Multicast transmission, which can send the same information simultaneously to multiple users, is a key technology in content delivery networks. In this paper, we discuss a new multicast architecture with network coding proposed by Li et al. , which breaks limitation of existing IP multicast in terms of network resource utilization. Network coding based multicast can achieve the max-flow, which is the theoretical upper bound of network resource utilization. However, the max-flow transmission is not always effective and may not be robust against congestion because it maximally uses link capacity of multicast distribution tree. In this paper, we first introduce a load balancing method of network coding as an alternative use to the max-flow transmission. Next, we study the feasibility of network coding based multicast architecture from performance aspect and evaluate the network coding in terms of the max-flow and load balancing with a computer simulation. There has been no evaluation of network coding in practical network environment with packet losses and propagation delay. We also describe required key techniques and technical problems to implement network coding on the current IP networks. Our results will offer valuable insight for designing the future Internet with higher and more effective network utilization.

In this paper, we consider the broadcast storm problem in dense wireless ad hoc networks where interference among densely populated wireless nodes causes significant packet loss. To resolve the problem, we apply randomized network coding (RNC) to the networks. RNC is a completely different approach from existing techniques to resolve the problem, and it reduces the number of outstanding packets in the networks by encoding several packets into a single packet. RNC is a kind of linear network coding, and it is suited to wireless ad hoc networks because it can be implemented in a completely distributed manner. We describe a procedure for implementing the wireless ad hoc broadcasting with RNC. Further, with several simulation scenarios, we provide some insights on the relationship between the system parameters and performance and find that there is the optimal length of coding vectors for RNC in terms of packet loss probability. We also show a guideline for the parameter setting to resolve the broadcast storm problem successfully.

Application-level multicast has drawn a lot of attention as an alternative to IP multicast. In application-level multicast, multicast related features, such as group membership management, packet replication and packet forwarding are implemented at end-hosts instead of routers. The host perceived transmission quality and multicast forwarding responsibility depend on its position in the multicast distribution tree. This nature of application-level multicast motivates selfish members to alter their position by unrightful means to maximize their private benefits. Uncooperative behaviors of these selfish members, i.e. cheating, increase unfairness between selfish members and faithful members. In the context of bulk data distribution, this unfairness between members significantly impacts the receiver throughput. In this paper, to alleviate the negative impact of cheating members, we propose a new tree building protocol which builds dual multicast trees. Our proposed protocol constructs a shortest-widest path tree as the 1st tree. The members having lower position in the 1st tree are located at higher position in the 2nd tree in exchange for their unfairness. To investigate performance of our proposed protocol, it is compared with the existing application-level multicast protocol. Our simulation results show that our protocol outperforms the existing protocol from the view point of throughput and resource utilization against member cheating.

Large parts of the Internet are still incapable of native multicast, and ubiquitous deployment of multicast will take a long time. There are two approaches to provide wide-area multicast service in today's Internet. One is tunneling approach and the other is application-level multicast approach. In this paper, we focus on application-level multicast approach and propose a new scheme which improves the performance penalties of application-level multicast by making use of network support. Because in application-level multicast, endhosts provide multicast functionality instead of routers, application-level multicast delivery tree is inherently less efficient than IP multicast tree. Therefore, in our scheme, the router on the application-level multicast delivery tree alters the tree based on network-level delivery path. We evaluate our scheme with simulation experiment. Our simulation results indicate that our scheme improves the performance of application-level multicast. Further we compare our scheme to the tunneling approach from the viewpoint of transmission performances. The results reveal applicable domains of both approaches.

This survey summarizes the state-of-the-art research on network coding, mainly focusing on its applications to computer networking. Network coding generalizes traditional store-and-forward routing techniques by allowing intermediate nodes in networks to encode several received packets into a single coded packet before forwarding. Network coding was proposed in 2000, and since then, it has been studied extensively in the field of computer networking. In this survey, we first summarize linear network coding and provide a taxonomy of network coding research, i.e., the network coding design problem and network coding applications. Moreover, the latter is subdivided into throughput/capacity enhancement, robustness enhancement, network tomography, and security. We then discuss the fundamental characteristics of network coding and diverse applications of network coding in details, following the above taxonomy.

Application-level multicast (ALM) is a feasible alternative to IP multicast. In ALM, multicast related features, such as group membership management, multicast routing and packet replication, are implemented at end-hosts instead of routers. A multicast distribution tree is constructed in the application layer, so all nodes in this tree are end-hosts. Packet transmission between end-hosts uses conventional IP unicast service. Therefore, all end-hosts can enjoy multicast communications without IP multicast service. However, ALM has a serious problem that the multicast distribution tree is intrinsically fragile and an end-host failure causes tree partitions. In this paper, to deal with this problem, we propose a new tree construction protocol which makes outdegrees of intermediate nodes be balanced. The degree-balanced distribution tree can reduce the average number of nodes decoupled by tree partitions. To investigate performance of our protocol, it is compared with an existing ALM protocol. Our simulation results show that our protocol outperforms the existing protocol from the viewpoints of robustness, loss probability and receiver-perceived delay.

In this paper we propose the Zone-based Energy Aware data coLlection (ZEAL) protocol. ZEAL is designed to be used in agricultural applications for wireless sensor networks. In these type of applications, all data is often routed to a single point (named “sink” in sensor networks). The overuse of the same routes quickly depletes the energy of the nodes closer to the sink. In order to minimize this problem, ZEAL automatically creates zones (groups of nodes) independent from each other based on the trajectory of one or more mobile sinks. In this approach the sinks collects data queued in sub-sinks in each zone. Unlike existing protocols, ZEAL accomplish its routing tasks without using GPS modules for location awareness or synchronization mechanisms. Additionally, ZEAL provides an energy saving mechanism on the network layer that puts zones to sleep when there are no mobile sinks nearby. To evaluate ZEAL, it is compared with the Maximum Amount Shortest Path (MASP) protocol. Our simulations using the ns-3 network simulator show that ZEAL is able to collect a larger number of packets with significantly less energy in the same amount of time.

One of the most important technical problems in reliable multicast protocol is reducing redundant feedback information, e.g. NAKs, to avoid feedback implosion. A number of feedback suppression mechanisms have been proposed to deal with this problem. In the MBONE, which is a virtual multicast network and makes multi-point communication across the Internet feasible, the source link, the links directly connected to or very close to the source, is reported to contribute high percentile packet loss. When a well-known NAK suppression mechanism is applied, in the case of the source link loss, all receivers suffer the same packet loss and NAK suppression mechanism does not work effectively. In this paper we propose a Reliable Multicast Protocol Applying Local FEC, called Local FEC, where the source link loss is recovered with FEC applied locally only to the source link. To investigate performance of our proposed protocol, it is compared with a popular reliable multicast protocol with NAK suppression mechanism. Our performance analysis results with mathematical analysis and computer simulation show that our proposed protocol outperforms the NAK suppression protocol from the viewpoint of scalability and wasted bandwidth.