User Independent Paging Scheme for Mobile IP

Multi-step paging has been widely proposed in personal communications services (PCS) systems to reduce the signaling overheads. Similar ideas can be applied to Mobile IP to provide IP paging services. However, current proposed multi-step paging schemes are user dependent under which the partition of paging areas and the selection of paging sequence are different for each user. The performance of a user dependent paging scheme for individual users may be affected by many factors. It is often difficult to achieve perfect performance for each user. In addition, when multiple users are paged at the same time, user dependent paging schemes may consume significant system resources. This paper introduces a user independent paging scheme where the paging criterion is not based on individual user information. The goal of user independent paging is to provide satisfactory overall performance of the whole system, when personalized optimal performance for each user is hard to obtain. The user independent paging scheme is proposed for IP mobility for its easy implementation and convenient combination with paging request aggregation. The paging criterion adopted is the mobility rate of each subnet determined by the aggregated movements of all mobile users. In order to implement the proposed scheme, a concept of “semi-idle state” is introduced and the detailed solution for obtaining mobility rate is presented. Analytical results show that when paging one user at a time, the performance of the proposed user independent paging scheme is comparable to that of the paging schemes based on perfect knowledge of user movement statistics. When paging multiple users simultaneously and when the knowledge on individual user behavior is not perfectly accurate, the proposed scheme has remarkable advantages in terms of reducing the overall paging cost. Jiang Xie received her B.E. degree from Tsinghua University, Beijing, China, in 1997, M.Phil. degree from Hong Kong University of Science and Technology in 1999, and M.S. and Ph.D. degrees from Georgia Institute of Technology in 2002 and 2004, respectively, all in electrical engineering. She is currently an assistant professor with the Department of Electrical and Computer Engineering at the University of North Carolina-Charlotte. Her current research interests include resource and mobility management of wireless networks,QoS provisioning, and next-generation Internet. She is a member of IEEE and ACM.     

Efficient Resource Allocation for Wireless Multicast

In this paper, we propose a bandwidth-efficient multicast mechanism for heterogeneous wireless networks. We reduce the bandwidth cost of an Internet protocol (IP) multicast tree by adaptively selecting the cell and the wireless technology for each mobile host to join the multicast group. Our mechanism enables more mobile hosts to cluster together and leads to the use of fewer cells to save the scarce wireless bandwidth. Besides, the paths in the multicast tree connecting to the selected cells share more common links to save the wireline bandwidth. Our mechanism supports the dynamic group membership and offers mobility of group members. Moreover, our mechanism requires no modification to the current IP multicast routing protocols. We formulate the selection of the cell and the wireless technology for each mobile host in the heterogeneous wireless networks as an optimization problem. We use integer linear programming to model the problem and show that the problem is NP-hard. To solve the problem, we propose a distributed algorithm based on Lagrangean relaxation and a network protocol based on the algorithm. The simulation results show that our mechanism can effectively save the wireless and wireline bandwidth as compared to the traditional IP multicast.     

Congestion control for fair resource allocation in networks with multicast flows

We consider the problem of congestion control in networks which support both multirate multicast sessions and unicast sessions. We present a decentralized algorithm which enables the different rate-adaptive receivers in different multicast sessions to adjust their rates to satisfy some fairness criterion. A one-bit ECN marking strategy to be used at the nodes is also proposed. The congestion-control mechanism does not require any per-flow state information for unicast flows at the nodes. At junctions nodes of each multicast tree, some state information about the rates along the branches at the node may be required. The congestion-control mechanism takes into account the diverse user requirements when different receivers within a multicast session have different utility functions, but does not require the network to have any knowledge about the receiver utility functions.     

A scalable multicast key management scheme for heterogeneous wireless networks

Secure multicast applications require key management that provides access control. In wireless networks, where the error rate is high and the bandwidth is limited, the design of key management schemes should place emphasis on reducing the communication burden associated with key updating. A communication-efficient class of key management schemes is those that employ a tree hierarchy. However, these tree-based key management schemes do not exploit issues related to the delivery of keying information that provide opportunities to further reduce the communication burden of rekeying. In this paper, we propose a method for designing multicast key management trees that match the network topology. The proposed key management scheme localizes the transmission of keying information and significantly reduces the communication burden of rekeying. Further, in mobile wireless applications, the issue of user handoff between base stations may cause user relocation on the key management tree. We address the problem of user handoff by proposing an efficient handoff scheme for our topology-matching key management trees. The proposed scheme also addresses the heterogeneity of the network. For multicast applications containing several thousands of users, simulations indicate a 55%-80% reduction in the communication cost compared to key trees that are independent of the network topology. Analysis and simulations also show that the communication cost of the proposed topology-matching key management tree scales better than topology-independent trees as the size of multicast group grows.     

