• Journal of Internet Computing and Services
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• v.17 no.5
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• pp.1-8
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• 2016

This paper proposes a novel broadcast scheduling algorithm for wireless large-scale networks based on theory of complex networks. In the proposed algorithm, the network topology is formed based on a scale-free network and the probability of link distribution is analyzed. In this paper, the characteristics of complex systems are analyzed (which are not concerned by the existing broadcast scheduling algorithm techniques) and the optimization of network transmission efficiency and network time delay are provided.

• Journal of Communications and Networks
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• v.13 no.1
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• pp.26-31
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• 2011

In this paper, we formulate the minimum power multicast problem in wireless networks as a mixed integer linear programming problem and then propose a Lagrangean relaxation based algorithm to solve this problem. By leveraging on the information from the Lagrangean multiplier, we could construct more power efficient routing paths. Numerical results demonstrate that the proposed approach outperforms the existing approaches for broadcast, multicast, and unicast communications.

• Journal of Communications and Networks
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• v.16 no.6
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• pp.613-619
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• 2014

Multicast routing algorithms designed for wireline networks are not suitable for wireless environments since they cannot efficiently exploit the inherent characteristics of wireless networks such as the broadcast advantage. There are many routing protocols trying to use these advantages to decrease the number of required transmissions or increase the reception probability of data (e.g., opportunistic routing).Reducing the number of transmissions in a multicast tree directly decreases the bandwidth consumption and interference and increases the overall throughput of the network. In this paper, we introduce a distributed multicast routing protocol for wireless mesh networks called NCast which take into account the data delivery delay and path length when constructing the tree. Furthermore, it effectively uses wireless broadcast advantage to decrease the number of forwarding nodes dynamically when a new receiver joins the tree.Our simulation results show that NCast improves network throughput, data delivery ratio and data delivery delay in comparison with on demand multicast routing protocol. It is also comparable with multichannel multicast even though it does not use channeling technique which eliminates the interference inherently.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.3
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• pp.400-410
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• 2010

In an identity-based threshold broadcast encryption (IDTHBE) scheme, a broadcaster chooses a set of n recipients and a threshold value t, and the plaintext can be recovered only if at least t receivers cooperate. IDTHBE scheme is different from the standard threshold public key encryption schemes, where the set of receivers and the threshold value are decided from the beginning. This kind of scheme has wide applications in ad hoc networks. Previously proposed IDTHBE schemes have ciphertexts which contain at least n elements. In addition, the security of theses schemes relies on the random oracles. In this paper, we introduce two new constructions of IDTHBE for ad hoc networks. Our first scheme achieves S-size private keys while the modified scheme achieves constant size private keys. Both schemes achieve approximately (n-t)-size ciphertexts. Furthermore, we also show that they are provablesecurity under the decision bilinear Diffie-Hellman Exponent (BDHE) assumption in the standard model.

• Journal of Korea Multimedia Society
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• v.21 no.11
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• pp.1288-1296
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• 2018

PBS(Pairwise Broadcast Synchronization) is a well-known synchronization scheme for WSN(Wireless Sensor Networks). As PBS needs the set of node-pairs for network-wide synchronization by over-hearing, GPA(Group-Wise Pair Selection Algorithm) was also proposed after PBS. However, GPA is complex and requires too many message transmissions, leading to much power consumption. Besides, GPA is not appropriate to topology change or mobile wireless sensor networks. So, we propose a new and energy-efficient pair-node selection algorithm for PBS. The proposed scheme's performance has been evaluated and compared with GPA by simulation. The results are shown to be better than GPA.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.6
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• pp.1113-1132
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• 2011

In wireless sensor networks (WSNs), most energy saving asynchronous MAC protocols are custom tailored for unicast communications only. However, broadcast protocols are very commonly used in WSNs for a variety of functionalities, such as gathering network topology information, event monitoring and query processing. In this paper, we propose a novel low-power asynchronous broadcast MAC protocol called Alarm Broadcast (A-CAST). A-CAST employs the strobe preamble that specifies the residual waiting time for the following data transmission. Each receiver goes back to sleep upon hearing the strobe preamble for the residual time duration, to conserve energy and to wake up just before data transmission starts. We compute the energy consumption of A-CAST via rigorous mathematical analysis. The analytic results show that A-CAST outperforms B-CAST, a simple broadcast extension of the well-known B-MAC. We also implement A-CAST on sensor motes and evaluated its performance through real experiments. Our experimental results show that A-CAST reduces the energy consumption by up to 222% compared to the previously proposed protocols.

