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Proceedings ArticleDOI

Data forwarding in extremely low duty-cycle sensor networks with unreliable communication links

Yu Gu1, Tian He1
06 Nov 2007-pp 321-334
TL;DR: Interestingly, it is revealed that allowing opportunistic looping can actually reduce the end-to-end delay of dynamic switch-based forwarding, and these are the most encouraging results to date in this new research direction.
Abstract: In extremely low duty-cycle sensor networks, end-to-end communications cannot afford to maintain an always-awake communication backbone. Low duty-cycle, accompanied by the unreliable nature of wireless communication, makes it essential to design a new data forwarding scheme for such networks, so as to achieve network energy efficiency, reliability, and timeliness in an integrated fashion.In this work, we introduce the concept of dynamic switch-based forwarding (DSF) that optimizes the (i) expected data delivery ratio, (ii) expected communication delay, or (iii) expected energy consumption. DSF is designed for networks with possibly unreliable communication links and predetermined node communication schedules. Interestingly, we reveal that allowing opportunistic looping can actually reduce the end-to-end delay. To our knowledge, these are the most encouraging results to date in this new research direction. In this paper, DSF is evaluated with a theoretical analysis, extensive simulation, and physical testbed consisting of 20 MicaZ motes. Results reveal the remarkable advantage of DSF in extremely low duty-cycle sensor networks in comparison to three well-known solutions (ETX [3], PRRxD [19] and DESS [16]). We also demonstrate our solution defaults into ETX in always-awake networks and DESS in perfect-link networks.

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Citations
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Proceedings ArticleDOI
20 Sep 2009
TL;DR: Opportunistic Flooding is introduced, a novel design tailored for low-duty-cycle networks with unreliable wireless links and predetermined working schedules and achieves significantly shorter flooding delay while consuming only 20-60% of the transmission energy.
Abstract: Intended for network-wide dissemination of commands, configurations and code binaries, flooding has been investigated extensively in wireless networks. However, little work has yet been done on low-duty-cycle wireless sensor networks in which nodes stay asleep most of time and wake up asynchronously. In this type of network, a broadcasting packet is rarely received by multiple nodes simultaneously, a unique constraining feature that makes existing solutions unsuitable. Combined with unreliable links, flooding in low-duty-cycle networks is a new challenging issue.In this paper, we introduce Opportunistic Flooding, a novel design tailored for low-duty-cycle networks with unreliable wireless links and predetermined working schedules. The key idea is to make probabilistic forwarding decisions at a sender based on the delay distribution of next-hop nodes. Only opportunistically early packets are forwarded using links outside the energy optimal tree to reduce the flooding delay and redundancy in transmission. To improve performance further, we propose a forwarder selection method to alleviate the hidden terminal problem and a link-quality-based backoff method to resolve simultaneous forwarding operations. We evaluate Opportunistic Flooding with extensive simulation and a test-bed implementation consisting of 30 MicaZ nodes. Evaluation shows our design is close to the optimal performance achievable by oracle flooding designs. Compared with improved traditional flooding, our design achieves significantly shorter flooding delay while consuming only 20% ~ 60% of the transmission energy in various low-duty-cycle network settings.

268 citations


Cites background from "Data forwarding in extremely low du..."

  • ...While pioneering projects have been proposed for lowduty-cycle unicasts [8, 24, 47], research is surprisingly inadequate for low-duty-cycle flooding, an important function for disseminating network-wide commands, alerts and configurations [11], time synchronization [25], and code binaries [14]....

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  • ...Recently, DSF [8] offered a new data forwarding technique that optimizes data delivery ratio, endto-end delay or energy consumption for data delivery in low-dutycycle sensor networks....

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  • ...Recently,DSF[8] offered a new data forwarding technique that optimizes data delivery ratio, end­to-end delay or energy consumption for data delivery in low-duty­cycle sensor networks....

