Multicast Method Research Articles

Coded multicasting for content delivery over predictable time-varying satellite communication networks

With the development of astronautic technology, communication satellites now have a tremendous gain in both quantity and quality, and have already shown their capability on multi-functional converged communication other than telecommunication. Under this circumstance, increasing the transmission efficiency of satellite communication network becomes a top priority. In this paper, we focus on content delivery service on satellite networks, where each ground station may have prefetched some file fragments. We cast this problem into a coded caching framework so as to exploit the coded multicast gain for minimizing the satellite communication load. We first propose an optimization-based coded multicast scheme by considering the special property that the satellite network topology is predictable and time-variant. Then, a greedy based fast algorithm is proposed, which can tremendously reduce the computation complexity with a small loss in optimality. Simulation experiments conducted on two Walker constellation satellite networks show that our proposed coded multicast method can efficiently reduce the communication load of satellite networks.

A Reverse Shortest Path Tree-Based Multicast Joining Node Selection Method

Network layer multicast is a powerful method for transmitting data from sources to multiple group members. When joining a multicast group, a group member first sends a request to a designated router (DR). Then, the DR selects a node in the existing multicast tree (known as a multicast joining node, or MJN) to establish a multicast distribution path from the MJN to itself. The MJN selection method runs on the DR and has a significant impact on the distribution of the multicast tree, that directly affects the load distribution in the network. However, the current MJN selection method cannot effectively detect the load status of the downlink multicast path in the case of asymmetric routing, leading to network congestion and limiting the number of multicast groups that the network can accommodate (multicast capacity). To solve this problem, we propose an MJN selection method based on the reverse shortest path tree (RSPT). RSPT can effectively detect the load status of downlink multicast paths in case of routing asymmetry. Based on the detection results of RSPT, DR can select the MJN with the lowest path load to join the multicast tree. Our experimental results indicate that compared to existing multicast methods, our method has a lower cost and delay, and can effectively balance the network load in the case of asymmetric routing, increasing multicast capacity by more than two times.

ESSA: Design of a Programmable Efficient Sparse Spiking Neural Network Accelerator

Spiking neural networks (SNNs) have been witnessing the developing trends to reduce the model size and improve the hardware efficiency for area- and energy-based applications, which are processed by model pruning and data compressions. However, it is challenging to exploit the unstructured sparsity of SNNs for the dense neuromorphic processors. In this article, we present an efficient sparse SNN accelerator (ESSA), which leverages both the temporal sparsity of spike events and the spatial sparsity of weights in SNN inference. It provides both the compressed weights for sparse SNNs and the uncompressed weights for compact SNNs. The self-adaptive spike compression is proposed for sparse spike scenarios, leading to the improvement of throughput by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.2\times $ </tex-math></inline-formula> . ESSA executes a flexible fan-in–fan-out tradeoff by using combinable dendrites, which overcomes the fan-in limitation in neuromorphic systems. Furthermore, a low-latency intrachip spike multicast method is adopted to reduce the resource overhead. Implemented on the Xilinx Kintex Ultrascale field-programmable gate array (FPGA), ESSA achieves an equivalent performance of 253.1 GSOP/s and an energy efficiency of 32.1 GSOP/W for 75% weight sparsity at 140 MHz. The implementation of a four-layer fully connected SNN is expected to perform <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.6~\mu \text{s}$ </tex-math></inline-formula> per time step and the energy consumption is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$14.6~\mu \text{J}$ </tex-math></inline-formula> . Our results demonstrate that ESSA outperforms several state-of-the-art application-specific integrated circuit (ASIC) or FPGA neuromorphic processors.

An Adaptive Hierarchical Hybrid Multicast Based on Information-Centric Networking

