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...es for routing protocols that exploit connectivity determined by lower level link estimations to form a routing topology. Many wireless routing protocols assume connectivity by hearing certain packets=-=[2, 16, 17, 18, 19]-=-. For example, ROUTE REQUEST and ROUTE REPLY messages are often building blocks for creating a routing structure. However, Figure 1(a) suggest that long unreliable links are likely to influence these ...

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...es for routing protocols that exploit connectivity determined by lower level link estimations to form a routing topology. Many wireless routing protocols assume connectivity by hearing certain packets=-=[2, 16, 17, 18, 19]-=-. For example, ROUTE REQUEST and ROUTE REPLY messages are often building blocks for creating a routing structure. However, Figure 1(a) suggest that long unreliable links are likely to influence these ...

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...es for routing protocols that exploit connectivity determined by lower level link estimations to form a routing topology. Many wireless routing protocols assume connectivity by hearing certain packets=-=[2, 16, 17, 18, 19]-=-. For example, ROUTE REQUEST and ROUTE REPLY messages are often building blocks for creating a routing structure. However, Figure 1(a) suggest that long unreliable links are likely to influence these ...

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...00 being the minimum. A node can be configured as a base station to route over standard serial port interface by attaching an extra hardware board. The base station serves as the traffic sink. TinyOS =-=[15]-=- provides a programming environment and a complete network stack on this platform. Its active message layer provides a connectionless packet abstraction, with a normal packet size being about 30 bytes...

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...es for routing protocols that exploit connectivity determined by lower level link estimations to form a routing topology. Many wireless routing protocols assume connectivity by hearing certain packets=-=[2, 16, 17, 18, 19]-=-. For example, ROUTE REQUEST and ROUTE REPLY messages are often building blocks for creating a routing structure. However, Figure 1(a) suggest that long unreliable links are likely to influence these ...

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...st cell density is often an application-specific or deployment parameter since it affects overall network hop count, latency, channel utilization, network lifetime, and quality of links. For example, =-=[20]-=- adjusts the transmit power to control the topology and minimize energy required to transport data. Neighborhood management essentially has three components: insertion, eviction, and reinforcement. Fo...

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...ted over the entire packet to determine successful packet reception. A link-level acknowledgment can be sent by the receiver for each packet successfully received. A simple CSMA-based MAC is employed =-=[22]-=-; it adds a random delay before listening for an idle channel and backs off with a random delay over a predefined window when the channel is busy. 2.2 Empirical Observations To characterize the empiri...

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...be one directed diffusion flow along a simple gradient or a single selection query. To ground the hardware and physical configuration factors, we focus on large sensor fields of Berkeley TinyOS motes =-=[13]-=- spread roughly as a uniform grid over a large, essentially unobstructed, indoor space. Our study is conducted in four stages. Section 2 presents an empirical characterization of the links experienced...

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...ams using memory much smaller than the number of distinct classes of packets. Heuristics are used in [7] to identify a set of most frequently occurring packet classes. Two algorithms are presented in =-=[10]-=- to identify all values with frequency of occurrence exceeding a user specified threshold. A sliding window approach is used in [5] that can be generalized to estimate statistical information of a dat...

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...iques in databases. There is a growing body of work in gathering statistics on Internet packet streams using memory much smaller than the number of distinct classes of packets. Heuristics are used in =-=[7]-=- to identify a set of most frequently occurring packet classes. Two algorithms are presented in [10] to identify all values with frequency of occurrence exceeding a user specified threshold. A sliding...

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...ariance in quality are asfunction of distance. For large collections of nodes, this simple model exhibits qualitatively the irregular connectivity patterns that have been observed in real deployments =-=[8]-=-. Section 3 investigates simple, efficient estimators for determining these link probabilities. Here, a node can estimate the quality of the link from other nodes passively by collecting statistics on...

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...snooping comes at a cost, since the node listens for packets that are not necessarily addressed to it, but in many cases the packets are received anyways. Various low-power listening mechanisms exist =-=[21]-=- that would enable snooping at a much lower cost. An alternative approach is to use received signal strength as an indication of link quality. However, the use of forward error correction and uncertai...

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...requently occurring packet classes. Two algorithms are presented in [10] to identify all values with frequency of occurrence exceeding a user specified threshold. A sliding window approach is used in =-=[5]-=- that can be generalized to estimate statistical information of a data stream. Finally, [6] showed a simple FREQUENCY algorithm that estimates frequency of Internet packet streams with limited space. ...