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  • ...In order to deliver a packet, a sender may have to wait for a certain period of time (termed sleep latency [8]) until its receiver becomes active....

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Proceedings ArticleDOI
16 Apr 2012
TL;DR: This paper introduces ORW, a practical opportunistic routing scheme for wireless sensor networks that reduces radio duty-cycles on average by 50% and delays by 30% to 90% when compared to the state of the art.
Abstract: Traditionally, routing in wireless sensor networks consists of two steps: First, the routing protocol selects a next hop, and, second, the MAC protocol waits for the intended destination to wake up and receive the data. This design makes it difficult to adapt to link dynamics and introduces delays while waiting for the next hop to wake up. In this paper we introduce ORW, a practical opportunistic routing scheme for wireless sensor networks. In a duty-cycled setting, packets are addressed to sets of potential receivers and forwarded by the neighbor that wakes up first and successfully receives the packet. This reduces delay and energy consumption by utilizing all neighbors as potential forwarders. Furthermore, this increases resilience to wireless link dynamics by exploiting spatial diversity. Our results show that ORW reduces radio duty-cycles on average by 50% (up to 90% on individual nodes) and delays by 30% to 90% when compared to the state of the art.

213 citations

Journal ArticleDOI
TL;DR: This work proposes a novel jamming detection scheme that effectively detects sophisticated jamming attacks that cannot be detected with existing techniques and enables the formation of robust sensor networks for dependable delivery of alarm notifications.
Abstract: An integral part of most security- and safety-critical applications is a dependable and timely alarm notification However, owing to the resource constraints of wireless sensor nodes (ie, their limited power and spectral diversity), ensuring a timely and jamming-resistant delivery of alarm messages in applications that rely on wireless sensor networks is a challenging task With current alarm forwarding schemes, blocking of an alarm by jamming is straightforward and jamming is very likely to remain unnoticed In this work, we propose a novel jamming detection scheme as a solution to this problem Our scheme is able to identify the cause of bit errors for individual packets by looking at the received signal strength during the reception of these bits and is well-suited for the protection of reactive alarm systems with very low network traffic We present three different techniques for the identification of bit errors based on: predetermined knowledge, error correcting codes, and limited node wiring We perform a detailed evaluation of the proposed solution and validate our findings experimentally with Chipcon CC1000 radios The results show that our solution effectively detects sophisticated jamming attacks that cannot be detected with existing techniques and enables the formation of robust sensor networks for dependable delivery of alarm notifications Our scheme also meets the high demands on the energy efficiency of reactive surveillance applications as it can operate without introducing additional wireless network traffic

137 citations


Cites background from "Data forwarding in extremely low du..."

  • ...To meet these demands, existing surveillance applications [11], [13], [9], [21] combine low duty-cycling with reactive notification....

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  • ...To meet these demands, existing surveillance applications [Gu and He 2007; He et al. 2006; Dutta et al. 2005; Strasser et al. 2007] combine low duty-cycling with reactive noti.cation....

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Journal ArticleDOI
TL;DR: Two novel dynamic duty-cycle scheduling schemes (called DSR and DSP) are proposed in order to reduce sleep latency, while achieving balanced energy consumption among sensor nodes in wireless sensor networks (WSNs) with energy harvesting capability.
Abstract: In this letter, we propose two novel dynamic duty-cycle scheduling schemes (called DSR and DSP) in order to reduce sleep latency, while achieving balanced energy consumption among sensor nodes in wireless sensor networks (WSNs) with energy harvesting capability. In DSR, each sensor node is allowed to adjust its duty-cycle according to the current amount of residual energy only. Since the residual energy of nodes in energy-harvesting WSNs can increase over time due to their harvesting opportunity, the estimation of prospective increase in their residual energy is useful to achieve our goal. Hence, DSP allows each of sensor nodes to reduce its duty-cycle more aggressively in proportion to such an increase. Through NS-2 simulations, we verified that our proposed schemes outperform the duty-cycle scheduling scheme used in a representative existing MAC protocol such as RI-MAC.

