Browsing by Subject "UDP"

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    Analysis and mitigation of interference in multi-radio multi-channel wireless mesh networks
    (2013) Uluçınar, Alper Rifat
    Wireless mesh networking, which is basically forming a backbone network of mesh routers using wireless links, is becoming increasingly popular for a broad range of applications from last-mile broadband access to disaster networking or P2P communications, because of its easy deployment, self-forming, self-configuration, and self-healing properties. The multi-hop nature of wireless mesh networks (WMNs) aggravates inter-flow interference and causes intra-flow interference and severely limits the network capacity. One technique to mitigate interference and increase network capacity is to equip the mesh routers with multiple radios and use multiple channels. The radios of a mesh router can then simultaneously send or receive packets on different wireless channels. However, careful and intelligent radio resource planning, including flow-radio and channel assignment, is necessary to efficiently make use of multiple radios and channels. This first requires analyzing and modeling the nature of co-channel and adjacent channel interference in a WMN. Through real-world experiments and observations made in an indoor multihop multi-radio 802.11b/g mesh networking testbed we established, BilMesh, we first analyze and model the nature of co-channel and adjacent channel interference. We conduct extensive experiments on this testbed to understand the effects of using multi-radio, multi-channel relay nodes in terms of network and application layer performance metrics. We also report our results on using overlapping in addition to orthogonal channels for the radios of the mesh routers. We then turn our attention to modeling and quantifying adjacent channel interference. Extending BilMesh with IEEE 802.15.4 nodes, we propose computational methods to quantify interference between channels of a wireless communication standard and between channels of two different standards (such as Wi-Fi and ZigBee). Majority of the studies in the literature on channel assignment consider only orthogonal channels for the radios of a multi-radio WMN. Having developed quantitative models of interference, next we propose two optimization models, which use overlapping channels, for the joint flow-radio and channel assignment problems in WMNs. Then we propose efficient centralized and distributed heuristic algorithms for coupling flows and assigning channels to the radios of a WMN. The proposed centralized and distributed schemes make use of overlapping channels to increase spectrum utilization. Using solid interference and capacity metrics, we evaluate the performances of the proposed schemes via extensive simulation experiments, and we observe that our schemes can achieve substantial improvement over single-channel and random flow-radio and channel assignment schemes.
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    Effects of physical channel separation on application flows in a multi-radio multi-hop wireless mesh network: an experimental study on BilMesh testbed
    (Academic Press, 2014) Ulucinar, A. R.; Korpeoglu, I.; Karasan, E.
    In this paper, we introduce BilMesh, an indoor 802.11 b/g mesh networking testbed we established, and we report about our performance experiments conducted on multi-hop topologies with single-radio and multi-radio relay nodes. We investigate and report the effects of using multi-radio, multi-channel relay nodes in the mesh networking infrastructure in terms of network and application layer performance metrics. We also study the effects of physical channel separation on achievable end-to-end goodput perceived by the applications in the multi-radio case by varying the channel separation between the radio interfaces of a multi-radio relay node. We have observed that the difference between TCP and UDP goodput performances together with the delay and jitter performance depends on the hop count. We also observed that assigning overlapping channels with a central frequency separation of 5-15 MHz may render the CSMA mechanism used in 802.11 MAC ineffective and hence reduce the overall network performance. Finally, we provide some suggestions that can be considered while designing related protocols and algorithms to deal with the observed facts.
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    Fixed-point analysis of a network of routers with persistent TCP/UDP flows and class-based weighted fair queuing
    (Springer New York LLC, 2017) Tunc C.; Akar, N.
    Fixed-point models have already been successfully used to analytically study networks consisting of persistent TCP flows only, or mixed TCP/UDP flows with a single queue per link and differentiated buffer management for these two types of flows. In the current study, we propose a nested fixed-point analytical method to obtain the throughput of persistent TCP and UDP flows in a network of routers supporting class-based weighted fair queuing allowing the use of separate queues for each class. In particular, we study the case of two classes where one of the classes uses drop-tail queue management and is intended for only UDP traffic. The other class targeting TCP, but also allowing UDP traffic for the purpose of generality, is assumed to employ active queue management. The effectiveness of the proposed analytical method is validated in terms of accuracy using ns-3 simulations and the required computational effort.
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    High throughput udp-based peer-to-peer secure data transfer
    (2018-05) Doğan, Fadime Tuğba
    High throughput sequencing (HTS) platforms have been developed in recent years. These technologies enable researchers to answer a wide range of biological questions by obtaining whole or targeted segments of genomes of individuals. However, HTS technologies generate very large amounts of data. Even after using the best compression algorithms, data size is still huge due to large original le size. As most of the genome projects' contributors are located in di erent countries, transfer of the data becomes an important problem in genomics. Currently used methods for genome data sharing is transferring the les via File Transfer Protocol (FTP), Tsunami protocol or Aspera Software, storing them on public databases or clouds, working on the les stored on central servers and circulating external hard disks. However, all of these methods have some drawbacks like cost, speed, or privacy. In this thesis, to address this problem, we introduce an application called BioPeer. BioPeer uses an open source UDPbased UDT protocol written by Barchart, Inc for data transfer. We implement peer-to-peer le sharing architecture to BioPeer. This architecture is similar to BitTorrent, where large les are transferred in chunks, and synchronized between peers within the same project. To ensure every client is able to connect other clients, we employ NAT traversal via UDP hole punching method. So, users who are behind NAT devices are able to send and receive data from other peers. To provide secure le transfer, BioPeer encrypts les using Advanced Encryption Standard (AES) cipher. Symmetric encryption keys are exchanged via RSA (Rivest-Shamir-Adleman) algorithm. Additionally, content distribution network (CDN) infrastructure is implemented in order to achieve high throughput with BioPeer.
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    Performance modeling of communication networks offered with a mixture of persistent TCP and UDP flows
    (2013) Çalış, Gökhan
    A damped fixed-point approximation is proposed to characterize the throughput of persistent TCP and UDP flows in a network of router links supporting per-class queuing and Deficit Round Robin (DRR) scheduling among classes. In particular, we study the case of two classes where one of the classes uses drop-tail queue management and is intended for UDP traffic. The other class targeting TCP traffic is assumed to use Active Queue Management (AQM). The effectiveness of the proposed analysis method in this scenario is validated by extensive NS3 simulations. Moreover, we study, using the proposed fixed-point algorithm, the potential gain of employing the many-to-one communications paradigm with respect to the conventional one-to-one communications in which a client downloads a specific content from one server only.