ERTP: Energy-efficient and Reliable Transport Protocol for data streaming in Wireless Sensor Networks
Introduction
Many applications in Wireless Sensor Networks (WSNs) produce streaming data [19], [22], [23], [24]. In this class of applications, each sensor node periodically samples and relays the sensed data to a central data collection node, referred to as the base station or the sink. In such applications, two important requirements are: end-to-end reliability and long-term operation. A data packet needs to be reliably relayed to the sink. Typically, the end-to-end transmission latency is not a primary concern in this class of applications, but energy-efficiency is. WSNs are expected to operate independently for weeks, or even for months. Our recent Wireless Sensor Network deployment in the Burdekin delta, Australia, for water monitoring [19] is one such example. Our application involves streaming sensed data such as pressure, water flow rate, and salinity periodically from many scattered sensors to the sink node which in turn gets relayed via an IP network to a remote site for archiving, processing and presentation. In our deployment, we observed that the channel quality of radio links between sensor nodes is unreliable and the packet error rate in each link varied considerably over time [19]. Similar observation has also been reported in the literature [16], [17], [25].
Often, the reliability requirements for data streaming applications are not absolute but rather statistical in their nature. That is, the reliability is determined by the quantity of data packets delivered to the sink rather than the reliability of each data packet. For example, in the Burdekin deployment, we would like to study sensor readings over a reasonable scale of time such as a week or a day, but not over the scale of a minute or a second. In fact, we require that at least 75% of data packets per day from each sensor node are received at the sink [19] for offline processing. Using a statistical reliability metric when designing a reliable transport protocol guarantees delivery of enough information to the users, and also reduces the number of transmissions when compared to an absolute reliability metric. Previous studies in [8], [20] have also shown that the statistical reliability approach can significantly reduce energy consumption.
While many transport protocols for WSNs have been studied in the literature, most of them do not address both requirements, i.e., transmission reliability and energy-efficiency, for data streaming applications. Current work focuses on either providing reliability for data transmission, or minimizing energy consumption, but not both. In this paper, we discuss the design and implementation of an Energy-efficient Transport Protocol (ERTP) that ensures statistically reliable delivery of sensor data to the sink for data streaming applications in WSNs. To reduce energy consumption, ERTP achieves end-to-end reliability by controlling the reliability at each hop dynamically. ERTP uses Stop-and-Wait Hop-by-Hop Implicit Acknowledgment (SW HBH iACK) for loss recovery. In wireless links, the transmitter can overhear forwarding transmissions and interprets them as iACKs. Obviously, when a packet reaches the sink, there will be no further forwarding so the sink node needs to send an explicit ACK (eACK). The transmitter retransmits the packet if, after a certain timeout, no acknowledgment has been received. The primary contributions of the paper are summarized as follows:
- •
We present an analysis of the trade-off between energy consumption and end-to-end reliability for ERTP, in which HBH iACK approach and duplicate detection are used at each sensor node. To balance energy consumption and reliability, ERTP dynamically controls the maximum number of retransmissions at each sensor node.
- •
We propose a distributed algorithm for retransmission timeout estimation in ERTP. Determining how long the node should wait for an iACK is non-trivial since iACK timeout depends on the time it takes a packet to be forwarded by the downstream node. The simulation results in Section 4 show that the proposed retransmission timeout algorithm is significantly more energy-efficient than other approaches. To the best of our knowledge, ours is the first work which investigates adaptive retransmission timeout estimation for the class of HBH iACK protocols in WSNs.
- •
We design, implement, and evaluate ERTP in TinyOS [6] for real-world sensor networks. Our extensive evaluations show that ERTP can reduce energy consumption by more than 45% when compared to current approaches. Consequently, sensor nodes are more energy-efficient and the lifespan of the unattended WSN is increased.
The remainder of the paper is organized as follows. Related studies are described in Section 2. The protocol details are described in Section 3. The simulation and implementation results are presented in Sections 4 Simulation, 5 Implementation and experimental evaluation. The paper is concluded in Section 6.
