능동네트워크에서의 지역 등록 기법을 이용한 효율적인 인증 방안

이효성 건국대학교 대학원 2005 국내석사

영문초록: As Internet access through mobile devices is increasing, Mobile IP is the protocol to provide the mobility of a host on the existing IP. Request for wireless network becomes complicated gradually and network traffic is increasing. To overcome this situation, the structure of network node should be changed to accept new service quickly and economically by executing program code in node itself. Active network's research can use net resources more properly because of executing program within node itself. Mobile IP micro-mobility allow greater support for real-time services on a Mobile IP network by minimizing the period of time when a mobile node is unable to send or receive IP packets due to the delay in the Mobile IP Registration process. However, on Mobile IP network with AAA servers that are capable of performing Authentication, Authorization, and Accounting(AAA) services, every Registration has to be traversed to the home network to achieve new session keys, that are distributed by home AAA server, for a new Mobile IP session. This communication delay is the time taken to re-authenticate the mobile node and to traverse between foreign and home network even if the mobile node has been previously authorized to Visited AAA server. In order to reduce these extra time overheads, we present a method that performs Regional Registration without requiring further involvement by home AAA server. Using the characteristics of the active network, by employing active nodes in the wireless local mobility management environment, we can optimize the mechanism of registration and path setup for the mobile data traffic. In this paper, we propose the authentication mechanism using a regional registration in Active network

Efficient Control Plane Management for Mobile Networks

Joonwoo Kim 고려대학교 대학원 2023 국내박사

With deploying the 5G networks globally, the discussion for 5G advanced and 6G networks have started. Until 5G networks, to guarantee the quality of service (QoS) of the target services for each generation, the wireless network technical community (e.g., 3GPP) focused on increasing the key performance indicator (KPI) of mobile networks with respect to data rate, latency, and connection density. However, since the emerging novel services (e.g., non-public networks (NPNs) and autonomous driving) for the next generation mobile networks require user/organization customization and global coverage, those requirements are considered as the key requirements in 5G advanced and 6G networks. Due to developments of the container technology, network functions (NFs) have been modularized into several cloud-native network functions (CNFs). Moreover, because of their flexibility and scalability in deploying novel services, NPNs enabling to provide customized services to the user/organization are expected to adopt cloud-native environments in which NFs are disaggregated into several CNFs and CNFs are provisioned in the edge clouds. Consequently, cloud-native environments based-NPNs can allow easy and rapid service launch/upgrade and reduce the capital and operational expenditures (CAPEX/OPEX). However, to efficiently manage CNFs in NPNs, a sophisticated control plane management scheme should be designed. Thus, we propose a deep Q-network-based CNF placement algorithm (DQN-CNFPA) that jointly minimizes the costs incurred by launching and operating CNFs in edge clouds and the backhaul control traffic overhead by learning spatiotemporal service request patterns. The evaluation results based on real mobile data collected by Telecom Italia demonstrate that DQN-CNFPA can reduce the total cost by up to 26.2% compared with a conventional scheme that does not learn spatiotemporal service request patterns. Meanwhile, non-terrestrial networks (NTNs) are perceived as a key enabling technology in 5G advanced and 6G networks due to their global coverage and network resilience. Nonetheless, because the distance between the user and the space node (e.g., satellite) is long, NTNs cannot avoid long propagation delays, and thus an excessively increased signaling delay for the control plane procedures (e.g., session establishment and handover) is expected. To address this issue, we introduce a novel space mobile network (SMN) architecture in which space nodes act on core networks (CNs) and RANs by provisioning RAN/CN NFs. Based on the use of SMN, we devised persistent tunnel-based session establishment and cluster-based handover procedures to further reduce the session establishment and handover times, respectively. Simulation results based on open-sources for satellite communications and mobile networks demonstrate that the proposed session establishment and handover procedures can reduce the completion times by 7.8%—33.2% and 19.7%-–53.7%, respectively, compared to the conventional approaches. Since space and air nodes (e.g., satellites and unmanned aerial vehicles (UAVs)) have continuous and high-speed mobility, frequent handovers and load balancing issues occur in NTNs. Thus, we propose a multi-agent deep reinforcement learning-based mobility management algorithm (MARL-MMA) that can jointly mitigate the frequent handover and load balancing issues. Furthermore, MARL-MMA considers various features from the space and air nodes. Evaluation results demonstrate that MARL-MMA can reduce the handover control traffic by up to 84.4% compared to a conventional mobility management scheme that only considers the signal strength.

