Multicast Requests Research Articles

A Packet Scheduling Scheme Using Multicast RTS in Wireless Mesh Networks

SUMMARYOne of the problems in wireless mesh networks is HOL (Head of Line) blocking at relay nodes. To overcome that problem, packet scheduling schemes using the MRTS (Multicast Request to Send [RTS]) frame, an extension of the RTS frame, have been proposed. The sender first multicasts an MRTS frame to multiple destination candidates. Then the sender transmits the data packet to the candidate which earliest returns a CTS frame. That mechanism could solve the HOL blocking problem. In principle, as the number of the candidates increases, the transmission success rate increases; however the overhead also increases. Under the existing scheduling schemes, the sender always arranges more than two candidates, which would increase the overhead. In this paper, to reduce the overhead, we propose a scheduling scheme which restricts the number of candidates to not more than two at any time. Simulations shown that, in comparison with the existing scheme, our scheme provides higher throughput and fairness.

A method of segment protection based on p-cycle for dynamic multicast with limited-range wavelength converter in WDM network

In the optical multicast network, node and link failures have very important influence on the network survivability which may lead to multiple destinations cannot receive data. Based on the wavelength layered-graph method, a method of efficiency-score based on heuristic algorithm of pre-configured cycle (p-Cycle) based-segment protection (ESHS) for dynamic multicast with limited-range wavelength conversion was presented in this paper. By finding the multicast tree segment protection, the total available p-Cycles are constructed for the multicast. Then we calculate each p-Cycle efficiency-score, the highest efficient-score p-Cycle is selected as the multicast route protection p-Cycle. The simulation results show that the ESHS can get higher performance than the existing ESHT algorithm, in terms of multicast request blocking probability and wavelength utilization.

Slotted Advance Reservation for Multicast-Incapable Optical Wavelength Division Multiplexing Networks

In this paper we investigate techniques for provisioning advance reservation (AR) multicast requests in multicast-incapable (MI) networks, which lack the ability to split an incoming signal to multiple output ports, without performing an O-E-O conversion. AR traffic consists of connection requests that arrive and reserve network resources at some time before they need them to ensure better qualityof service than on-demand requests would receive. The traditional approach of providing multicast support in MI networks is to use an overlay approach in which a set of lightpaths is established from the source to each multicast destination member independently. This approach is wasteful of wavelength resources, particularly as the multicast destination set grows. We propose two alternative overlay approaches that take advantage of multiple-hop overlay-tree structures to limit the consumption of wavelengths in the network. We investigate static traffic scenarios on various network topologies and develop integer linear programs (ILPs) to optimally solve all three of the overlay-tree problems presented in this work with the goal of minimizing the total number of wavelengths required to service a multicast request set. We also present efficient heuristics that build and select overlay-trees that lower dynamic connection blocking and wavelength consumption. We compare the heuristics to the optimal ILPs on a small-scale network, and then further evaluate the heuristics on several large-scale topologies. In all scenarios, we are able to conclude that by sacrificing a minimization of O-E-O conversions, our more flexible overlay approaches, called drop at member node (MI-DMN) and dropatany node (MI-DAN), are superiorinterms of resource usage when compared with the traditional na��ve approach. Further dynamic traffic evaluations reveal that blocking may be lowered over the na��ve approach by more thantwoordersofmagnitudeatlowtomedium traffic loads.

A Heuristic Approach for Multicast Traffic Grooming in Optical WDM Mesh Networks

Abstra —Traffic grooming is being considered as a key functionality of WDM networks, in which, multiple low speed traffic requests are groomed into a single high capacity wavelength channel. In this work, multicast traffic grooming problem is addressed to maximize the bandwidth utilization for a set of sessions in an optical WDM mesh topology. We propose a heuristic approach called Prioritized Multicast Traffic Grooming (PMTG) for constructing multicast tree and a first fit algorithm for wavelength assignment. After successful grooming of multicast requests, PMTG algorithm have successfully reduced the maximum number of wavelengths required in a link at the same time bandwidth utilization has greatly improved. We have simulated the heuristic approach PMTG with different network topologies and compared the performance with Multicast Traffic Grooming with Shortest Path (MTG-SP) algorithm. The simulation results show that the proposed heuristic algorithm produces better result than MTG-SP based algorithm.