• Journal of Communications and Networks
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• v.10 no.2
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• pp.213-220
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• 2008

This paper analyzes a broadcasting technique for wireless multi-hop sensor networks that uses a form of cooperative diversity called opportunistic large arrays (OLAs). We propose a method for autonomous scheduling of the nodes, which limits the nodes that relay and saves as much as 32% of the transmit energy compared to other broadcast approaches, without requiring global positioning system (GPS), individual node addressing, or inter-node interaction. This energy-saving is a result of cross-layer interaction, in the sense that the medium access control (MAC) and routing functions are partially executed in the physical (PHY) layer. Our proposed method is called OLA with a transmission threshold (OLA-T), where a node compares its received power to a threshold to decide if it should forward. We also investigate OLA with variable threshold (OLA-VT), which optimizes the thresholds as a function of level. OLA-T and OLA-VT are compared with OLA broadcasting without a transmission threshold, each in their minimum energy configuration, using an analytical method under the orthogonal and continuum assumptions. The trade-off between the number of OLA levels (or hops) required to achieve successful network broadcast and transmission energy saved is investigated. The results based on the analytical assumptions are confirmed with Monte Carlo simulations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1249-1272
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• 2016

In this paper, we propose a symmetric key establishment scheme for wireless sensor networks which tries to minimize the resource usage while satisfying the security requirements. This is accomplished by taking advantage of the communication pattern of wireless sensor networks and adopting heterogeneous wireless sensor networks. By considering the unique communication pattern of wireless sensor networks due to the nature of information gathering from the physical world, the number of keys to be established is minimized and, consequently, the overhead spent for establishing keys decreases. With heterogeneous wireless sensor networks, we can build a hybrid scheme where a small number of powerful nodes do more works than a large number of resource-constrained nodes to provide enhanced security service such as broadcast authentication and reduce the burden of resource-limited nodes. In addition, an on-demand key establishment scheme is introduced to support extra communications and optimize the resource usage. Our performance analysis shows that the proposed scheme is very efficient and highly scalable in terms of storage, communication and computation overhead. Furthermore, our proposed scheme not only satisfies the security requirements but also provides resilience to several attacks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.12
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• pp.1208-1218
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• 2012

Disseminating broadcast information stably and reliably in IEEE 802.11-like CSMA wireless networks requires that a source should seek collision-free transmission to multiple receivers and keep track of the reception state of the multiple receivers. We propose a simple yet efficient feedback scheme for stable reliable broadcast in wireless networks, called 2-polling feedback, where the state of two receivers are checked by a source before its broadcast transmission attempt We present a performance analysis of the class of reliable broadcast feedback schemes in terms of two performance metrics (packet transmission delay and packet stable time). The analysis results show that the proposed 2-polling feedback scheme outperforms the current existing classes of feedback schemes in the literature, i.e., all-polling feedback and 1-polling feedback. The 2-polling feedback scheme has lower asymptotic complexity than the all-polling feedback, and has the same asymptotic complexity as the 1-polling feedback but exhibits almost 50 % reduction in packet stable time.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1995.06a
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• pp.97-100
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• 1995

In transmission of image sequences over ATM networks, the packet loss problem and channel sharing efficiency are important. As a possible solution two-layer video coding methods have been proposed. These methods transmit video information over the network with different levels of protection with respect to packets loss. In this paper, a two-layer coding method using pyramid structure is proposed and several realizations of two-layer video coding methods are presented and their performances are compared.