Proxy mobile IPv6 기반의 mobile CDN 구현 방안 연구

김태국 高麗大學校 大學院 2014 국내박사

Nowadays the mobile devices such as smartphones, tablet PCs, and laptops have been spread all over the world and the mobile services on such devices have become much more diversified and bandwidth-demanding. It currently leads to great R&D efforts towards better economics and efficiency in the related technologies such as mobility management and service content delivery beyond the traditional technologies in current use. This dissertation describes a realization method of the mobile content delivery network (CDN) on IP networks based on the proxy mobile IPv6 (PMIPv6). CDN is composed of many distributed content servers in a network, which is designed to deliver multimedia services efficiently and economically to users. The content servers near users can quickly deliver contents upon their request, which can in turn reduce the traffic in the networks by shortening the delivery path from the servers and users. CDN has been recently applied to mobile communication networks to realize the mobile CDN, which is generally implemented by overlaying the CDN service structure over the existing mobile communication networks. Therefore, the content management of CDN operates independently but coupled with the mobility handling signaling of the mobile communication network to serve the contents to moving users seamlessly. It can be figured out as a logical combination of two heterogeneous networks, causing great complexities and restrictions in the content distribution management, network scalability, flexibility in upgrading evolution etc. On the other hand, the mobile Internet protocol (MIP) has been developed so that PMIPv6, a network-based mobility management protocol standard, is now employed into the advanced mobile networks in order to handle the ever-increasing Internet-based services efficiently. The core functional entities of PMIPv6 are the local mobility anchor (LMA) and the mobile access gateway (MAG). In PMIPv6, mobile nodes (MNs) do not participate in the mobile handover signaling procedures, which means that all the processing loads related to mobility management are taken care by the IP networks leaving MNs free from the processing loads related mobility management. It is noted that such the data-centric characteristics of PMIPv6 is to be in a quite good match with the requirements of the signaling mechanism of CDN. This dissertation proposes the two key themes in realizing the mobile CDN on the IP networks: a mobile CDN architecture in the IP networks and a content handover scheme for realizing mobile content delivery based on PMIPv6. In the first part, it was proposed a novel architecture for mobile CDN based on PMIPv6. The proposed architecture is composed of high level cache servers, low level cache servers, LMA, and MAG, combining the CDN network architecture and the PMIPv6-based IP network architecture. The proposed architecture forms a basis of constructing a mobile CDN on the IP network. In the second part, a content handover scheme is proposed which is realized by combining the CDN content management scenario and the mobility management procedure of PMIPv6. The proposed handover scheme can be classified into two methods: A method of pre-downloading contents before handover and a method of selecting an optimal CDN-cache server when handover occurs. The proposed handover scheme can offer several benefits such as seamless handover and routing path optimization. The proposed mobile CDN architecture and handover schemes are expected to be useful for seamlessly providing Internet multimedia contents in the mobile wireless communication environments.

네트워크 이동성 제공을 위한 계층적 네트웍 라우팅과 비대칭 터널링을 이용한 동적경로 최적화 방법 : A Dynamic Route Optimization Method to Support Network Mobility with Hierarchical Mobile Network Binding