Delay-constrained survivable multicast routing problem in WDM networks with shared segment-based protection

For a delay-constrained multicast transmission request, the goal of delay-constrained survivable multicast routing problem is to provide the primary multicast tree and the tree protecting sparse resources. The shared segment-based protection (SSBP) method is used in this article to protect the delay-constrained multicast transmission. Two heuristic methods are proposed to find the delay-constrained primary tree and the backup segments with delay constraint. Experiments are conducted to evaluate the performance of the proposed methods, and the performance to be evaluated includes wavelength efficiency ratio (WER), blocking ratio (BR), and executing time. Simulations show that the SSBP method can get better BR and WER than the previous results demonstrated Din and Jiang (Comput Commun 35(10):1172---1184, 2012).

Dynamic Multicast Traffic Grooming in Optical WDM Mesh Networks: Lightpath Versus Light-Tree

With the rising popularity of multicast applications, various algorithms using either lightpath or light-tree schemes have been proposed for dynamic multicast traffic grooming in meshed wavelength division multiplexing (WDM) networks. To the best of our knowledge, however, no systematic comparison has ever been made between the performance of the two schemes in minimizing network blocking probability. In this paper, we address the dynamic multicast traffic grooming problem in WDM networks and present comprehensive comparisons between these two schemes in different cases. Our main contributions are twofold: first, we compare the performance of the existing lightpath- and light-tree-based grooming algorithms and show that, in most cases, the lightpath-based methods outperform the light-tree-based ones. We discuss and explain such observations. Second, we propose a lightpath-based algorithm, called the LightPath Fragmentation (LPF) method, to further improve the network blocking performance. Numerous simulations show that the LPF method steadily outperforms the existing algorithms in different cases. Effects of the ratio of unicast traffic loads versus overall traffic loads and the average number of destinations of each multicast request are also studied.

Efficient Resource Allocation for All-Optical Multicasting Over Spectrum-Sliced Elastic Optical Networks

Recently, optical orthogonal frequency-division multiplexing technology has attracted intensive research interest because spectrum-sliced elastic optical networks (EONs) can be constructed based on it. In this paper, we investigate how to serve multicast requests over EONs with multicast-capable routing, modulation level, and spectrum assignment (RMSA). Both EON planning with static multicast traffic and EON provisioning with dynamic traffic are studied. For static EON planning, we formulate two integer linear programming (ILP) models, i.e., the joint ILP and the separate ILP. The joint ILP optimizes all multicast requests together, while the separate ILP optimizes one request each time in a sequential way. We also propose a highly efficient heuristic that is based on an adaptive genetic algorithm (GA) with minimum solution revisits. The simulation results indicate that the ILPs and the GA provide more efficient EON planning than the existing multicast-capable RMSA algorithms that use the shortest path tree (SPT) and the minimal spanning tree (MST). The results also show that the GA obtains more efficient EON planning results than the separate ILP with much less running time, as it can optimize all multicast requests together in a highly efficient manner. For the dynamic EON provisioning, we demonstrate that the GA is also applicable, and it achieves lower request blocking probabilities than the benchmark algorithms using SPT and MST.

Multicast Traffic Grooming based Light-tree in WDM Mesh Networks

Abstract Multicast applications such as video conferencing, weather forecasting and on-line multi player gaming are major areas of Internet traffic growth. The disparity between bandwidth offered by a wavelength and the bandwidth requirement of a multicast connection can be purposefully solved by grooming low bandwidth connection requests into a high bandwidth wavelength channel in an optical network. In this paper, we discuss multicast traffic grooming problem using light-tree approach with static multicast connection requests. As higher layer electronic ports such as transmitters and receivers are dominant cost factors in a WDM mesh networks, it is critical to reduce their number when grooming multicast traffic into high bandwidth trees. This paper propose a heuristic algorithm called Saturated-Light-Tree based Multicast Traffic Grooming (SLTMTG) that solves grooming, routing and wavelength assignment problems. SLTMTG algorithm is based on grooming of multicast traffic to constrained light-trees in which traffic is groomed for better resource utilizations. This approach is used to minimize the grooming cost as well as wavelength requirement. Here, proposed approach tries to satisfy all connection requests. The performance of proposed algorithm has compared with existing Multicast Traffic Grooming (MTG) algorithm. The results are compared on several standard networks to measure cost and wavelength utilization.

