Rendezvous-based data dissemination for supporting mobile sinks in multi-hop clustered wireless sensor networks

In wireless sensor networks, a clustering-based technique is considered as an efficient approach for supporting mobile sinks without using position information. It exploits a Backbone-based Virtual Infrastructure (BVI) which uses only cluster heads (CHs) to construct routing structures. Since sensor nodes have constrained energy and are failure-prone, the effective design of both a clustering structure to construct a BVI and a routing protocol in the BVI is an important issue to achieve energy-efficient and reliable data delivery. However, since previous studies use one-hop clustering for a BVI, they are not robust against node and link failures and thus leading low data delivery ratio. They also use flooding-based routing protocols in a BVI and thus leading high energy consumption. Thus, in this paper, we propose a rendezvous-based data dissemination protocol based on multi-hop clustering (RDDM). Since RDDM uses a multi-hop clustering to provide enough backup sensor nodes to substitute a CH and enough backup paths between neighbor CHs, it can provide high robustness against node and link failures. By using a rendezvous CH, RDDM constructs routing paths from source nodes to mobile sinks without flooding in our BVI and thus can save energy of sensor nodes. By considering movement types of sinks, RDDM finds out a shorter path between a source node and a mobile sink through signaling only between neighbor CHs and thus can reduce the energy consumption. Analysis and simulation results show that RDDM provides better performance than previous protocols in terms of energy consumption and data delivery ratio.     

An Efficient Reader Anticollision Algorithm in Dense RFID Networks With Mobile RFID Readers

In parallel with the proliferation of radio-frequency identification (RFID) systems, many RFID readers have been increasingly employed. In such an environment, collision among readers becomes a serious problem. Existing anticollision algorithms, depending on the information of neighboring readers, may require constant effort in order to grasp such information. Although it may be given by a server or a coordinator, they may not be suitable in dense and dynamic RFID networks with mobile readers. In this paper, we propose an efficient reader anticollision algorithm using a polling server in dense and dynamic RFID networks with mobile readers. Owing to the assistance of the server, the readers can rapidly decide whether they can work or not without interfering neighbors and can be easily synchronized. Our proposed algorithm is simple and makes readers aware of neighbors to minimize reader collisions. Performance evaluation shows how many readers can operate in a network and indicates that our proposed algorithm is more efficient than distributed color selection, colorwave, and hierarchical Q-learning algorithm, particularly in dense and mobile environments.      

Integrating RFID and WLAN for indoor positioning and IP movement detection

Location awareness in an indoor environment and wireless access to Internet applications are major research areas towards the overwhelming success of wireless and mobile communications. However, the unpredictable indoor radio propagation and handover latency due to node mobility are the main challenging issues that need to be addressed. For tackling efficiently both problems of indoor localization and handover management, we propose combining key benefits of two outstanding wireless technologies, i.e. radio frequency identification (RFID) and a wireless local area network (WLAN) infrastructure. WLANs, such as IEEE 802.11 (WiFi), are now very common in many indoor environments for providing wireless communication among WiFi-enabled devices by accessing an Access Point (infrastructure mode) or through peer to peer connections (ad hoc mode). However, the small cell size of the Access Points (APs) in a WiFi-based network drives the need for frequent handovers leading to increased latency. RFID is an emerging technology consisting of two basic components, a tag and a reader, and its main purpose is the automatic identification of tagged objects by a reader. However, in the presence of multiple readers, RFID suffers from the so-called reader collision problem, mainly due to the inability for direct communication among them. In this paper, we propose a hybrid RFID and WLAN system; the RFID technology is employed for collecting information that is used for both localization and handover management within the WLAN, whereas the WLAN itself is utilized for controlling and coordinating the RFID reading process. In our system architecture, tag IDs of a RFID tag deployment are correlated with both location and topology information in order to determine the position and predict the next subnetwork of a Mobile Node (MN) with a reader attached to its mobile device. The role of the WLAN is to coordinate the readers when accessing the RFID channel for retrieving tags?? IDs, hence compensating the persisting RFID collision problem among multiple readers. Numerical results based on extensive simulations validate the efficiency of the proposed hybrid system in providing accurate and time efficient localization and reducing the IP handover latency.     