정문상 경북대학교 대학원 2007 국내박사

IETF NEMO 워킹그룹에서는 최근에 다수의 이동 노드들을 한꺼번에 효율적으로 관리하기 위한 네트워크 이동성에 관한 기본 프로토콜을 제시하였다. 그러나 IETF의 접근방법은 계층적으로 구성되는 이동 네트워크 환경에서 하위 이동 네트워크의 데이터 전달 경로가 항상 모든 상위 이동 네크워크의 홈 에이전트들을 거쳐가야 하는 핀볼 라우팅 문제 (pinball routing problem)를 가지고 있다. 이 문제를 해결하기 위한 다양한 경로 최적화 방안들이 제시되었으나 도메인내 통신방법 및 시그널링 과부하문제와 부가적인 핸드오프 처리 등의 여러 가지 문제점을 가지고 있다. 본 논문에서는 최상위 이동 라우터의 HoA를 이용한 비대칭 터널링 방법과 계층적 지역 바인딩을 통해 시그널링 및 데이터 전달에 있어서 보다 효율적인 경로설정 최적화 방법을 제시하였다. 기존의 여러가지 경로 최적화 방안과의 성능 비교를 통해 본 논문에서 제시한 방법이 부가적인 핸드오프 처리 없이 효율적으로 도메인내 통신과 시그널링을 처리할 수 있음을 보였다. 먼저, 기존의 네트워크 이동성을 제공하는 경로 최적화 방법들에서 제기되는 문제점들은 다음과 같다. 대부분의 경로 최적화 방법들은 하위 이동네트워크와 자신의 홈 에이전트 간의 터널링 경로를 최소화 하기 위해 하위 이동 네트워크가 속해있는 도메인의 최상위 이동라우터의 CoA를 바인딩 주소로 사용함으로 인해 추가적인 핸드오프가 발생하게 된다. 즉, 차량 네트워크 환경 (VNE : Vehicular Network Environment)과 같이 최상위 이동라우터가 하위 이동네트워크들을 포함하여 이동하는 경우 하위 모든 이동라우터는 최상위 이동라우터의 CoA가 변경됨에 따라 부가적인 핸드오프 과정을 수행해야 한다. 이러한 부가적인 핸드오프 수행은 대규모의 핸드오프 시그널링을 동반하게되고 이에 따른 실시간 서비스에 대한 서비스 끊어짐이 발생하게 된다. 또한 효율적인 도메인 내 통신 및 핸드오프를 정의하지 않고 있어 도메인 내 이동 및 통신시의 비효율적인 시그널링 및 통신경로를 제공하게 된다. 또한 홈에이전트가 이동성을 가지는 경우나 여러 개의 이동 네트워크가 그룹으로 이동하는 경우의 핸드오프 처리 및 통신을 지원하지 못하고 이에 따른 확장성 및 오버헤드를 가지는 문제점들이 있다. 본 논문에서는 이러한 문제점들을 효율적으로 해결할 수 있는 계층적 이동 네트워크 바인딩이라는 새로운 경로 최적화 방법을 제시하였다. 계층적 이동 네트워크 바인딩은 하위 이동 네트워크의 경로 최적화에서 basic support protocol과 동일한 시그널링 복잡성을 가지면서 기존의 여러 가지 경로 최적화 방안들과 유사한 전송 지연시간을 가지도록 비대칭 터널링과 최상위 MR의 HoA를 이용한 경로 최적화 방안을 제시하였다. 또한 이동 네트워크에서 도메인내 통신을 효율적으로 지원하기 위해 기존의 Mobile IPv6에서 RA 메시지를 확장하고 최상위 이동라우터의 HoA 및 CoA를 전달하기 위한 root-MR 옵션을 정의하였다. 또한 이동 네트워크의 도메인 내 통신 및 핸드오프 처리를 지원하기 위해 계층적 지역 바인딩 알고리즘과 비대칭 터널링을 통한 효율적인 패킷 전송을 지원할 수 있도록 IPv6 라우팅 헤더 옵션을 확장한 목적지 라우팅 헤더 (DRH : Destination Routing Header)를 정의하고 이들을 통한 도메인간 및 도메인내 통신 프로시져를 보여준다. 이를 통해 하위 이동네트워크의 계층 레벨에 상관없이 최적화된 경로를 제공하면서 빠른 시그널링과 효율적인 데이터 전달을 지원할 수 있도록 하였다. 제시한 계층적 이동 네트워크 바인딩 구조는 기존의 경로 최적화 방안에서의 부가적인 핸드오프 문제, 도메인내 통신의 지원 문제 등을 해결하였다. 또한 IETF basic support protocol 및 기존의 경로 최적화 방안들과의 각각의 특징을 비교 분석 하였고 이에 따른 시뮬레이션 결과를 보여주었다. 계층적 이동 네으워크 바인딩 구조는 앞으로의 WPAN, 유비쿼터스 컴퓨팅 및 차량 네트워크 환경 등 다양한 이동 환경에서 네트워크 이동성을 효율적으로 제공해 줄 수 있을 것이다.

