• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권8호
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• pp.1805-1824
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• 2013

Recently, the use of wireless body area networks (WBAN) has been increasing rapidly in medical healthcare applications. WBANs consist of smart nodes that can be used to sense and transmit vital data such as heart rate, temperature and ECG from a human body to a medical centre. WBANs depend on limited resources such as energy and bandwidth. In order to utilise these resources efficiently, a very well organized medium access control (MAC) protocol must be considered. In this paper, a new, adaptive and energy-efficient MAC protocol, entitled isMAC, is proposed for WBANs. The proposed MAC is based on multi-channel communication and aims to prolong the network lifetime by effectively employing (i) a collision prevention mechanism, (ii) a coordinator node (WCN) selection algorithm and (iii) a transmission power adjustment approach. The isMAC protocol has been developed and modelled, by using OPNET Modeler simulation software. It is based on a networking scenario that requires especially high data rates such as ECG, for performance evaluation purposes. Packet delay, network throughput and energy consumption have been chosen as performance metrics. The comparison between the simulation results of isMAC and classical IEEE 802.15.4 (ZigBee) protocol shows that isMAC significantly outperforms IEEE 802.15.4 in terms of packet delay, throughput and energy consumption.

• 한국통신학회논문지
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• 제35권2A호
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• pp.153-164
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• 2010

본 논문은 무선 애드혹 네트워크에서 채널 효율성 및 네트워크 성능 향상을 위한 멀티채널 MAC 프로토콜을 제안한다. 멀티채널 MAC 프로토콜 설계에는 랑데부 문제(rendezvous problem)와 멀티채널 히든 노드 문제 등 두개의 주요한 문제가 있다. 기존에 제안된 여러 멀티채널 MAC 프로토콜에서는 하나의 채널을 공통 컨트롤 채널로 사용하여 컨트롤 패킷 교환을 통해 이러한 문제들을 해결하였는데, 이것은 데이터 채널이 증가할수록 높은 경쟁으로 인한 공통 컨트롤 채널의 병목 현상을 초래하여 비효율적인 데이터 채널 이용의 원인이 된다. 본 논문에서 제안하는 멀티채널 MAC 프로토콜은 멀티채널 히든 노드 문제를 해결하기 위해 TDMA 방식을 사용하였고, 데이터를 동시에 송수신할 수 있도록 하여 네트워크 성능을 높인다. 또한 공통 컨트롤 채널을 사용하지 않기 때문에 공통 컨트롤 채널 병목 현상이 발생하지 않고, 전송 또는 수신할 데이터가 없는 노드는 슬립(sleep) 상태를 유지하도록 하여 에너지 절감(energy savings)이 가능하다. 모의실험결과는 제안한 MAC 프로토콜이 기존의 방법에 비해 네트워크 성능 및 채널 효율성을 향상시키고 에너지를 절감할 수 있다는 것을 보여준다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.5035-5057
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• 2019

Advancements in nanotechnology and novel nano materials in the past decade have provided a set of tools that can be used to design and manufacture integrated nano devices, which are capable of performing sensing, computing, data storing and actuation. In this paper, we have proposed cooperative nano communication using Power Switching Relay (PSR) Wireless Power Transfer (WPT) protocol and Time Switching Relay (TSR) WPT protocol over independent identically distributed (i.i.d.) Rayleigh fading channels in the Terahertz (THz) Gap frequency band to increase the range of transmission. Outage Probability (OP) performances for the proposed cooperative nano communication networks have been evaluated for the following scenarios: A) A single decode-and-forward (DF) relay for PSR protocol and TSR protocol, B) DF multi-relay network with best relay selection (BRS) for PSR protocol and TSR protocol, and C) DF multi-relay network with multiple DF hops with BRS for PSR protocol and TSR protocol. The results have shown that the transmission distance can be improved significantly by employing DF relays with WPT. They have also shown that by increasing the number of hops in a relay the OP performance is only marginally degraded. The analytical results have been verified by Monte-Carlo simulations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2512-2529
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• 2015