A distributed energy-efficient clustering scheme for deploying IDS in MANETs

Cluster-based intrusion detection systems, where cluster heads (CHs) detect misbehavior of their member nodes, have been proposed in mobile ad-hoc networks (MANETs) in order to protect the network and save the energy. However, long-term survival of all nodes is more important so as not to partition the network. The extension of the network lifetime in the cluster-based IDS depends on which nodes are selected as CHs, which consume much more energy than cluster members due to monitoring them and detecting intrusions. In this paper, we propose a Distributed Energy Efficient Cluster Formation (DEECF) scheme, which exploits the expected residual energy of mobile nodes to select CHs and starts the cluster formation from leaf nodes to reduce the number of clusters. The scheme consists of the cluster construction algorithm and the cluster maintenance algorithm, both of which can be performed at each node in a distributed way without any global knowledge. We prove the correctness of the algorithms, and show that the DEECF scheme is more energy efficient than other clustering schemes by extensive simulation.     

An efficient and fair cooperative approach for resource management in wireless networks

In cellular networks, the implementation of various resource management processes, such as bandwidth reservation and location updates, has been based on the one‐to‐one resource management information exchange paradigm, between the mobile nodes and the base stations. In this paper, we design and demonstrate the use of a distributed cooperative scheme that can be applied in the future wireless networks to improve the energy consumption for the routine management processes of mobile terminals, by adopting the peer‐to‐peer communication concept of wireless ad hoc networks. In our approach, the network is subdivided into one‐hop ad hoc clusters where the members of each cluster cooperate to perform the required management functions, and conventional individual direct report transmissions of the mobile terminals to the base stations are replaced by two‐hop transmissions. The performance evaluation and the corresponding numerical results presented in this paper confirm that our proposed scheme reduces significantly the overall system energy consumption when compared with the conventional one‐to‐one direct information management exchange approach. Furthermore the issue of fairness in dynamically selecting the various cluster heads in successive operational cycles of the proposed scheme is analyzed, and an enhanced algorithm is proposed and evaluated, which improves significantly the cluster head selection fairness, in order to balance the energy consumption among the various mobile terminals. Copyright © 2005 John Wiley & Sons, Ltd.     

Taxonomy and Challenges of the Integration of RFID and Wireless Sensor Networks

Radio frequency identification and wireless sensor networks are two important wireless technologies that have a wide variety of applications in current and future systems. RFID facilitates detection and identification of objects that are not easily detectable or distinguishable by using conventional sensor technologies. However, it does not provide information about the condition of the objects it detects. WSN, on the other hand, not only provides information about the condition of the objects and environment but also enables multihop wireless communications. Hence, the integration of these technologies expands their overall functionality and capacity. This article investigates recent research work and applications that integrate RFID with sensor networks. Four classes of integration are discussed: integrating tags with sensors, integrating tags with WSN nodes and wireless devices, integrating readers with WSN nodes and wireless devices, and a mix of RFID and WSNs. Finally, a discussion of new challenges and future work is presented.     

Using dummy data for RFID tag and reader authentication

Radio-Frequency IDentification (RFID) technology is an essential enabler of a multitude of intelligent applications. The robust authentication of RFID system components is critical in providing trustworthy data delivery from/to tags. In this paper, we propose an authentication protocol based on monitoring the transmissions between readers and tags in the system. The proposed authentication scheme is based on injecting decoys within the exchanged communications (between RFID readers and tags) and is used in the authentication process. Furthermore, the proposed authentication scheme is mathematically modeled and validated using extensive simulation. The simulations results show that the proposed scheme provides a 100% confidence level in the authentication of tags and detection of compromised readers.     

Keyless Security in Wireless Networks

Security and privacy issues in RFID technology gain tremendous popularity recently. However, existing work on RFID authentication problems always make assumptions such as (1) hash function can be fully employed in designing RFID protocols; (2) channels between readers and server are always secure. The first assumption is not suitable for EPC Class-1 Gen-2 tags, which has been challenged in many research work, while the second one cannot be directly adopted in mobile RFID applications where wireless channels between readers and server are always insecure. To solve these problems, in this paper, we propose a novel ultralightweight and privacy-preserving authentication protocol for mobile RFID systems. We only use bitwise XOR, and several special constructed pseudo-random number generators to achieve our aims in the insecure mobile RFID environment. We use GNY logic to prove the security correctness of our proposed protocol. The security and privacy analysis show that our protocol can provide several privacy properties and avoid suffering from a number of attacks, including tag anonymity, tag location privacy, reader privacy, forward secrecy, and mutual authentication, replay attack, desynchronization attack etc. We implement our protocol and compare several parameters with existing work, the evaluation results indicate us that our protocol significantly improves the system performance.     

