Ki-Il Kim

Internet multicast provisioning issues for hierarchical architecture

The ASM (any source multicast) have been proposed to forward IP multicast datagram. However, there remain unsolved deployment issues such as network management and address allocation of multicast sessions. To overcome the above issues, largely new three multicast mechanisms-SGM (Small Group Multicast), ALM (Application Level Multicast) and SSM (Source Specific Multicast)-have been proposed. While the SGM and ALM can support multicast service without constructing the multicast routing tree, SSM constructs the multicast routing tree rooted in the source. SGM is proposed to support a very large number of small multicast groups. However, since SGM needs an additional packet header to service multicast, modification of the legacy routers is inevitable. ALM provides multicast by means of a combination of unicast in WAN and multicast in LAN. Since the standard is not fixed, this mechanism has limited implementation conditions. SSM identifies the multicast session not by G but by (S, G) pair. This mechanism solves the multicast address allocation problem, which is the biggest issue in the ASM. However, all routers along the delivery path must maintain the state (S, G) in order to transmit multicast data. Though the three new mechanisms can solve the many of the problems, one feature of ASM, the scalability problem is not be removed at all. We propose a fast deployment mechanism, which is based on SSM as well as the use the Internet hierarchical architecture. This mechanism may help multicast deployment without any modification of the IP layer while the advantage of SSM is kept. A key feature of the new mechanism is the use of a different multicast service for macro level multicast and micro level multicast.

New approach for mobile multicast based on SSM

The issue for mobile multicast is classified as two trends. One is route optimization and the other is how fast the multicast routing tree can be reconstructed. In the case of reconstructing the multicast tree, the FA must join the multicast group whenever the attachment point is changed. This mechanism has the advantage of route optimization for transmitting multicast data. However, the tree reconstruction may have occurred whenever the mobile host moves. Its overhead may be increased rapidly. In order to service multicast, the other way is the use of tunneling without tree reconstruction. Because the HA (home agent) is already being subscribed in the multicast session, the multicast datagram is transmitted to the HA. The HA tunnels it to the current FA (foreign agent), to which the mobile host is attached. When this mechanism is applied, the tree reconstruction is not needed. However, the path from the HA to FA may not be optimized. The longer the path distance is, the more the packet delay may increase. If the FA does not support IGMP, a more serious problem is caused. As stated above, the two mechanisms may not be implemented easily on the current network. We propose a mobile multicast mechanism based on SSM (source-specific multicast), which is proposed in order to support one-to-many transmission efficiently. However, automatic tunneling is used instead of the source-based tree. The key feature of this mechanism is to remove the overload caused by tree reconstruction and to optimize the multicast path simultaneously when the handoff occurred.

Two phase edge-to-edge distributed measurement based admission control mechanism in large IP networks

This paper proposes the TPED MBAC (two-phase edge-to-edge distributed measurement based admission control) mechanism that provides the guarantee of user QoS requirements and the fairness of blocking probability between flows traversing different path lengths in large IP networks. The proposed mechanism has two provisioning phases, the quantitative provisioning phase and the qualitative provisioning phase, in admission control and performs WRR scheduling based on the hop counter for probing packet transmission. Additionally, the proposed mechanism uses the optimized probing packet rate instead of the peak rate. For the performance evaluation of the proposed mechanism, we present simulation results in terms of the fairness of blocking probability and the loss probability using the ns-2 simulator.

Robust and cost-efficient group communication using overlay multicast in mobile ad hoc networks

Previous multicast schemes for MANET (mobile ad hoc networks) are mostly classified as tree-based schemes and mesh-based schemes depending on their multicast delivery structure. Tree-based schemes cannot cope with network mobility due to frequent tree reconfiguration. On the other hand, mesh-based schemes waste unnecessary resource due to delivery along multiple paths. We propose to use an overlay multicast to handle network mobility efficiently with minimized resource. In our scheme, DDT (data delivery tree) can remain static as long as unicast route between members that are related to data forwarding remains reachable. Thus, it can not only minimize the effects of network mobility, but also bring about low additional control overhead. Such distinct advantages are specifically evaluated through the results of the simulation.

Domain based approach for QoS provisioning over Mobile IP

Mobile IP (MIP) is proposed to ensure packet routing to a mobile host in the Internet regardless of the attachment point. MIP defines two functional entities, home agent (HA) and foreign agent (FA) to manage the mobile host location. Also, MIP defines the tunneling mechanism to deliver packets that are destined for the mobile nodes home address. This tunneling mechanism has difficulties in adapting to the IntServ and DiffServ Internet service architectures. Since both services identify the service session as three-tuples - destinations IP address, IP protocol number and destination port - a new different service session must be defined over the IP tunnel. Current MIP QoS works concentrate on how to guarantee QoS over the IP tunnel and map it to the end-to-end service session, but seem to neglect the host mobility supporting protocol. We regard this protocol as an important factor. The current protocol has a hierarchical architecture with both micro and macro mobility. So, if MIP QoS can be organized in the same hierarchical architecture, better QoS can be obtained. Since MIP can support host mobility in a macro network, IntServ and Diffserv must be applied in this section. However, since several schemes are proposed to support fast handoff in the micro level, several QoS mechanisms may be applied in this level. This paper specifics a hierarchical scheme which uses not only aggregate RSVP flows between domain level agents, but also a specific local policy between domain level agent and mobile host in a domain.