A delay-constrained and priority-aware channel assignment algorithm for efficient multicast in wireless mesh networks

Many popular applications of wireless mesh networks (WMNs) depend on delay-constraint multicast communication. To support such multicast communication, this paper proposes a distributed and polynomial-time heuristic channel assignment algorithm for WMNs. The proposed algorithm considers that the multicast session requests arrive dynamically and have different priorities. When a delay-constrained multicast session is issued, the multicast tree corresponding to the session is first established. The proposed algorithm divides the path delay constraint of the multicast tree into a number of the node-based delay constraints. This algorithm also devises multiple channel selection criteria to exploit all available channels of the WMN. Using these selection criteria, each node on the multicast tree can select the best channel to meet its node delay constraint and minimize the total interference for all existing multicast sessions. In the interference minimization, the priority factor is taken into account to prevent high-priority multicast sessions from incurring more interference than low-priority multicast sessions. Finally, this paper performs simulations to demonstrate the effectiveness of the proposed heuristic channel assignment algorithm through comparison with the optimal solution.

Optical Many Casting Using QoS Depend Layer Aware Mechanism

Many distributed applications require a group of destinations to be coordinated to a single source. Multicasting is a communication paradigm to implement these distributed applications. In multicasting, at least one of the member in the group cannot satisfy the service requirement of the application, the multicast request said to be blocked. On the contrary in manycasting, destinations can join or leave the group, depending upon whether it satisfies the service requirement or not. Manycasting is performed over optical burst-switched (OBS) networks based on multiple qualities of service (QoS) constraints. The multiple constraints can be in the form of physical layer impairments, transmission delay, and reliability of the link. Destinations qualify only if they satisfy the Qos constraints. We develop a simple yet efficient routing algorithm which is based on the classic shortest path algorithm. The proposed layer aware FEC (L-FEC) generates repair symbols so that protection of less important dependency layers can be used with protection of more important layers for combined error correction.

Multicast Overlay for High-Bandwidth Applications Over Optical WDM Networks

Multicast communication in wavelength division multiplexed (WDM) networks is traditionally supported by the assumption that the optical crossconnects are multicast capable, i.e., they are capable of switching an incoming signal to more than one output interface. A naive method of supporting this functionality in a multicast-incapable (MI) environment is by creating a virtual topology consisting of lightpaths from the multicast source to each destination of the multicast session. For large sets of multicast requests, however, the network bandwidth consumed by such a scheme may become unacceptable due to the unicasting nature of the lightpaths. We refer to this method as achieving multicast via WDM unicast (MVWU). To support users' multicast requests (from higher electronic layers) in MI networks, we propose two overlay solutions: drop at member node (DMN) and drop at any node (DAN). In these solutions, we achieve multicasting by creating a set of lightpath routes (possibly multiple hops) in the overlay layer from the source node of a request to each destination member. In the DMN case, we allow a lightpath route to originate/terminate only at source and destination members of a request, whereas in the DAN model we impose no such restrictions. We first consider a static traffic model, wherein the set of multicast requests is known ahead of time, and present integer linear programs (ILPs) to solve these problems (MVWU, DMN, and DAN) with the goal of minimizing the total number of wavelengths required to service the set. We also present an efficient heuristic and compare its performance to the ILP for a small network, and run simulations over real-world, large-scale networks. Moreover, we present lower bounds to calculate the minimum number of wavelengths required by the DMN and DAN models. Finally, we evaluate the performance of the heuristic (minimization of the number of wavelengths) under a dynamic traffic scenario and also evaluate the blocking performance for a fixed number of wavelengths.

Delay-constrained survivable multicast routing problem in WDM networks

In WDM network, link failure may cause service disruption and may lead to lose significant information. Especially, for a multicast transmission when link on a light-tree that carries traffic to multiple destinations failed, the traffic to all the downstream destinations along the failed link will be affected. For a given multicast request with a maximum delay denoted as Δ, the delay-constrained survivable multicast mechanism provides the primary multicast tree and some sparse resources to protect it. When link failure occurred, the multicast transmission is recovered by using sparse resources while ensuring that the backup tree can satisfy the delay constraint. This problem is called Delay-Constrained Survivable Multicast Routing Problem (DCSMRP). In this article, three protection methods are used to solve this problem; they are: Delay Constrained Link-disjoint Tree Protection (DCLTP), Delay Constrained Disjoint-Paths Protection (DCDPP) and Delay Constrained Span p-Cycle Protection (DCSP). Three multicast routing methods are proposed for the respective protecting methods to find the primary multicast tree and backup resources with delay constraint. Experiments are conducted to evaluate the resource utility ratio (RUR), blocking ratio (BR) and executing time (RT) of these methods. Simulations show that the DCSP method can get best BR for the cases with greater delay bound (for the cases with delay bound Δ>5.5ms.) The RUR of DCSP is worse than that of DCLTP and DCDPP (in the cases with delay bound Δ⩾7.5msec), and the computational time of the DCDPP is faster than that of the DCSP and DCLTP.

