• Journal of Institute of Control, Robotics and Systems
• /
• v.6 no.8
• /
• pp.629-637
• /
• 2000

Unbalance between user requirements and insufficient network resources makes a congestion. In the future since the communication networks will have very heavy traffic congestion will be more serious. The ATM networks was recommended to support the B-ISDN service for the future multimedia communication. In thie sense of congestion avoidance and recovery the ABR service category in ATM networks allows the feedback flow control mechanism to dynamically allocate the idle bandwidth of the network to users fairly and to control the network congestion rapidly In this paper we introduce a congestion control scheme using systematical approach to confirm robust stability with respect to unknown round trip delay for the network which has both unicast and multicast connections.

• ETRI Journal
• /
• v.29 no.6
• /
• pp.745-754
• /
• 2007

In this paper, we present the Enhanced Communication Transport Protocol-Part 5 (ECTP-5), which provides scalable and reliable multicast communication service for many-to-many applications by constructing high quality recovery trees from two-layer logical trees and repairing the losses via unicast automatic repeat request-based error control. In order to realize the protocol, we developed feasible protocol architectures and building blocks including additional functions which deal with engineering details, such as membership dynamics and sender coordination. Experimental results show that ECTP-5 scales well with various session sizes and packet loss rates in terms of control overhead and recovery latency.

• Journal of the Korea Society of Computer and Information
• /
• v.21 no.10
• /
• pp.77-83
• /
• 2016

To verify the trustworthiness of messages, public key certificates and certificate revocation list(CRL) has been standardized for vehicular networks. However, timely distribution of large CRLs to vehicles should be more elaborated with low bandwidth utilization from a practical point of view. To address this concern, we propose a CRL distribution scheme using long term evolution(LTE) point-to-multicast transmission, namely the enhanced multimedia broadcast multicast service(eMBMS). The schem is much more resource efficient than the existing unicast CRL distribution schemes for vehicular networks and it allows realizing the regional CRL distribution schemes efficiently in LTE network. By means of ns-3 simulation, we analyze the performance, latency, and execution time of the scheme in terms of varying coverage of the multimedia broadcast multicast service over single frequency network (MBFSN).

• Journal of Communications and Networks
• /
• v.4 no.3
• /
• pp.246-255
• /
• 2002

Constrained minimum Steiner tree (CMST) problem is a key issue in multicast routing with quality of service (QoS) support. Bounded shortest path algorithm (BSMA) has been recognized as one of the best algorithms for the CMST problem due to its excellent cost performance. This algorithm starts with a minimumdelay tree, and then iteratively uses a
-shortest-path (KSP) algorithm to search for a better path to replace a “superedge” in the existing tree, and consequently reduces the cost of the tree. The major drawback of BSMA is its high time complexity because of the use of the KSP algorithm. For this reason, we investigate in this paper the possibility of more efficient implementations of BSMA by using different methods to locate the target path for replacing a superedge. Our experimental results indicate that our methods can significantly reduce the time complexity of BSMA without deteriorating the cost performance.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.7
• /
• pp.1533-1546
• /
• 2013

Wireless multicast is considered as an effective transmission mode for the future mobile social contact services supported by Long Time Evolution (LTE). Though wireless multicast has an excellent resource efficiency, its performance suffers deterioration from the channel condition and wireless resource availability. Cognitive Radio (CR) and Device to Device (D2D) are two solutions to provide potential resource. However, resource allocation for cognitive wireless multicast based on D2D is still a great challenge for LTE social networks. In this paper, a joint sub-carriers and power allocation model based on D2D for general cognitive radio multicast (CR-D2D-MC) is proposed for Orthogonal Frequency-Division Multiplexing (OFDM) LTE systems. By opportunistically accessing the licensed spectrum, the maximized capacity for multiple cognitive multicast groups is achieved with the condition of the general scenario of imperfect spectrum sensing, the constrains of interference to primary users (PUs) and an upper-bound power of secondary users (SUs) acting as multicast source nodes. Furthermore, the fairness for multicast groups or unicast terminals is guaranteed by setting a lower-bound number of the subcarriers allocated to cognitive multicast groups. Lagrange duality algorithm is adopted to obtain the optimal solution to the proposed CR-D2D-MC model. The simulation results show that the proposed algorithm improves the performance of cognitive multicast groups and achieves a good balance between capacity and fairness.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.5
• /
• pp.1241-1248
• /
• 1998

