• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.510-513
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• 2010

In hierarchical wireless sensor network, Sensor nodes forming a cluster with a hierarchy. And there are being study for balanced energy consumption between cluster nodes. When forming network routing path, if there are configured incorrectly then it can be wasting energy. In this paper to solve these problem, We propose that it can consider sensor's communication range to create minimum hop layer when cluster heads configure routing path.

• Journal of Korea Multimedia Society
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• v.13 no.6
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• pp.849-864
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• 2010

This paper proposes a multipath routing protocol called cross-layer multipath AODV (CM-AODV) for wireless ad hoc networks, which selects multiple routes on demand based on the signal-to-interference plus noise ratio (SINR) measured at the physical layer. Note that AODV (Ad hoc On-demand Distance Vector) is one of the most popular routing protocols for mobile ad hoc networks. Each time a route request (RREQ) message is forwarded hop by hop, each forwarding node updates the route quality which is defined as the minimum SINR of serialized links in a route and is contained in the RREQ header. While achieving robust packet delivery, the proposed CM-AODV is amenable to immediate implementation using existing technology by neither defining additional packet types nor increasing packet length. Compared to the conventional multipath version of AODV (which is called AOMDV), CM-AODV assigns the construction of multiple paths to the destination node and makes it algorithmically simple, resulting in the improved performance of packet delivery and the less overhead incurred at intermediate nodes. Our performance study shows that CM-AODV significantly outperforms AOMDV in terms of packet delivery ratio and average end-to-end delay, and results in less routing overhead.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2022-2028
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• 2017

Recently, the energy shortage of sensors and the leakage of private information are considered as serious problems as the number of sensors is increasing due to the technological advance in Internet-of-Things. RF energy harvesting, in which sensors collect energy from external RF signals, and physical layer security become increasingly important to solve these problems. In this paper, we propose a time switching-based network analog coding for improving information security in wireless networks where the relay can harvest energy from source signals. We formulate 2-hop relay networks where an eavesdropper tries to overhear source signals, and find an optimal time switching ratio for maximizing the minimum required secrecy capacity using mathematical analysis. Through simulations under various environments, it is shown that the proposed scheme improves the minimum required secrecy capacity significantly, compared to the conventional scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1849-1854
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• 2017

Recently, RF energy harvesting, in which energy is collected from the external RF signals, is considered as a promising technology to resolve the energy shortage problem of wireless sensors. In addition, it is important to guarantee secure communication between sensors for implementing Internet-of-Things. In this paper, we propose a power splitting-based network analog coding for maximizing a physical layer security in 2-hop networks where the wireless-powered relay can harvest energy from the signals transmitted by two sources. We formulate systems where two sources, relay, and eavesdropper exist, and find an optimal power splitting ratio for maximizing the minimum required secrecy capacity using an exhaustive search. Through simulations under various environments, it is demonstrated that the proposed scheme improves the minimum required secrecy capacity by preventing the eavesdropper from overhearing source signals, compared to the conventional scheme.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.772-776
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• 2004

This paper proposes an interference avoidance approach for Constraint-Based Routing (CBR) algorithm in the Multi-Protocol Label Switching (MPLS) network. The MPLS network itself has a capability of integrating among any layer-3 protocols and any layer-2 protocols of the OSI model. It is based on the label switching technology, which is fast and flexible switching technique using pre-defined Label Switching Paths (LSPs). The MPLS network is a solution for the Traffic Engineering(TE), Quality of Service (QoS), Virtual Private Network (VPN), and Constraint-Based Routing (CBR) issues. According to the MPLS CBR, routing performance requirements are capability for on-line routing, high network throughput, high network utilization, high network scalability, fast rerouting performance, low percentage of call-setup request blocking, and low calculation complexity. There are many previously proposed algorithms such as minimum hop (MH) algorithm, widest shortest path (WSP) algorithm, and minimum interference routing algorithm (MIRA). The MIRA algorithm is currently seemed to be the best solution for the MPLS routing problem in case of selecting a path with minimum interference level. It achieves lower call-setup request blocking, lower interference level, higher network utilization and higher network throughput. However, it suffers from routing calculation complexity which makes it difficult to real task implementation. In this paper, there are three objectives for routing algorithm design, which are minimizing interference levels with other source-destination node pairs, minimizing resource usage by selecting a minimum hop path first, and reducing calculation complexity. The proposed CBR algorithm is based on power factor calculation of total amount of possible path per link and the residual bandwidth in the network. A path with high power factor should be considered as minimum interference path and should be selected for path setup. With the proposed algorithm, all of the three objectives are attained and the approach of selection of a high power factor path could minimize interference level among all source-destination node pairs. The approach of selection of a shortest path from many equal power factor paths approach could minimize the usage of network resource. Then the network has higher resource reservation for future call-setup request. Moreover, the calculation of possible path per link (or interference level indicator) is run only whenever the network topology has been changed. Hence, this approach could reduce routing calculation complexity. The simulation results show that the proposed algorithm has good performance over high network utilization, low call-setup blocking percentage and low routing computation complexity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.6
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• pp.768-777
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• 2020

In this paper, we describe recent research results on AODV routing protocol, which is widely deployed at mobile ad hoc networks, and AODV related routing protocols with multi-path routing schemes. We suggest the critical problems which minimum hop routing schemes have, such as AODV routing protocol, and then, propose a new C-AODV routing protocol with two routing metrics: the primary metric is the hop count, the secondary metric is the sum of link delay times. We implemented C-AODV protocol by modifying AODV at the NS-3, and thus, elaborate on how we change the original AODV source code of NS-3 in order to implement the C-AODV scheme. We show numerical comparison of C-AODV scheme with the original AODV scheme and then, discuss how much the C-AODV enhances routing performance over AODV protocol. In conclusion, we present future research items.