Scalable IPv6 multi-homing scheme based on end-to-end argument

The motivation of the multi-homing is to improve reliability and load sharing. However, the existing multi-homing schemes for IPv6 seem to simply focus on preserving connectivity via other links when one of the links fails. In this paper, we present a multi-homing scheme in IPv6 considering the load sharing and delay latency, and reliability. The simulation results show the distinct performance of our approach.

Hierarchical admission control scheme for supporting mobility in mobile IP

A lot of different researches have been done for guaranteeing quality-of-service (QoS) to the mobile host in the Internet regardless of the attachment points. However, most of the researches concentrate on adopting the integrated service (IntServ) or differentiated service (DiffServ) over the tunneling section between the home agent and the foreign agent. Also, most researches seem to neglect admission control considering handoff and the QoS architecture. In the big picture for QoS, the end-to-end QoS can be guaranteed by combining, intra-domain QoS and inter-domain QoS. So, if it is possible to guarantee intra-domain QoS, inter-domain QoS can be guaranteed by negotiation between domains. We present the intra-domain QoS guarantee mechanism, which can support host mobility. We redefine intra-domain QoS as an interoperation of micro-level QoS and macro-level QoS, considering protocols that support host mobility and currently discussed in IETF Mobile IP WG. For the microlevel QoS, several admission control mechanisms may limit the handoff dropping and cell overload probability in wireless network. But, it is not enough. Whenever the mobile host moves between different subnet, it may be blocked if available bandwidth is not reserved between gateway home agent and current gateway foreign agent. So, new admission control considering mobility in the macro-level QoS has to be developed. In our proposal, bandwidth broker (BB) in DiffServ network performs the admission control based on the available bandwidth between the gateway home agent and the current gateway foreign agent in addition to neighboring gateway foreign agents, where the mobile host may possibly visit during the lifetime of the connection.

Fuzzy searching and routing in unstructured mobile peer-to-peer networks

Peer-to-Peer (P2P) networks offer a scalable solution for efficient query searching and sharing across the unstructured networks. With an increased overhead due to large amount of object searching and routing in unstructured P2P networks, it is a challenge to continue QoS routing among different mobile peers. Most existing mobile P2P protocols focus on inflexible techniques to route queries and discover objects of interest. Such common techniques incur a relatively high search time due to remarkable network traffic and duplication of query messages. The correlation between routing and mobility is crucial to efficiently search and route the query object in an overlay to avoid unnecessary consumption of network resources. Our previous fuzzy search controller model (Shah and Kim in 12th IEEE international conference on dependable, autonomic and secure computing (DASC), 2014) reduced the search time query processing in P2P networks, but it caused low hit rate and a high overhead due to peer mobility. Thus, this article proposes a scalable fuzzy controller based on probabilistic walk for unstructured mobile P2P networks to reduce the search time with controlled mobility. The search time is reduced by jumping a query walker to a 2-hop away ultrapeer, selected through a fuzzy scheme. Furthermore, each mobile ultrapeer shares its pong cache with its directly connected ultrapeer in order to increase the hit rate and reduce the network overhead. Simulations show that the fuzzy search controller gives better performance than the competing protocols in terms time 10% reduction in response time and 15% increase in hit rate in different mobility scenarios.

A mobility-based temperature-aware routing protocol for Wireless Body Sensor Networks

A large number of temperature-aware routing algorithms have been proposed to prevent the damage of surrounding tissues caused by temperature rise in wireless body sensor network. But, since the existing temperature-aware routing algorithms for WBSN have not taken account of human postural mobility, large of packet are lost due to topological partitioning. To solve this problem, in this paper, we propose a new temperature-aware routing algorithm by employing store and carry scheme. Simulation results are given to provide the suitability of the proposed routing algorithm by demonstrating its performance in terms of reducing the number of hot spots, packet delivery delay and packet loss.

A survey on network simulators in three-dimensional wireless ad hoc and sensor networks

As steady research in wireless ad hoc and sensor networks is going on, performance evaluation through relevant network simulator becomes indispensable procedure to demonstrate superiority to comparative schemes and suitability in most literatures. Thus, it is very important to establish credibility of simulation results by investigating merits and limitations of each simulator prior to selection. Based on this motivation, in this article, we present a comprehensive survey on current network simulators for new emerging research area, three-dimensional wireless ad hoc and sensor networks which is represented by airborne ad hoc networks and underwater sensor networks by reviewing major existing simulators as well as presenting their main features in several aspects. In addition, we address the outstanding mobility models which are main components in simulation study for self-organizing ad hoc networks. Finally, open research issues and research challenges are discussed and presented.