| 1. |
- Rohner, Christian, et al.
(författare)
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Interactions between TCP, UDP and Routing Protocols in Wireless Multi-hop Ad hoc Networks
- 2005
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Ingår i: Proceedings of the 1st IEEE ICPS Workshop on Multi-hop Ad hoc Networks: from theory to reality (REALMAN 2005).
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Konferensbidrag (refereegranskat)abstract
- The achieved throughput in an ad hoc network is affected by many factors, including radio interference between hops, the ability of the routing protocol to react on topology changes and a complex interaction between the application and underlying protocols. This paper studies experimentally the impact of these factors on UDP and TCP throughput. Furthermore, when both TCP and UDP share some hops in an ad hoc network there is a complex interaction between the transport protocols as well as with the routing protocol. Our results show that this interaction results in significant UDP jitter, instable routes and significantly lower TCP throughput. We use a controlled real testbed for the experiments and a graphical tool that captures the interactions.
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| 2. |
- Gold, Richard, et al.
(författare)
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A virtualized link layer with support for indirection
- 2004
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Ingår i: ACM SIGCOMM Workshop on Future Directions in Network Architecture (FDNA'04). - Portland : ACM New York, NY, USA. ; , s. 28-34
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Konferensbidrag (refereegranskat)abstract
- The current Internet today hosts several extensions for indirection like Mobile IP, NAT, proxies, route selection and various network overlays. At the same time, user-controlled indirection mechanisms foreseen in the Internet architecture (e.g., loose source routing) cannot be used to implement these extensions. This is a consequence of the Internet's indirection semantics not being rich enough at some places and too rich at others. In order to achieve a more uniform handling of indirection we propose SelNet, a network architecture that is based on a virtualized link layer with explicit indirection support. Indirection in this context refers to user-controlled steering of packet flows through the network. We discuss the architectural implications of such a scheme and report on implementation progress.
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| 3. |
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| 4. |
- Lundgren, Henrik, et al.
(författare)
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A Large-scale Testbed for Reproducible Ad hoc Protocol Evaluations
- 2002
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Ingår i: Proceedings of the 3rd annual IEEE Wireless Communications and Networking Conference, 2002. WCNC2002.. - 0780373766 ; , s. 412-418
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Konferensbidrag (refereegranskat)abstract
- We have built an ad hoc protocol evaluation testbed (APE) in order to perform large-scale, reproducible experiments. APE aims at assessing several different routing protocols in a real-world environment instead of by simulation. We present the APE testbed architecture and report on initial experiments with up to 37 physical nodes that show the reproducibility and scalability of our approach. Several scenario scripts have been written that include strict choreographic instructions to the testers who walk around with ORiNOCO equipped laptops. We introduce a mobility metric called virtual mobility that we use to compare different test runs. This metric is based on the measured signal quality instead of the geometric distance between nodes, hence it reflects how a routing protocol actually perceives the network's dynamics.
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| 5. |
- Lundgren, Henrik, et al.
(författare)
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A Large-scale Testbed for Reproducible Ad hoc Protocol Evaluations
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We have built an Ad hoc Protocol Evaluation testbed (APE) in order to perform large-scale, reproducible experiments. APE aims at assessing several different routing protocols in a real world environment instead of by simulation. We present the APE testbed architecture and report on initial experiments with up to 37 physical nodes that show the reproducibility and scalability of our approach. Several scenario scripts have been written that include strict choreographic instructions to the testers who walk around with ORiNOCO equipped laptops. We introduce a metric called Virtual Mobility that we use to compare different testruns. This metric is based on the measured signal quality instead of the geometric distance between nodes, hence it reflects how a routing protocol actually perceives the network's dynamics.
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| 6. |
- Lundgren, Henrik, et al.
(författare)
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Coping with Communication Gray Zones in IEEE 802.11b based Ad hoc Networks
- 2002
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Ingår i: Proceedings of the 5th ACM international workshop on Wireless mobile multimedi. - 1581134746
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Konferensbidrag (refereegranskat)abstract
- Our experiments with IEEE 802.11b based wireless ad hoc networks show that neighbor sensing with broadcast messages introduces "communication gray zones": in such zones data messages cannot be exchanged although the HELLO messages indicate neighbor reach
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| 7. |
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| 8. |
- Lundgren, Henrik, et al.
(författare)
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Coping with Communication Gray Zones in IEEE 802.11b based Ad hoc Networks
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Our experiments with IEEE 802.11b based wireless ad hoc networks show that neighbor sensing with broadcast messages introduces “communication gray zones”: in such zones data messages cannot be exchanged although the HELLO messages indicate neighbor reachability. This leads to a systematic mismatch between the route state and the real world connectivity, resulting in disruptive behavior for some ad hoc routing protocols. Concentrating on AODV we explore this issue and evaluate three different techniques to overcome the gray zone problem. We present quantitative measurements of these improvements and discuss the consequences for ad hoc routing protocols and their implementations.
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| 9. |
- Lundgren, Henrik, 1972-
(författare)
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Implementation and Experimental Evaluation of Wireless Ad hoc Routing Protocols
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A wireless ad hoc network consists of a number of mobile nodes that temporarily form a dynamic infrastructure-less network. New routing protocols that can adapt to the frequent topology changes induced by node mobility and varying link qualities are needed. During the last decade dozens of different ad hoc routing protocols have been proposed, optimized and partially compared, mainly through simulation studies.This thesis takes an experimental approach to the evaluation of ad hoc routing protocols. We argue that real world experiments are needed in order to complement simulation studies, and to gain practical experience and insights that can provide feedback to routing protocol design and existing simulation models. For example, we discovered a performance discrepancy for the AODV protocol between real world experiments and corresponding simulation studies. This so called ``communication gray zone'' problem was explored and countermeasures were implemented. As a result we could eliminate this performance problem to a large extent.We have implemented a software-based testbed called APE to carry out efficient and systematic experimental evaluation of ad hoc routing protocols. Experiments with up to 37 participating ad hoc nodes have demonstrated APE's ability to scale efficiently and assess repeatability between test runs. APE is part of our methodology for test repeatability in a real world ad hoc routing protocol testbed. It addresses the repeatability issue induced by stochastic factors like the radio environment and node mobility. Using APE, we have performed a systematic experimental evaluation of three ad hoc routing protocols (AODV, OLSR and LUNAR). Our results show that TCP does not work satisfactorily even in very small networks with limited mobility.
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| 10. |
- Lundgren, Henrik, et al.
(författare)
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The Gray Zone Problem in IEEE 802.11b based Ad hoc Networks
- 2002
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Ingår i: ACM SIGMOBILE Mobile Computing and Communications Review. ; 6:3, s. 104-105
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Tidskriftsartikel (refereegranskat)abstract
- Our experiments with IEEE 802.11b based wireless ad hoc networks show that neighbor sensing with broadcast messsages introduces "communication gray zones": in such zones data messages cannot be exchanged although the HELLO messages indicate neighbor reach
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