Route optimization methods in network mobility

박정훈 성균관대학교 2007 국내석사

The development of wireless network technology and demand from users for mobility support has motivated the Internet engineering task force (IETF) to introduce mobile IP, mobile IPv6, and its extension, the network mobility (NEMO) basic support protocol. In the NEMO environment, mobile networks can form a nested structure. In nested mobile networks that use the NEMO basic support (NBS) protocol, pinball routing problem occurs because packets are routed to all home agents of the mobile routers using nested tunneling. In addition, the nodes in same mobile networks can communicate with each other regardless of Internet connectivity. However, the nodes in some mobile networks based on NBS can not communicate when the network is disconnected from the Internet. In this thesis, I propose the route optimization methods to solve these problems. In Chapter II, the proposed scheme uses the mobility anchor point, introduced in hierarchical mobile IPv6 mobility management, and modifies the binding update message to minimize overhead in route optimization. I evaluate route optimization cost in terms of delay. The results demonstrate a minimum performance improvement of 30% and shorter routing delay than NBS in non-optimized cases. In Chapter III, I introduce a new IPv6 routing header, named the destination-information header (DH), which uses DH instead of routing header type 2 to optimize the route in the nested mobile network. The proposed scheme shows at least 10% better performance than ROTIO and similar performance improvement as DBU in inter-route optimization. With respect to intra-route optimization, the proposed scheme always uses the optimal routing path. In addition, handover mechanism in proposed scheme outperforms existing schemes and is less sensitive to network size than existing schemes. 무선 네트워크 기술의 발전과 이동성 지원에 대한 사용자의 요구가 증대됨에 따라 Mobile IP[1]와 Mobile IPv6[2], 그리고 이를 확장한 NEtwork MObility (NEMO) Basic Support 프로토콜[3]이 등장하게 되었다. NEMO환경에서 이동네트워크가 중첩되어 구성될 경우 NBS (NEMO Basic Support) 프로토콜을 사용하는 네트워크에서는 패킷이 네트워크를 구성하는 이동라우터(MR, Mobile Router)의 홈에이전트(HA, Home Agent)를 모두 거치면서 중첩 터널링이 수행되는 핀볼라우팅 문제가 발생한다. 또 이동네트워크 내부 노드들은 이동네트워크의 인터넷 연결성과는 관계없이 통신이 가능해야 하지만 NBS를 사용하는 네트워크에서는 불가능하다. 이러한 문제들을 해결하기 위하여 본 연구에서는 두 가지 이동네트워크 환경에서의 경로최적화 기법을 제안한다. 2장에서는 HMIPv6 (Hierarchical Mobile IPv6 Mobility Management) [4]에서 제안한 MAP (Mobility Anchor Point)을 사용한 경로최적화 기법인 ROME (Route Optimization with MAP based Enhancement)을 제안한다. ROME은 MAP에 기반하고 BU (Binding Update) 메시지를 변경하여 경로최적화를 위한 오버헤드를 최소화한다. ROME 및 기존 경로최적화 기법들의 성능을 분석하기 위해 경로최적화에 따른 비용을 지연시간의 관점에서 비교 분석한다. ROME은 경로최적화를 수행할 경우 기존의 기법에 비해 최소 30%이상 뛰어난 성능을 보이고, 경로최적화를 수행하지 않았을 경우에도 NBS에 비하여 뛰어난 성능을 보인다. 3장에서는 이동네트워크 내외부와 경로최적화가 가능한 ROAD (Route Optimization using Additional Destination-information)을 제안한다. ROAD는 새로운 IPv6 라우팅 헤더 DH (Destination-information Header)를 정의하고 이를 라우팅 헤더 타입2를 대신하여 사용함으로써 중첩된 이동네트워크에서의 경로최적화를 구현한다. 또한, ROAD는 네트워크 이동 시 효율적인 핸드오버 기법을 제공한다. ROAD는 외부 경로최적화에서 기존 기법인 ROTIO에 비하여 최소 10% 이상의 성능향상을 보이며 DBU와는 거의 동일한 성능을 보인다. 또한 내부 경로최적화에서는 ROTIO와 DBU에 비하여 최적화된 경로를 선택하여 통신함을 확인할 수 있다. ROAD의 핸드오버 기법은 ROTIO와 DBU에 비하여 성능이 뛰어나며 네트워크의 크기에도 영향을 매우 적게 받아 가장 뛰어난 성능을 나타낸다.

Enabling Network-based Mobility Management in Next-Generation All-IP Networks: Analysis from the Perspective of Security and Performance