Multicast multi-granular grooming based on integrated auxiliary grooming graph in optical networks

In order to improve the bandwidth utilization efficiency and reduce the blocking probability for multicast requests in optical networks, the multicast traffic grooming approach was proposed to groom a lot of low-speed traffic to a few of high-speed light-trees. At the same time, in order to save the ports and the cost of optical cross-connect, the multicast waveband grooming approach was proposed to groom multiple light-trees to a few of waveband tunnels. However, the existing approaches all did not consider the joint performances of improving bandwidth utilization efficiency, reducing blocking probability and saving ports for multicast requests. Therefore, in this article, we propose a new multicast multi-granular grooming approach to perform the hierarchical sequential grooming to improve the joint performances based on a newly developed integrated auxiliary grooming graph (IAGG) that includes multiple wavelength integrated grooming graphs (WIGGs) and one waveband virtual topology layered graph (BVLG) to support both the multicast traffic grooming and multicast waveband grooming. In order to achieve the map of light-tree to the virtual topology layer in WIGG or BVLG, we present a light-segment map method, where a light-tree will be divided to several light-segments each of which will be independently mapped to the virtual topology layer. Since different definitions of blocking probability may lead to different objectives, we define two kinds of blocking probability, mean blocking probability of requests (MBPR) and mean blocking probability of users (MBPU). According to the two definitions of blocking probability, we propose two multicast multi-granular grooming heuristic algorithms, Heuristic Algorithm with minimizing MBPR and Heuristic Algorithm with minimizing MBPU based on IAGG. Simulation results show that the two proposed algorithms are both efficient and have better performances than traditional multicast grooming algorithm.

Location-Based TDMA MAC for Reliable Aeronautical Communications

The growth of data traffic as air traffic increases is leading to bottlenecks. We propose a new time division multiple access (TDMA) protocol termed location-based TDMA (LBTM) to accommodate increasing data traffic and air-to-air communications. LBTM provides all three modes of communication: unicast, multicast, and broadcast. ACK needs a long guard time for reliable multicast in the aeronautical environment, because it is a long distance communication system. LBTM uses location information to overcome this problem. We can reduce the guard time of ACK and prevent collisions. In our scheme, multicast aircraft calculate ACK arrival time to ensure that ACKs arrive at the sender at different times. Therefore, LBTM reduces the amount of guard time of ACK and the total average time to complete a reliable multicast MAC request. This results in a significant increase in network utilization and throughput.

Minimum energy multicast/broadcast routing with reception cost in wireless sensor networks

In this paper, we study the minimum energy multicast/broadcast problem with reception cost in wireless sensor networks. Suppose there are n sensors in the network. Each node v has l(v) transmission power levels to choose and its reception cost is B(v) if it receives a message. The problem of our concern is: given a multicast (broadcast) request, how to find a multicast (broadcast) tree such that the total energy cost of the multicast tree including transmitting cost and reception cost is minimized. There are two cases for reception cost: one is that for any node v, the reception cost of v only relies on v itself and is irrelevant with its transmitting node, the other is that the reception cost of v relies on not only itself but also its transmitting node. For the first case, we firstly propose a general approximation algorithm MEB-R-G for the broadcast problem. Moreover, for the multicast problem, we propose a general algorithm MEM-R-G and prove its approximation ratio, we also present a greedy algorithm. For the second case, we also propose a general approximation algorithm MEM-RT-G, and prove its approximation ratio.

QoS multicast routing in cognitive radio ad hoc networks

SUMMARYIn this paper, we discussed the issues of QoS multicast routing in cognitive radio ad hoc networks. The problem of our concern was: given a cognitive radio ad hoc network and a QoS multicast request, how to find a multicast tree so that the total bandwidth consumption of the multicast is minimized while the QoS requirements are met. We proposed two methods to solve it. One is a two‐phase method. In this method, we first employed a minimal spanning tree‐based algorithm to construct a multicast tree and then proposed a slot assignment algorithm to assign timeslots to the tree links such that the bandwidth consumption of the tree is minimized. The other is an integrated method that considers the multicast routing together with the slot assignment. Extensive simulations were conducted to show the performance of our proposed methods. Copyright © 2011 John Wiley & Sons, Ltd.