Analysis of energy consumption for multiple object identification system with active RFID tags

Radio frequency identification (RFID) systems are very effective for identifying objects. Existing published works focus on designing efficient collision resolution protocols for the tag identification problem in RFID systems with passive RFID tags. However, advances in low‐cost and low‐power sensing technologies will make active RFID tags more popular and affordable in the near future. In multiple object identification systems with active tags, the tags are designed for extremely low‐cost large‐scale applications such that battery replacement is not feasible. This imposes a critical energy‐constraint on the communication protocols used in these systems. In this paper, we analyze energy consumption and identification times for several protocols. The objective is to decrease energy consumption of tags by reducing both the total identification time and the total active time. Copyright © 2007 John Wiley & Sons, Ltd.     

Radio frequency identification: technologies,applications, and research issues

A radio frequency identification (RFID) system is a special kind of sensor network to identify an object or a person using radio frequency transmission. A typical RFID system includes transponders (tags) and interrogators (readers): tags are attached to objects/persons, and readers communicate with the tags in their transmission ranges via radio signals. RFID systems have been gaining more and more popularity in areas such as supply chain management, automated identification systems, and any place requiring identifications of products or people. RFID technology is better than barcode in many ways, and may totally replace barcode in the future if certain technologies can be achieved such as low cost and protection of personal privacy. This paper provides a technology survey of RFID systems and various RFID applications. We also discuss five critical research issues: cost control, energy efficiency, privacy issue, multiple readers' interference, and security issue. Copyright © 2006 John Wiley & Sons, Ltd.     

Pipelined forwarding with energy balance in hexagonal wireless sensor networks

This paper presents a pipelined forwarding scheme with energy balance for hexagonal wireless sensor networks (H‐WSN). An H‐WSN consists of hexagonal clusters in which the distance between any two cluster heads is , where R is the radius of a hexagonal cluster. A trade‐off exists in pipelined forwarding for an H‐WSN; that is, reducing pipeline lengths can decrease data forwarding delay, but it will adversely increase the number of clusters, which consequently increases the total collecting time of a mobile sink. This paper therefore introduces a mobile sink data collecting and routing scheme to dynamically adjust the pipeline lengths and to periodically switch pipeline directions. With this mobile sink data collecting and routing, the overall system throughput is increased, and the energy consumptions among all cluster heads are balanced. Copyright © 2012 John Wiley & Sons, Ltd.     

Evaluating the energy consumption of the RFID tag collision resolution protocols

RFID technology acts as a bridge to connect the physical world with the digital space, and RFID system is pervading our daily life in the last few years. The energy consumed by the reader and a tag in resolving the collisions caused by multiple tags is a key issue that affects life time of mobile reader and active tags, as well as the identification accuracy of passive tags. In this paper, the energy consumed by the reader and a tag in resolving the tag collision is examined for the commonly used RFID tag collision resolution protocols, including the frame slotted ALOHA based and the binary query tree based protocols. Numeric evaluation is also performed and the result verifies that regarding to energy consumption, the dynamic frame slotted ALOHA protocol for the Class-1 RFID system performs best among the frame slotted ALOHA protocols, and the modified binary query tree protocol also performs better than the standard binary query tree protocols.     

