Asynchronous Duty Cycling Research Articles

A new methodology for evaluating the neighbor discovery time in schedule-based asynchronous duty-cycling wireless sensor networks

Duty cycling is a fundamental mechanism for battery-operated wireless networks, such as wireless sensor networks. Due to its importance, it is an integral part of several Medium Access Protocols and related wireless technologies. In Schedule-based Asynchronous Duty Cycle, nodes activate and deactivate their radio interfaces according to a pre-designed schedule of slots, which guarantees overlapping uptime between two neighbors, independent of the offset between their internal clocks, making communication between them possible. This paper presents a new methodology for evaluating the Neighbor Discovery Time (NDT) of Schedule-based Asynchronous Duty Cycle. Differently from previous methodologies, it accounts for the possibility of the slots in the schedules of the two neighbors not being perfectly border-aligned — an unrealistic assumption in practice. By means of simulation, we show that not taking this under consideration can lead to an overestimate of the NDT by a factor of 2 depending on the particular scenario, thus justifying the importance of our work.•We propose a new subslot-based methodology for computing the NDT of a wakeup schedule used for asynchronous duty cycling.•It replaces the traditional slot-based methodology, by dividing slots into subslots, allowing for the analysis of non-integer clock offsets between nodes, and further allowing mathematical models to consider the more realistic continuous-time case.•Our validation data shows that the slot-based methodology may overestimate NDT by a factor of up to 2, making the proposed subslot-based methodology much more precise.

Relay node selection scheme and deep sleep period for power management in energy‐harvesting wireless sensor networks

SummaryThis paper presents Relay node selection scheme and Deep sleep period for power management in Energy Harvesting Wireless Sensor Networks (RD‐EHWSN), a new energy‐saving scheme founded on asynchronous duty cycling. RD‐EHWSN reduces sensor node energy consumption and guarantees equilibrium energy use between sensor nodes in WSN with the energy harvesting capacity by adjusting these sensor nodes duty cycles more drastically and deeply by according to the estimated value of its residual energy on the basis of future‐presented harvested energy, and this is done through the use of a new proposed energy threshold policy. RD‐EHWSN also grips the benefit of transmitter initiated using the low power listening (LPL) technique with short preamble messages and uses a new relay node selection procedure to achieve the load balancing in WSN. We implemented RD‐EHWSN by using OMNeT++/MiXiM. For evaluation, we compared it with PS‐EHWSN, under multiple concurrent multihop traffic flows scenarios and scenarios in which nodes can harvest different energy harvesting rate. In all experiments, RD‐EHWSN significantly outperformed the PS‐EHWSN scheme; the results of simulation demonstrate that our scheme enhances the general yielding of WSN thru lessening the energy consumption and the mean latency, as well as raising the packet delivery ratio and the throughput. Moreover, RD‐EHWSN improves the WSN lifetime and ensures it operates in good condition in the case where the energy harvesting rate is lower by comparing it with the PS‐EHWSN scheme.

DACODE: Distributed adaptive communication framework for energy efficient industrial IoT-based heterogeneous WSN

As the cornerstone of IoT-based systems, WSN connecting a wide range of intelligent sensor nodes is expected to bring significant changes in the near future. Due to the limited battery capacity of the sensor node, WSN considers maximizing network lifetime by minimizing the power consumption to be the most important challenge. To this end, we propose a Distributed Adaptive Communication with On/Off switching and Dual queuing for Energy efficiency (DACODE) as a novel asynchronous duty cycling mechanism. The performance evaluation shows that the proposed mechanism significantly reduces power consumption while maintaining network throughput and guaranteeing data urgency and queue stability.

COFlood: Concurrent Opportunistic Flooding in Asynchronous Duty Cycle Networks

For energy constraint wireless IoT nodes, their radios usually operate in duty cycle mode. With low maintenance and negotiation cost, asynchronous duty cycle radio management is widely adopted. To achieve fast network flooding is challenging in asynchronous duty cycle networks. Recently, concurrent flooding, which allows a set of nodes (called concurrent senders ) to immediately broadcast the received packet without any backoff, is a promising approach to improve the flooding speed. We observe that selecting either large or small number of concurrent senders cannot achieve the optimal flooding speed in different deployments. There is a tradeoff between the degradation of concurrent broadcast efficiency and the missing of early receiving chance. In this article, we propose COFlood (Concurrent Opportunistic Flooding), a practical and efficient concurrent flooding protocol in asynchronous duty cycle networks. First, COFlood constructs a concurrent flooding tree in distributed manner. The non-leaf nodes are selected as concurrent senders and they can cover the entire network while reserving the most capacity of concurrent broadcast for later added opportunistic concurrent senders. Moreover, we find that exploiting both early wake-up nodes and long lossy links can speed up the concurrent flooding tree-based network flooding by increasing the early receiving chances. Then, COFlood develops a lightweight method to select the nodes that meet the conditions of these two opportunities as opportunistic concurrent senders. We implement COFlood in TinyOS and evaluate it on two real testbeds. In comparison with state-of-the-art concurrent flooding protocol, completion time and energy consumption can be reduced by up to 35.3% and 26.6%.