Many information-centric services have emerged, such as IPTV and video conferencing. These services put a lot of demands on scalable multicast communication. However, traditional IP multicast has low adoption because of its poor scalability. Therefore, some stateless multicast methods were proposed, which encapsulate the destination’s information into the packet header without requiring routers to maintain the multicast forwarding state. However, stateless multicast also faces some problems, such as ingress router overload, high forwarding overhead, packet redundancy, etc. In addition, most multicast methods cannot optimize the multicast tree because the multicast flow is simply forwarded along the shortest path tree from the source to receivers. This paper proposes an Adaptive Hierarchical Hybrid Multicast (AHHM) based on Information-Centric Networking. To balance the forwarding states and forwarding overhead, AHHM is designed as a two-layer structure, in which the upper layer establishes a stateful main tree and the lower layer establishes several stateless sub trees. The router on the main tree is defined as the multicast join node (MJN), and AHHM uses the Name Resolution System to maintain the mapping between each multicast group name and corresponding MJNs. To optimize the multicast transmission path, we designed the minimum cost selection strategy for users to select the appropriate MJN to join. Simulation results show that compared with Source-Specific Multicast (SSM) and Bit Index Explicit Replication (BIER), AHHM can not only reduce the multicast forwarding states but also reduce the control overhead and link load.

Exploiting Reliable and Scalable Multicast Services in IaaS Datacenters

A large number of servers are interconnected using a specific datacenter network to deliver the infrastructure as a service (IaaS). Multicast can jointly utilize the network resources and further reduce the consumption of network bandwidth more than individual unicast. The source of a multicast service, however, does not need to be in a specific location as long as certain constraints are satisfied. This means the multicast can have uncertain sources, which could reduce the network resource consumption more than a traditional multicast service and further improve the quality of service. In this paper, we propose a novel reliable multicast service with uncertain sources named ReMUS. The goal is to minimize the sum of the transfer cost and the recovery cost, although finding such a ReMUS is very challenging. Thus, we design a source-based multicast method to solve this problem by exploiting the flexibility of sources when no recovery nodes exist in the network. Furthermore, we design a general multicast method to jointly exploit the benefits of uncertain sources and recovery nodes to minimize the total cost of ReMUS. We conduct extensive evaluations under Internet2 and datacenter networks. The results indicate that our methods can efficiently realize the reliable and scalable multicast with uncertain sources, irrespective of the settings of networks and multicasts. To the best of our knowledge, we are the first to study the reliable multicast service under uncertain sources.

The MBSFN-based eMBMS using the method of Incremental Allocation of Radio Resource between Unicast and Multicast (IARR-UM)

The evolved Multimedia Broadcast Multicast Service (eMBMS) using the Multicast Broadcast Single Frequency Network (MBSFN) technique was designed for having multimedia streaming services using the multicast/broadcast way over the cellular network. Since (1) the unit of resource allocation in eMBMS-MBSFN is a subframe, (2) the code rate of an eMBMS-MBSFN session is based on the lowest Modulation and Coding Scheme (MCS) among involved User Equipments (UEs) of the eMBMS-MBSFN session and (3) the resource allocation for eMBMS-MBSFN cannot be so instantly and dynamically adjusted based on the status of involved UEs, triggering eMBMS-MBSFN in the inappropriate time and allocating inappropriate resource to eMBMS, for which a framework of how to set the configuration of the allocated resource for eMBMS-MBSFN has been defined in the standard, may cause (1) the radio resources to be wasted and (2) the low streaming quality and code rate. Based on the MBMS operation on Demand (MooD) concept, this work proposed the Incremental Allocation of Radio Resource between Unicast and Multicast (IARR-UM) method to dynamically allocate radio resources to eMBMS based on the current Radio Access Network’s (RAN’s) congestion situation such that some suitable multimedia streaming services are switched to eMBMS and others still use unicast communication. To effectively use eMBMS to mitigate RAN’s congestion, the proposed IARR-UM method (1) dynamically increases/decreases the amount of radio resources allocated to eMBMS, i.e., modifying the configuration of the allocated resource for eMBMS-MBSFN using the standard’s framework, based on the situation of RAN’s congestion, (2) uses the Knapsack algorithm to select a subset of suitable multimedia streaming services to be eMBMS sessions according to the given amount of radio resources allocated to eMBMS, and then (3) design a Common Subframe Allocation (CSA) pattern that can have the lower amount of redundant radio resources allocated to eMBMS. The results of the performance evaluation shown that the proposed method can (1) provide UEs with appropriate radio resources and (2), although the throughput may be reduced in some cases, effectively reduce (increase) the UEs’ invalid packet rates (data rates), especially in the higher density of UEs’ situation.

