Anfeng Liu

Design principles and improvement of cost function based energy aware routing algorithms for wireless sensor networks

Cost function based routing has been widely studied in wireless sensor networks for energy efficiency improvement and network lifetime elongation. However, due to the complexity of the problem, existing solutions have various limitations. In this paper, we analyze the inherent factors, design principles and evaluation methods for cost function based routing algorithms. Two energy aware cost based routing algorithms named Exponential and Sine Cost Function based Route (ESCFR) and Double Cost Function based Route (DCFR) have been proposed in this paper. For ESCFR, its cost function can map small changes in nodal remaining energy to large changes in the function value. For DCFR, its cost function takes into consideration the end-to-end energy consumption, nodal remaining energy, resulting in a more balanced and efficient energy usage among nodes. The performance of the cost function design is analyzed. Extensive simulations demonstrate the proposed algorithms have significantly better performance than existing competing algorithms.

Joint Optimization of Lifetime and Transport Delay under Reliability Constraint Wireless Sensor Networks

This paper first presents an analysis strategy to meet requirements of a sensing application through trade-offs between the energy consumption (lifetime) and source-to-sink transport delay under reliability constraint wireless sensor networks. A novel data gathering protocol named Broadcasting Combined with Multi-NACK/ACK (BCMN/A) protocol is proposed based on the analysis strategy. The BCMN/A protocol achieves energy and delay efficiency during the data gathering process both in intra-cluster and inter-cluster. In intra-cluster, after each round of TDMA collection, a cluster head broadcasts NACK to indicate nodes which fail to send data in order to prevent nodes that successfully send data from retransmission. The energy for data gathering in intra-cluster is conserved and transport delay is decreased with multi-NACK mechanism. Meanwhile in inter-clusters, multi-ACK is returned whenever a sensor node sends any data packet. Although the number of ACKs to be sent is increased, the number of data packets to be retransmitted is significantly decreased so that consequently it reduces the node energy consumption. The BCMN/A protocol is evaluated by theoretical analysis as well as extensive simulations and these results demonstrate that our proposed protocol jointly optimizes the network lifetime and transport delay under network reliability constraint.

ActiveTrust: Secure and Trustable Routing in Wireless Sensor Networks

Wireless sensor networks (WSNs) are increasingly being deployed in security-critical applications. Because of their inherent resource-constrained characteristics, they are prone to various security attacks, and a black hole attack is a type of attack that seriously affects data collection. To conquer that challenge, an active detection-based security and trust routing scheme named ActiveTrust is proposed for WSNs. The most important innovation of ActiveTrust is that it avoids black holes through the active creation of a number of detection routes to quickly detect and obtain nodal trust and thus improve the data route security. More importantly, the generation and the distribution of detection routes are given in the ActiveTrust scheme, which can fully use the energy in non-hotspots to create as many detection routes as needed to achieve the desired security and energy efficiency. Both comprehensive theoretical analysis and experimental results indicate that the performance of the ActiveTrust scheme is better than that of the previous studies. ActiveTrust can significantly improve the data route success probability and ability against black hole attacks and can optimize network lifetime.

RMER: Reliable and Energy-Efficient Data Collection for Large-Scale Wireless Sensor Networks

We propose a novel event data collection approach named reliability and multipath encounter routing (RMER) for meeting reliability and energy efficiency requirements. The contributions of the RMER approach are as follows. 1) Fewer monitor nodes are selected in hotspot areas that are close to the Sink, and more monitor nodes are selected in nonhotspot areas, which can lead to increased network lifetime and event detection reliability. 2) The RMER approach sends data to the Sink by converging multipath routes of event monitoring nodes into a one-path route to aggregate data. Thus, energy consumption can be greatly reduced, thereby enabling further increased network lifetime. Both theoretical and experimental simulation results show that RMER applied to event detection outperforms other solutions. Our results clearly indicate that RMER increases energy efficiency by 51% and network lifetime by 23% over other solutions while guaranteeing event detection reliability.

Lifetime and Energy Hole Evolution Analysis in Data-Gathering Wireless Sensor Networks

Network lifetime is a crucial performance metric to evaluate data-gathering wireless sensor networks (WSNs) where battery-powered sensor nodes periodically sense the environment and forward collected samples to a sink node. In this paper, we propose an analytic model to estimate the entire network lifetime from network initialization until it is completely disabled, and determine the boundary of energy hole in a data-gathering WSN. Specifically, we theoretically estimate the traffic load, energy consumption, and lifetime of sensor nodes during the entire network lifetime. Furthermore, we investigate the temporal and spatial evolution of energy hole and apply our analytical results to WSN routing in order to balance the energy consumption and improve the network lifetime. Extensive simulation results are provided to demonstrate the validity of the proposed analytic model in estimating the network lifetime and energy hole evolution process.

