam, et al.
(författare)
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Optimal Content Retrieval Latency for Chunk Based Cooperative Content Replication in Delay Tolerant Networks
- 2013
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Konferensbidrag (refereegranskat)abstract
- Modern content distribution networks face an increasing multitude of content generators. In order to reach the minimal content retrieval latency in the content distribution networks, content shall be disseminated towards consumers based on its popularity taken from the content distribution networks. This, Combined with dividing media into chunks (heterogeneous valuation of information) and contact duration of the consumers with the access points in delay tolerant networks led us to a novel system for content management in large scale distributed systems. In order to determine where to replicate content we formulated the problem as an integer programming problem. The cost function of this minimization problem is the accumulated weighted communication delay among the content replication servers and also the main content server. Various practical constraints such as limited total budget for content replication in each service provider, limited storage size and downlink bandwidth of the content replication servers are considered. A centralized solution to the problem is derived which gives the performance bound for any decentralized content replication strategy for the presented scenarios.
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| 2. |
- Amani, Payam, et al.
(författare)
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Towards optimal content replication and request routing in content delivery networks
- 2015
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Ingår i: 2015 IEEE International Conference on Communications (ICC). - 9781467364324 ; , s. 5733-5739
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Konferensbidrag (refereegranskat)abstract
- Cooperative content replication and request routing (C2R3) has emerged as a promising technique to enhance the efficiency of content delivery networks (CDN). Most existing approaches to C2R3 focus on efficient bandwidth usage and assume a hierarchical CDN architecture targeted towards the delivery of specific content types (e.g., video). Therefore, C2R3 problem of covering the broad range of content types with minimum content access delay in a general CDN architecture has attracted little attention. As a potential solution to C2R3, cooperative web caching techniques have become mature. However, these techniques were designed to improve performance indicators tailored to web contents only (i.e., hit rate and byte hit rate). Arguably, improving such indicators does not necessarily lead to optimal access delay especially when the current trend of user-generated contents with diverse popularities and sizes are taken into account. In this paper, we formulate C2R3 as an optimization problem with the objective of minimizing content access delay in a general CDN architecture. A new performance indicator is introduced, and two popularity-based cooperative algorithms are proposed to approach the NP-hard C2R3 problem. Under broad ranges of cache size and popularity distribution parameters, we compare the proposed methods with a cooperative recency-based web caching method. Our simulation results show that the popularity-based methods outperform the recency-based method, and demonstrate close to optimal performance in representative scenarios of real-world situations.
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| 3. |
- Bastani, Saeed, et al.
(författare)
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A social node model for realising information dissemination strategies in delay tolerant networks
- 2012
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Ingår i: Proceedings of the 15th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems. - New york : ACM Press. ; , s. 79-88, s. 78-79
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Konferensbidrag (refereegranskat)abstract
- In Delay Tolerant Networks (DTNs) as an emerging content dissemination platform, mobile nodes opportunistically exchange content as they meet, with the intent of disseminating content among nodes that share common interests. During a meeting, nodes can exchange both content of direct interest to themselves as well as content that is of interest to a larger set of nodes that may be encountered in the future. The utility of DTN is governed by the content exchange opportunity (the amount of content that can be exchanged during a meeting) as well as the selection of content to be exchanged in order to maximise the interest nodes will have in information they are exposed to. Considering that there is a cost associated with the content exchange (e.g. battery usage, buffer occupancy or consumed transmission opportunity) the aim for nodes participating in content dissemination should be to maximise their payoff. In this paper, we contribute a generic framework for describing the characteristics of content exchange among participating nodes in a network. We incorporate a distributed information popularity measurement and the pairwise interaction of nodes modelled as a bargaining problem. The outcome of this process is the fair split up of dwelling time as a network resource and the selection of which content objects to exchange in order to maximise the nodes’ payoff. The framework is generally intended to be used as a capstone for investigation of content dissemination properties and various content exchange strategies in a DTN, a topic addressed in this paper and experiments conducted to validate the function and correctness of the proposed framework.
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| 4. |
- Bastani, Saeed, et al.
