• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.98-101
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• 2019

In this paper, we propose the power-based pipelined-forwarding MAC protocol which can select relay nodes according to the residual power and energy harvesting rate in EH-WSN (energy-harvesting wireless sensor networks). The proposed MAC follows a pipelined-forwarding scheme in which nodes repeatedly sleep and wake up in an EH-WSN environment and data is continuously transmitted from a high-level node to a low-level node. The sleep interval is adaptively controlled so that nodes with low energy harvesting rate can be charged sufficiently, thereby minimizing the transmission delay and increasing the network lifetime. Simulation shows that the proposed MAC protocol improves the balance of residual power and network lifetime.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1377-1399
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• 2020

In search and rescue mission, micro aerial vehicles (MAVs) are typically used to capture image and video from an aerial perspective and transfer the data to the ground station. Because of the power limitation, a cluster of MAVs are required for a large search area, hence an ad-hoc wireless network must be maintained to transfer data more conveniently and fast. However, the unstable link and the intermittent connectivity between the MAVs caused by MAVs' movement may challenge the packet forwarding. This paper proposes a delay tolerant packet forwarding algorithm based on location estimation for MAV networks, called DTN_est algorithm. In the algorithm, ferrying MAVs are used to transmit data between MAVs and the ground station, and the locations of both searching MAVs and ferrying MAVs are estimated to compute the distances between the MAVs and destination. The MAV that is closest to the destination is selected greedy to forward packet. If a MAV cannot find the next hop MAV using the greedy strategy, the packets will be stored and re-forwarded once again in the next time slot. The experiment results show that the proposed DTN_est algorithm outperforms the typical DTN_geo algorithm in terms of packet delivery ratio and average routing hops.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.128-139
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• 2017

Vehicular Ad hoc Network (VANET) is one of technologies to realize various ITS services for safe driving and efficient traffic control. However, data delivery in VANETs is complicated due to high mobility and unreliable wireless transmission. In this paper, we develop a novel forwarding scheme to deliver packets in a reliable and timely manner. The proposed forwarding scheme uses traffic statistics to predict the encounter of two vehicles, and optimize its forwarding decision by taking into consideration the probability of successful transmission between them at the encounter place. We evaluate our scheme through simulations and show that our proposed scheme provides reliable data delivery in VANETs.

• Journal of the Korea Society of Computer and Information
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• v.14 no.4
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• pp.59-67
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• 2009

In wireless sensor networks (WSNs), geographic greedy forwarding fails to move a packet further towards its destination if the sender does not have any closer node to the destination in its one hop transmission region. In this paper, we propose a enhanced geographic routing, called CGR(Cost based Geographic Routing) for efficient data delivery against void problem environment. CGR first establishes Shadow Bound Region and then accomplishes Renewing Cost Function Algorithm for effective greedy forwarding data delivery. Our simulation results show significant improvements compared with existing schemes in terms of routing path length, success delivery ratio and energy efficiency.

• Journal of the Korea Society of Computer and Information
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• v.26 no.3
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• pp.69-75
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• 2021

Limitation of the TCP/IP network technology included in the vehicle communication is due to the frequent mobility of the vehicle, the increase in intermittent connection requirements, and the constant presence of the possibility of vehicle hacking. VNDN technology enables the transfer of the name you are looking for using textual information without the need for vehicle identifiers like IP/ID. In addition, intermittent connectivity communication is possible rather than end-to-end connection communication. The data itself is the subject of communication based on name-based forwarding using two types of packets: Interest packet and Data packet. One of the issues to be solved for the realization of infotainment services under the VNDN environment is the traffic explosion caused by data broadcasting. In this paper, we analyze and compare the existing technologies to reduce the data broadcast storm. Through this, we derive and analyze the requirements for presenting the best data mitigation technique for solving the data explosion phenomenon in the VNDN environment. We expect this paper can be utilized as prior knowledge in researching improved forwarding techniques to resolve the data broadcast explosion in connected vehicles over NDN.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.280-285
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• 2021