Secure and Energy-Efficient Disjoint Multipath Routing for WSNs

Recent advances in microelectromechanical system (MEMS) technology have boosted the deployment of wireless sensor networks (WSNs). Limited by the energy storage capability of sensor nodes, it is crucial to jointly consider security and energy efficiency in data collection of WSNs. The disjoint multipath routing scheme with secret sharing is widely recognized as one of the effective routing strategies to ensure the safety of information. This kind of scheme transforms each packet into several shares to enhance the security of transmission. However, in many-to-one WSNs, shares have high probability to traverse through the same link and to be intercepted by adversaries. In this paper, we formulate the secret-sharing-based multipath routing problem as an optimization problem. Our objective aims at maximizing both network security and lifetime, subject to the energy constraints. To this end, a three-phase disjoint routing scheme called the Security and Energy-efficient Disjoint Route (SEDR) is proposed. Based on the secret-sharing algorithm, the SEDR scheme dispersively and randomly delivers shares all over the network in the first two phases and then transmits these shares to the sink node. Both theoretical and simulation results demonstrate that our proposed scheme has significant improvement in network security under both scenarios of single and multiple black holes without reducing the network lifetime.

Research on the energy hole problem based on unequal cluster-radius for wireless sensor networks

Clustering provides an effective way for prolonging the lifetime of a wireless sensor network. When cluster heads cooperate with each other to forward their data to the base station via multi-hop communication, the cluster head closer to the base station are burdened with heavier relay traffic and trend to die much faster, leaving areas of the energy hole problem and causing network partition. To address the problem, we propose a theoretically analytical method for the energy consumption with different cluster-radius in clustering network. The main conclusions are presented as follows: (1) The expression of cluster-radius @t is given while the network lifetime is maximal. (2) In clustering network, the lifetime is longer than the network with the data transmitted directly. (3) We propose a novel and simple strategy to avoid the energy hole problem for data gathering scheme. Employing an unequal cluster-radius and alternate between dormancy and work is the core idea. That is, the network lifetime depends on the node which has the maximal energy consumption. And it is not the same node in this circumstance. So the total energy consumption is less than the network which employing an optimum and fixed cluster-radius and it can achieve an obvious improvement on the network lifetime. The theoretical analysis and simulation results show that the strategy is very simple and it can effectively avoid the energy hole problem. Therefore, the conclusions can present a better design guideline for wireless sensor networks.

Achieving Source Location Privacy and Network Lifetime Maximization Through Tree-Based Diversionary Routing in Wireless Sensor Networks

Wireless sensor networks (WSNs) have been proliferating due to their wide applications in both military and commercial use. However, one critical challenge to WSNs implementation is source location privacy. In this paper, we propose a novel tree-based diversionary routing scheme for preserving source location privacy using hide and seek strategy to create diversionary or decoy routes along the path to the sink from the real source, where the end of each diversionary route is a decoy (fake source node), which periodically emits fake events. Meanwhile, the proposed scheme is able to maximize the network lifetime of WSNs. The main idea is that the lifetime of WSNs depends on the nodes with high energy consumption or hotspot, and then the proposed scheme minimizes energy consumption in hotspot and creates redundancy diversionary routes in nonhotspot regions with abundant energy. Hence, it achieves not only privacy preservation, but also network lifetime maximization. Furthermore, we systematically analyze the energy consumption in WSNs, and provide guidance on the number of diversionary routes, which can be created in different regions away from the sink. In addition, we identify a novel attack against phantom routing, which is widely used for source location privacy preservation, namely, direction-oriented attack. We also perform a comprehensive analysis on how the direction-oriented attack can be defeated by the proposed scheme. Theoretical and experimental results show that our scheme is very effective to improve the privacy protection while maximizing the network lifetime.

LSCD: A Low-Storage Clone Detection Protocol for Cyber-Physical Systems

Cyber-physical systems (CPSs) have recently become an important research field not only because of their important and varied application scenarios, including transportation systems, smart homes, surveillance systems, and wearable devices but also because the fundamental infrastructure has yet to be well addressed. Wireless sensor networks (WSNs), as a type of supporting infrastructure, play an irreplaceable role in CPS design. Specifically, secure communication in WSNs is vital because information transferred in the networks can be easily stolen or replaced. Therefore, this paper presents a novel distributed low-storage clone detection protocol (LSCD) for WSNs. We first design a detection route along the perpendicular direction of a witness path with witness nodes deployed in a ring path. This ensures that the detection route must encounter the witness path because the distance between any two detection routes must be smaller than the witness path length. In the LSCD protocol, clone detection is processed in a nonhotspot region where a large amount of energy remains, which can improve energy efficiency as well as network lifetime. Extensive simulations demonstrate that the lifetime, storage requirements, and detection probability of our protocol are substantially improved over competing solutions from the literature.

QoE-ensured price competition model for emerging mobile networks

The ubiquitous availability of devices such as smartphones, tablets, and other portable devices enables the collection of massive amounts of distributed data from the daily lives of citizens. These types of emerging mobile networks can provide new forms of valuable information that are currently not available on this scale via any traditional data collection methods. In such networks, price competition is the most important factor among the participants (mobile devices, services organizers [SOs], and users), highly affecting their quality of experience. In this article, we first explain how a game theory model can depict social behavior, price competition, and the evolutionary relationship among devices, SOs, and users, and then provide insights to understand the price competition process of the participants in mobile networks. Finally, we outline several important open research directions.