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106
Link-level Measurements from an 802.11b Mesh Network
- In SIGCOMM
, 2004
"... This paper anal yzes the causes of packetl oss in a 38-node urban mul ti-hop 802.11b network. The patterns and causes oflv# are important in the design of routing and errorcorrection proto colv as wel as in networkplqq"(v The paper makes the fol l owing observations. The distribution of inter-n ..."
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Cited by 567 (11 self)
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This paper anal yzes the causes of packetl oss in a 38-node urban mul ti-hop 802.11b network. The patterns and causes oflv# are important in the design of routing and errorcorrection proto colv as wel as in networkplqq"(v The paper makes the fol l owing observations. The distribution of inter-nodel oss rates is rel'RfivD' uniform over the wh ol range oflv$ rates; there is no clq$ threshol separating "in range" and "out of range." Mostls ks have relj tivel stabl el oss rates from one second to the next, though a smal l minority have very burstyl osses at that time scal e. Sign al to-noise ratio and distance have lv tl e predictive val e forl oss rate. Thel arge number of lv ks with intermediate l oss rates is probabl y due to mul ti-path fading rather than attenuation or interference. The phenomena discussed here are al l wel l -known. The contributions of this paper are an understanding of their rel ative importance, of how they interact, and of the impl ications for MAC and routing protocol design.
Jigsaw: Solving the puzzle of enterprise 802.11 analysis
- In SIGCOMM
, 2006
"... The combination of unlicensed spectrum, cheap wireless interfaces and the inherent convenience of untethered computing have made 802.11-based networks ubiquitous in the enterprise. Modern universities, corporate campuses and government offices routinely deploy scores of access points to blanket thei ..."
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Cited by 174 (12 self)
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The combination of unlicensed spectrum, cheap wireless interfaces and the inherent convenience of untethered computing have made 802.11-based networks ubiquitous in the enterprise. Modern universities, corporate campuses and government offices routinely deploy scores of access points to blanket their sites with wireless Internet access. However, while the fine-grained behavior of the 802.11 protocol itself has been well studied, our understanding of how large 802.11 networks behave in their full empirical complexity is surprisingly limited. In this paper, we present a system called Jigsaw that uses multiple monitors to provide a single unified view of all physical, link, network and transport-layer activity on an 802.11 network. To drive this analysis, we have deployed an infrastructure of over 150 radio monitors that simultaneously capture all 802.11b and 802.11g activity in a large university building (1M+ cubic feet). We describe the challenges posed by both the scale and ambiguity inherent in such an architecture, and explain the algorithms and inference techniques we developed to address them. Finally, using a 24-hour distributed trace containing more than 1.5 billion events, we use Jigsaw’s global cross-layer viewpoint to isolate performance artifacts, both explicit, such as management inefficiencies, and implicit, such as co-channel interference. We believe this is the first analysis combining this scale and level of detail for a production 802.11 network.
Improving Loss Resilience with Multi-Radio Diversity in Wireless Networks
- In MobiCom
, 2005
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Recent and Emerging Topics in Wireless Industrial Communications: A Selection
, 2007
"... In this paper we discuss a selection of promising and interesting research areas in the design of protocols and systemsforwirelessindustrialcommunications.Wehaveselected topicsthathaveeitheremergedashottopicsintheindustrial communicationscommunityinthelastfewyears(likewireless sensornetworks),orwhi ..."
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Cited by 96 (1 self)
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In this paper we discuss a selection of promising and interesting research areas in the design of protocols and systemsforwirelessindustrialcommunications.Wehaveselected topicsthathaveeitheremergedashottopicsintheindustrial communicationscommunityinthelastfewyears(likewireless sensornetworks),orwhichcouldbeworthwhileresearchtopicsin thenextfewyears(forexamplecooperativediversitytechniques for error control, cognitive radio/opportunistic spectrum access for mitigation of external interferences).
Industrial Wireless Sensor Networks: Challenges, Design Principles, and Technical Approaches
- IEEE Trans. on Industrial Electronics
, 2009
"... Abstract—In today’s competitive industry marketplace, the companies face growing demands to improve process efficiencies, comply with environmental regulations, and meet corporate fi-nancial objectives. Given the increasing age of many industrial systems and the dynamic industrial manufacturing mark ..."
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Cited by 89 (2 self)
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Abstract—In today’s competitive industry marketplace, the companies face growing demands to improve process efficiencies, comply with environmental regulations, and meet corporate fi-nancial objectives. Given the increasing age of many industrial systems and the dynamic industrial manufacturing market, intel-ligent and low-cost industrial automation systems are required to improve the productivity and efficiency of such systems. The col-laborative nature of industrial wireless sensor networks (IWSNs) brings several advantages over traditional wired industrial mon-itoring and control systems, including self-organization, rapid deployment, flexibility, and inherent intelligent-processing capa-bility. In this regard, IWSN plays a vital role in creating a highly reliable and self-healing industrial system that rapidly responds to real-time events with appropriate actions. In this paper, first, technical challenges and design principles are introduced in terms of hardware development, system architectures and protocols, and software development. Specifically, radio technologies, energy-harvesting techniques, and cross-layer design for IWSNs have been discussed. In addition, IWSN standards are presented for the system owners, who plan to utilize new IWSN technologies for industrial automation applications. In this paper, our aim is to pro-vide a contemporary look at the current state of the art in IWSNs and discuss the still-open research issues in this field and, hence, to make the decision-making process more effective and direct. Index Terms—Cross-layer design, industrial wireless sensor net-works (IWSNs), ISA100, ultrawideband (UWB), wireless HART,
Symbol-level Network Coding for Wireless Mesh Networks
"... This paper describes MIXIT, a system that improves the throughput of wireless mesh networks. MIXIT exploits a basic property of mesh networks: even when no node receives a packet correctly, any given bit is likely to be received by some node correctly. Instead of insisting on forwarding only correct ..."