(författare)
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On the Performance of Vehicular Communications with a Measurement-Based Radio Propagation Model
- 2016
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Ingår i: IEEE 21st International Workshop on Computer Aided Modelling and Design of Communication Links and Networks (CAMAD). - 9781509025589 ; , s. 6-11
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Konferensbidrag (refereegranskat)abstract
- The choice of channel propagation model used for the simulation-based study of Vehicular Ad hoc NETworks (VANETs) plays a key role in the accuracy of conclusions drawn about the performance of applications proposed for these networks. Relying on simplistic channel models, as frequently practised in previous works, leads either to pessimistic or optimistic conclusions. In the view of this, in this paper, we use a realistic measurement-based channel model, implement it in OMNet++ simulator, construct a traffic scenario representing the basic building block of urban traffic networks, and investigate the performance of VANETs in terms of packet reception ratio (PRR). We further compare the performance of VANET under this measurement-based model with two more simplistic channel models used by the practitioners of the existing network simulation tools. Our results show that, for the most part of the simulated scenario, the PRR performance is significantly worse in the measurement-based channel model compared to the PRRs achieved with the simplistic models. However, there is an exception that, in close distances from an intersection and when the sender-receiver pairs are situated on different roads, the measurement-based model leads to better PRR performance.
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| 5. |
- Bastani, Saeed, et al.
(författare)
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The Effect of Hidden Terminal Interference on Safety-Critical Traffic in Vehicular Ad Hoc Networks
- 2016
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Ingår i: Proceedings of the 6th ACM Symposium on Development and Analysis of Intelligent Vehicular Networks and Applications (DIVANet '16). - New York, NY, USA : ACM. - 9781450345064 ; , s. 75-82
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In Vehicular Ad hoc NETworks (VANETs) where safety applications rely on broadcast communications, the hidden terminal problem can severely impact the reliability of these applications. Particularly, in forced flow traffic scenarios as the primary case of safety-critical situations, reliability is paramount for inter-vehicle communications to be useful. Not surprising, in these scenarios, the hidden terminal effect is expected to be especially severe, mainly due to the high vehicle density. Accurate characterization of this problem and the extent of its impact on reliability requires that realistic aspects of the traffic system and radio propagation environment are taken into consideration. In this paper, we investigate the hidden terminal problem under realistic conditions with focus on safety-critical traffic scenarios. A state-of-the-art radio propagation model targeted for vehicular environments is employed to characterise the interference power induced by hidden nodes. Our combinations of experiments with various velocities and lane configurations show that, in a road segment operating at full capacity, the hidden terminal interference causes a significant decline in the reachable distance of safety messages, leading to broadcast coverage smaller than safety applications requirements.
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| 6. |
- Cho, Daewoong, et al.
(författare)
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Big Data helps SDN to optimize its controllers
- 2018. - 1
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Ingår i: Big Data and Software Defined Networks. - London : IET Digital Library. - 9781785613043 - 9781785613050 ; , s. 389-408
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Bokkapitel (refereegranskat)abstract
- In this chapter, we first discuss the basic features and recent issues of the SDN control plane, notably the controller element. Then, we present feasible ideas to address the SDN controller-related problems using Big Data analytics techniques. Accordingly, we propose that Big Data can help various aspects of the SDN controller to address scalability issue and resiliency problem. Furthermore, we proposed six applicable scenarios for optimizing the SDN controller using the Big Data analytics: (i) controller scale-up/out against network traffic concentration, (ii) controller scale-in for reduced energy usage, (iii) backup controller placement for fault tolerance and high availability, (iv) creating backup paths to improve fault tolerance, (v) controller placement for low latency between controllers and switches, and (vi) flow rule aggregation to reduce the SDN controller's traffic. Although real-world practices on optimizing SDN controllers using Big Data are absent in the literature, we expect scenarios we highlighted in this chapter to be highly applicable to optimize the SDN controller in the future.
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| 7. |
- Erickson, Xavante, et al.
(författare)
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Personalized Seizure Detection Using Spiking Neural Networks
- 2023
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Ingår i: 2023 IEEE International Conference on Omni-Layer Intelligent Systems, COINS 2023. - 9798350346473
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Konferensbidrag (refereegranskat)abstract
- Around 50 million people worldwide suffer from Epilepsy, making it one of the most common neurological diseases. Epilepsy is characterized by sudden intermittent seizures, often imposing profound social and physical limitations. More importantly, the risk of premature death in these patients is up to three times that of the corresponding healthy population. It is estimated that 30% of the population with epilepsy is at risk of severe trauma, or premature death, despite currently available treatments. Smart wearable systems could mitigate many of the risks associated with epilepsy and seizures by providing early warnings for the patients and caretakers to take precautions. However, wearable systems are highly constrained in terms of resources and, therefore, are generally unable to utilize modern machine learning, due to their limited computing power, memory storage, and energy/battery budget. To address this issue, in this paper, we consider personalized seizure detection by adopting spiking neural networks, which are known to be efficient in terms of energy. Our experimental results demonstrate that our personalized spiking neural networks are on par with their artificial neural network counterparts in terms of performance, reaching a sensitivity of 78.8 % and a specificity of 76.9 %.