An unequal cluster-based routing protocol in wireless sensor networks

Clustering provides an effective method for prolonging the lifetime of a wireless sensor network. Current clustering algorithms usually utilize two techniques; selecting cluster heads with more residual energy, and rotating cluster heads periodically to distribute the energy consumption among nodes in each cluster and extend the network lifetime. However, they rarely consider the hot spot problem in multihop sensor networks. When cluster heads cooperate with each other to forward their data to the base station, the cluster heads closer to the base station are burdened with heavier relay traffic and tend to die much faster, leaving areas of the network uncovered and causing network partitions. To mitigate the hot spot problem, we propose an Unequal Cluster-based Routing (UCR) protocol. It groups the nodes into clusters of unequal sizes. Cluster heads closer to the base station have smaller cluster sizes than those farther from the base station, thus they can preserve some energy for the inter-cluster data forwarding. A greedy geographic and energy-aware routing protocol is designed for the inter-cluster communication, which considers the tradeoff between the energy cost of relay paths and the residual energy of relay nodes. Simulation results show that UCR mitigates the hot spot problem and achieves an obvious improvement on the network lifetime. Guihai Chen obtained his B.S. degree from Nanjing University, M. Engineering from Southeast University, and PhD from University of Hong Kong. He visited Kyushu Institute of Technology, Japan in 1998 as a research fellow, and University of Queensland, Australia in 2000 as a visiting professor. During September 2001 to August 2003, he was a visiting professor at Wayne State University. He is now a full professor and deputy chair of Department of Computer Science, Nanjing University. Prof. Chen has published more than 100 papers in peer-reviewed journals and refereed conference proceedings in the areas of wireless sensor networks, high-performance computer architecture, peer-to-peer computing and performance evaluation. He has also served on technical program committees of numerous international conferences. He is a member of the IEEE Computer Society. Chengfa Li was born 1981 and obtained his Bachelor’s Degree in mathematics in 2003 and his Masters Degree in computer science in 2006, both from Nanjing University, China. He is now a system programmer at Lucent Technologies Nanjing Telecommunication Corporation. His research interests include wireless ad hoc and sensor networks. Mao Ye was born in 1981 and obtained his Bachelor’s Degree in computer science from Nanjing University, China, in 2004. He served as a research assistant At City University of Hong Kong from September 2005 to August 2006. He is now a PhD candidate with research interests in wireless networks, mobile computing, and distributed systems. Jie Wu is a professor in the Department of Computer Science and Engineering at Florida Atlantic University. He has published more than 300 papers in various journal and conference proceedings. His research interests are in the areas of mobile computing, routing protocols, fault-tolerant computing, and interconnection networks. Dr. Wu serves as an associate editor for the IEEE Transactions on Parallel and Distributed Systems and several other international journals. He served as an IEEE Computer Society Distinguished Visitor and is currently the chair of the IEEE Technical Committee on Distributed Processing (TCDP). He is a member of the ACM, a senior member of the IEEE, and a member of the IEEE Computer Society.     

An unequal cluster-based routing scheme for multi-level heterogeneous wireless sensor networks

In wireless sensor networks (WSNs), clustering can significantly reduce energy dissipation of nodes, and also increase communication load of cluster heads. When multi-hop communication model is adopted in clustering, “energy hole” problem may occur due to unbalanced energy consumption among cluster heads. Recently, many multi-hop clustering protocols have been proposed to solve this problem. And the main way is using unequal clustering to control the size of clusters. However, many of these protocols are about homogeneous networks and few are about heterogeneous networks. In this paper, we present an unequal cluster-based routing scheme for WSNs with multi-level energy heterogeneity called UCR-H. The sensor field is partitioned into a number of equal-size rectangular units. We first calculate the number of clusters in each unit by balancing energy consumption among the cluster heads in different units. And then we find the optimal number of units by minimizing the total energy consumption of inter-cluster forwarding. Finally, the size of clusters in each unit is elaborately designed based on node’s energy level and the number of clusters in this unit. And a threshold is also designed to avoid excessive punishment to the nodes with higher energy level. Simulation results show that our scheme effectively mitigates the “energy hole” problem and achieves an obvious improvement on the network lifetime.     

Improving performance in delay/disruption tolerant networks through passive relay points

In this paper, we study the case of a limited number of mobile nodes trying to communicate in a large geographic area, forming a delay/disruption tolerant network (DTN). In such networks the mobile nodes are disconnected for significantly long periods of time. Traditional routing protocols proposed for mobile ad hoc networks or mesh networks, which assume at least one path between each source and destination, are ineffective in DTNs. One approach to improve communication is through gossip based protocols because these protocols do not rely on a fixed path. Another approach is to control the movement of the mobile nodes and/or use special mobile nodes called ferry nodes. Others try to employ a fixed infrastructure including stationary relay points. One scheme in stationary relay point approach is to use base stations as relay points which need their own power supply. In this paper, we study a passive approach where mobile nodes deposit/retrieve messages to/ from known stationary locations in the geographic region. Messages are delivered from a source by being deposited at one or more locations that are later visited by the destination. A proposed implementation of our approach using read/writable passive Radio Frequency Identification (RFID) tags, one per point location, is considered in this work. Passive RFID technology is desirable because it operates wirelessly and without the need for attached power. Our simulation results indicate that our approach can achieve competitive message delay and delivery rates. We also demonstrate several techniques for optimizing the stationary relay node placement, namely relay pruning, probability based relay distribution and a genetic algorithm; the genetic algorithm is shown to provide the best solutions to this problem.     

