Uyen Trang Nguyen

On multicast routing in wireless mesh networks

There are two fundamental approaches to multicast routing: shortest path trees (SPTs) and minimum cost trees (MCTs). The SPT algorithms minimize the distance (or cost) from the sender to each receiver, while the MCT algorithms such as minimum Steiner trees (MSTs) minimize the overall edge cost of the multicast tree. In wireless multi-hop networks, the tree cost can be redefined to exploit the wireless broadcast advantage: a minimum cost tree is one which connects sources and receivers by issuing a minimum number of transmissions (MNT). Among the different approaches, SPT is the more commonly used method for multicast routing in the Internet. The MNT approach was originally considered for energy-constrained wireless networks such as sensor and mobile ad-hoc networks. It is not clear how the different types of trees compare when used in WMNs. In this paper, we present a simulation-based performance comparison of SPTs, MSTs and MNT trees in WMNs using most concerned performance metrics such as packet delivery ratio, throughput, end-to-end delay, delay jitter and multicast traffic overheads. Based on the experimental results, we provide insights into the performance of multicast routing algorithms in WMNs and recommendations for suitable routing approaches.

Multicast Routing in Wireless Mesh Networks: Minimum Cost Trees or Shortest Path Trees?

There exist two fundamental approaches to multicast routing: shortest path trees (SPTs) and minimum cost trees (MCTs). The SPT algorithms minimize the distance (or cost) from the sender to each receiver, whereas the MCT algorithms minimize the overall cost of the multicast tree. Due to the very large scale and unknown topology of the Internet, computing MCTs for multicast routing in the Internet is a very complex problem. As a result, the SPT approach is the more commonly used method for multicast routing in the Internet, because it is easy to implement and gives minimum delay from the sender to each receiver, a property favored by many real-life applications. Unlike the Internet, a wireless mesh network (WMN) has a much smaller size, and its topology can be made known to all nodes in the network. This makes the MCT approach an equally viable candidate for multicast routing in WMNs. However, it is not clear how the two types of trees compare when used in WMNs. In this article we present a simulation-based performance comparison of SPTs and MCTs in WMNs, using performance metrics, such as packet delivery ratio, end-to-end delay, and traffic impacts on unicast flows in the same network.

Study of Different Types of Attacks on Multicast in Mobile Ad Hoc Networks

Security is an essential requirement in mobile ad hoc networks (MANETs). Compared to wired networks, MANETs are more vulnerable to security attacks due to the lack of a trusted centralized authority, easy eavesdropping, dynamic network topology, and limited resources. The security issue of MANETs in group communications is even more challenging because of the involvement of multiple senders and multiple receivers. In this paper, we present a simulationbased study of the impacts of different types of attacks on mesh-based multicast in MANETs. We consider the most common types of attacks, namely rushing attack, blackhole attack, neighbor attack and jellyfish attack. Specifically we study how the processing delay of legitimate nodes, the number of attackers and their positions affect the performance metrics of a multicast session such as packet delivery ratio, throughput, end-to-end delay, and delay jitter. To the best of our knowledge, this is the first paper that studies the vulnerability and the performance of multicast in MANETs under various security threats.

Rate-adaptive multicast in mobile ad-hoc networks

A current trend in wireless communications is to enable wireless devices to transmit at different rates. That multirate capability has been defined in many standards such as 802.11a, 802.11b, 802.11g, and HiperLAN2. We propose a rate-adaptive multicast (RAM) protocol that is multirate-aware. During the process of path discovery, the quality of wireless links is estimated to suggest optimal transmission rates, which are then used to calculate the total transmission time incurred by the mobile nodes on a path. Among several considered paths from a source to a destination, RAM selects the path with the lowest total transmission time. Our work is the first that proposes the use of the multirate capability in multicast. The proposed RAM protocol works with any multirate standards, and does not require any modifications to the standards. Our simulation results show that RAM outperforms single-rate multicast in terms of packet delivery ratio, packet end-to-end delay, and throughput of the multicast group.

Bandwidth efficient multicast routing in multi-channel multi-radio wireless mesh networks

Multi-channel multi-radio (MCMR) wireless mesh networking is an emerging technology that enables high-throughput networking capability using multiple channels and multiple radios per mesh router. Traditional multicast routing algorithms such as shortest path trees and minimum Steiner trees do not consider the wireless broadcast advantage or the underlying channel assignments (i.e., channel diversity) in a MCMR wireless mesh network (WMN). In this paper, we propose a multicast routing algorithm for MCMR WMNs that takes into account the wireless broadcast advantage and channel diversity in order to minimize the amount of network bandwidth consumed by the routing tree. The algorithm does so by minimizing the number of transmissions required to deliver one packet from the source to all the destinations of a multicast group. Experimental results show that the proposed algorithm constructs routing trees having the least number of transmissions when compared with traditional trees such as shortest path trees, minimum Steiner trees, and minimum number of forwarders trees.