An Identifier and Locator Decoupled Multicast Approach (ILDM) Based on ICN

Many bandwidth-intensive applications (such as online live, online games, etc.) are more suitable for using multicast to transmit information. Due to the advantages in scalability, Shared Tree (ST) is more suitable for large-scale deployment than Source-Based Tree (SBT). However, in ST-based multicast, all multicast sources need to send multicast data to a center node called a core, which will lead to core overload and traffic concentration. Besides, most existing multicast protocols use the shortest path between the source or the core and each receiver to construct the multicast tree, which will result in traffic overload on some links. In this paper, we propose an Identifier and Locator Decoupled Multicast approach (ILDM) based on Information-Centric Networking (ICN). ILDM uses globally unique names to identify multicast services. For each multicast service, the mapping between the multicast service name and the addresses of multicast tree nodes is stored in the Name Resolution System (NRS). To avoid core overload and traffic aggregation, we presented a dynamic core management and selection mechanism, which can dynamically select a low-load core for each multicast service. Furthermore, we designed a path state-aware multicast tree node selection mechanism to achieve traffic load balancing by using low-load links more effectively. Experimental results showed that our proposed multicast approach outperformed some other multicast methods in terms of core load, number of join requests, link load, traffic concentration, and routing state.

Research on Formation Keeping of Multi-rotor UAVs Based on Improved Virtual Structure Method

Multi-UAV cooperative formation flight (CFF) can greatly improve the damage resistance and mission completion efficiency of single UAV, so it has become a research hotspot in recent years. The entire process of multi-UAV formation flight can be decomposed into target tracking, formation keeping, obstacle avoidance and collision avoidance. The research of formation keeping mainly uses the leader-follower or virtual structure method. The former has the problem of single point of failure, and the formation error will be amplified step by step. The latter is difficult to select virtual leader, and is hard to adjust the formation adaptively with limited communication conditions. Based on the virtual structure and multicast method, this paper proposes a recursive fusion strategy which reduces the requirement of communication frequency between UAVs, increases the adaptability of formation to single point of failure, and improves the accuracy and adaptability of formation keeping to a certain extent. On this basis, the cascade PID model is used to design the formation controller. Finally, the effectiveness of the strategy is verified by using MATLAB.

The Effect of Replicated Archetypes on Machine Learning

The investigation of red-black trees is acompelling obstacle. In fact, few end-users would disagree with the explorationof e-business, which embodies the intuitive principles of hardware and architecture. Rescat, our new framework for multicast methods, is the solution to all of thesegrand challenges [1].

DCSN-Cast: Deep compressed sensing network for wireless video multicast

The purpose of wireless video multicast is to send a video signal simultaneously to multiple heterogeneous users, each of whom desires video quality that matches its channel condition. The current compressed sensing (CS)-based wireless video multicast has some advantages but also some shortcomings, such as high computational and low reconstruction quality, especially at high packet loss rates. This paper aims to improve the current CS-based multicasts, and proposes two deep compressed sensing networks for wireless video multicast, abbreviated as DCSN-Cast. We first consider a residual DCSN-Cast (DCSRN-Cast), which consists of two parts: a fully connected network and a deep residual network. The fully connected network takes the measurements of CS as input and outputs the preliminary reconstructed image, while the deep residual network takes this preliminary reconstructed image and outputs the final reconstructed image. The second scheme is a fully connected deep neural network (DCSFCN-Cast) which prunes the convolutional neural network under consideration to reduce the complexity. Extensive experiments show that the proposed DCSN-Cast outperforms the state-of-the-art CS-based wireless video multicast methods, especially at high packet loss rates.

A New IPTV Multicast Fast Reroute Method

This document proposes an IP multicast fast convergence method based on differentiating primary and backup PIM(Protocol Independent Multicast) join. The multicast stream is only sent along one of the multicast primary and backup path, which enables the efficient multicast delivery under both normal and abnormal conditions. The Single stream FRR(Fast Re-Route) solution has the advantages of implementing fast multicast protection and of avoiding double multicast bandwidth occupation in both normal and abnormal situations.