Protocol design for scalable and reliable group rekeying

We present the design and specification of a protocol for scalable and reliable group rekeying together with performance evaluation results. The protocol is based upon the use of key trees for secure groups and periodic batch rekeying. At the beginning of each rekey interval, the key server sends a rekey message to all users consisting of encrypted new keys (encryptions, in short) carried in a sequence of packets. We present a scheme for identifying keys, encryptions, and users, and a key assignment algorithm that ensures that the encryptions needed by a user are in the same packet. Our protocol provides reliable delivery of new keys to all users eventually. It also attempts to deliver new keys to all users with a high probability by the end of the rekey interval. For each rekey message, the protocol runs in two steps: a multicast step followed by a unicast step. Proactive forward error correction (FEC) multicast is used to reduce delivery latency. Our experiments show that a small FEC block size can be used to reduce encoding time at the server without increasing server bandwidth overhead. Early transition to unicast, after at most two multicast rounds, further reduces the worst-case delivery latency as well as user bandwidth requirement. The key server adaptively adjusts the proactivity factor based upon past feedback information; our experiments show that the number of NACKs after a multicast round can be effectively controlled around a target number. Throughout the protocol design, we strive to minimize processing and bandwidth requirements for both the key server and users.     

Stateless overlay multicast with in-packet bloom filters

Due to the difficulty of deploying Internet protocol (IP) multicast on the Internet on a large scale, overlay multicast has been considered as a promising alternative to develop the multicast communication in recent years. However, the existing overlay multicast solutions suffer from high costs to maintain the state information of nodes in the multicast forwarding tree. A stateless overlay multicast scheme is proposed, in which the multicast routing information is encoded by a bloom filter (BF) and encapsulated into the packet header without any need for maintaining the multicast forwarding tree. Our scheme leverages the node heterogeneity and proximity information in the physical topology and hierarchically constructs the transit-stub overlay topology by assigning geometric coordinates to all overlay nodes. More importantly, the scheme uses BF technology to identify the nodes and links of the multicast forwarding tree, which improves the forwarding efficiency and decreases the false-positive forwarding loop. The analytical and simulation results show that the proposal can achieve high forwarding efficiency and good scalability.     

Managing IP services over a PACS Packet Network

We have developed a system and network architecture to provide IP services in the Personal Access Communications System (PACS). IP datagrams are delivered to PACS users through the PACS packet-mode data service, achieving more efficient usage of wireless resources and supporting multimedia applications such as MBone audio and video. The architecture presented in this article augments the PACS voice network with IP routers and backbone links, called the PACS Packet Network (PPN), and is connected to the global Internet via gateways. Compared to the cellular digital packet data (CDPD) network, which employs its own network-layer mobility protocol and thus supports roaming within the CDPD network only, we have incorporated Mobile IP into the PACS handoff mechanism to further achieve global IP mobility. We have also developed native PACS multicast and a group management scheme to efficiently handle dynamic IP multicast and MBone connectivity. These features seamlessly integrate PACS into the global Internet and provide standard-conforming IP services with global mobility     

IPv6网络中组播路由--PIM技术研究

随着网络宽带用户和下一代互联网的发展,多媒体业务相关服务如网络电视(IPTV)需求的日益增长刺激了IP组播技术的普及和发展,使其成为新一代网络中不可缺少的关键技术.与单播应用相比,采用IP组播技术分发信息常常能从本质上减少整个网络对带宽的需求.文章从IPv6网络的各种组播技术入手,详细介绍了当前在实际网络中获得广泛应用的基于协议无关组播(PIM)的组播路由技术 ,重点介绍了域内组播路由中使用最广泛的PIM稀疏模式(PIM-SM).对整个PIM-SM组播路由协议在IPv6网络中的运行过程进行了论述,最后介绍了其在未来IPTV等网络应用中的前景.     