Lee, Jonghyouk 성균관대학교 일반대학원 2010 국내박사

This dissertation discusses network-based mobility management for next-generation networks. The previously developed host-based mobility management protocols mainly depend upon mobility signaling generated by mobile nodes and are thus not widely used in real wireless mobile networks. The IETF has standardized a network-based mobility management protocol, Proxy Mobile IPv6, for handling mobility signaling through mobility service provisioning entities. The objective of this study is to explore the current state of the art of mobility management protocols and to develop advanced schemes for improving the performance of Proxy Mobile IPv6. More specifically, an in-depth review of current mobility management protocols including Proxy Mobile IPv6 is provided. Then, numerical performance analysis of current mobility management protocols is performed in order to identify mobility management protocols' strengths, emergent shortcomings, design tradeoffs, and performance impact factors. Then, secure handover scenarios for Proxy Mobile IPv6 are presented. Under the scenarios, a mobile node is securely authenticated while handover authentication latency is also minimized. Next, a global mobility scheme for extending the coverage of mobility service by supporting inter-domain handovers is presented. The global mobility scheme consists of two different modes: reactive mode and proactive mode. The reactive mode allows a mobile node performs its inter-domain handovers by establishing a tunnel between crossing domains. On the other hand, in the proactive mode, a mobility service provisioning entity sends mobility signaling to a correspondent node on behalf of a mobile node when the mobile node performs its inter-domain handovers. Finally, a paging scheme for enhancing the scalability of Proxy Mobile IPv6 architecture by supporting large numbers of mobile nodes with decreased mobility signaling is proposed. Under the proposed paging scheme, only mobility signaling to update location information of active mobile nodes is generated. The reduced mobility signaling thus enhances the availability and scalability of Proxy Mobile IPv6 architecture. 본 학위 논문에서는 네트워크 기반의 네트워크 이동성 관리 프로토콜에 대한 연구를 수행하였다. 기존에 개발 된 호스트기반의 네트워크 이동성 관리 프로토콜은 이동 단말기가 생성하는 시그널에 의존하였기 때문에 실제 무선 이동 네트워크에서 널리 사용되지 못 하고 있다. 이러한 문제점을 해결하기 위해 IETF 에서는 네트워크 기반의 이동성 관리 프로토콜로 Proxy Mobile IPv6을 표준화 하였다. 본 학위 논문의 목표는 이동성 관리 프로토콜에 대한 최신 동향을 연구하고 Proxy Mobile IPv6 의 성능을 향상시키기 위한 확장 기법들을 개발하는 것에 있다. 좀 더 구체적으로 말하면, Proxy Mobile IPv6을 포함하여 기존의 이동성 관리 프로토콜에 대한 리뷰를 수행한다. 그 후, 각각의 이동성 관리 프로토콜이 가지는 장단점과 성능요소를 파악하기 위한 성능분석을 수행한다. Proxy Mobile IPv6 환경에서 안전한 핸드오버를 제공하기 위한 두 가지의 시나리오를 제안한다. 제안된 핸드오버 시나리오에서 이동 단말기는 안전하고 빠른 핸드오버를 수행 하게 된다. Proxy Mobile IPv6 환경에서 이동성 보장 지역을 확장하기 위한 서로 다른 도메인간의 핸드오버를 지원하는 글로벌 핸드오버 기법을 제안한다. 제안된 글로벌 핸드오버 기법은 두 가지의 다른 방법을 제공하며 반응적인 기법은 서로 다른 도메인간의 터널링을 통한 글로벌 핸드오버를 지원하며 선행적인 기법에서는 도메인에 존재하는 네트워크 기기에 의한 시그널을 통해 글로벌 핸드오버를 지원한다. 마지막으로 Proxy Mobile IPv6 아키텍처의 확장성을 높이기 위한 방법으로 페이징 기법을 제안한다. 제안된 페이징 기법을 통해 오직 활동성을 지닌 이동 단말기만이 시그널을 생성함으로써 Proxy Mobile IPv6 아키텍처의 확장성을 높인다.