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| 8. |
- Fitzgerald, Emma, et al.
(författare)
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Intention Sharing for Medium Access Control in Wireless LANs
- 2015
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Ingår i: MobiWac '15 Proceedings of the 13th ACM International Symposium on Mobility Management and Wireless Access. - New York, NY, USA : ACM. - 9781450337588 ; , s. 21-30
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a new class of MAC protocols for wireless LANs based on sharing of transmission intentions. We develop an example protocol implementation based on distributed, co-operative scheduling of data frames. Sched- ules are non-binding, requiring minimal negotiation between nodes. The protocol is implemented on top of standard 802.11 so that backwards compatibility with legacy nodes is maintained. We have developed efficient algorithms to merge multiple schedules from neighbouring nodes and find suitable gaps in which to schedule a given node’s frames. To test the protocol’s performance, we conducted simulation studies us- ing OMNeT++. Our results show that our protocol achieves higher throughput and lower delay than 802.11 under high offered loads, and eliminates frame collisions.
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| 9. |
- Franco, Antonio, et al.
(författare)
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OMAC: An Opportunistic Medium Access Control Protocol for IEEE 802.11 Wireless Networks
- 2015
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Ingår i: Prooceedings of IEEE Globecom 2015. ; 2015 IEEE Globecom Workshops (GC Wkshps)
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Konferensbidrag (refereegranskat)abstract
- The ambitious goal of the upcoming IEEE 802.11ax (HEW) standard for wireless LANs (WLANs) to enhance throughput by four times (and beyond), compared with IEEE 802.11ac, demands a radical improvement of present medium access control (MAC) functionality. To this end, a promising paradigm would be a graceful migration towards new MAC protocols which incorporate higher certainty in their decisions. However, this requires adequate information to be available to the devices, which in turn incurs excessive costs due to information exchange between devices. Also, scalability becomes an issue for emerging dense networks. In this paper, we take a step forward by proposing an opportunistic MAC (OMAC), which restrains these costs, while increasing throughput of the new generation HEW. OMAC eliminates overhead costs by solely relying on the local capability of devices in measuring signal activities in the channel. A particular OMAC node continually collects and records the received signal strengths (RSS) overheard from the channel, and regards each individual RSS level as being transmitted by a unique node without the need to know the actual identity of the node. The OMAC node uses this knowledge to select a recorded RSS as its reference, and triggers a desired transmission policy whenever a transmission with an RSS sufficiently close to this reference RSS is detected. Our results, obtained using simulations, indicate that OMAC improves the throughput performance significantly, and that the performance gain increases with an increase in network density.
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| 10. |
- Gokan Khan, Michel, et al.
(författare)
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NFV-Inspector : A Systematic Approach to Profile and Analyze Virtual Network Functions
- 2018
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Ingår i: 2018 IEEE 7th International Conference on Cloud Networking (CloudNet). - : IEEE. - 9781538668313 ; , s. 1-7
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Konferensbidrag (refereegranskat)abstract
- Network Function Virtualization (NFV) focuses on decoupling network functions from proprietary hardware (i.e., middleboxes) by leveraging virtualization technology. Combining it with Software Defined Networking (SDN) enables us to chain network services much easier and faster. The main idea of using these technologies is to consolidate several Virtual Network Functions (VNFs) into a fewer number of commodity servers to reduce costs, increase VNFs fluidity and improve resource efficiency. However, the resource allocation and placement of VNFs in the network is a multifaceted decision problem that depends on many factors, including VNFs resource demand characteristics, arrival rate, configuration of underlying infrastructure, available resources and agreed Quality of Services (QoS) in Service Level Agreements (SLAs). This paper presents a bottom-up open-source NFV analysis platform (NFV-Inspector) to (1) systematically profile and classify VNFs based on resource capacities, traffic demand rate, underlying system properties, placement of VNFs in the network, etc. and (2) extract/calculate the correlation among the QoS metrics and resource utilization of VNFs. We evaluated our approach using an emulated virtual Evolved Packet Core platform (Open5GCore) to showcase how complex relation among various NFV service chains can be systematically profiled and analyzed.
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