A ring-based multicast routing topology with QoS support in wireless mesh networks

Wireless mesh networking (WMN) is an emerging technology for future broadband wireless access. The proliferation of the mobile computing devices that are equipped with cameras and ad hoc communication mode creates the possibility of exchanging real-time data between mobile users in wireless mesh networks. In this paper, we argue for a ring-based multicast routing topology with support from infrastructure nodes for group communications in WMNs. We study the performance of multicast communication over a ring routing topology when 802.11 with RTS/CTS scheme is used at the MAC layer to enable reliable multicast services in WMNs. We propose an algorithm to enhance the IP multicast routing on the ring topology. We show that when mesh routers on a ring topology support group communications by employing our proposed algorithms, a significant performance enhancement is realized. We analytically compute the end-to-end delay on a ring multicast routing topology. Our results show that the end-to-end delay is reduced about 33 %, and the capacity of multicast network (i.e., maximum group size that the ring can serve with QoS guarantees) is increased about 50 % as compared to conventional schemes. We also use our analytical results to develop heuristic algorithms for constructing an efficient ring-based multicast routing topology with QoS guarantees. The proposed algorithms take into account all possible traffic interference when constructing the multicast ring topology. Thus, the constructed ring topology provides QoS guarantees for the multicast traffic and minimizes the cost of group communications in WMNs.     

OMAC: A new access control architecture for overlay multicast communications

Multicast communications concern the transfer of data among multiple users. Multicast communications can be provided at the network layer—an example is IP multicast—or at the application layer, also called overlay multicast. An important issue in multicast communications is to control how different users—senders, receivers, and delivery nodes—access the transmitted data as well as the network resources. Many researchers have proposed solutions addressing access control in IP multicast. However, little attention has been paid to overlay multicast. In this paper, we investigate the access control issues in overlay multicast and present OMAC: a new solution to address these issues. OMAC provides access control for senders, receivers, and delivery nodes in overlay multicast. The proposed architecture, which is based on symmetric key cryptosystem, centralizes the authentication process in one server whereas it distributes the authorization process among the delivery nodes. Moreover, delivery nodes are utilized as a buffer zone between end systems and the authentication server, making it less exposed to malicious end systems. To evaluate our work, we have used simulation to compare the performance of OMAC against previous solutions. Results of the simulation show that OMAC outperforms previous multicast access control schemes. Copyright © 2010 John Wiley & Sons, Ltd.     

移动IP环境下的RSVP研究

资源预留协议RSVP能够为用户提供端到端的传输带宽。为保证在移动IP下的服务质量,针对RSVP协议提出很多改进方案,如隧道RSVP,MRSVP和HMRSVP等。对宏移动和微移动下的RSVP扩展方案进行了讨论,最后提出进一步的研究方向。     

下一代网络通用移动性管理技术初探

针对下一代网络(NGN)的通用移动性要求,阐述了符合NGN全IP网络传送这一特点的两类移动性解决方案——基于网络层解决方案(移动IP)和基于应用层解决方案(移动SIP),比较了它们在支持终端移动性、个人移动性和业务移动性支持上的优缺点,进而分析两者结合方案,提出将网络层移动性管理进行联合优化设计,是研究NGN通用移动性管理技术的一种努力方向。     

Efficient multicast search under delay and bandwidth constraints

The issue of a multicast search for a group of users is discussed in this study. Given the condition that the search is over only after all the users in the group are found, this problem is called the Conference Call Search (CCS) problem. The goal is to design efficient CCS strategies under delay and bandwidth constraints. While the problem of tracking a single user has been addressed by many studies, to the best of our knowledge, this study is one of the first attempts to reduce the search cost for multiple users. Moreover, as oppose to the single user tracking, for which one can always reduce the expected search delay by increasing the expected search cost, for a multicast search the dependency between the delay and the search cost is more complicated, as demonstrated in this study. We identify the key factors affecting the search efficiency, and the dependency between them and the search delay. Our analysis shows that under tight bandwidth constraints, the CCS problem is NP-hard. We therefore propose a search method that is not optimal, but has a low computational complexity. In addition, the proposed strategy yields a low search delay as well as a low search cost. The performance of the proposed search strategy is superior to the implementation of an optimal single user search on a group of users. Amotz Bar-Noy received the B.Sc. degree in 1981 in Mathematics and Computer Science and the Ph.D. degree in 1987 in Computer Science, both from the Hebrew University, Israel. From October 1987 to September 1989 he was a post-doc fellow in Stanford University, California. From October 1989 to August 1996 he was a Research Staff Member with IBM T. J. Watson Research Center, New York. From February 1995 to September 2001 he was an associate Professor with the Electrical Engineering-Systems department of Tel Aviv University, Israel. From September 1999 to December 2001 he was with AT research labs in New Jersey. Since February 2002 he is a Professor with the Computer and Information Science Department of Brooklyn College - CUNY, Brooklyn New York. Zohar Naor received the Ph.D. degree in Computer Science from Tel Aviv University, Tel Aviv, Israel, in 2000. Since 2003 he is with the University of Haifa, Israel. His areas of interests include wireless networks, resource management of computer networks, mobility, search strategies, and multiple access protocols.     

