• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.237-252
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• 2017

In recent years, data centers have become the core infrastructure to deal with big data processing. For these big data applications, network transmission has become one of the most important factors affecting the performance. In order to improve network utilization and reduce job completion time, in this paper, by real-time monitoring from the application layer, we propose job-aware priority scheduling. Our approach takes the correlations of flows in the same job into account, and flows in the same job are assigned the same priority. Therefore, we expect that flows in the same job finish their transmissions at about the same time, avoiding lagging flows. To achieve load balancing, two approaches (Flow-based and Spray) using ECMP (Equal-Cost multi-path routing) are presented. We implemented our scheme using NS-2 simulator. In our evaluations, we emulate real network environment by setting background traffic, scheduling delay and link failures. The experimental results show that our approach can enhance the Hadoop job execution efficiency of the shuffle stage, significantly reduce the network transmission time of the highest priority job.

• Journal of Internet Computing and Services
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• v.8 no.4
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• pp.81-91
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• 2007

Binding update for the routing optimization in MIPv6 can make the involved nodes vulnerable to various attacks. Therefore, secure binding update becomes an important research issue in MIPv6, and several protocols have been proposed for this purpose. In this paper, we compare several existing binding update protocols such as RR, SUCV and OMIPv6 and analyze the vulnerability of nodes to the possible attacks and drawbacks of address management and scalability and overhead of encryption operations. Then, we suggest the design requirements for the secure binding update and propose an advanced protocol based on the design principle. Through the analysis, we show that our protocol can achieve a higher level of security against the various attacks and enable better management of address, provide the location privacy and reduce the computational overhead of mobile nodes with constraint computational power.

• 한국정보컨버전스학회:학술대회논문집
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• 2008.06a
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• pp.199-204
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• 2008

Sensor nodes have various energy and computational constraints because of their inexpensive nature and ad-hoc method of deployment. Considerable research has been focused at overcoming these deficiencies through faster media accessing, more energy efficient routing, localization algorithms and system design. Our research attempts to provide a method of improvement MAC performance in these issues. We show that traditional carrier-sense multiple access(CSMA) protocols like IEEE 802.11 do not handle the first constraint adequately, and do not take advantage of the second property, leading to degraded latency and throughput as the network scales in size, We present more efficient method of a medium access for real-time wireless sensor networks. Proposed MAC protocol is a randomized CSMA protocol, but unlike previous legacy protocols, does not use a time-varying contention window from which a node randomly picks a transmission slot. To reduce the latency for the delivery of event reports, it carefully decides a fixed-size contention window, non-uniform probability distribution of transmitting in each slot within the window. We show that it can offer up to several times latency reduction compared to legacy of IEEE 802.11 as the size of the sensor network scales up to 256 nodes using widely used simulator ns-2. We, finally show that proposed MAC scheme comes close to meeting bounds on the best latency achievable by a decentralized CSMA-based MAC protocol for real-time wireless sensor networks which is sensitive to latency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.1064-1072
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• 2005

For the efficient operation of sensor networks, it is very important to design sensor networks for sensors to utilize their energies in very effective ways. Cluster-based routing schemes such as LEACH can achieve their energy efficiencies by delivering data between cluster heads and sensor nodes. In those cluster-based schemes, cluster reconfiguration algorithm is one of the most critical issues to achieve longer operation lifetime of sensor networks. In this paper, we propose a new energy efficient cluster reconfiguration algorithm. Proposed method does not require any location or energy information of sensors, and can configure clusters with fair cluster regions such that all the sensors in a sensor network can utilize their energies equally. The performances of the proposed scheme have been compared with LEACH and LEACH-C.