A mixed satellite TV channel transmission scheme to enhance frequency bandwidth utilization

SummaryIn the recent past, television (TV) industry has started to provide users with ultra high definition (ultra‐HD) and/or 3‐dimensional TV programs, which on the one hand, can bring users greatly enhanced viewing experience, while on the other hand, considerably increases the transmission bandwidth requirements and may lead to bandwidth shortage situations in many different types of TV systems. In particular, this bandwidth shortage poses a serious challenge in the current satellite TV broadcasting systems because of the strictly limited bandwidth available in C and Ku frequency bands. Aiming at mitigating the bandwidth shortage problem, this paper proposes an innovative mixed channel transmission scheme for the next generation satellite TV systems. The proposed scheme integrates the merits of using both broadcast and multicast methods, both Ku and Ka frequency bands, as well as both wide‐shaped and spot antenna beam types. According to the conducted comprehensive simulation experiments, this mixed scheme is able to effectively enhance the frequency bandwidth utilization with still providing users affordable quality of experience. Moreover, to cope with the impact brought by ever increasing number of provided TV channels, this paper enhances the proposed scheme by using multicast method to transmit those least popular global channels, which can efficiently reduce the quality of experience degradation up to 90% in Ku‐ and Ka‐band frequency resource restricted scenarios.

Asymmetric Directional Multicast for Capillary Machine-to-Machine Using mmWave Communications.

The huge demand for high data rate machine-to-machine (M2M) services has led to the use of millimeter Wave (mmWave) band communications with support for a multi-Gbps data rate through the use of directional antennas. However, unnecessary sector switching in multicast transmissions with directional antennas results in a long delay, and consequently a low throughput. We propose asymmetric directional multicast (ADM) for capillary M2M to address this problem in mmWave communications. ADM provides asymmetric sectorization that is optimized for the irregular deployment pattern of mulicast group members. In ADM, an M2M gateway builds up asymmetric sectors with a beamwidth of a different size to cover all multicast group members with the minimum number of directional transmissions. The performance of ADM under various simulation environments is evaluated through a comparison with legacy mmWave multicast. The results of the simulation indicate that ADM achieves a better performance in terms of the transmission sectors, the transmission time, and the aggregate throughput when compared with the legacy multicast method.

Optical multicast system for data center networks.

We present the design and experimental evaluation of an Optical Multicast System for Data Center Networks, a hardware-software system architecture that uniquely integrates passive optical splitters in a hybrid network architecture for faster and simpler delivery of multicast traffic flows. An application-driven control plane manages the integrated optical and electronic switched traffic routing in the data plane layer. The control plane includes a resource allocation algorithm to optimally assign optical splitters to the flows. The hardware architecture is built on a hybrid network with both Electronic Packet Switching (EPS) and Optical Circuit Switching (OCS) networks to aggregate Top-of-Rack switches. The OCS is also the connectivity substrate of splitters to the optical network. The optical multicast system implementation requires only commodity optical components. We built a prototype and developed a simulation environment to evaluate the performance of the system for bulk multicasting. Experimental and numerical results show simultaneous delivery of multicast flows to all receivers with steady throughput. Compared to IP multicast that is the electronic counterpart, optical multicast performs with less protocol complexity and reduced energy consumption. Compared to peer-to-peer multicast methods, it achieves at minimum an order of magnitude higher throughput for flows under 250 MB with significantly less connection overheads. Furthermore, for delivering 20 TB of data containing only 15% multicast flows, it reduces the total delivery energy consumption by 50% and improves latency by 55% compared to a data center with a sole non-blocking EPS network.

Robust spatial multicasting for randomly distributed sensors

Beamforming is used in sensor networks to transfer data to remote stations with enhanced communication. When the position of array nodes and directions are known, it is better to form an approximate uniform linear array (ULA), uniform circular array (UCA) and uniform elliptical array (UEA). Since it is not always possible to find actual sensors matching with the ideal positions of ULA, UCA and UEA, least-square (LS) estimation is used to calculate weights of the array elements. LS estimation does not give realisable weight values and yields transmission in unintended directions. Also, if many single beams arrays are used to transfer data simultaneously to different users, co-channel interference occurs. In this study, to overcome these problems, multibeam array with restriction imposed on the weights is proposed and is reformulated as Tikhonov regularised LS (TRLS) method. This proposed spatial multicasting method is found to be robust up to 90% position variation of sensors for the ULA with weights under control improving the power efficiency and hence the spectral efficiency and data rate. Moreover, it is also observed that when a faulty node is substituted by nearby nodes, the weights calculated using TRLS method need not be recalculated.