132 citations

Proceedings ArticleDOI
19 Apr 2009
TL;DR: This paper remodel the broadcast problem with active/dormant cycles in this new context, seeking a balance between efficiency and latency with coverage guarantees, and demonstrates that this problem can be translated into a graph equivalence, and develops a centralized optimal solution.
Abstract: Broadcast is one of the most fundamental services in wireless sensor networks (WSNs). It facilitates sensor nodes to propagate messages across the whole network, serving a wide range of higher-level operations and thus being critical to the overall network design. A distinct feature of WSNs is that many nodes alternate between active and dormant states, so as to conserve energy and extend the network lifetime. Unfortunately, the impact of such cycles has been largely ignored in existing broadcast implementations that adopt the common assumption of all nodes being active all over the time. In this paper, we revisit the broadcast problem with active/dormant cycles. We show strong evidence that conventional broadcast approaches will suffer from severe performance degradation, and, under low duty-cycles, they could easily fail to cover the whole network in an acceptable timeframe. To this end, we remodel the broadcast problem in this new context, seeking a balance between efficiency and latency with coverage guarantees. We demonstrate that this problem can be translated into a graph equivalence, and develop a centralized optimal solution. It provides a valuable benchmark for assessing diverse duty-cycle-aware broadcast strategies. We then extend it to an efficient and scalable distributed implementation, which relies on local information and operations only, with built-in loss compensation mechanisms. The performance of our solution is evaluated under diverse network configurations. The results suggest that our distributed solution is close to the lower bounds of both time and forwarding costs, and it well resists to the network size and wireless loss increases. In addition, it enables flexible control toward the quality of broadcast coverage.

124 citations


Cites background from "Data forwarding in extremely low du..."

  • ...DSF (Dynamic Switch-based Forwarding) [7] considers data forwarding in low duty-cycles, but focuses on unicast from a data source to a sink....

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  • ...There have been recent works investigating low dutycycle wireless sensor networks [14][7]....

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  • ...section, we present the results based on the following typical configurations, which are mainly adopted from [7][8][10][19]....

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References
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Journal Article
TL;DR: S-MAC as discussed by the authors is a medium access control protocol designed for wireless sensor networks, which uses three novel techniques to reduce energy consumption and support self-configuration, including virtual clusters to auto-sync on sleep schedules.
Abstract: This paper proposes S-MAC, a medium-access control (MAC) protocol designed for wireless sensor networks. Wireless sensor networks use battery-operated computing and sensing devices. A network of these devices will collaborate for a common application such as environmental monitoring. We expect sensor networks to be deployed in an ad hoc fashion, with individual nodes remaining largely inactive for long periods of time, but then becoming suddenly active when something is detected. These characteristics of sensor networks and applications motivate a MAC that is different from traditional wireless MACs such as IEEE 802.11 in almost every way: energy conservation and self-configuration are primary goals, while per-node fairness and latency are less important. S-MAC uses three novel techniques to reduce energy consumption and support self-configuration. To reduce energy consumption in listening to an idle channel, nodes periodically sleep. Neighboring nodes form virtual clusters to auto-synchronize on sleep schedules. Inspired by PAMAS, S-MAC also sets the radio to sleep during transmissions of other nodes. Unlike PAMAS, it only uses in-channel signaling. Finally, S-MAC applies message passing to reduce contention latency for sensor-network applications that require store-and-forward processing as data move through the network. We evaluate our implementation of S-MAC over a sample sensor node, the Mote, developed at University of California, Berkeley. The experiment results show that, on a source node, an 802.11-like MAC consumes 2–6 times more energy than S-MAC for traffic load with messages sent every 1–10s.

