Mobile Multicast Research Articles

Predictive versus Reactive—Analysis of Handover Performance and Its Implications on IPv6 and Multicast Mobility

Handovers in mobile packet networks commonly produce packet loss, delay and jitter, thereby significantly degrading network performance. Mobile IPv6 handover performance is strongly topology dependent and results in inferior service quality in wide area scenarios. To approach seamless mobility in IPv6 networks predictive, reactive and proxy schemes have been proposed for improvement. In this article we analyse and compare handover performance and frequencies for the corresponding protocols, as they are an immediate measure on service quality. Using analytical methods as well as stochastic simulations, we calculate the performance decreases originating from different handover schemes, the expected number of handovers as functions of mobility and proxy ratios, as well as the mean correctness of predictions. In detail we treat the more delicate case of these rates in mobile multicast communication. It is obtained that performance benefits, expected from simple analysis of predictive schemes, do not hold in practice. Reactive and predictive handovers rather admit comparable performance. Hierarchical proxy environments--foremost in regions of high mobility--can significantly reduce the processing of inter---network changes. Reliability of handover predictions is found on average at about 50%.

An Analysis Comparison of Reliability Mechanisms for Improving Reliable Mobile Multicast Protocols

Existing reliable multicast protocols are designed to perform well in wired networking environments. However, in mobile networking environments, these reliable mobile multicast protocols are not optimal as they do not take into account the limitations of power (energy), storage capacity, processing power, impairments of wireless communication channels, and the frequent changes of location and the resulting loss of network connectivity. This paper analyses four hybrid reliable multicast schemes, namely NAK-based schemes, ACK-based schemes, ACK-based schemes with FEC (Forward Error Correction), and NAK-based schemes with FEC that are suitable for mobile networking environments and quantifies their performance. These four schemes differ from the generic sender-initiated and receiver-initiated reliable multicast protocols in that they rely on a mixture of multicasting and unicasting for providing reliability. This analysis is used to show that NAK-based schemes with FEC is best suited for reliable multicasting in mobile environments as they provide excellent performance in terms of average wireless channel utilization and average processing time, independently of the number of MHs.

IP mobile multicast: Challenges and solutions

This article outlines the challenges of IP multicast over Mobile IP. Then it provides a comprehensive overview of existing multicast solutions to handle mobile sources and receivers in both the Mobile IPv4 and the Mobile IPv6 environments. The solutions are classified into different classes in light of how the network infrastructure is used and the nature of the multicast members (receivers or sources). For each solution, we present a brief overview; we describe the architecture and the proposed protocol; we discuss the advantages and the limitations; and we compare qualitatively all the solutions of each class based on common criteria such as optimal routing, join latency, handover transparency, etc.

A timer-based mobile multicast routing protocol in mobile networks

Mobile computing and multimedia application are two emerging trends in computer systems. Multicasting reduces the amount of multimedia traffics by delivering a single stream of information to many recipients simultaneously. Regarding mobile hosts, however, the naı̈ve deployment of existing multicast routing protocols is not a suitable because they implicitly assume static hosts and do not consider the dynamic changes in the location of group members. In this paper, we present a new efficient mobile multicast routing protocol in terms of tree reconstruction overhead, data delivery length, etc. The proposed protocol introduces FMA (Foreign Multicast Agent) for mobile group membership; JOIN, GROUP timer for mobile multicast routing . The periodic join operation by the two timers makes it possible to utilize the characteristic that the mobile multicasting has according to the speed of mobile hosts. Various performance evaluation results illustrate that the proposed protocol shows performance enhancements over existing protocols.

Dynamic retransmission control for reliable mobile multicast

Most existing multicast protocols adopt a static retransmission scheme (unicast or multicast) to retransmit lost packets. In the mobile multicast environment, static multicast retransmission mode may lead to congestion in the receivers' wireless interfaces, while static unicast mode may result in great network load. Both static unicast and multicast retransmission modes will cause a performance loss. This paper logically divides the mobile multicast network into fixed and mobile parts, and focuses on the mobile part. Then this paper analyzes the retransmission costs when multicast or unicast mode is chosen. Two main parameters are used to compare their efficiencies: the average air-interface utilization of each receiver and the average network load. Based on the results of analysis, two new algorithms, called NLPA (Network Load Priority Algorithm) and AUPA (Air-interface Utilization Priority Algorithm) are presented. Finally, simulation results conclude that, with proper parameters, both NLPA and AUPA can dynamically alternate between unicast and multicast retransmission modes according to the conditions of network and receiver, and avoid congestion in receivers' wireless interfaces as well as great network load, with a better use of network and terminal resources.

