On-board Switching Research Articles

Architecture design and performance analysis of a novel memory system for high-bandwidth onboard switching fabric

The development of the space–air–ground integration has put higher demands on satellite network. It needs to support high-bandwidth, large-capacity and various quality of service guarantees. However, the satellite onboard switching is facing the problem of resource constraints and special requirements of hardware complexity and scheduling efficiency. For this, this paper proposes a novel memory architecture for high-bandwidth onboard switching fabric. To reduce hardware complexity, multiplexer is used in the input side to merge k input ports into one internal bus, while the output demultiplexer splits an internal bus into k output links. Shared memory architecture is adopted in the input module to improve the memory efficiency, and a buffered crossbar is used to interconnect the input modules to the output modules. A discrete-time queuing model is formulated, and an iterative approach is used to quantitatively analyze the performance of the proposed architecture. The throughput and delay are calculated under different switch size, input load, and buffer capacity. The numerical results can serve as a guidance on deciding the required buffer size and appropriate speedup ratio. This work is validated by both simulations and FPGA implementations. Synthesize result show that using the state-of-the-art Xilinx VU13P FPGA, a switching fabric with 48 ports can be implemented and the peak throughput of the proposed architecture can reach 480 Gbps. Compared with existing combined input-crosspoint queuing, the proposed architecture can significantly reduce the packet delay and the memory resource cost.

Design of a 640-Gbps Two-Stage Switch Fabric for Satellite On-Board Switches

Due to the limitation of hardware resources and high reliability requirements for satellite-borne switching equipments and the demand for the increasing network bandwidth, a new type of two-stage satellite on-board switch fabric is presented in this paper. The fully connected structure is composed of eight input modules and eight output modules. And each module has four shared-buffer memories, which guarantee the premise of high-throughput. Compared with the traditional three-stage CLOS switch fabric, central modules are not used in this design. And compared with the complicated inter-stage scheduling algorithm, this paper uses an improved WRR algorithm which supports multi-priority variable-length packets scheduling. This design reduces the consumption of hardware resources and meets the design requirements of satellite-borne switches. In addition, we used the Xilinx FPGA to implement this $32\times32$ two-stage switch fabric, and used ModelSim 10.6d to simulate and analyze the entire design. The simulation results show that the peak throughput of this structure can reach 640 Gbps when the system clock frequency is 200 MHz.

Power Management for Multicore Processors via Heterogeneous Voltage Regulation and Machine Learning Enabled Adaptation

This work is based on the vision that the ultimate power integrity and efficiency may be best achieved via a heterogeneous chain of voltage processing starting from onboard switching voltage regulators (VRs), to on-chip switching VRs, and finally to networks of distributed on-chip linear VRs. As such, we propose a heterogeneous voltage regulation (HVR) architecture encompassing regulators with complimentary characteristics in response time, size, and efficiency. By exploring the rich heterogeneity and tunability in HVR, we develop systematic workload-aware power management policies to adapt heterogeneous VRs with respect to workload change at multiple temporal scales to significantly improve system power efficiency while providing a guarantee for power integrity. The proposed techniques are further supported by hardware-accelerated machine learning (ML) prediction of nonuniform spatial workload distributions for more accurate HVR adaptation at fine time granularity. Our evaluations based on the PARSEC benchmark suite show that the proposed adaptive three-stage HVR reduces the total system energy dissipation by up to 23.9% and 15.7% on average compared with the conventional static two-stage voltage regulation using off-chip and on-chip switching VRs. Compared with the three-stage static HVR, our runtime control reduces system energy by up to 17.9% and 12.2% on average. Furthermore, the proposed ML prediction offers up to 4.1% reduction of system energy.

An ICN/SDN-Based Network Architecture and Efficient Content Retrieval for Future Satellite-Terrestrial Integrated Networks

With the tremendous increase in the amount of network contents and emerging applications, traditional network architecture starts to exhibit management and efficiency problems. The evolving STIN, as a combination of satellite networks and terrestrial networks, also faces similar obstacles. To address this challenge, technologies like ICN and SDN, which were initially proposed for terrestrial networks, could provide viable and promising solutions in STIN. In this article, we propose a novel architecture to provide flexible management and efficient content retrieval for STIN. Our architecture consists of a three-layer satellite network in which satellites of each layer are assigned to different functionalities. In order to achieve compatibility with ICN, we also design a new on-board switch based on protocol oblivious forwarding switch. In so doing, the proposed architecture inherits the advantages of ICN and SDN. Additionally, concerning the issue of the most traffic contribution in content retrieval applications, we propose a simple yet effective cooperative content retrieval scheme for terrestrial users. Furthermore, to make the best use of in-network caching and achieve further efficiency improvement of content retrieval, a cooperative caching scheme and a coded caching scheme are also proposed. The feasibility of these caching schemes is analyzed, and numerical evaluations show that the proposed content retrieval schemes in this architecture can achieve significant traffic load reduction.