Adaptive dynamic duty cycle mechanism for energy efficient medium access control in wireless multimedia sensor networks

AbstractMultimedia applications require significantly higher bandwidth than conventional textual applications. Furthermore, multimedia stream requires time sensitive and involves high‐energy consumption, which become more challenging on resource constrained networks such as wireless multimedia sensor network (WMSN). As a result, developing an energy efficient algorithm to prolong the network lifetime is the main reoccurring issue in WMSN. Although the duty cycling mechanism has been proven to be an efficient solution for energy saving in various WSN applications, the tradeoff between energy efficiency and quality of service (QoS) on WMSN remains striking. In this article, an adaptive dynamic duty cycle mechanism for energy‐efficient medium access control (ADE‐MAC) is proposed for WMSNs. ADE‐MAC uses a unique asynchronous duty cycle approach to schedule the sleep pattern of each sensor node which can be adapted according to the incoming traffic rate and queuing delay at each node. In the proposed system, the overhead of synchronization is avoided because every node has its own scheduling sleep, and the only sender node must wake up the receiver nodes by using preambles packets. The findings that result from comprehensive simulation show that ADE‐MAC outperforms the baseline approaches in term of delivery ratio by 12%, less packet overhead by 28%, less end‐to‐end delay by 19%, and less power consumption by 41% compared to the baseline mechanisms.

Investigation of MAC Algorithms for Cross-Boundary Exchange between Wireless Sensor Networks

Increasing deployments of wireless sensor networks (WSNs), following the trend of the Internet of Thing (IoT), heightens the probability of the spatial overlap between WSNs in the same local area. The direct communication between distinctive networks can be supported by the direct interconnection between sensor nodes in any possible intersecting area. The packet transfer between the neighbouring networks offers multiple benefits by sharing data or network resources. However, the communication protocol adopted by each WSN can be different due to its conditions design and preferences preventing transmission and reception of packets from other network domains. One of the possible solutions for the compatibility problem is using a lightweight communication protocol for communication across the boundary while allowing networks to use its preferred communication stack inside its domain. This work investigates the MAC algorithm used for communication across the network boundary. The synchronous/asynchronous duty cycle MAC algorithm is practically evaluated by using a testbed. The experiment results suggest using the synchronous duty cycle protocol for communication across the network boundary consumes less energy offers improved latency and reliability than the previously proposed asynchronous duty cycle protocol.

Towards an Improved Energy Efficient and End-to-End Secure Protocol for IoT Healthcare Applications

In this paper, we proposed LCX-MAC (local coordination X-MAC) as an extension of X-MAC. X-MAC is an asynchronous duty cycle medium access control (MAC) protocol. X-MAC used one important technique of short preamble which is to allow sender nodes to quickly send their actual data when the corresponding receivers wake up. X-MAC node keeps sending short preamble to wake up its receiver node, which causes energy, increases transmission delay, and makes the channel busy since a lot of short preambles are discarded, as these days Internet of Things (IoT) healthcare with different sensor nodes for the healthcare is time-critical applications and needs a quick response. A possible improvement over X-MAC is that local information of each node will share with its neighbour node. This local information exchanged will cause much less overhead than in the nodes which are synchronized. To calculate the effect of this the local coordination on X-MAC in this paper, we built an analytical model of LCX-MAC that incorporates the local coordination in X-MAC. The analytical results show that LCX-MAC outperformed X-MAC and X-MAC/BEB in terms of throughput, delay, and energy.

An NDT Model for Block Designs Operating Under Asymmetrical Duty Cycling

Reducing energy consumption is of paramount importance in wireless networks, particularly now with the increasing popularity of the Internet of Things. One of the most effective tools for that is duty cycling the radio. In particular, asynchronous methods have been repeatedly studied in the literature. In this letter, we consider the asymmetrical case of asynchronous duty cycling, i.e., when nodes operate under different duty cycles because of different energy requirements. More specifically, we derive upper and lower bounds, as well as an approximate model for the neighbor discovery time of nodes operating under asymmetrical block designs. We further validate our model by comparing it to empirical data.