Fast adaptive routing supporting mobile senders in Source Specific Multicast

IP multicast deployment recently progresses, but group services often remain restricted to limited domains and fail to comply with route-optimizing mobility management of the next generation Internet. Source Specific Multicast (SSM) facilitates transparent inter-domain routing and is expected to globally disseminate to many users and services. However, mobility support for Source Specific Multicast is still known to be a major open problem. In this paper, we propose the Enhanced Tree Morphing (ETM) protocol for extending SSM routing to mobile multicast sources. The scheme dynamically adapts SSM forwarding states to sender mobility, and transforms (morphs) source specific distribution trees into new, optimal trees rooted at a relocated source. ETM is simple, robust and secure, while it admits superior performance in packet forwarding at a low signaling overhead. Extensive evaluations based on a full protocol implementation, and simulations based on real-world topology data are performed, granting full insight into the properties of packet loss and delay stretch, protocol convergence times and router state evolution during single and rapidly repeated handovers. In a constant bit rate scenario, an ETM source handover typically leads to a slightly increasing delay of the first data packet, only. When operating on realistic network topologies, the protocol uniformly converges within less than 50 ms, thereby sustaining robustness under rapid source movement at all speeds common to our mobile world. Further optimizations are identified for FMIPv6 and for multihomed nodes.     

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

Efficient paging and multicast schemes for Mobile Virtual Private Networks

The issue of providing a mobile virtual private network (MVPN) service by a cellular network is addressed in this study. The main focus of this study is on two aspects of MVPN handling: a multicast transmission, and location management of the MVPN members. Virtual private networks (VPNs) already exist in wired networks. The growing number of mobile users increases the demand for mobile services. It is expected that future wireless networks will have to provide wireless internet services, and in particular, to support MVPNs. In order to maintain an MVPN service offering, the system must support an efficient information delivery to the MVPN members. In order to achieve this goal, the physical locations of the MVPN members must be known to the system. In this study, we present methods to efficiently route and transmit information to the MVPN members, without affecting the quality of the personal service provided to each and every MVPN member. It is shown that the wireless MVPN bandwidth requirement is significantly less than the equivalent bandwidth required by a wired VPN. The offered bandwidth utilization is significantly better than the efficiency of IP‐based multicast transmission in the Internet, and the proposed IP‐based multicast transmission in cellular networks. Copyright © 2005 John Wiley & Sons, Ltd.     

Investigation of multicast‐based mobility support in all‐IP cellular networks

To solve the IP mobility problem, the use of multicast has been proposed in a number of different approaches, applying multicast in different characteristic ways. We provide a systematic discussion of fundamental options for multicast‐based mobility support and the definition and experimental performance evaluation of selected schemes. The discussion is based on an analysis of the architectural, performance‐related, and functional requirements. By using these requirements and selecting options regarding network architecture and multicast protocols, we identify promising combinations and derive four case studies for multicast‐based mobility in IP‐based cellular networks. These case studies include both the standard any‐source IP multicast model as well as non‐standard multicast models, which optimally utilize the underlying multicast. We describe network architecture and protocols as well as a flexible software environment that allows to easily implement these and other classes of mobility‐supporting multicast protocols. Multicast schemes enable a high degree of flexibility for mobility mechanisms in order to meet the service quality required by the applications with minimal protocol overhead. We evaluate this overhead using our software environment by implementing prototypes and quantifying handoff‐specific metrics, namely, handoff and paging latency, packet loss and duplication rates, as well as TCP goodput. The measurement results show that these multicast‐based schemes improve handoff performance for high mobility in comparison to the reference cases: basic and hierarchical Mobile IP. Comparing the multicast‐schemes among each other the performance for the evaluated metrics is very similar. As a result of the conceptual framework classification and our performance evaluations, we justify specific protocol mechanisms that utilize specific features of the multicast. Based on this justification, we advocate the usage of a source‐specific multicast service model for multicast‐based mobility support that adverts the weaknesses of the classical Internet any‐source multicast service model. Copyright © 2006 John Wiley & Sons, Ltd.     

高校“三多模式”WLAN业务网络分流建设模式

随着中国移动对于WLAN网络建设逐步展开,越来越多的WLAN个性化业务需求在各个用户或者企业中出现,为了既要满足用户需求,同时又满足移动WLAN网络建设要求,多种WLAN业务的衍生方案应运而生,本方案着重讨论在多个SSID、多种认证方式以及多类型IP地址业务需求下的WLAN网络建设及数据分流模式。