• Journal of Communications and Networks
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• v.4 no.2
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• pp.148-157
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• 2002

This paper investigates schemes to improve TCP performance in multipath forwarding networks. In multipath routing, packets to the same destination are sent to multiple next-hops in either packet-level or flow-level forwarding mode. Effective bandwidth is increased since we can utilize unused capacity of multiple paths to the destination. In packet-level multipath forwarding networks, TCP performance may not be enhanced due to frequent out-of-order segment arrivals at the receiver because of different delays among paths. To overcome this problem, we propose simple TCP modifications. At the sender, the fast retransmission threshold is adjusted taking the number of paths into consideration. At the receiver, the delayed acknowledgment scheme is modified such that an acknowledgment for an out-of-order segment arrival is delayed in the same way for the in-order one. The number of unnecessary retransmissions and congestion window reductions is diminished, which is verified by extensive simulations. In flow-level multipath forwarding networks, hashing is used at routers to select outgoing link of a packet. Here, we show by simulations that TCP performance is increased in proportion to the number of paths regardless of delay differences.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.47-54
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• 2004

By using wireless terminal, the number of users who wish to use the multimedia service like the Internet as well as Short Message Services and voice service has increased dramatically over the last years. We propose the method that improves Mobile IPv4 (MIPv4) Regional Registration in wireless mobile networks to decrease traffic's transmission delay and message generation compared with an existing method We design the scheme in MIPv4 environments that a packet do not pass through the home agent transmitted from correspondent node to mobile node, if a mobile node moves to other mobility agent. Simulation results show that the proposed method significantly reduces the expenses for registration and delivering packet.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.3
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• pp.655-659
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• 2016

In this paper, we propose new detection and detour methods against packet drop attacks for availability in the Internet of Things (IoT) based on the IEEE 802.15.4e and RPL protocol standards that employ IPv6. We consider the rank value of RPL and the consecutive packet drops to improve the detection metrics, and also take into account the use of both sibling and child nodes on a RPL routing path to construct the detour method. Our simulation results show that the proposed detection method is faster than the previous result, and the detour method improves the detour success rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8B
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• pp.712-721
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• 2012

In this paper, we propose an Enhanced cross-layer Geographic Forwarding (EGF) protocol for wireless sensor networks (WSNs). EGF uses an optimal back-off time to make the packet forwarding decisions using only source and destination's location information and energy cost without information about neighbor nodes' location or the number of one hop neighbor nodes. EGF is also a cross-layer protocol by combining efficient asynchronous MAC and geographic routing protocol. The proposed protocol can find optimal next hop location quickly without broadcasting node's location update and with minimizing overhead. In our performance evaluation, EGF has better performance in terms of packet success ratio, energy efficiency and end-to-end delay in wireless sensor networks.

• Journal of information and communication convergence engineering
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• v.10 no.3
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• pp.231-236
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• 2012

For real-time wireless sensor network applications, it is essential to provide different levels of quality of service (QoS) such as reliability, low latency, and fault-tolerant traffic control. To meet these requirements, an (m,k)-firm based real-time routing protocol has been proposed in our prior work, including a novel local transmission status indicator called local DBP (L_DBP). In this paper, a fault recovery scheme for (m,k)-firm real-time streams is proposed to improve the performance of our prior work, by contributing a delay-aware forwarding candidates selection algorithm for providing restricted redundancy of packets on multipath with bounded delay in case of transmission failure. Each node can utilize the evaluated stream DBP (G_DBP) and L_DBP values as well as the deadline information of packets to dynamically define the forwarding candidate set. Simulation results show that for real-time service, it is possible to achieve both reliability and timeliness in the fault recovery process, which consequently avoids dynamic failure and guarantees meeting the end-to-end QoS requirement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.848-857
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• 2011

Due to the advantages of a conveniet, inexpensive installation, flexibility, and scalability, Wireless AMR systems are recently preferred over wired AMR systems. However, a multi-hop supported AMR network, which generally covers large areas, may create energy wastage problem, energy unbalance, and high interference hazard due to a large amount of concurrent-intensive metering data in the network. Therefore in this paper we propose a novel data gathering method which can solve abovementioned problems as well as conserve energy, by reducing the traffic in the network. In addition, the experimental results demonstrate that the proposed scheme shows superior performance to the conventional data transmission method.