On the Lifetime of Asynchronous Software-Defined Wireless Sensor Networks

In this article, we consider a software-defined wireless sensor network (WSN) architecture which conserves energy by applying asynchronous duty cycling. In asynchronous sensor networks, the overhearing adversely impacts the energy consumption of the nodes. Using a mathematical model, we compute the maximum lifetime of the network and accordingly propose a multichannel operation and transmit power control to reduce the effect of overhearing in asynchronous networks. Our comprehensive test results confirm that for the network with load-aware nonuniform sensor node deployment, the network lifetime is much higher compared to a uniform deployment. We also show that the use of data aggregation software-defined WSNs (SDWSNs) can improve the network lifetime as compared to the data gathering networks.

PRIB-MAC: a preamble-based receiver initiated MAC protocol for broadcast in wireless sensor networks

Synchronizing data communication between nodes with energy efficiency by adapting different duty cycling mechanisms is the most important task of Medium Access Control (MAC) protocol in wireless sensor networks (WSNs). Most of the low-duty-cycle MAC protocols address the issue of unicast efficiently, ignoring the broadcast performance, which presents significant challenges due to the duty cycling. In this paper, we propose an asynchronous low-duty-cycle MAC protocol for broadcasts in WSN that incorporates the advantages of existing sender-initiated and receiver-initiated MAC protocols. The Preamble-Based Receiver-Initiated Broadcast MAC (PRIB-MAC) protocol is built on RI-MAC unicast MAC protocol by adding a preamble to support broadcasting. It is found that the duration of the preamble depends on the time difference in the wake-up schedule of the nodes and with an optimized wake-up schedule, the preamble duration of just 2% of the slot duration can give 100% node coverage in very less time compared with ADB: an efficient multi-hop broadcast protocol based on asynchronous duty cycling in WSNs.

Chase++: Fountain-Enabled Fast Flooding in Asynchronous Duty Cycle Networks

Due to limited energy supply on many Internet of Things (IoT) devices, asynchronous duty cycle radio management is widely adopted to save energy. Flooding is a critical way to disseminate messages through the whole network. Capture effect enabled concurrent broadcast is appealing to accelerate network flooding in asynchronous duty cycle networks. However, when the flooding payload's size is large, the concurrent broadcast performance is far from efficient due to the frequently unsatisfied capture effect. Intuitively, senders can send a short packet containing partial flooding payload to keep concurrent broadcast efficiency. In practice, we still face two challenges. Considering packet loss, a receiver needs an effective way to recover the entire flooding payload from several received packets as soon as possible. Moreover, considering different channel states of different senders, how a sender chooses the optimal packet length to guarantee high channel utilization is not easy. In this paper, we propose Chase++ a Fountain-code based concurrent broadcast control layer to enable fast flooding in asynchronous duty cycle networks. Chase++ uses Fountain code to alleviate the negative influence of a certain part of the flooding payload's continuous loss. Moreover, Chase++ adaptively selects packet length with the local estimation of channel utilization. Specifically, Chase++ partitions long payload into several short payload blocks, further encoded into many encoded payload blocks by Fountain-code. Then, with temporal and spatial features of the sampled RSS (received signal strength) sequence, a sender estimates the number of concurrent senders. Finally, according to the estimated number of concurrent senders, the sender determines the optimal number of encoded payload blocks in a packet and assembles the encoded payload blocks as lots of packets. Then, the concurrent broadcast layer continuously transmits these packets. Receivers can recover the original flooding payload after several independent encoded payload blocks are collected. We implement Chase++ in TinyOS with TelosB nodes. We further evaluate Chase++ on Local testbed with 50 nodes and Indriya testbed with 95 nodes. The improvement of network flooding speed can reach 23.6% and 13.4%, respectively.

An Enhanced Energy Efficient Hybrid Asynchronous Duty Cycle MAC in Wireless Sensor

Wireless sensor network (WSN) has countless potential application in many areas due to its easy deployment process, lower installation cost, less cabling required, and high mobility. However, limited energy residue (especially deposited in small size battery) is always a major obstacle in WSN. Improving mechanism on MAC layer is one of the potential research that could increase battery lifespan. In the active phase of the MAC layer, a node can receive and transmit packet when awake. Then, a node is in a sleep phase, it switches off the radio automatically to save energy and gives alert. While in idle listening phase, node still using the energy. Duty cycling performed in MAC layer don’t involve turning off their radio and switching sleep mode but repeating off/on process. Therefore, this study proposed mechanism of WSN that used in order to enhance power energy using duty cycle in MAC layer. The proposed of asynchronous duty cycle MAC layer using a hybrid duty cycle MAC in implementation the performance of WSN. In addition, this paper also elaborated the design asynchronous hybrid duty cycle MAC with multi-hop broadcast.