Summary of GOOSE Substation Communication

The fast real-time application message is an object-oriented substation event—GOOSE (Generic Object Oriented Substation Event). It mainly works on the process layers and bay layers of digital substation. GOOSE intelligent substation communication network can realize the key function of the overall intelligent sub- station functions. This paper will make a systematic analysis of GOOSE. At first, it will provide a detailed analy- sis of the transmission mechanism and process of GOOSE message. As certain practical operability lacks the actual application of the multicast filtering method which is applied to GOOSE message based on IEC61850 standard, this paper will summarize three message filtering methods, compare the advantages and disadvantages in topological networks of different kinds in accordance with the instantaneity of GOOSE intelligent substation communication network and draw a conclusion that the independent configuration scheme of GOOSE and SV can adapt to the requirement of times, so as to provide theoretical references for the selection of practical intelli- gent substation communication network in the future.

Distribution of the maximally allowable packet loss ratio between the links of the multicast route in the wireless network

The task concerning the maximally allowable packet loss ratio distributed between route links (from source to destination vertices), which enters into the multicast routing problem, is analyzed using the reliable multicast transmission methods standardized for Wi-Fi networks in 2012. In certain particular cases, the explicit form of accurate solutions has been obtained. In the general case, approximate algorithms based on the greedy strategy are proposed and their efficiency is estimated.

Seamless handover between unicast and multicast multimedia streams

With the deployment of heterogeneous networks, mobile users are expecting ubiquitous connectivity when using applications. For bandwidth-intensive applications such as Internet Protocol Television (IPTV), multimedia contents are typically transmitted using a multicast delivery method due to its bandwidth efficiency. However, not all networks support multicasting. Multicasting alone could lead to service disruption when the users move from a multicast-capable network to a non-multicast network. In this paper, we propose a handover scheme called application layer seamless switching (ALSS) to provide smooth real-time multimedia delivery across unicast and multicast networks. ALSS adopts a soft handover to achieve seamless playback during the handover period. A real-time streaming testbed is implemented to investigate the overall handover performance, especially the overlapping period where both network interfaces are receiving audio and video packets. Both the quality of service (QoS) and objective-mapped quality of experience (QoE) metrics are measured. Experimental results show that the overlapping period takes a minimum of 56 and 4 ms for multicast-to-unicast (M2U) and unicast-to-multicast (U2M) handover, respectively. The measured peak signal-to-noise ratio (PSNR) confirms that the frame-by-frame quality of the streamed video during the handover is at least 33 dB, which is categorized as good based on ITU-T recommendations. The estimated mean opinion score (MOS) in terms of video playback smoothness is also at a satisfactory level.

Research on Multicast Flooding Suppression in Smart Substation

The existence of a large number of multicast flooding data in the process level of smart substation,causes serious influence on the real-time performance and reliability of network.Through the exchange principle of Ethernet,the forwarding process of second-layer multicast in network is introduced. Combined with the application in intelligent substation and some experimental data, through in-depth analysis of the 802.1Q VLAN isolating broadcast domain,setting static multicast to change the static MAC address table ,and GMRP to change the multicast information on Ethernet switch through the interactive protocol data, the multicast flooding suppression method is illustrated. And based on the practical engineering situation, the three kinds of methods are compared from the characteristics of debugging operation and maintenance convenience and reliability of intelligent equipment,then the technology route recommendation is given.

A Multicast Routing Algorithm for Datagram Service in Delta LEO Satellite Constellation Networks

Satellites can broadcast datagram over wide areas, therefore, the satellite network has congenital advantages to implement multicast service. LEO satellite has the property of efficient bandwidth usage, lower propagation delay and lower power consumption in the user terminals and satellites. Therefore, the constellation network composed by LEO satellites is an essential part of future satellite communication networks. In this paper, we propose a virtual center based multicast (VCMulticast) routing algorithm for LEO satellite constellation network. The algorithm uses the geographic center information of group users to route multicast datagrams, with less memory, computer power and signaling overhead. We evaluate the delay and performance of our algorithm by means of simulations in the OPENET simulator. The results indicate that the delay of the proposed multicast method exceeds the minimum propagation by at most 29.1% on the average, which is a quite acceptable achievement, considering the resource overhead reduction that can be introduced by our proposal