A Novel RFID Data Mining System: Integration of Effective Sequential Pattern Mining and Fuzzy Rules Generation Techniques

Data warehousing and Data mining find enormous applications; RFID technology is one among them. A RFID data warehousing system with novel data cleaning, transformation and loading technique has been proposed in the previous work. The system has been dedicatedly implemented in one of the significant RFID applications tracking of goods in warehouses. The warehoused RFID data is in specific format and so an effective mining system is required to mine the needed information from the database. The existing mining algorithms are inefficient in extracting the information from the warehoused RFID data. In this paper, a novel data mining system is proposed, which effectively extracts the information regarding the nature of movement of the RFID tags. The proposed mining system generates an intermediate dataset (I-dataset) from the warehoused dataset. From the I-dataset, sequential patterns are mined with different pattern length combinations. From the mined sequential patterns, fuzzy rules are generated, which depicts the nature of movement of the RFID tags. The implementation results show that the proposed mining system performs well by extracting the significant RFID tags and its combinations and the nature of movement of the tags.     

电能表RFID智能化签封管理的应用

RFID,即电子签封,它是指通过无线射频方式来进行的非接触双向通信,来对目标进行识别和数据的交换。非接触是RFID的最大特点,可以很好的完成移动式读写和固定式读写的通信要求,目前有着比较广泛的应用。在电能表上应用,可以对电能表在各种条件下进行精准识别,获得正确的相应数据,从而实现对电能表的有效管理。基于此,对电能表RFID智能化签封管理的应用进行分析,希望给相关人员提供一定借鉴。     

基于CMRA路由协议改进算法

为了延长无线传感网络的生存时间,需要设计满足高效率、低功耗的路由算法。一种CMRA（intercluster head multi-hop routing algorithm）算法被提出来,这种算法通过节点通信能量消耗模型建立最小能量路径树,但CMRA对于簇头选择的能量分配不均衡,造成簇头结点负载过重。提出一种新的路由算法CMRA-EE（CMRA-energy efficient）,在簇头选举阶段引入节点能量参数,同时将簇头节点能量与距离作为代价参数,从而平衡了网络节点能耗。通过仿真对CMRA-EE算法进行性能分析与评价,结果显示,CMRA-EE算法在延长无线传感网有效生存时间方面比CMRA算法有了明显的改善。     

能耗均衡和可靠的无线传感器网络分簇算法

为了解决热区问题和单点失效问题,提出了一种新的无线传感器网络分簇算法。算法将网络划分为非均匀的栅格,每个栅格的节点分别构成一个簇,根据节点失效概率确定栅格簇首的数目,并由栅格的多个簇首协作完成该栅格节点的数据收集。算法通过调整各个栅格中可参与簇首轮换的节点数目,从长远均衡节点之间的能耗。通过建立包含多个簇首的簇,算法降低了簇成员对单个簇首的依赖性。此外,算法还采取了一些降低能耗的措施。实验结果表明,该算法能够达到较高的能耗均衡程度和数据收集可靠性,并可以延长网络的生命周期。     

一种具有阅读器匿名功能的射频识别认证协议

在射频识别(RFID)的应用中,安全问题特别是用户隐私问题正日益凸显。因此,(用户)标签信息的隐私保护的需求越来越迫切。在RFID系统中,标签的隐私保护不仅是对外部攻击者,也应该包括阅读器。而现有许多文献提出的认证协议的安全仅针对外部攻击者,甚至在外部攻击者的不同攻击方法下也并不能完全保证安全。该文提出两个标签对阅读器匿名的认证协议:列表式RFID认证协议和密钥更新式RFID认证协议。这两个协议保证了阅读器对标签认证时,标签的信息不仅对外部攻击者是安全的而且对阅读器也保持匿名和不可追踪。相较于Armknecht等人提出的对阅读器匿名和不可追踪的认证协议,该文所提的协议不再需要增加第三方帮助来完成认证。并且密钥更新式RFID匿名认证协议还保证了撤销后的标签对阅读器也是匿名性和不可追踪的。