Exploiting Concurrency for Opportunistic Forwarding in Duty-Cycled IoT Networks

Due to limited energy supply of Internet of Things (Zhao et al. 2018) (IoT) devices, asynchronous duty cycle radio management is widely adopted to save energy. Since the sleep schedules of nodes are unsynchronized, a sender has to repeatedly send frames to coordinate with its receiver or keep sleeping until the receiver’s wake-up time will come according to receiver’s sleep-wake schedule. In such contexts, opportunistic forwarding, which takes the earliest forwarding opportunity instead of a deterministic forwarder, shows great advantage in utilizing channel resource for duty-cycled IoT networks. The multiple forwarding choices with temporal and spatial diversity increase the chance of collision tolerance in opportunistic forwarding, potentially enhancing the overall performance of duty-cycled multi-hop networks. However, since the current channel contention mechanisms mainly focus on collision avoidance, it is too conservative to exploit concurrency. To address this problem, in this article, we propose COF to fully exploit the potential Concurrency for Opportunistic Forwarding in duty-cycled IoT networks. COF achieves concurrent transmission by: (i) measuring conditional link quality under the interference of on-going transmissions, and then (ii) further modeling the benefit of potential concurrency opportunities. According to the expected benefit of concurrency, COF decides whether or not to transmit in concurrent way. COF also adopts concurrency flag and signal features to avoid data collision caused by disordered concurrent transmissions and enhance the accuracy of conditional link quality estimation. COF can be easily integrated into the conventional unsynchronized and duty-cycled protocols. We have implemented COF and evaluated its performance on a 40-node testbed. The results show that COF can effectively exploit potential concurrency in opportunistic forwarding and COF outperforms the state-of-art protocols under diverse traffic load and network density.

Revisiting Probabilistic Schedule-Based Asynchronous Duty Cycling

Schedule-based asynchronous duty cycling is a simple duty cycling technique that requires no synchronization, control traffic or expensive computation. Thus, it is an interesting choice for WSNs. However, most of the literature on the design of asynchronous schedules has been limited by the exaggerated restriction that the schedules present a property named rotation closure. While more flexible probabilistic schedules have been proposed, they were considered inferior under the argument that they do not provide an upper bound on the communication latency. In this paper we revisit the probabilistic schedules with the goal of showing they may be the preferred method in several scenarios. We argue that under realistic assumptions no schedule can guarantee a latency upper bound. We show that probabilistic schedules better support asymmetric duty cycle operation, while also providing unlimited duty cycle granularity and range. Finally, by means of simulation, we compare a probabilistic schedule belonging to the family of Birthday Protocols, the Birthday–Listen–and–Transmit (BLT), with traditional deterministic schedules. Results show that, on top of its other qualitative advantages, BLT achieves competitive latencies.

Towards energy efficient duty cycling in underwater wireless sensor networks

Underwater Wireless Sensor Networks devices are usually battery powered and thereby their lifetime is limited. This issue leads to lose data measurements and thus to a performance loss of the underlying UWSN application. It also increases the maintenance cost in Internet of Underwater Things scenarios with a huge number of UWSN devices. Additionally, the unique characteristics of UWSNs pose several constraints such as the high energy consumption, long propagation delay, and node mobility. Duty Cycle management is one of the key technologies to solve this issue. In this context, the use of duty cycle based algorithms for opportunistic, autonomous and energy efficient duty cycle management can mitigate the undesirable impact of underwater communications, consequently, improve the overall efficiency of the algorithms designed for the UWSNs. In this article, we study the energy efficient data collection for asynchronous duty cycle MAC protocols for underwater sensor networks. To this end, we improve two previously proposed receiver initiated MAC protocols that use a nodes, (1) residual energy, and (2) its sleep-awake pattern to improve the overall network lifetime. We show that the considerations made in the protocols have a great impact on the performance of the network. Our results show that the protocols minimize the collisions while alleviating the need for excessive handshake and also the average active time of a node is minimized.

