• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1219-1222
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• 2005

인터넷상의 망 장비는 크게 2 계층 스위치와 3 계층 라우터로 구분할 수 있으며, 2 계층 스위치는 IEEE 802.1D, IEEE 802.1Q 규격에 따라 수신된 이더넷(Ethernet) 프레임의 목적지 MAC 주소에 기반한 2 계층 스위칭 기능을 제공하며, 3 계층 라우터는 IETF 의 규격에 따라 수신된 이더넷 프레임의 목적지 IP 주소에 기반한 3 계층 라우팅 기능을 제공한다. 하지만 최근에는 기술의 발달에 따라서 엄연히 구분된 두 가지 기능을 하나의 시스템에서 제공하는 것에 대한 요구가 증가하게 되었다. 이에 본 논문에서는 가상 랜(VLAN) 기반의 2 계층 스위치에서 가상 인터페이스 기반의 라우팅 기능을 구현한 후, 라우팅 기능을 원하는 가상 랜 가입자에게 해당 가상 랜을 가상 인터페이스(Virtual Interface)에 맵핑하는 것에 의해서 3 계층 라우팅 기능을 제공하는 시스템 구조 및 제안된 시스템에서의 패킷 처리 절차를 제시하고자 한다. 본 논문에 제시된 방법에 의해서 가입자들은 저렴한 비용으로 인터넷 서비스를 제공받을 수 있으며, 망 사업자는 다른 가상 랜간의 통신을 위한 가상 랜 라우팅(VLAN Routing) 기능을 부가적으로 쉽게 제공할 수 있고, 해당 시스템의 인터페이스를 2 계층 스위치 포트 또는 3 계층 라우터 포트로 융통성있게 설정할 수 있다.

• Journal of IKEEE
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• v.24 no.1
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• pp.326-332
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• 2020

This paper presents the design of a routing metric for energy-efficient and low-delay path selection and a new routing protocol utilizing the metric in duty-cycyled wireless sensor networks. The new routing metric based on duty cycle, EDW, can reduce the energy and delay of transmission paths, which represents total waiting time from source to destination due to duty cycle. Therefore, in this paper, we propose a new multipath routing protocol based on cross-layer information utilizing the new routing metric, and simulation results show that the proposed protocol shows better performance of end-to-end delay and energy consumption.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.494-513
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• 2019

A multi-channel access problem based on hypergraph model in ultra-dense small cell networks is studied in this paper. Due to the hyper-dense deployment of samll cells and the low-powered equipment, cumulative interference becomes an important problem besides the direct interference. The traditional binary interference model cannot capture the complicated interference relationship. In order to overcome this shortcoming, we use the hypergraph model to describe the cumulative interference relation among small cells. We formulate the multi-channel access problem based on hypergraph as two local altruistic games. The first game aims at minimizing the protocol MAC layer interference, which requires less information exchange and can converge faster. The second game aims at minimizing the physical layer interference. It needs more information interaction and converges slower, obtaining better performance. The two modeled games are both proved to be exact potential games, which admit at least one pure Nash Equilibrium (NE). To provide information exchange and reduce convergecne time, a cloud-based centralized-distributed algorithm is designed. Simulation results show that the proposed hypergraph models are both superior to the existing binary models and show the pros and cons of the two methods in different aspects.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.2
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• pp.283-288
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• 2019

LPWA (Low Power Wide Area) networks have been considered as one of the technologies which can be implemented in IoT (Internet of Things) applications by providing less power and longer communication range compared with existing wireless technologies. In this paper, we investigate LoRa which is one of representative technologies for LPWA networks. First, we present general properties and several technologies of LPWA networks. Then, the technical specification, properties, and pros/cons of LoRa are studied. Finally, we discuss analysis of LoRa's performance and its ehancement technologies by focusing on physical layer and MAC (Medium Access Control) layer.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.362-375
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• 2004