IPv6 모바일 네트워크에서의 주소 자동 설정 및 경로 최적화 기술 연구

이동근 建國大學校 2006 국내박사

한글초록 : 본 논문에서는 IPv6를 기반으로 하는 모바일 네트워크(NEMO: Network Mobility)에서 중요한 문제인 경로 최적화를 해결하는 기술을 제안한다.모바일 네트워크는 네트워크 전체가 네트워크 토폴로지를 유지한 채로 이동할 수 있는 수단을 제공한다. 따라서 모바일 네트워크에서는 모든 노드가 네트워크의 이동성과 투명하게 인터넷과 연결을 할 수 있다. 이런 모바일 네트워크는 그 특성상 모바일 네트워크 내부에 하나 이상의 또 다른 모바일 네트워크가 존재하는 중첩된 구조를 허용한다(Nested Mobile Network: nested-NEMO). 이런 중첩된 구조는 모바일 네트워크가 적용되는 실제 환경에서 빈번하게 나타날 것으로 예상되고 있지만, 현재의 네트워크 이동성 지원 기술로는 nested-NEMO에서 심각한 라우팅 문제를 야기 시키며 그 결과, 심각한 성능 저하를 초래하거나 심지어 적용이 불가능한 상황에 처하게 될 수 도 있다.따라서 본 논문에서는, nested-NEMO 에서 최적화된 경로로 패킷 전송을 가능하게 하는 새로운 기술을 제안함으로써 모바일 네트워크의 성능을 향상시키고, 네트워크의 부하를 줄이는 것을 목표로 한다. 본 논문에서 제안하는 경로 최적화 기술은 nested-NEMO를 모바일 라우터들이 하나의 업 링크 인터페이스를 가지는 계층화된 트리 구조를 볼 것인지 아니면, nested-NEMO 내부의 모바일 라우터들이 모두 같은 프리픽스를 가지는 특수한 형태의 MANET(Mobile Ad-hoc Network)으로 볼 것인지에 따라 두 가지 기술로 구분된다. 계층화된 트리구조에서의 경로 최적화는 Mobile IPv6의 Hierarchical Mobile IPv6(MIPv6)를 응용하여 지원한다. 이 기술을 통해 nested-NEMO의 내부 노드와 인터넷의 외부 노드 간 통신을 위한 경로최적화는 물론, nested-NEMO 내부 노드 간 통신에서의 경로 최적화 까지 모두 지원을 하게 된다.Nested-NEMO의 내부 구조를 특수한 MANET으로 볼 경우, 경로 최적화는 ad-hoc 라우팅 프로토콜을 통해 자연스럽게 지원될 수 있다. 이 경우 모바일 라우터들은 라우팅 프로토콜을 통해 nested-NEMO의 내부 정보를 수집하고, 이를 바탕으로 최적화된 경로를 통해 통신을 할 수 가 있다. 그러나 대부분의 ad-hoc 라우팅 프로토콜은 노드들이 미리 라우팅이 가능한 주소를 가지고 있다고 가정을 하게 된다. Nested-NEMO의 모바일 라우터들은 인터넷에서 글로벌한 라우팅이 가능하도록 하기 위해 새로 이동한 네트워크에서 Care-of Address(CoA)를 획득하여 자신의 홈 네트워크의 홈 에이전트(Home Agent: HA)에게 등록을 하여야 한다. 따라서 nested-NEMO를 특수한 MANET으로 볼 때의 경로 최적화는 nested-NEMO 내부의 모바일 라우터들이 빠르게 CoA를 획득할 수 있도록 하는 기술이 우선되어야 한다.본 논문에서는 이와 같이 인터넷과 연결이 가능한 특수한 형태의 MANET에서 사용할 수 있는 빠른 주소 자동 설정 기술을 제안하고 이를 기반으로 하는 경로 최적화 기법을 제시한다 영문초록 : This thesis describes new route optimization techniques for mobile network based on IPv6. A mobile network is an entire network, moving as a unit, which dynamically changes its point of attachment to the Internet and its reachability in the topology. A mobile network is connected to the global Internet via one or more Mobile Routers (MRs). With a current basic Network Mobility (NEMO) Support, all the communications to and from a node in a mobile network must go through the bi-directional tunnel established between the Mobile Router and its Home Agent(HA) when the mobile network is away from the home. However, a mobile network may be nested. Using the proposed protocol by NEMO on the nested mobile network, it builds a tunnel within a tunnel overhead limit. In order to avoid this overhead, it is required to optimize the routing path from the MR in the nested mobile network to the HA of the MR. In this thesis, we propose the route optimization for nested mobile network. Our route optimization techniques have two approaches. One is hierarchical approach and the other is MANET approach.Hierarchical route optimization is based on HMIPv6. Nested mobile network has an aggregated hierarchy of mobile networks, so the hierarchical mobility management is well applicable. Our proposal can give localized mobility management functions as well as route optimization for the nested mobile networks.Another approach for route optimization is using ad-hoc routing protocol. In the case of arbitrary sized nested NEMO networks, the Mobile Routers naturally form an ad-hoc network that can efficiently use ad-hoc routing protocols. However, the majority of routing protocols assume that mobile nodes in ad hoc networks are configured with IP addresses before they begin communications in the network. Thus, Auto-configuration is a desirable goal in implementing route optimization for MANEMO(MANET + NEMO).In this thesis, we investigate a MANET topology that all the nodes in MANET want to connect to the Internet through a special node called the Internet Gateway and we propose a new IPv6 address auto-configuration mechanism in MANET. Our solution uses stateless and stateful approach. Based on address auto-configuration for MANET, we propose route optimization technique for nested NEMO

