| 1. |
- Lavén, Andreas, et al.
(author)
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Latency Aware Anypath Routing and Channel Scheduling for Multi-Radio Wireless Mesh Networks
- 2014
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In: IEEE WCNC'14 Track 3 (Mobile and Wireless Networks). - : IEEE. - 9781479930838
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Conference paper (peer-reviewed)abstract
- Wireless mesh network (WMN), radio nodes that form a mesh topology, is an interesting architectural candidate for the future wireless Internet. A dense access network can rapidly be deployed at a reasonable cost because there is no need to wire the mesh access points. However, WMNs typically do not perform well with latency-sensitive data traffic, such as Voice over IP (VoIP), due to restricted bandwidth. In this paper, we present the design, implementation and evaluation of LA-APOLSR for hybrid WMNs, where mesh nodes have two radios; a fixed radio for receiving and a switchable radio which rapidly changes channels to send to neighbor nodes. The key novelty of our approach is to use anypath routing for latency-sensitive traffic while normal traffic is treated using single path routing. Also, we develop a novel queuing strategy which prioritizes latency-sensitive traffic. A detailed evaluation using KAUMesh, an in-house multi-radio wireless mesh testbed, shows a reduction in latency and packet loss for VoIP traffic without negatively impacting competing TCP background traffic.
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| 2. |
- Lavén, Andreas, et al.
(author)
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Performance Evaluation of the Anypath Routing and Forwarding Mechanism AP-OLSR
- 2013
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In: MSWiM '13 Proceedings of the 16th ACM international conference on Modeling, analysis & simulation of wireless and mobile systems. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450323536 ; , s. 81-90
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Conference paper (other academic/artistic)abstract
- Wireless mesh networks (WMNs) consist of several small routers relaying packets wirelessly toward the destination or the Internet. A dense deployment enables the rapid creation of wireless access networks at a reasonable cost. The capacity of a wireless mesh network can be increased by using a diverse set of channels to allow simultaneous transmissions without causing interference. An interesting approach is to use one fixed wireless network interface for receiving and at least one switchable interface for sending. However, such a channel assignment suffers from switching overhead.In order to minimize the channel switching latency, we have developed a novel packet routing and forwarding strategy, AP-OLSR, which uses multiple next hop candidates tuned to different channels. When forwarding a packet, nodes pick the neighbor which is on a channel that gives a good balance between local switching overhead and global path quality.In this paper, we present a thorough evaluation of AP-OLSR with scenarios involving both single and multiple gateways, as well as single and competing flows. The evaluation shows that AP-OLSR can improve performance in both latency and throughput.
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| 3. |
- Chow, Lawrence, et al.
(author)
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Channel Aware Rebuffering for Wireless Media Streaming with Handoff Control
- 2013
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In: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM). - : IEEE Press. - 9781479913534 ; , s. 4434-4439
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Conference paper (peer-reviewed)abstract
- Packet/frame 'rebuffering' in wireless video streaming typically considers only connectivity from the mobile terminal to its network access point (AP). However, in the presence of multiple APs with the possibility of handoffs, the overall wireless environment should be considered. We develop a model capturing joint rebuffering & handoff dynamics in wireless video streaming, and design a new channel-aware joint rebuffering & handoff control scheme, aiming to minimize the long-run average cost of video jitters and freezes. We first characterize the optimal control in the general case of multiple wireless APs/channels and multiple states per channel. Subsequently, we evaluate the system performance in key important cases, using experimental traces of wireless channel data. We explore the relationship between optimal rebuffering thresholds and overall channel dynamics, and evaluate the associated joint handoff control. The performance results demonstrate the importance of jointly managing rebuffering and handoff controls to achieve high-performance wireless video streaming.
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| 4. |
- di stasi, Giovanni, et al.
(author)
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Combining Multi-Path Forwarding and Packet Aggregation for Improved Network Performance in Wireless Mesh Networks
- 2014
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In: Computer Networks. - : Elsevier. - 1389-1286 .- 1872-7069. ; 68, s. 26-37
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Journal article (peer-reviewed)abstract
- Wireless mesh networks (WMNs) based on the IEEE 802.11 standard are becoming increasingly popular as a viable alternative to wired networks. WMNs can cover large or difficult to reach areas with low deployment and management costs. Several multi-path routing algorithms have been proposed for such kind of networks with the objective of load balancing the traffic across the network and providing robustness against node or link failures. Packet aggregation has also been proposed to reduce the overhead associated with the transmission of frames, which is not negligible in IEEE 802.11 networks. Unfortunately, multi-path routing and packet aggregation do not work well together, as they pursue different objectives. Indeed, while multi-path routing tends to spread packets among several next-hops, packet aggregation works more efficiently when several packets (destined to the same next-hop) are aggregated and sent together in a single MAC frame. In this paper, we propose a technique, called aggregation aware forwarding, that can be applied to existing multi-path routing algorithms to allow them to effectively exploit packet aggregation so as to increase their network performance. In particular, the proposed technique does not modify the path computation phase,but it just influences the forwarding decisions by taking the state of the sending queues into account.We demonstrated our proposed technique by applying it to Layer-2.5, a multi-path routing and forwarding paradigm for WMNs that has been previously proposed.We conducted a thorough performance evaluation by means of the ns-3 network simulator, which showed that our technique allows to increase the performance both in terms of network throughput and end-to-end delay.
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| 5. |
- Karlsson, Jonas, 1977-, et al.
(author)
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The Interaction Between TCP Reordering Mechanisms and Multi-path Forwarding in Wireless Mesh Networks
- 2012
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In: 2012 IEEE 8th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). - : IEEE Press. - 9781467314299 ; , s. 276-283
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Conference paper (peer-reviewed)abstract
- Routing packets over multiple disjoint paths towards a destination can increase network utilization by load-balancing the traffic over the network. In wireless mesh networks, multi-radio multi-channel nodes are often used to create a larger set of interference-free paths thus increasing the chance of load-balancing. The drawback of load-balancing is that different paths might have different delay properties, causing packets to be reordered. This can reduce TCP performance significantly, as reordering is interpreted as a sign of congestion. Packet reordering can be avoided by letting the network layer forward traffic strictly on flow-level. This would avoid the negative drawbacks of packet reordering, but will also limit the ability to achieve optimal network throughput. On the other hand, there are several proposals that try to mitigate the effects of reordering at the transport layer. In this paper, we perform an in-depth evaluation of such TCP reordering mitigations in multi-radio multi-channel wireless mesh networks when using multi-path forwarding. We evaluate two TCP reordering mitigation techniques implemented in the Linux kernel. The transport layer mitigations are compared using different multi-path forwarding strategies. Our findings show that, in general, flow-level forwarding gives the best TCP performance and that transport layer reordering mitigations only marginally can improve performance
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