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...le networks, but it requires sequence number propagation and sequence number settling time tuning, which may differ in each deployment. We rely on techniques similar to poison-reverse or splithorizon =-=[11]. -=-By monitoring forwarding traffic and snooping on the parent address in each neighbor’s messages, neighboring child nodes can be identified and will not be considered as potential parents. We only ne...

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...lues with frequency of occurrence exceeding a user specified threshold. A sliding window approach is used in [5] that can be generalized to estimate statistical information of a data stream. Finally, =-=[6]-=- showed a simple FREQUENCY algorithm that estimates frequency of Internet packet streams with limited space. We first consider table management that seeks to retain a stable subset of high-quality lin...

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... for MT a substantial noise margin should be used in parent selection to enhance stability. Another cost metric is path reliability, which is a product of link qualities along the path. It is used in =-=[24]-=- to optimize end-to-end success rate without link retransmission. It has a tendency to yield long paths. We do not study this metric as our protocols take advantage of link retransmissions. 6. EVALUAT...

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...d packets can be damaged or totally missed by the receiver. Furthermore, the link error dynamics are expected to be very different for low power wireless radios. Many link estimation techniques exist =-=[23]-=-, so we desired to test many of the established candidates under conditions similar to our sensor network. The resource constraints significantly limit the amount of processing and storage that can be...

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...ty for wired and power-rich wireless networks is well established. It is widely deployed over the Internet in protocols such as Internal Gateway Routing Protocol (IGRP) [12] and Enhanced IGRP (EIGRP) =-=[1]-=-. Link quality is measured as the percent of packets that arrived undamaged on a link. It is reported by the network interface hardware or firmware, and is calculated as a moving average. In IGRP, pac...

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...ty for wired and power-rich wireless networks is well established. It is widely deployed over the Internet in protocols such as Internal Gateway Routing Protocol (IGRP) [12] and Enhanced IGRP (EIGRP) =-=[1]-=-. Link quality is measured as the percent of packets that arrived undamaged on a link. It is reported by the network interface hardware or firmware, and is calculated as a moving average. In IGRP, pac...

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... probing to estimate link quality for wired and power-rich wireless networks is well established. It is widely deployed over the Internet in protocols such as Internal Gateway Routing Protocol (IGRP) =-=[12]-=- and Enhanced IGRP (EIGRP) [1]. Link quality is measured as the percent of packets that arrived undamaged on a link. It is reported by the network interface hardware or firmware, and is calculated as ...

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...lgorithm is an understanding of the loss behavior of the link under various circumstances. Previous studies have indicated that radio connectivity is imperfect and non-uniform, even in ideal settings =-=[3, 4, 8]-=-. Rather than carry along a detailed model of the platform or the propagation physics, we seek a simple characterization of the channel that can be used in topology formation. 2.1 Hardware Platform Th...

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...es for routing protocols that exploit connectivity determined by lower level link estimations to form a routing topology. Many wireless routing protocols assume connectivity by hearing certain packets=-=[2, 16, 17, 18, 19]-=-. For example, ROUTE REQUEST and ROUTE REPLY messages are often building blocks for creating a routing structure. However, Figure 1(a) suggest that long unreliable links are likely to influence these ...

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...ory and 4kB of data memory. The network device is a RF Monolithics 916MHz, amplitude shift keying (ASK) RF transceiver, capable of delivering up to 40 kbps; it emits less than a milliwatt of RF power =-=[14]-=-. The RF transmit power can be tuned in software, with 0 being the maximum and 100 being the minimum. A node can be configured as a base station to route over standard serial port interface by attachi...

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...sages received, giving all nodes a chance to get established. To estimate N, there exists much prior work in the database literature to estimate the number of distinct values over a continuous stream =-=[9]-=-. However, in the case when periodic beacons are present, we simply count the average number of beacons received between beacons from a particular node. The insertion policy should reinforce good neig...

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...lgorithm is an understanding of the loss behavior of the link under various circumstances. Previous studies have indicated that radio connectivity is imperfect and non-uniform, even in ideal settings =-=[3, 4, 8]-=-. Rather than carry along a detailed model of the platform or the propagation physics, we seek a simple characterization of the channel that can be used in topology formation. 2.1 Hardware Platform Th...