Minimum Interference Channel Assignment for Multicast in Multi-Radio Wireless Mesh Networks

Multi-radio, multi-channel wireless mesh networking is an emerging wireless technology which enables the use of multiple radios in each wireless mesh router. Each radio is assigned to a particular channel based on a channel assignment algorithm in order to solve some objective function, e.g., maximizing network throughput or minimizing wireless interference. Multicast is a form of communication that delivers information from a source to a set of destinations simultaneously. In this paper, we propose a channel assignment (CA) algorithm for multicast using both orthogonal and partially overlapping channels. The algorithm enables the nodes in a multicast tree to operate with minimum interference. We evaluate the performance of the proposed CA using various multicast group sizes and numbers of available channels, and compare it with that of the multi-channel multicast (MCM) algorithm proposed by Zeng et al. (2007).

Socellbot: A new botnet design to infect smartphones via online social networking

Given the popularity of both smartphones and online social networking, it is only a matter of time before attackers exploit both to launch new types of attacks. In this paper, we propose a new cellular botnet named SoCellBot that exploits online social networks (OSNs) to recruit bots and uses OSN messaging systems as communication channels between bots. Our proposed botnet is the first that uses the OSN platform as a means to control cellular bots. The structure and characteristics of OSNs make this botnet harder to detect, more resilient to bot failures and more cost-effective to cellular bots. Our objective is to raise awareness of new mobile botnets that exploit OSNs to recruit bots so that preventive measures can be implemented to deter this kind of attack in the future. We also analyze the behaviors of the proposed botnet via simulation to offer a better understanding of this new type of botnet.

Preemptive Multicast Routing in Mobile Ad-hoc Networks

Preemptive route maintenance allows a routing algorithm to maintain connectivity by preemptively switching to a path of higher quality when the quality of the currently used path is deemed questionable. Preemptive routing initiates recovery actions early by detecting that a link is likely to be broken soon and searching for a new path before the current path actually breaks. Preemptive route maintenance has been used for unicast (point-to-point) communications in wired networks and in mobile ad-hoc networks (MANETs) to minimize the number of route breaks and thus packet losses, and end-to-end delays. In addition to these advantages, we show that preemptive route maintenance can help minimize control overhead and improve the scalability of multicast routing protocols in MANETs. In this paper, we present design and implementation issues of preemptive routing for multicast in MANETs. We then describe a preemptive multicast routing protocol based on ODMRP (On-Demand Multicast Routing Protocol), which we call PMR (Preemptive Multicast Routing). PMR significantly improves the scalability of ODMRP: it offers similar or higher packet delivery ratios while incurring much less control overhead. Our simulation results have confirmed these advantages of PMR.

Mobility-Aware Modeling and Analysis of Dense Cellular Networks With

The unrelenting increase in the population of mobile users and their traffic demands drive cellular network operators to densify their network infrastructure. Network densification shrinks the footprint of base stations (BSs) and reduces the number of users associated with each BS, leading to an improved spatial frequency reuse and spectral efficiency, and thus, higher network capacity. However, the densification gain comes at the expense of higher handover rates and network control overhead. Hence, users mobility can diminish or even nullifies the foreseen densification gain. In this context, splitting the control plane (C-plane) and user plane (U-plane) is proposed as a potential solution to harvest densification gain with reduced cost in terms of handover rate and network control overhead. In this paper, we use stochastic geometry to develop a tractable mobility-aware model for a two-tier downlink cellular network with ultradense small cells and C-plane/U-plane split architecture. The developed model is then used to quantify the effect of mobility on the foreseen densification gain with and without C-plane/ U-plane split. To this end, we shed light on the handover problem in dense cellular environments, show scenarios where the network fails to support certain mobility profiles, and obtain network design insights.

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Traditional multicast routing algorithms such as shortest path tree (SPT) and minimum Steiner tree (MST) do not consider the wireless broadcast advantage or the underlying channel assignments in a multi-channel multi-radio (MCMR) wireless mesh network (WMN). We propose a multicast routing algorithm for MCMR WMNs that takes into account the above factors in order to minimize the amount of network bandwidth consumed by a routing tree. Experimental results show that routing trees constructed by the proposed algorithm outperform traditional trees such as SPTs, MSTs and minimum number of forwarders trees (MFTs) with respect to packet delivery ratio, throughput and end-to-end delay.