An ad hoc network is a multi-hop wireless network. Its limited bandwidth and frequently changing topology require that its protocol should be robust, simple, and energy conserving. We have proposed PoolODMRP to reduce its control overhead greatly by its one-hop local route maintenance. However, PoolODMRP still has some shortcomings. In this paper, we propose PDAODMRP (passive data acknowledgement ODMRP) to extend PoolODMRP. Compared with PoolODMRP, PDAODMRP has the following contributions: (1) It knows the status of its downstream forwarding nodes by route information collected from data packets instead of BEACON signal of MAC layer; (2) it max simplifies the route information collected from data packets by pool nodes; (3) it adopts a dynamic local route maintenance to enforce its local route maintenance; (4) it adopts the route evaluation policy of NSMP (neighbor supporting multicast protocol). Compared with PoolODMRP, PDAODMRP has lower control overhead, lower data delivery delay, and lower data overhead.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.540-543
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• 2004

Address Resolution Protocol (ARP) cache poisoning is a MAC layer attack that can only be carried out when an attacker is connected to the same local network as the target machines. ARP is not a new problem, but wireless network introduces a new attack point and more vulnerable to the attack. The attack on wireless network cannot be detected by current detection tool installed on wired network. In order to detect the ARP poisoning attack, there must be a ARP poisoning detection tool for wireless LAN environment. This paper proposes linux-based ARP poisoning detection system equipped with wireless LAN card and Host AP device driver

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.206-208
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• 2004

A new method to control a remote robot with PDA and wireless network is presented. The needs of remote control systems using a home network environments are increased in these days. To solve the shortage of IP address in network, authorized TCP/IP and unauthorized TCP/IP address are used. The unauthorized TCP/IP is obtained by using MAC Address in the system and Network Layer. The model in the system is similar to Sever&Client in structure. Using this system, it is very easy to combine one network device with other network system. A robot system and PDA are used to show the effectiveness of the control system in home network environments.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.225-226
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• 2008

본 논문은 스케줄링 기반 Ad-hoc Network에서의 Relay Network Protocol에 관한 것으로, Koinonia V2.0의 MAC Layer Protocol을 기반으로 Relay Network Protocol을 설계하였다. Ad-hoc Network 기반의 Relay Network Protocol은 단일 주파수 채널을 이용한 Relay Network Protocol과 듀얼 주파수 채널을 이용한 Relay Network Protocol이 있다. 전자는 하나의 모뎀 칩을 사용하여 시스템이 단순하고 전력소모가 적은 반면, 데이터 전송 속도가 낮아지고, 후자는 데이터 전송 속도에서 손해를 보지 않는 반면, 시스템이 복잡하고 전력소모가 많은 단점이 있다. 본 연구를 통해 Ad-hoc Network 기반의 Relay Network Protocol 구현에 대한 방법론을 제시할 수 있었다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.632-638
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• 2012

ZigBee network, based on PHY, MAC layer provides a specification for a suite of high level communication protocols using small, low-power digital radio based on an IEEE 802.15.4 standard. Meshing is a type of daisy chaining from one device to another. This technique allows the short range of an individual node to be expanded and multiplied, covering a much larger area. Each wireless technology that makes it to market serves a special purpose or function. Zigbee provides short-range connectivity in what is called a personal-area network (PAN). Within ZigBee PAN coordinator as manages an entire ZigBee network, the short range of frequency band was only selected because the technology allows typically less than 100 kbp or ZigBee troubles in retransmission processing and delaying data tranmission works to create unproductive condition of work. This research was proposed the method, based on short range frequency of zigBee nodes enable to long range of remote data transmission with specific algorithm tools.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.361-364
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• 2011

Nowadays, an explosive increase of mobile devices has triggered a lot of research into radio resource management. Therefore, many studies have been done and still underway to use this limited resource efficiently. However, most of the existing studies focused on efficiency in mac layer. In this paper, I proposed a timer to manage radio resource, which refreshes the timer's values based on the number of connections dynamically. This dynamic timer enables Base Station (BS) to be able to manage available radio resources efficiently and accommodate much more Mobile Stations (MSs). Simulation result showed that BS with dynamic timer could accommodate the MS about 30% more, compared with BS with a static timer in terms of radio resource management. Dynamic timer is not restricted to any specific network standard. So its mechanism is practical and implementable without changing the original standard, which can contribute to service providers by increasing capability that BS can support.