New Theory for Deadlock-Free Multicast Routing in Wormhole-Switched Virtual-Channelless Networks-on-Chip

A new theory for deadlock-free multicast routing especially used for on-chip interconnection network (NoC) is presented in this paper. The NoC router hardware solution that enables the deadlock-free multicast routing without utilizing virtual channels is introduced formally. The special characteristic of the NoC is that, wormhole packets can cut-through at flit-level and can be interleaved in the same channel with other flits of different packets by multiplexing it using a rotating flit-by-flit arbitration. The routing paths of each flit can be guaranteed correct because flits belonging to the same packet are labeled with the same local Id-tag on every communication channel. Hence, multicast deadlock problem can be solved at each router by further applying a hold-release tagging mechanism to control and manage conflicting multicast requests.

Quality-of-Transmission-Aware Manycasting Over Optical Burst-Switched Networks

Many next-generation distributed applications, such as grid computing, require a single source to communicate with a group of destinations. Traditionally, such applications are implemented using multicast communication. A typical multicast session requires creating the shortest-path tree to a fixed number of destinations. The fundamental issue in multicasting data to a fixed set of destinations is receiver blocking. If one of the destinations is not reachable, the entire multicast request (say, grid task request) may fail. Manycasting is a generalized variation of multicasting that provides the freedom to choose the best subset of destinations from a larger set of candidate destinations. We propose an impairment-aware algorithm to provide manycasting service in the optical layer, specifically OBS. We compare the performance of our proposed manycasting algorithm with traditional multicasting and multicast with over provisioning. Our results show a significant improvement in the blocking probability by implementing optical-layer manycasting.

Provisioning Subwavelength Multicast Sessions With Flexible Scheduling Over WDM Networks

The distribution of large data sets from a centralized node to several destination sites is frequently required by many data-intensive networking applications; this distribution can be efficiently achieved by the means of multicasting. Multicasting has been typically considered for on-demand applications and services, e.g., video-on-demand, IPTV, etc., which usually require start of data transmission immediately. We consider that multicast sessions can be provisioned starting with flexible times and that the multicast client can specify a maximum allowed time by which all data needs to be delivered to destinations. This is true for e-Science and high-performance applications, in which data distribution is not necessarily immediate. In this paper, we study the problem of provisioning dynamic multicast data-distribution requests (MDDRs) with flexible scheduling over optical WDM networks. We consider the practical case of fractional-capacity multicast sessions that require less than the entire wavelength capacity (nodes are equipped with multicast-capable opaque switches). We devise provisioning methods based on the multicast tree (or light-tree) distribution model. In our first approach (named Rand), we generate multiple randomized alternate trees on which we try to provision the multicast session and then assign wavelengths and schedule the session. In our second approach (named AllSlots), we dynamically generate light-trees depending on the network state. In our next approach (named Break), when provisioning an entire tree fails, we try to “break” the tree into time-independent subtrees. We also study the impact of allowing data to be buffered at intermediary nodes and then transmitted toward destinations (method named Buffer) and consider an approach that partitions the data sets. Finally, we study the impact of the switch architecture on our provisioning by restricting our approaches to full-wavelength MDDRs.

QoS-Based Manycasting Over Optical Burst-Switched (OBS) Networks

Many distributed applications require a group of destinations to be coordinated with a single source. Multicasting is a communication paradigm to implement these distributed applications. However in multicasting, if at least one of the members in the group cannot satisfy the service requirement of the application, the multicast request is said to be blocked. On the contrary in manycasting, destinations can join or leave the group, depending on whether it satisfies the service requirement or not. This dynamic membership based destination group decreases request blocking. We study the behavior of manycasting over optical burst-switched networks (OBS) based on multiple quality of service (QoS) constraints. These multiple constraints can be in the form of physical-layer impairments, transmission delay, and reliability of the link. Each application requires its own QoS threshold attributes. Destinations qualify only if they satisfy the required QoS constraints set up by the application. We have developed a mathematical model based on lattice algebra for this multiconstraint problem. Due to multiple constraints, burst blocking could be high. We propose two algorithms to minimize request blocking for the multiconstrained manycast (MCM) problem. Using extensive simulation results, we have calculated the average request blocking for the proposed algorithms. Our simulation results show that MCM-shortest path tree (MCM-SPT) algorithm performs better than MCM-dynamic membership (MCM-DM) for delay constrained services and real-time service, where as data services can be better provisioned using MCM-DM algorithm.