A Novel Mobility and QoS Provisioning in Mobile Multi-Homing Environments

김대순 경희대학교 2009 국내박사

Multi-Homing technology is a versatile solution to improve the network performances such as higher throughput through a load sharing, advanced reliability through multiple connections and supporting ubiquitous access through multiple interfaces. The multi-homing technology has been studied in network layer. The major protocol for multi-homing is the SHIM6 (Site Multi-homing by IPv6 Intermediation). The SHIM6 is currently being defined by the IETF shim6 working group to provide multiple connections between hosts with multiple provider independent addresses. To achieve this, a SMIM6 layer is placed in the IP layer to assure that the same IP address pair is provided to the upper layers to identify a given communication, while the traffics can use different IPv6 addresses which are called locator to be able to enforce different paths. Although the requirement of enhanced reliability, load sharing and ubiquitous internet access is achieved using multi-homing i.e. multiple interfaces, it suffers performance degradation in terms of quality of service (QoS) provisioning, routing efficiency, path exploration and fault detection, under mobile environment. As the contemporary applications and uses of internet are moving towards mobility and ubiquity a good number of mobility protocols e.g. Mobile IP, Proxy Mobile IP, Hierarchical Mobile IP and NEMO have been introduced. However Mobile IP based protocols have reported with many difficulties e.g. signal storm, overhead of processing signals and efficient route selection. These difficulties in turn contribute to the different (QoS) parameters. Therefore, as a preliminary work of the thesis we have introduced a QoS provisioning scheme based on available bandwidth, end-to-end delay and Signal-to-Interference Ratio. Proposed scheme uses SHIM6 protocol and outperforms the existing algorithm in terms of higher throughput and delay. SHIM6 protocol lacks mobility support. Therefore, we propose mobility supported enhanced SHIM6 protocol to incorporate host mobility, network mobility and nested mobility. For host mobility, we define the binding update requesting procedure which includes locator lists which are care of address to notify new location of nodes. Furthermore, we define binding prefix requesting procedure to announce prefix information of nodes in mobile network to upper routers and home agents. From these proposed procedures, we achieve route optimization between the communicating nodes. In addition, we propose inter-domain handover and intra-domain handover scheme for host and network mobility. Finally, we addressed the obstacles of SHIM6 protocol for time critical applications. Therefore, we define path fault detection and path exploring scheme to reduce path recovery time more efficiently. In the basic SHIM6, the path exploring procedure starts after one of the path fault for reducing overhead on a network. So we called SHIM6 path exploring is light weighted procedure. However, our proposed scheme focuses on time critical applications and therefore, we define path fault detection procedure to trace current alive paths before path exploring procedure starts. Test-bed and simulation results show that integration of QoS provisioning, mobility supported enhanced SHIM6 protocol and fault detection and path exploration scheme provide better performance in terms of route selection, end-to-end delay and throughput.

A Study on Advanced CORE Mechanism in Mobile Ad Hoc Networks

정세준 연세대학교 2003 국내석사

A mobile ad hoc network is a temporal network formed by a collection of wireless mobile nodes without the aid of any existing network infrastructure or centralized administration. Each mobile node participating in the mobile ad hoc network should also be willing to route and forward packets for other mobile nodes. However, a node may misbehave not by participating in the routing protocol or by agreeing to forward packets and then failing to do so, because it is overloaded, selfish, malicious, or broken. Since the mobile ad hoc network maximizes total network throughput by using all available nodes for routing and forwarding, misbehaving nodes can be a significant problem. Some recent papers have discussed this topic and proposed various approaches based on nodes cooperation. In this paper, we focus on the problem of nodes selfishness in the mobile ad hoc network. We first discuss related work including recently proposed CORE mechanism. The CORE is a generic mechanism based on reputation to enforce cooperation among the nodes of the mobile ad hoc network. However, while the CORE mechanism can detect and punish selfish nodes it has critical limitation: it cannot increase network throughput degraded by nodes misbehavior. Therefore, in this paper, we propose an extension to the existing CORE mechanism in order to improve network performance and then evaluate our scheme through detailed simulations. 이동 ad hoc 네트워크는 기존의 어떠한 기반구조 없이 무선 이동 노드들 자체로 구성되는 네트워크이다. 따라서 각 노드는 라우팅 프로토콜 및 패킷 전송에 적극 참여해야 하는 책임을 지닌다. 그러나 전송 경로의 단선, 트래픽 과부하, 이기적이거나 악의적인 노드의 오 동작과 같은 이유로 각 노드는 그러한 임무를 적절히 수행하지 못할 가능성이 있다. 이동 ad hoc 네트워크는 가능한 모든 노드들을 이용한 네트워킹으로 최대의 성능을 이끌어내기 때문에 노드들의 오 동작은 네트워크의 성능에 치명적인 악영향을 끼칠 수 있다. 따라서, 본 논문에서는 먼저 노드 이기주의에 초점을 맞추어 최근 몇 년간 제시된 관련 연구 결과들에 대해 먼저 논의할 것이다. 이 중 최근에 제안된 CORE 메커니즘은 평판 시스템을 기반으로 하여 오 동작 노드를 탐지하고 그에 따른 징계를 내림으로써 노드들의 협력을 촉진시킬 수 있는 일반적인 메커니즘이다. 그러나, 이 메커니즘은 오 동작 노드들로 인해 감소된 네트워크의 성능을 끌어올리지 못하는 한계를 지니고 있다. 따라서, 우리는 본 논문에서 그러한 문제점을 해결할 수 있는 기존 CORE 메커니즘에 대한 확장을 제안하고 다양한 시뮬레이션을 통해 그 성능을 평가한다.