Comparative analysis of contention based and TDMA based MAC protocols for wireless sensor networks

Wireless sensor networks have been widely considered as one of the most important technologies that promises wide range of applications in the field of medical, military, environment, home, agriculture, etc. A variety of Medium Access Control (MAC) protocols have been proposed for wireless sensor networks. This paper presents the comparative analysis of two MAC protocols–RI-MAC, receiver initiated asynchronous duty cycle MAC protocol which is a contention based protocol and ATMA, advertisement-based TDMA MAC protocol. The two MAC protocols are analyzed using four performance parameters such as end to end delay, throughput, packet delivery ratio and energy consumption.

Multiple Packet Transmissions in Duty Cycling WSNs: A DTMC-Based Throughput Analysis

Multiple packet transmissions (MPTs) improve performance by transmitting multiple packets in a single operational cycle. Asynchronous duty cycling medium access control (MAC) protocols such as receiver initiated MAC protocol (RI-MAC) transmit multiple packets in one cycle. In this letter, we develop two associated discrete time Markov chain (DTMC) models to model MPT that can be achieved via multiple node competitions. Furthermore, we present the way of incorporating those developed models with each other for evaluating performance of RI-MAC with MPT. Using the solution of DTMC models, network throughput of MPT is calculated and compared with the one achieved by single packet transmission MAC (e.g., S-MAC) protocol. Validation of analytical results through discrete-event simulations confirms the accuracy of modeling and discloses the operation of MPT in RI-MAC protocol.

Minimizing the Energy Consumption in Wireless Sensor Networks

Energy in Wireless Sensor networks (WSNs) represents an essential factor in designing, controlling and operating the sensor networks. Minimizing the consumed energy in WSNs application is a crucial issue for the network effectiveness and efficiency in terms of lifetime, cost and operation. Number of algorithms and protocols were proposed and implemented to decrease the energy consumption. Principally, WSNs operate with battery-powered sensors. Since Sensor's batteries have not been easily recharge. Therefore, prediction of the WSN represents a significant concern. Basically, the network failure occurs due to the inefficient sensor's energy. MAC protocols in WSNs achieved low duty-cycle by employing periodic sleep and wakeup. Predictive Wakeup MAC (PW-MAC) protocol was made use of the asynchronous duty cycling. It reduces the consumption of the node energy by allowing the senders to predict the receiver′s wakeup time. The WSN must be applied in an efficient manner to utilize the sensor nodes and their energy to ensure effective network throughput. To ensure energy efficiency the sensors' duty cycles must be adjusted appropriately to meet the network traffic demands. The energy consumed in each node due to its switching between the active and idle states was also estimated. The sensors are assumed to be randomly deployed. This paper aims to improve the randomly deployed network lifetime by scheduling the effects of transmission, reception and sleep states on the energy consumption of the sensor nodes. Results for these states with much performance metrics were also studied and discussed.

<italic>Chase</italic>: Taming Concurrent Broadcast for Flooding in Asynchronous Duty Cycle Networks

Asynchronous duty cycle is widely used for energy constraint wireless nodes to save energy. The basic flooding service in asynchronous duty cycle networks, however, is still far from efficient due to severe packet collisions and contentions. We present Chase , an efficient and fully distributed concurrent broadcast layer for flooding in asynchronous duty cycle networks. The main idea of Chase is to meet the strict signal time and strength requirements (e.g., Capture Effect) for concurrent broadcast while reducing contentions and collisions. We propose a distributed random inter-preamble packet interval adjustment approach to constructively satisfy the requirements. Even when requirements cannot be satisfied due to physical constraints (e.g., the difference of signal strength is less than a 3 dB), we propose a lightweight signal pattern recognition-based approach to identify such a circumstance and extend radio-on time for packet delivery. We implement Chase in TinyOS with TelosB nodes and extensively evaluate its performance. The implementation does not have any specific requirement on the hardware and can be easily extended to other platforms. The evaluation results also show that Chase can significantly improve flooding efficiency in asynchronous duty cycle networks.

Distributed Routing and Channel Selection for Multi-Channel Wireless Sensor Networks

We propose a joint channel selection and quality aware routing scheme for multi-channel wireless sensor networks that apply asynchronous duty cycling to conserve energy, which is common in many environmental monitoring applications. Energy resources may vary from node to node due to differential consumption as well as availability, as observed in rechargeable sensor networks. A data collection traffic pattern is assumed, where all sensor nodes periodically forward sensor data to a centralized base station (sink). Under these assumptions, the effect of overhearing dominates the energy consumption of the nodes. The proposed scheme achieves lifetime improvement by reducing the energy consumed in overhearing and also by dynamically balancing the lifetimes of nodes. Performance evaluations are presented from experimental tests as well as from extensive simulation studies, which show that the proposed scheme reduces overhearing by ∼60% with just 2 channels without significantly affecting the network performance.