Cross-Layer Routing and Scheduling for Onboard Processing Satellites with Phased Array Antenna

The advanced multibeam satellite equipped with phased array antenna and solid state power amplifiers can generate flexible beams, by managing interbeam interference to serve a very large number of users effectively over its coverage area. Onboard processing (OBP) functionality can enhance the flexibility of a large-scale antenna by speeding up computational processes and saving precious radio link spectrum. In this paper, we derive a cross-layer OBP design of switching/routing, beamforming, and user scheduling as taking advantage of fine spatial resolution capability of phased array antenna satellites. We evaluate tradeoff between OBP computational complexity and throughput performance, showing that the additional complexity of an increased number of switch ports and phased array antenna gain patterning is compensated by high throughput gain achieved by mitigating interference. Our analysis shows that throughput gain for the next generation satellite system can be as high as 40, compared with the conventional multiple beam antenna with travelling wave tube amplifiers, and that beamforming is critical for achieving high spectral efficiency in the crowded service area. We then investigate the impacts of onboard switching and phased array antenna beamforming to practical routing protocols, such as open short path first and routing information protocol.

Cost effective railway signalling by wireless communication among onboard controllers and switch controllers

The signalling system is one of the most costly systems in the railway infrastructure. The cost of the trackside controllers is particularly high because high-performance failsafe hardware and software are needed to supervise and control the many pieces of the field equipment. A signalling system is described that has a lower projected cost because of the application of the traditional token block mechanism to the virtual blocks dividing each controlled section. Its basic mechanism is the sharing by the wireless communication of the information about the exclusive rights with the virtual blocks, the status of the switches and the instructions for controlling the switches in the controlled section among the onboard controllers and the switch controllers, respectively. A telegram for each controlled section is circulated in turn among these controllers for the sharing. This mechanism provides an automatic train protection and an interlocking function without using the trackside controllers. Its application to a very high-density line might reduce the train operation density because of the telegram circulation time, but the reduction would be no greater than 20% on the highest density line if the current radio technology was used. A cost evaluation based on a 20-km double-track line showed that this system is about three times more cost effective than the communication-based train control system.

An interconnected multi-plane multi-stage fault-tolerant on-board switching fabric

The harsh space radiation environment compromises the reliability of an on-board switching fabric by leading to cross-point and switching element (SE) faults. Different from traditional fault-tolerant switching fabrics only taking cross-point faults into account, a novel Input and Output Parallel Clos network, referred to as the (p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ,p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )-IOPClos, is proposed to tolerate both cross-point and SE faults. In the (p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ,p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )-IOPClos, there are p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> expanded parallel switching planes in the input and output stages, respectively. The multiple input/output switching planes are interconnected through the middle stage to provide multiple paths in each stage by which the network throughput can be increased remarkably. Furthermore, the network reliability of the (p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ,p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )-IOPClos under the above both kinds of faults is analyzed. The corresponding implementation cost is also presented along with the network size. Both theoretical analysis and numerical results indicate that the (p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ,p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )-IOPClos outperforms traditional Clos-type networks at reliability, while has less implementation cost than the multi-plane Clos network.

基于模拟光突发交换结构的星载光网络资源预留机制研究

基于模拟光突发交换结构的星载光网络资源预留机制研究

An Asynchronous Burst Time Plan Generation Method for Broadband Satellite Multimedia System

In broadband satellite multimedia (BSM) system, burst time plan (BTP) is always periodically generated. We find that this method can have a great effect on the system response ability to bandwidth requests. A general analysis model of BTP generation method is given. An optimized BTP generation (O-BTPG) method is presented by deducing the optimal bandwidth allocation period (BAP) and bandwidth allocation latency (BAL) without considering the signaling overhead caused by BTP. Then a novel asynchronous BTP generation (A-BTPG) method in which the BTP is generated asynchronously according to the traffic load from users’ bandwidth requests is proposed. Simulation results show that A-BTPG can flexibly realize a trade-off between the system response ability and BTP signaling overhead. What’s more, it can be widely used in various regenerative onboard switching BSM systems.