Wireless mesh networks (WMNs) provide an efficient and flexible method to the field of wireless networking, but also bring many security issues. A mesh point may lose all of its available links during its movement. Thus, the mesh point needs to handover to a new mesh point in order to obtain access to the network again. For multi-domain WMNs, we proposed a new ID-based signcryption scheme and accordingly present a novel ID-based handover protocol for mesh points. The mutual authentication and key establishment of two mesh points which belong to different trust domains can be achieved by using a single one-round message exchange during the authentication phase. The authentication server is not involved in our handover authentication protocol so that mutual authentication can be completed directly by the mesh points. Meanwhile, the data transmitted between the two mesh points can be carried by the authentication messages. Moreover, there are no restrictions on the PKG system parameters in our proposed multi-domain ID-based signcryption scheme so our handover scheme can be easily applied to real WMNs circumstances. Security of the signcryption scheme is proved in the random oracle model. It shows that our protocol satisfies the basic security requirements and is resistant to existing attacks based on the security of the signcryption. The analysis of the performance demonstrates that the protocol is efficient and suitable for the multi-domain WMNs environment.

• 한국통신학회논문지
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• 제36권8B호
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• pp.1028-1037
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• 2011

최근 Selim등은 공개키 암호 기반의 프라이버시를 제공하기 위해 다중-컨텍스트 RFID 인증 프로토콜을 제안하였다. 하지만 Selim등이 제안한 프로토콜은 리더와 태그 간의 인증을 수행하는 과정에서 공개키 기반의 암호 알고리즘을 사용하므로 수동형 태그에는 적합하지 않을 뿐만 아니라 상호 인증 부재로 인한 위장 공격에 취약하다. 위와 같은 효율성 문제와 보안 취약점 해결을 위해 본 논문에서는 각각 다른 영역에서 단일 수동형 태그와 다양한 목적을 제공하는 리더들 간의 상호 인증을 제공함으로써 프라이버시 침해와 태그 위장 공격을 방지하며, 중계 공격과 서비스 거부 공격에 안전한 다중-컨텍스트 RFID 상호 인증 프로토콜을 제안한다. 결론적으로 제안한 프로토콜은 RFID 리더로부터 수집된 공간과 시간의 정보를 토대로 안전한 상호 인증이 수행되고, 수동형 태그에 적합하도록 안전한 일방향 해쉬 함수와 대칭키 암호 연산을 수행함으로써 강한 보안성과 높은 연산 효율성을 제공한다.

• Journal of Communications and Networks
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• 제10권4호
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• pp.455-464
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• 2008

To provide network services consistently under various network failures, enterprise networks increasingly utilize path diversity through multi-homing. As a result, multi-homed non-transit autonomous systems become to surpass single-homed networks in number. In this paper, we address an inevitable problem that occurs when networks with multiple entry points deploy firewalls in their borders. The majority of today's firewalls use stateful inspection that exploits connection state for fine-grained control. However, stateful inspection has a topological restriction such that outgoing and incoming traffic of a connection should pass through a single firewall to execute desired packet filtering operation. Multi-homed networking environments suffer from this restriction and BGP policies provide only coarse control over communication paths. Due to these features and the characteristics of datagram routing, there exists a real possibility of asymmetric routing. This mismatch between the exit and entry firewalls for a connection causes connection establishment failures. In this paper, we formulate this phenomenon into a state-sharing problem among multiple fire walls under asymmetric routing condition. To solve this problem, we propose a stateful inspection protocol that requires very low processing and messaging overhead. Our protocol consists of the following two phases: 1) Generation of a TCP SYN cookie marked with the firewall identification number upon a SYN packet arrival, and 2) state sharing triggered by a SYN/ACK packet arrival in the absence of the trail of its initial SYN packet. We demonstrate that our protocol is scalable, robust, and simple enough to be deployed for high speed networks. It also transparently works under any client-server configurations. Last but not least, we present experimental results through a prototype implementation.