When VNDN technology is used as a communication technology for infotainment application services of connected vehicles, it is possible to realize data-centric networking technology in which data is the subject of communication.Vehicle security attacks and hacks, performance degradation during long-distance data transmission, and frequent data loss It is possible to innovate the limitations of the current host-oriented Internet-based infotainment application service technology of connected vehicles. The data packet forwarding issue to deliver critical information data that is very sensitive to delay in the VNDN on a push-based basis to RSU (Road Side Unit), etc. is one of the issues to be solved for realizing VNDN-based application services. We comprehensively analyze existing forwarding techniques to support push-based data traffic under the environment, and compare and analyze each technique in terms of performance.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.165-173
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• 2009

Recent portable devices are so versatile that they have multiple communication channels and play several multimedia formats. Especially, many services are under development for users who connect Internet or nearby devices via WWAN (Wireless Wide Area Network) and/or WLAN (Wireless LAN). In case of paying the telecommunication cost proportional to the amount of data downloaded, it is necessary to reduce the cost by constructing a special ad hoc network in which each participating peer downloads a specific portion of the want-to-be-shared content over the payable WWAN channel and exchanges the remaining portion with other peers using the cost-free WLAN channel. If all peers participate in forwarding packets, some transmissions are redundant which results in the unnecessary consumption of bandwidth as well as the delayed content distribution time. In order to reduce the redundant transmission, this paper proposes both the excluding method which discourages some peers not to forward redundant packets, and the minimum cover set method in which only the minimum number of peers are in charge of forwarding packets. These two methods obviate redundant packet forwarding, and result in reduction of content distribution time by up to around 29%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.207-214
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• 2008

Under future internet environment, wireless sensor networks will be used in a wide range of applications. A major problem for designing sensor protocol is developing the most energy efficient technique to monitor an area of interest for a long time since sensors have some constraints such as small and a limited energy level. In addition, data latency is often a critical issue since sensory data is transmitted via multi hop fashion and need to be delivered timely for taking an appropriate action. Our motivation for designing a data forwarding protocol is to minimize energy consumption while keeping data latency bound in wireless sensor networks. In this paper, we propose a data forwarding protocol that consists of wakeup scheduling and MAC protocols, the latter of which is designed to achieve load balancing. Simulation results show that the proposed framework provides more energy-efficient delivery than other protocol.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.7
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• pp.1-8
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• 2011

Vehicular Ad-hoc Network (VANET) is a special form of Mobile Ad-hoc Network designed to provide communications among nearby vehicles without communications infrastructure. Some characteristics in VANET environment such as high mobility, dynamic topology and selfishness of nodes can cause degradation of network quality. In this paper, we propose an adaptive incentive/topology control scheme to improve network quality in VANET by stimulating real time data forwarding and reporting changes of network topology. In the proposed scheme, an incentive suggested by the source node is updated in real time simultaneously with data transmission to stimulate real time data forwarding. In addition, when the order of the nodes in the path is changed, nodes which report the changes of network topology will get an additional incentive. By computer simulation, it is shown that the proposed incentive/topology control scheme outperforms the conventional schemes with respect to data delivery time and data delivery ratio.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5442-5463
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• 2016

Designing efficient routing protocols for a wireless sensor network with mobile sinks (mWSN) is a challenging task since the network topology and data paths change frequently as sink nodes move. In this paper, we design a novel lightweight reactive ring based routing protocol called R3, which removes the need of proactively maintaining data paths to mobile sinks as they move in the network. To achieve high packet delivery ratio and low transmission cost, R3 combines ring based forwarding and trail based forwarding together. To support efficient ring based forwarding, we build a ring based structure for a network in a way such that each node in the network can easily obtain its ring ID and virtual angle information. For this purpose, we artificially create a virtual hole in the central area of the network and accordingly find a shortest cycled path enclosing the hole, which serves as base ring and is used for generating the remaining ring based structure. We accordingly present the detailed design description for R3, which only requires each node to keep very limited routing information. We derive the communication overhead by ring based forwarding. Extensive simulation results show that R3 can achieve high routing performance as compared with existing work.