5,354 citations

Proceedings ArticleDOI
07 Nov 2002
TL;DR: S-MAC uses three novel techniques to reduce energy consumption and support self-configuration, and applies message passing to reduce contention latency for sensor-network applications that require store-and-forward processing as data move through the network.
Abstract: This paper proposes S-MAC, a medium-access control (MAC) protocol designed for wireless sensor networks Wireless sensor networks use battery-operated computing and sensing devices A network of these devices will collaborate for a common application such as environmental monitoring We expect sensor networks to be deployed in an ad hoc fashion, with individual nodes remaining largely inactive for long periods of time, but then becoming suddenly active when something is detected These characteristics of sensor networks and applications motivate a MAC that is different from traditional wireless MACs such as IEEE 80211 in almost every way: energy conservation and self-configuration are primary goals, while per-node fairness and latency are less important S-MAC uses three novel techniques to reduce energy consumption and support self-configuration To reduce energy consumption in listening to an idle channel, nodes periodically sleep Neighboring nodes form virtual clusters to auto-synchronize on sleep schedules Inspired by PAMAS, S-MAC also sets the radio to sleep during transmissions of other nodes Unlike PAMAS, it only uses in-channel signaling Finally, S-MAC applies message passing to reduce contention latency for sensor-network applications that require store-and-forward processing as data move through the network We evaluate our implementation of S-MAC over a sample sensor node, the Mote, developed at University of California, Berkeley The experiment results show that, on a source node, an 80211-like MAC consumes 2-6 times more energy than S-MAC for traffic load with messages sent every 1-10 s

5,117 citations


"Data forwarding in extremely low du..." refers background in this paper

  • ...We note that many MAC protocols, such as B-MAC [18], S-MAC [25], FPA [13] and SCP-MAC [26], effectively deal with the issues of lossy radio links through FEC/ARQ and reduce duty-cycle through the Low-Power-Listening (LPL) [18]....

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  • ...We note that many MAC protocols, such as B-MAC [18], S-MAC [25], FPA [13] and SCP-MAC [26], effectively deal with the issues of lossy radio links through FEC/ARQ and re­duce duty-cycle through the Low-Power-Listening (LPL) [18]....

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Proceedings ArticleDOI
14 Sep 2003
TL;DR: Measurements taken from a 29-node 802.11b test-bed demonstrate the poor performance of minimum hop-count, illustrate the causes of that poor performance, and confirm that ETX improves performance.
Abstract: This paper presents the expected transmission count metric (ETX), which finds high-throughput paths on multi-hop wireless networks. ETX minimizes the expected total number of packet transmissions (including retransmissions) required to successfully deliver a packet to the ultimate destination. The ETX metric incorporates the effects of link loss ratios, asymmetry in the loss ratios between the two directions of each link, and interference among the successive links of a path. In contrast, the minimum hop-count metric chooses arbitrarily among the different paths of the same minimum length, regardless of the often large differences in throughput among those paths, and ignoring the possibility that a longer path might offer higher throughput.This paper describes the design and implementation of ETX as a metric for the DSDV and DSR routing protocols, as well as modifications to DSDV and DSR which allow them to use ETX. Measurements taken from a 29-node 802.11b test-bed demonstrate the poor performance of minimum hop-count, illustrate the causes of that poor performance, and confirm that ETX improves performance. For long paths the throughput improvement is often a factor of two or more, suggesting that ETX will become more useful as networks grow larger and paths become longer.

3,656 citations

Proceedings ArticleDOI
03 Nov 2004
TL;DR: B-MAC's flexibility results in better packet delivery rates, throughput, latency, and energy consumption than S-MAC, and the need for flexible protocols to effectively realize energy efficient sensor network applications is illustrated.
Abstract: We propose B-MAC, a carrier sense media access protocol for wireless sensor networks that provides a flexible interface to obtain ultra low power operation, effective collision avoidance, and high channel utilization. To achieve low power operation, B-MAC employs an adaptive preamble sampling scheme to reduce duty cycle and minimize idle listening. B-MAC supports on-the-fly reconfiguration and provides bidirectional interfaces for system services to optimize performance, whether it be for throughput, latency, or power conservation. We build an analytical model of a class of sensor network applications. We use the model to show the effect of changing B-MAC's parameters and predict the behavior of sensor network applications. By comparing B-MAC to conventional 802.11-inspired protocols, specifically SMAC, we develop an experimental characterization of B-MAC over a wide range of network conditions. We show that B-MAC's flexibility results in better packet delivery rates, throughput, latency, and energy consumption than S-MAC. By deploying a real world monitoring application with multihop networking, we validate our protocol design and model. Our results illustrate the need for flexible protocols to effectively realize energy efficient sensor network applications.