基于Round-Robin方法的星载光交换混合门限组装算法研究

基于Round-Robin方法的星载光交换混合门限组装算法研究

基于突发流的星载光交换数据信道调度算法

基于突发流的星载光交换数据信道调度算法

A branch and price algorithm for the SS/TDMA problem with cardinality constraint

In this paper, we consider a square n×n traffic matrix D and a satellite having l≤n receiving and transmitting antennas. Transmissions are allowed by interconnecting pairs of receiving–transmitting antennas, through an on-board switch. We also assume that no preemption of the communications is allowed, and that changing the configuration of the switch requires a negligible time. We ask for a set of switch configurations that minimizes the total time occurring for transmitting the entire traffic matrix. In the literature, an exact method has been already proposed for the SS/TDMA optimization problem without cardinality constraint (i.e. for instances having l=n), but only heuristics have been proposed for the general case. In this paper, from a known MILP formulation we derive an extended formulation, and we use a column generation method to obtain its LP-relaxation. We address the derived pricing problem through a polynomial time algorithm based on solvers for the k-cardinality assignment problem. We insert this lower bound method in a two-phase branch and price algorithm in order to obtain the optimal solutions. To compare our new exact method with the one proposed in literature to solve the SS/TDMA optimization problem without cardinality constraint, we extend this older method to consider the cardinality constraint. The final computational experiments, comparing our new method with other already known methods, show the efficiency of our algorithms. Scope and purposeSatellites are the commonly used devices to wirelessly connect two distant earth points. Since satellites are very expansive devices, it is important to schedule the communications requests in an efficient manner. A satellite receives transmissions requests between pairs of earth stations, and these requests can be described by a traffic matrix. One method used in practice to satisfy these requests is called Satellite-Switched Time-Division-Multiple-Access (SS/TDMA) which requires to partition the traffic matrix entries in sets called frames and to transmit the elements of each different frame in a single time slot. Each frame must contain at most one communication involving the same earth station and the number of its nonzero entries must be at most equal to the number of satellite antennas. Since a satellite has to complete the transmission of a frame before starting the transmission of the next one, each frame is associated with a completion time equal to the maximum transmission time of its entries. A crucial decision, to minimize the total satellite used time, is how to partition the given traffic matrix. Our aim is to provide an effective exact algorithm for finding optimal solutions to the SS/TDMA problem and to compare it with other methods already known in the literature.

Stratospheric communication platforms as an alternative for space program

PurposeThe purpose of this paper is to examine the potential applications of stratospheric communication platforms (SCP), which have been recently introduced as an alternative for satellite communications.Design/methodology/approachVarious applications, solutions and services are planned by using aircraft or airship SCP, which could be classified as digital narrowband or broadband, depending on the broadband required. The platforms as base stations can provide service for fixed and mobile applications, with commercial and military solutions. Subscribers will use uplink to the platform for transmitting and receiving information, where onboard SCP switching devices will downlink to the ground station and route traffic directly to other subscribers within the same platform coverage, to another platform via optical inter‐platform links, trough heterogeneous networks including satellite or to the terrestrial telecommunications network. Each SCP can deploy an antenna for large coverage area or a multibeam antenna capable of projecting numerous spot beams within its potential coverage area.FindingsThis paper outlines the findings of fixed and mobile applications, features, testing and some specific development programs of SCP using aircraft solutions, such as SkyTower and airship solutions, such as CRL/TAO/NAL.Research limitations/implicationsParticular consideration is given to the use of SCP for delivery of future broadband, broadcast and multimedia wireless communications including research for new communication, navigation and surveillance (CNS) implications.Practical implicationsSCP will provide communication facilities that can exploit the best features for both terrestrial and satellite schemes.Originality/valueEmerging solutions of voice, data and video over IP are offered by SCPs operating in the stratosphere at altitudes of up to 25 km.

Performance analysis and simulation of various burst time plan generation methods in broadband satellite multimedia system

The Burst Time Plan (BTP) generation is the key for resource allocation in Broadband Satellite Multimedia (BSM) system. The main purpose of this paper is to minimize the system response time to users’ request caused by BTP generation as well as maintain the Quality of Service (QoS) and improve the channel utilization efficiency. Traditionally the BTP is generated periodically in order to simplify the implementation of the resource allocation algorithm. Based on the analysis we find that Periodical BTP Generation (P-BTPG) method cannot guarantee the delay performance, channel utilization efficiency and QoS simultaneously, especially when the capacity requests arrived randomly. The Optimized BTP Generation (O-BTPG) method is given based on the optimal scheduling period and scheduling latency without considering the signaling overhead. Finally, a novel Asynchronous BTP Generation (A-BTPG) method is proposed which is invoked according to users’ requests. A BSM system application scenario is simulated. Simulation results show that A-BTPG is a trade-off between the performance and signaling overhead which can improve the system performance insensitive to the traffic pattern. This method can be used in the ATM onboard switching satellite system and further more can be expended to Digital Video Broadcasting-Return Channel Satellite (DVB-RCS) system or IP onboard routing BSM system in the future.