Performance analysis of multicast algorithms for mobile satellite communication networks

With the rise of mobile computing and an increasing need for ubiquitous high-speed data connections, Internet-in-the-sky solutions are becoming increasingly viable. To reduce the network overhead of one-to-many transmissions, the multicast protocol has been devised. The implementation of multicast in these low earth orbit (LEO) constellations is a critical component to achieving an omnipresent network environment. This paper examines the system performance associated with two terrestrial-based multicast mobility solutions, distance vector multicast routing protocol (DVMRP) with mobile IP and on demand multicast routing protocol (ODMRP). These protocols are implemented and simulated in a satellite LEO constellation. Results from the simulation trials show the ODMRP protocol provided greater than 99% reliability in packet deliverability, at the cost of more than 8 bits of overhead for every 1 bit of data for multicast groups with multiple sources. In contrast, DVMRP proved robust and scalable, with data-to-overhead ratios increasing logarithmically with membership levels. DVMRP also had less than 70 ms of average end-to-end delay, providing stable transmissions at high loading and membership levels.

Scalable multicast protocol in IP-based mobile networks

In this paper, we present an alternative design, RBMoM (Range-Based Mobile Multicast), for efficiently supporting multicast for mobile hosts on the Internet. The current version of Mobile IP proposes two approaches to support mobile multicast, which are remote subscription and bi-directional tunneling. The former provides the shortest routes for delivery of multicast datagrams to mobile hosts; the latter hides host mobility from all other members of the group (therefore, no any overhead in the multicast tree maintenance). RBMoM intends to trade off between the shortest delivery path and the frequency of the multicast tree reconfiguration by controlling the service range of the multicast home agent (MHA). Actually, we will find that remote subscription and bi-directional tunneling are the extremes of RBMoM. From the point of view of the MHA and the service range concepts, RBMoM is a generalization of both approaches and a unifying mobile multicast approach. The simulation results show that RBMoM can adapt to the fluctuation of both host movement and the number of mobile group members, and outperforms the current two Mobile IP multicast solutions.

Mobile multicast with routing optimization for recipient mobility

This paper explores the issues of multicasting for mobile hosts using IETF Mobile IP. Mobile IP suggests two approaches for mobile multicasting, namely, remote subscription (MIP-RS) and bi-directional tunneling (MIP-BT). While having the advantage of optimal routing efficiency, MIP-RS uses a naive join-and-leave policy for mobile hosts to participate in the groups of interest and causes serious packet losses while roaming. MIP-BT is free from packet losses due to roaming; however, MIP-BT and its modification MoM suffer from the triangle routing problem, resulting in inefficient routing and wastage of system resources. We propose a new mobile multicasting protocol called mobile multicast with routing optimization (MMROP) that employs a modified join-and-leave mechanism, and routes the missing data sequence due to the "out-of-synch" problem to other agents in the adjacent networks via tunneling for roaming terminals. With MMROP, the mobility agent (foreign or home agent) in Mobile IF, in addition to mobility management, is extended to assist multicasting for mobiles. The mobility agent is not necessarily a multicast router. From the perspective of the multicast router, the mobility agent is a group participant, and from the mobiles, the agent serves as the proxy of multicast services. As a result, MMROP enjoys no packet losses from roaming as in MIP-BT, and optimal routing efficiency as in MIP-RS. We also conducted a simulation study and developed a cost analytical model to evaluate the performance of MMROP, in comparison to MIP-RS, MIP-BT, and MoM. The results demonstrate that MMROP has optimal routing efficiency, low delivery cost and high robustness, as compared to other approaches.

Performance Analysis of a Multicast Protocol for Wireless Environments

This paper presents a performance study, using both analytical modeling and simulation techniques, of a new end-to-end reliable multicast protocol for use in environments with wireless access. The proposed pro tocol, called the reliable mobile multicast protocol (RM2), divides a multicast tree into sub-trees where subcasting is applied within the relatively smaller regions using a hierarchical tree of retransmission servers (RSs). RM2 is receiver-oriented in that the transmitter does not need to know its receivers, hence offering better scalability. The Internet Group Management Protocol is used to manage group membership whereas the IETF's Mobile IP offers support to user mobility through a temporary IP address. Each RS has a retransmission subcast ad dress shared by its members which may be dynamically configured using allocation schemes such as the IETF's MADCAP. More important, RM2 uses a dynamic re transmission strategy to switch between multicast and unicast retransmission modes according to the amount of extra load generated in the network and in the wire less interfaces by packet retransmissions. It is shown through analytical modeling and simulation that RM2's dynamic adaptation is not only important but also necessary when considering mobile wireless access.

Mobile multicasting in wireless ATM networks

Multicasting is a desired function in both wired and wireless networks. Currently, multicasting‐based applications have pervasive presence and influence in our Internet. Wireless ATM aims to support different traffic types over a high speed wireless network. In particular, traditional approaches towards multicasting in wired networks cannot be directly applied to mobile ATM networks. This includes the mechanism proposed to handle mobility in wired networks. In this paper, we address the issues behind multicasting in wireless ATM networks and the underlying mechanisms to support handoffs of both unicast and multicast connections. Through simulation, we evaluated the performance of optimal core‐based tree (CBT), late‐joined CBT, optimal source‐based tree (SBT), and late‐joined SBT during changing multicast host membership conditions. In addition, we evaluated the impact of multicast receivers' migration on the total link cost of the resultant multicast tree. Simulation results revealed that source‐based trees incur more total link costs under both dynamic host membership and receivers' migration scenarios. However, it generates less control messages than the distributed CBT and SBT approaches.