3,631 citations


"Data forwarding in extremely low du..." refers background or methods in this paper

  • ...• Link Quality Measurement: To measure the pairwise link quality between a node and its neighbors, the link quality measurement component at each individual node sends a number of packets to each of its neighbors and utilizes the link layer acknowledgement from B-MAC [18] to calculate the pairwise link quality....

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  • ...Link Quality Measurement: To measure the pairwise link quality between a node and its neighbors, the link quality measurement component at each individual node sends a number of packets to each of its neighbors and uti­lizes the link layer acknowledgement from B-MAC [18] to calculate the pairwise link quality....

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  • ...We note that many MAC protocols, such as B-MAC [18], S-MAC [25], FPA [13] and SCP-MAC [26], effectively deal with the issues of lossy radio links through FEC/ARQ and reduce duty-cycle through the Low-Power-Listening (LPL) [18]....

    [...]

  • ...We note that many MAC protocols, such as B-MAC [18], S-MAC [25], FPA [13] and SCP-MAC [26], effectively deal with the issues of lossy radio links through FEC/ARQ and re­duce duty-cycle through the Low-Power-Listening (LPL) [18]....

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  • ...In addition, B-MAC [18] has already used link-level implicit acknowledge­ment to support .xed round-trip transmission time....

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Proceedings ArticleDOI
03 Nov 2004
TL;DR: The FTSP achieves its robustness by utilizing periodic flooding of synchronization messages, and implicit dynamic topology update and comprehensive error compensation including clock skew estimation, which is markedly better than that of the existing RBS and TPSN algorithms.
Abstract: Wireless sensor network applications, similarly to other distributed systems, often require a scalable time synchronization service enabling data consistency and coordination. This paper describes the Flooding Time Synchronization Protocol (FTSP), especially tailored for applications requiring stringent precision on resource limited wireless platforms. The proposed time synchronization protocol uses low communication bandwidth and it is robust against node and link failures. The FTSP achieves its robustness by utilizing periodic flooding of synchronization messages, and implicit dynamic topology update. The unique high precision performance is reached by utilizing MAC-layer time-stamping and comprehensive error compensation including clock skew estimation. The sources of delays and uncertainties in message transmission are analyzed in detail and techniques are presented to mitigate their effects. The FTSP was implemented on the Berkeley Mica2 platform and evaluated in a 60-node, multi-hop setup. The average per-hop synchronization error was in the one microsecond range, which is markedly better than that of the existing RBS and TPSN algorithms.

2,267 citations


"Data forwarding in extremely low du..." refers background or methods in this paper

  • ...We use FTSP [17] for the purpose of time synchronization among motes and Deluge [8] for the purpose of wireless reprogramming....

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  • ...To understand neighbors’ wake-up times, local synchronization is needed, which can be achieved using a MAC-layer timestamping technique [17], which achieves 2....

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  • ...,100 milliseconds), the accuracy requirement on time synchronization (in coverage scheduling) can be reduced, since such state-of-the-art solutions as FTSP [17] can easily achieve sub-millisecond accuracy....

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  • ...4000With Opportunistic Looping as FTSP [17] can easily achieve sub-millisecond accuracy....

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  • ...We use FTSP [17] for the purpose of time synchronization among motes and Deluge [8] for the purpose of wireless repro­ gramming....

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