Exact Statistics of a Complex Markov Chain through State Reduction: A Satellite On-board Switching Example

Satellite on-board switching offers the possibility of covering a wide area with increased total capacity. In order to show a mechanism for reducing a highly dimensional complex Markov chain, in this paper we use a terrestrial packet grouping approach to minimize the on-board switching operations. By carefully redirecting some transitions to different states, we can evaluate exact statistics of the original complex Markov chain from the analysis of a much simpler reduced Markov chain. Although we use a communication example close to our research interest, the method can have a much wider area of application.

Downlink Cross-layer Design for On-board Switch OFDM Based Scheme

该文基于一种全新的基于OFDM的星载交换方案，给出了此星载交换方案的星地下行链路跨层设计工作流程和相关实现方法，此方法根据星地下行链路信号发射功率上限、关于每个地面设备的当前点波束星地下行链路信道状态、每个星地下行链路传输业务目的地、业务类型、业务传输速率要求等参数，实现在属于不同地面设备的各个星地下行链路传输业务之间自适应分配子载波并自适应配置每个子载波的调制制式，生成每个传输业务与子载波的对应关系，充分利用链路资源并满足传输业务的QoS要求。

ND-RAPID: a multidimensional scalable fault-tolerant optoelectronic interconnection for high-performance computing systems

Feature Issue on Photonics in SwitchingThe increasing demand for bandwidth coupled with saturating electrical systems is leading the drive for optics as an interconnect technology. High-performance computing systems (HPCS) consist of a large number of components such as processors, memories, and interconnection links. As the number of components in HPCS increases, the probability of a failure also increases. Therefore, it becomes imperative that the system be fault tolerant to ensure high availability even in the presence of faults. We propose a multidimensional optoelectronic architecture, nD-RAPID (reconfigurable and scalable all-photonic interconnect for distributed and parallel systems), where n can be 1, 2, or 3. nD-RAPID provides high bandwidth, low latency, dynamic reconfiguration, and fault tolerance. While designing the fault-tolerant routing algorithm, we have tried to ensure that it provides optimum performance in the absence of faults, shows minimal degradation in the presence of faults, and can tolerate a reasonable number of faults. In the presence of faults the on-board switching mechanism dynamically reconfigures itself to reroute packets along nonfaulty links. Extensive simulation results are presented that compare nD-RAPID with other popular HPCS topologies.

Cross‐layer protocols for satellite communication networks: part II

Cross‐layer protocols for satellite communication networks: part II

Integrated Connection Admission Control and Bandwidth on Demand Algorithm for a Broadband Satellite Network with Heterogeneous Traffic

There are many system proposals for satellite-based broadband communications that promise high capacity and ease of access. Many of these proposals require advanced switching technology and signal processing on-board the satellite(s). One solution is based on a geosynchronous (GEO) satellite system equipped with on-board processing and on-board switching. An important feature of this system is allowing for a maximum number of simultaneous users, hence, requiring effective medium access control (MAC) layer protocols for connection admission control (CAC) and bandwidth on demand (BoD) algorithms. In this paper, an integrated CAC and BoD algorithm is proposed for a broadband satellite communication system with heterogeneous traffic. A detailed modeling and simulation approach is presented for performance evaluation of the integrated CAC and BoD algorithm based on heterogeneous traffic types. The proposed CAC and BoD scheme is shown to be able to efficiently utilize available bandwidth and to gain high throughput, and also to maintain good Grade of Service (GoS) for all the traffic types. The end-to-end delay for real-time traffic in the system falls well within ITU's Quality of Service (QoS) specification for GEO-based satellite systems.

Critical issues of onboard switching in DVB-S/RCS broadband satellite networks

The next generation of broadband satellite networks is challenged to accommodate multimedia services while concurrently integrating with terrestrial IP networks. With IP applications dominating the Internet, carrying IP traffic over the satellite has been under intensive study. Originally developed to bring digital television home through satellites, the DVB-S and DVB-RCS standards empower interactive satellite communications with economical standardized satellite terminals. Furthermore, onboard switching technology is increasingly gaining attention, due to optimized bandwidth usage, fully meshed network topology through one satellite hop, and quality of service guarantee. This article investigates the onboard switching technologies in DVB-S/DVB-RCS broadband satellite networks. Aside from the network system infrastructure and switch hardware architecture, the QoS mechanisms supported by the switch onboard the satellite are discussed in depth.