Section snippets
Related work
A list of relevant related work on transport protocols for WSNs is given in Table 1. We distinguish the transport protocols by three different characteristics: reliability, energy-awareness, and the type of data flows that they support (continuous data flows or a bulk data flow). As shown in Table 1, ERTP and RMST [11], to the best of our knowledge, are the only transport protocols for continuous data flow that take reliability and energy constraints into account. However, RMST [11] uses
ERTP: an Energy-efficient and Reliable Transport Protocol
In this section, we firstly provide an overview of ERTP that includes the requirements and our assumptions. We then discuss the details of the components of ERTP: the Hop-by-Hop Reliability Control, and the Hop-by-Hop Retransmission Timeout (RTO) Control. Finally, we discuss other details of ERTP that include link quality estimation, duplicate packet detection, and a distributed algorithm for RTO updating. Definition 1 The application layer end-to-end reliability for each sensor node α (0 < α < 1) is described
Simulation
In this section, we evaluate the performance of the ERTP through extensive simulations.
Implementation and experimental evaluation
Having validated the performance of ERTP by simulations in Section 4, we implemented ERTP in TinyOS 1.x and compared it to state-of-the-art reliable WSN communication protocol, Surge Reliable [15] in a 16 Fleck-3 [21] real network testbed. We selected node 0 as the sink and the other nodes generate packets of 40 bytes at the rate of one packet every 10 seconds. The application layer end-to-end reliability requirement is α = 0.95. Each experiment was run for 30 min, which is sufficient to evaluate
Conclusions
This paper has presented ERTP, an Energy-efficient and Reliable Transport Protocol for WSNs, which is designed for WSN data streaming applications. ERTP achieves the application layer end-to-end statistical reliability and energy-efficiency by dynamically controlling the maximum number of retransmissions, and exploring the wireless overhearing capability for implicit acknowledgment. We have presented the analysis of the trade-off between energy consumption and end-to-end reliability for ERTP,
Acknowledgments
The authors would like to thank CSIRO for the hardware and technical support, and Stephen Rothery for his help with protocol evaluation.
References (44)
- et al.
Understanding the real behavior of 802.11 and mote ad hoc networks
Pervasive and Mobile Computing
(2005) - et al.
Implicit hop-by-hop congestion control in wireless multihop networks
Elsevier Ad Hoc Networks
(2008) - IEEE Standard 802.15.4,...
- CC2420 Product Information and Data Sheet, Chipcon. Available from:...
- H. Lee, A. Cerpa, P. Levis, Improving wireless simulation through noise modeling, in: Information Processing in Sensor...
- B. Zurita Ares, C. Fischione, A. Speranzon, K.H. Johansson, On power control for wireless sensor networks: system...
- TinyOS. Available from:...
- Contiki Operating System. Available from:...
- Z. Rosberg, R. Liu, L.D. Tuan, S. Jha, A.Y. Dong, J. Zic, Energy Efficient Statistically Reliable Hybrid Transport...
- et al.
Event-to-sink reliable transport in wireless sensor networks
IEEE/ACM Transactions on Networking
(2005)
Experimental investigation of wireless link layer for multi-hop oceanographic-sensor networks
Electronics Letters
Cited by (75)
Markov decision process and network coding for reliable data transmission in wireless sensor and actor networks
2019, Pervasive and Mobile ComputingCitation Excerpt :Mahmood et al. [8] have discussed several reliability protocols in WSNs which are based on retransmission and redundancy techniques. In [15], an energy-efficient and reliable transport protocol has been proposed by Le et al. to balance energy consumption and reliability in WSNs. Park et al. [16] have proposed a downstream reliability mechanism which ensures the reliability from sink-to-sensors in wireless sensor networks.
Lotus effect optimization algorithm (LEA): a lotus nature-inspired algorithm for engineering design optimization
2024, Journal of SupercomputingNetwork Coding for Efficient File Transfer in Narrowband Environments
2023, Information Technology and ControlRelevance and Predictability in Wireless Multimedia Sensor Network in Smart Cities
2023, Convergence of IoT, Blockchain, and Computational Intelligence in Smart CitiesResearch on redundant transmission method of distribution network protection data based on device direct connection
2023, Proceedings of SPIE - The International Society for Optical EngineeringTransport Protocols for WSNs
2023, Signals and Communication Technology