• 정보처리학회논문지C
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• 제15C권4호
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• pp.289-296
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• 2008

최근, 무선 메쉬 네트워크에서 라우팅 프로토콜에 대한 연구가 활발히 진행되고 있으며 대표적인 proactive 라우팅 프로토콜인 DSDV (Destination-Sequenced Distance-Vector) 라우팅 프로토콜에서는 홉 수가 주요 라우팅 메트릭으로 사용된다. HMP (Hop-by-Hop) DSDV 및 EHMP (Enhanced HMP) DSDV 라우팅 프로토콜에서는 홉 수 및 한 홉 거리 내에 위치한 노드들의 잉여 대역폭을 고려하여 라우팅을 수행하고 있으나, 단대단 라우팅 관점에서 최적이 아닌 경로로 라우팅을 수행하는 단점이 있다. 본 논문에서는 이러한 단점을 극복하기 위해 홉 수 및 단대단 최소 잉여 대역폭을 고려한 CAMP (Cost-Aware Multi-Path) DSDV 라우팅 프로토콜을 제안한다. NS-2를 이용한 성능 분석을 통해 제안하는 라우팅 프로토콜은 홉 수 및 단대단 최소 잉여 대역폭 정보를 적절히 사용함으로써 처리율 및 패킷 전달율의 측면에서 DSDV, HMP DSDV 및 EHMP DSDV 프로토콜에 비해 더 우수한 성능을 가지며 HMP DSDV 및 EHMP DSDV 프로토콜과 같은 수의 관리 메시지를 가지게 됨을 보인다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.503-504
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• 2007

The most Important thing in Sensor Network Design is a Energy Efficiency. Limited sources of Sensor Mote tan occur merging of Protocol. In this paper, we proposed Cross Layer Protocol for Energy Efficienty. The proposed protocol can increase the network life time using multi hop transmission. sensor network should use multi hop communication and small radius because radio in wireless communication is the most spendable thing in sensor network.

• 한국컴퓨터정보학회논문지
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• 제6권4호
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• pp.68-73
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• 2001

MPLS(Multi protocol Label Switching)는 Network Traffic 흐름의 속도를 높이고 관리하기 쉽게 하기 위한 표준 기술이다. MPLS는 정해진 Pack 열에 특정 경로를 설정하는 것에 관여하고, 각 Pack 내에는 라벨이 있어 Router 입장에서는 그 Pack을 전달할 노드의 주소를 확인하여 소요시간을 절약한다. MPLS는 IP, ATM및 프레임 릴레이 Network protocol 등과 같이 작동한다. MPLS는 Network OSI 참조모델과 함께 3Layer가 아닌 Switching을 하는 2Layer에서 대부분의 Pack이 전달되게 한다. MPLS는 Traffic을 빠르게 움직이게 하며, QoS를 위한 Network관리를 쉽게 한다. 이런 이유에 MPLS 기술은 더 많고 특정한 Traffic을 전송하기 시작한 Network로 채택될 유망한 기술로 기대되고 있다.

• International journal of advanced smart convergence
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• 제8권2호
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• pp.109-115
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• 2019

Currently, LPWA(Low Power Wide Area) communication technology is widely used due to the development of IoT(Internet of Things) technology. Among the LPWA technologies, LoRaWAN(Long Range Wide Area Network) is widely used in many fields due to its wide coverage, stable communication speed, and low-cost modem module prices. In particular, LoRa(Long Range) can easily construct LoRaWAN with a dedicated gateway. So many organizations are building their own LoRaWAN-based networks. The LoRaWAN Gateway receives the LoRa packet transmitted from an End-device installed in the adjacent location, converts it into the Internet protocol, and sends the packet to the final destination server. Current LoRa Gateway uses a single-hop method, and each gateway must include a communication network capable of the Internet. If it is the mobile communication(i.e., WCDMA, LTE, etc.) network, it is required to pay the internet usage fee which is installed in each gateway. If the LoRa communication is frequent, the user has to spend a lot of money. We propose an idea on how to design a multi-hop protocol which enables packet routing between gateways by analyzing the LoRaWAN communication method implemented in its existing single-hop way in this paper. For this purpose, this paper provides an analysis of the standard specification of LoRaWAN and explains what was considered when such protocol was designed. In this paper, two gateways have been placed based on the functional role so as to make the multi-hop protocol realized: (i) hopping gateway which receives packets from the end-device and forwards them to another gateway; and (ii) main gateway which finally transmits packets forwarded from the hopping gateway to the server via internet. Moreover, taking into account that LoRaWAN is wireless mobile communication, a level-based routing method is also included. If the protocol proposed by this paper is applied to the LoRaWAN network, the monthly internet fee incurred for the gateway will be reduced and the reliability of data transmission will be increased.