The multicast scheme can improve the efficiency of multimedia retrieval service system, assuming that video transmission speed is faster than the playback rate and the store-and-play scheme. To best exploit the multicast benefits under bandwidth heterogeneous environment, we develop a multicast scheduling algorithm called MTS(Maximum Throughput Scheduling) which tries to maximize the amount of information transferred at each scheduling with subgrouping method. The MTS method compromises the multiple unicast method and the multicast method with lowest transmission rate. we compare the performance of MTS with that of MMS(Most Multicasting Scheduling) and EDS(Earliest Deadine Scheduling) via computer simulation. The performance results show that the MTS requires less number of service handlers to service the same number of subscribers.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.7C
• /
• pp.733-742
• /
• 2003

Unlikely unicast transmission, there are many elements that threaten security. Thus, key management of creating and distributing group keys to authorized group members is a critical aspect of secure multicast operations. To offer security in multicast environment, the recent researches are related to most group key distribution. In this thesis, we propose a group key management protocol for efficient, scalable, and multicast operation. This proposed protocol architecture can distribute traffic centralized to the key server. since the group key rekeyed by sub-group manager. The detailed simulation compared with other group key management protocol show that the proposed group key management protocol is better for join, leave, and data latency.

• ETRI Journal
• /
• v.37 no.6
• /
• pp.1108-1119
• /
• 2015

Multicast communication of mobile ad hoc networks is vulnerable to internal attacks due to its routing structure and high scalability of its participants. Though existing intrusion detection systems (IDSs) act smartly to defend against attack strategies, adversaries also accordingly update their attacking plans intelligently so as to intervene in successful defending schemes. In our work, we present a novel indirect internal stealthy attack on a tree-based multicast routing protocol. Such an indirect stealthy attack intelligently makes neighbor nodes drop their routing-layer unicast control packets instead of processing or forwarding them. The adversary targets the collision avoidance mechanism of the Medium Access Control (MAC) protocol to indirectly affect the routing layer process. Simulation results show the success of this attacking strategy over the existing "stealthy attack in wireless ad hoc networks: detection and countermeasure (SADEC)" detection system. We design a cross-layer automata-based stealthy attack on multicast routing protocols (SAMRP) attacker detection system to identify and isolate the proposed attacker. NS-2 simulation and analytical results show the efficient performance, against an indirect internal stealthy attack, of SAMRP over the existing SADEC and BLM attacker detection systems.

• The KIPS Transactions:PartC
• /
• v.13C no.6 s.109
• /
• pp.767-774
• /
• 2006

In order to support overlay multicast with scalability and reliability, in this paper, we introduced a new multicast tree construction method and a regional multicast. The architecture we introduce efficiently transmits streaming data to the users from multicast source in an environment in which non-multicast network and multicast network. The new multicast tree construction method enables the connection with a remote relay which is an optimum condition in case there is no relay in subnet. Besides, by defining a new service type to traffic class of IPv6 header, a selective adoption or FEC and a distinctive transmission became possible. In order to verify the effect of the solution we suggested, we embodied an environment which is similar to the actual service environment by a simulator and tested it. The result of the test shows that the proposed method is more efficient than the traditional unicast approach method and the existing overlay multicast.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.12C
• /
• pp.208-217
• /
• 2001

In mobile Internet environment, providing multicast requires much more complex mechanism comparing with the unicast Mobile IP routing protocol. This is because multicast datagrams are sent to a group address that do not belong to a specific network. The IETF Mobile IP suggested two approaches for mobile multicasting, namely remote subscription and hi-directional tunneling. In remote subscription, a mobile node may join a group via a local multicast router on the visited subnet. Therefore remote subscription may cause much datagram loss while reconstructing the delivery tee. In bi-directional tunneling, a mobile node may join a group via a hi-directional tunnel to its home agent. Bi-directional tunneling may suffer from inefficient routing. In this paper, we proposed a new mobile multicasting protocol, Mobile If Multicast using Local Broadcast(MIMLB) which can receive multicast datagrams as fast as possible and optimize routing path for multicast delivery. The MIMLB protocol uses hi-directional tunneling to receive multicast datagrams. And the MIMLB protocol can resolve datagram duplicated problem and optimize routing path by using local broadcast. Simulation results show that MIMLB reduces delivery path length and optimizes multicast routing path when a mobile nod? moves into a foreign network.