Efficient data sharing in mobile computing systems : replicated server allocation algorithms and peer-to-peer file sharing systems

송진우 Graduate School, Yonsei University 2010 국내박사

Nowadays, mobile device users get various services from telecommunication companies that seemed to be rather almost impossible about a decade ago. Such services are possible thanks to the advances in mobile and cellular communications technologies. Although we are enjoying the benefits from the technological advances, the current mobile devices still have insufficient computing capability and storage; because users ever demand smaller size devices with more added functionality and enhanced system performance. In general, mobile computing systems rely on decentralized server systems for efficient mobile services. Data sharing is a key problem to provide faster accessibility towards shared data for users by reducing costly accesses to the online servers. This dissertation addresses three kinds of data sharing systems in mobile computing systems for speeding up data accesses; they are the shared data allocation system in mobile networks, the cost-based shared data allocation system in mobile networks, and the peer-to-peer file sharing systems in mobile ad-hoc networks. The first system distributes replicated servers into a mobile network to speed up data accesses for uses. It is obviously profitable to allocate replicated servers at the cells where a lot of mobile users visit. For the first system we propose various replicated server allocation algorithms which exploit users’ moving patterns as well as data access patterns. Some of them are greedy algorithms and the rest are global search algorithms. The second system distributes replicated servers into a mobile network with considering the communication costs. The first system focused on the placement of replicated servers along with the moving paths of mobile users to maximize the hit ratios. When a mobile user wants to access some data in the area at which a replicated server is not located, the user fails to get the data and a miss is said to be occurred. Therefore, we suggest a solution to take care of such a miss by sending the file request to a replicated server nearby in the mobile network. That is, the users are allowed to request nearest replicated servers for their demands. However, such allowance does give rise to communication costs. The second system distributes replicated servers into a mobile network with considering the communication costs. In this system we propose several algorithms that allocate available replicated servers in the network so as to minimize the communication costs. In the third system some mobile devices themselves serve as replicated servers. Faster data communications among mobile devices such as cell phones and PDAs are always welcomed by mobile device users for exchanging data likes favorite movies, music, images, and text files. Thus mobile devices should be efficiently connected to construct a peer-to-peer file sharing system in a mobile ad-hoc network. In this system we propose three different file sharing systems that have double-layered topology. The double-layered topology not only enables fast data sharing among mobile users but also prevents multi-broadcast. The experimental results showed that the proposed algorithms for data sharing systems provide better performance than previous researches. In the first system the proposed algorithms showed better average hit ratios than the previous best algorithm by 2.7% ~ 4.5%. The vertex-based activity count algorithm, the simulated annealing algorithm, and the genetic algorithm showed the near optimal hit ratios. In the second system the proposed algorithms showed less average communication cost than the edge based replicated server allocation algorithms by 8.7% ~ 36.4%. The simulated annealing algorithm and the genetic algorithm allocated replicated servers with near optimal communication costs. In the third system the proposed systems improved the performance in terms of the average number of messages to find target files with respect to a previously known comparable system, ORION. Such improvement was possible because they could reduce the network traffics successfully by forcing super-peers to communicate among themselves instead of multi-broadcasting. The reduced MIS system showed the best performance and improved the performance by 48.9% over ORION. Moreover, we propose an enhanced double-layered P2P system in which super-peers are selected based on their mobility. Also, we propose two reliability improvement schemes, the avoidance scheme and the role changing scheme. They are applied to the proposed system to enhance the reliability of the system. Most of the previous P2P systems are evaluated under the `static' mobile P2P environment in which the number of peers is fixed and there are no dynamic joins and leaves. Moreover, there are many systems that do not even consider the mobility of peers. In mobile networks, the reliability that guarantees communication among peers is one of the crucial factors to be considered. The experimental results show that the proposed system with the two schemes improved the reliability over other double-layered systems in terms of the failure rate by up to 25 %, while increasing the network traffic marginally. There are five main contributions of this dissertation. First, we have proposed replicated server allocation algorithms for the first system which increased the hit ratios up to near optimal values. The proposed algorithms utilized the occurrence counts on vertices instead of on edges. Second, we modified the first system to allow the users to access the shared data through the replicated servers nearby in the mobile network, rather than through the online server. Therefore, the second system takes care of a miss by sending the file request to a replicated server nearby in the network. Third, we have proposed replicated server allocation algorithms for the second system which decreased the communication cost up to near optimal values. Fourth, we have proposed a few mobile P2P file sharing systems that have double layered topology for the third system. The proposed mobile P2P file sharing systems showed quite smaller average number of messages than ORION. Finally, we have proposed an enhanced double-layered mobile P2P system for reliability in the dynamic mobile environment.