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Cited by 82 (2 self)
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This paper describes MIXIT, a system that improves the throughput of wireless mesh networks. MIXIT exploits a basic property of mesh networks: even when no node receives a packet correctly, any given bit is likely to be received by some node correctly. Instead of insisting on forwarding only correct packets, MIXIT routers use physical layer hints to make their best guess about which bits in a corrupted packet are likely to be correct and forward them to the destination. Even though this approach inevitably lets erroneous bits through, we find that it can achieve high throughput without compromising end-to-end reliability. The core component of MIXIT is a novel network code that operates on small groups of bits, called symbols. It allows the nodes to opportunistically route groups of bits to their destination with low overhead. MIXIT’s network code also incorporates an end-to-end error correction component that the destination uses to correct any errors that might seep through. We have implemented MIXIT on a software radio platform running the Zigbee radio protocol. Our experiments on a 25-node indoor testbed show that MIXIT has a throughput gain of 2.8 × over MORE, a state-of-the-art opportunistic routing scheme, and about 3.9 × over traditional routing using the ETX metric.
Wireless technology in industrial networks
- Proceedings of the IEEE
, 2005
"... With the success of wireless technologies in consumer electronics, standard wireless technologies are envisioned for the deployment in industrial environments as well. Industrial applications involving mobile subsystems or just the desire to save cabling make wireless technologies attractive. Nevert ..."
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Cited by 72 (3 self)
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With the success of wireless technologies in consumer electronics, standard wireless technologies are envisioned for the deployment in industrial environments as well. Industrial applications involving mobile subsystems or just the desire to save cabling make wireless technologies attractive. Nevertheless, these applications often have stringent requirements on reliability and timing. In wired environments, timing and reliability are well catered for by fieldbus systems (which are a mature technology designed to enable communication between digital controllers and the sensors and actuators interfacing to a physical process). When wireless links are included, reliability and timing requirements are significantly more difficult to meet, due to the adverse properties of the radio channels. In this paper, we thus discuss some key issues coming up in wireless fieldbus and wireless industrial communication systems: 1) fundamental problems like achieving timely and reliable transmission despite channel errors; 2) the usage of existing wireless technologies for this specific field of applications; and 3) the creation of hybrid systems in which wireless stations are included into existing wired systems. Keywords—Bluetooth (BT), fieldbus systems, hybrid systems, IEEE 802.11, IEEE 802.15.4, real-time communications, wireless technologies.
Chaotic Maps as Parsimonious Bit Error Models of Wireless Channels
- In Proceedings of Infocom
, 2003
"... The error patterns of a wireless digital communication channel can be described by looking at consecutively correct or erroneous bits (runs and bursts) and by the distribution function of these run and burst lengths. A number of stochastic models exist that can be used to describe these distribution ..."
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Cited by 55 (3 self)
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The error patterns of a wireless digital communication channel can be described by looking at consecutively correct or erroneous bits (runs and bursts) and by the distribution function of these run and burst lengths. A number of stochastic models exist that can be used to describe these distributions for wireless channels, e.g., the GilbertElliot model.
Quality-aware routing metrics for time-varying wireless mesh networks
- IEEE JSAC
, 2006
"... Abstract—This paper considers the problem of selecting good paths in a wireless mesh network. It is well-known that picking the path with the smallest number of hops between two nodes often leads to poor performance, because such paths tend to use links that could have marginal quality. As a result, ..."
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Cited by 55 (0 self)
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Abstract—This paper considers the problem of selecting good paths in a wireless mesh network. It is well-known that picking the path with the smallest number of hops between two nodes often leads to poor performance, because such paths tend to use links that could have marginal quality. As a result, quality-aware routing metrics are desired for networks that are built solely from wireless radios. Previous work has developed metrics (such as ETX) that work well when wireless channel conditions are relatively static (DeCouto et al., 2003), but typical wireless channels experience variations at many time-scales. For example, channels may have low average packet loss ratios, but with high variability, implying that metrics that use the mean loss ratio will perform poorly. In this paper, we describe two new metrics, called modified expected number of transmissions (mETX) and effective number of transmissions (ENT) that work well under a wide variety of channel conditions. In addition to analyzing and evaluating the performance of these metrics, we provide a unified geometric interpretation for wireless quality-aware routing metrics. Empirical observations of a real-world wireless mesh network suggest that mETX and ENT could achieve a 50 % reduction in the average packet loss rate compared with ETX. Index Terms—Effective bandwidth, large deviations, mesh networks, path selection, quality-aware routing (QAR), routing protocols, wireless channel modeling, wireless networks. I.
Divert: Fine-grained Path Selection for Wireless LANs
, 2004
"... The performance of Wireless Local Area Networks (WLANs) often suffers from link-layer frame losses caused by noise, interference, multipath, attenuation, and user mobility. We observe that frame losses often occur in bursts and that three of the five main causes of frame losses--- multipath, attenua ..."
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Cited by 47 (4 self)
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The performance of Wireless Local Area Networks (WLANs) often suffers from link-layer frame losses caused by noise, interference, multipath, attenuation, and user mobility. We observe that frame losses often occur in bursts and that three of the five main causes of frame losses--- multipath, attenuation, mobility---depends on the transmission path traversed between an access point (AP) and a client station. In a typical WLAN
