Scalable network-on-chip architecture for configurable neural networks

Providing highly flexible connectivity is a major architectural challenge for hardware implementation of reconfigurable neural networks. We perform an analytical evaluation and comparison of different configurable interconnect architectures (mesh NoC, tree, shared bus and point-to-point) emulating variants of two neural network topologies (having full and random configurable connectivity). We derive analytical expressions and asymptotic limits for performance (in terms of bandwidth) and cost (in terms of area and power) of the interconnect architectures considering three communication methods (unicast, multicast and broadcast). It is shown that multicast mesh NoC provides the highest performance/cost ratio and consequently it is the most suitable interconnect architecture for configurable neural network implementation. Routing table size requirements and their impact on scalability were analyzed. Modular hierarchical architecture based on multicast mesh NoC is proposed to allow large scale neural networks emulation. Simulation results successfully validate the analytical models and the asymptotic behavior of the network as a function of its size.     

Routing and rate allocation in rate-based multi-class networks

In this paper, we investigate the performance of routing and rate allocation (RRA) algorithms in rate-based multi-class networks. On the arrival of a connection request, an RRA algorithm selects a route for the connection and allocates an appropriate rate on the route; failing this, it blocks the connection request. We measure the performance of an RRA algorithm in terms of its minimum weighted carried traffic. This performance criterion encompasses two widely used performance criteria, namely, weighted carried traffic and minimum carried traffic. We derive an upper bound on the minimum weighted carried traffic of any RRA algorithm. The bound can be computed by solving a linear program. Moreover, we show that the bound is achieved asymptotically, when the offered load and the link capacities are large, by a Partitioning RRA algorithm. Therefore the bound can be used as a performance benchmark for any RRA algorithm. We observe that the proposed Partitioning RRA algorithm, though asymptotically optimal, performs poorly at very low loads. We investigate the cause of this undesirable behaviour and obtain two improved asymptotically optimal RRA algorithms.     

Routing protocols in wireless mesh networks: challenges and design considerations

Wireless Mesh Networks (WMNs) are an emerging technology that could revolutionize the way wireless network access is provided. The interconnection of access points using wireless links exhibits great potential in addressing the “last mile” connectivity issue. To realize this vision, it is imperative to provide efficient resource management. Resource management encompasses a number of different issues, including routing. Although a profusion of routing mechanisms has been proposed for other wireless networks, the unique characteristics of WMNs (e.g., wireless backbone) suggest that WMNs demand a specific solution. To have a clear and precise focus on future research in WMN routing, the characteristics of WMNs that have a strong impact on routing must be identified. Then a set of criteria is defined against which the existing routing protocols from ad hoc, sensor, and WMNs can be evaluated and performance metrics identified. This will serve as the basis for deriving the key design features for routing in wireless mesh networks. Thus, this paper will help to guide and refocus future works in this area.

一种基于方向优先的车载Ad hoc路由策略*

针对城市车载网络在十字路口路由选择效率低下的问题,结合已有的地理位置路由协议,提出一种基于方向优先的地理位置路由策略。该策略通过信标的广播信息确定节点的类型,是属于普通节点、预测节点或者十字路口节点;然后再判断采取什么样的方式转发数据包,普通节点采取贪婪转发的方式,预测节点采取受限的贪婪转发,而十字路口节点决定路由策略的方向。通过NS2仿真分析,该路由策略能够以更少的跳数、更短的路径成功传递数据包。     

Convex Subspace Routing (CSR): Routing via anchor-based convex virtual subspaces in sensor networks

Convex Subspace Routing (CSR) is a novel approach for routing in sensor networks using anchor-based virtual coordinates. Unlike geographical routing schemes that require physical location information of nodes, obtaining which is often difficult, error-prone and costly, the Virtual Coordinate (VC) based schemes simply characterize each node by a vector of shortest hop distances to a selected subset of nodes known as anchors. Even though VC based routing (VCR) schemes benefits from having connectivity information implicitly embedded within the VCs, VCs lack the directional information available with physical coordinates. The major issues affecting routing using VCs are addressed. Due to local minima problem in the virtual space, the VCR schemes rely on backtracking or hill climbing techniques to overcome the local minima. Convex Subspace Routing, in contrast, avoids using anchors that cause local minima. It dynamically selects subsets of anchors that define subspaces to provide convex distance functions from source to destination. Consequently, it is less sensitive to anchor placement and over anchoring, and does not require tracking route history for backtracking, resulting in shorter packet lengths and energy efficient operation. Three techniques for selection of convex subspaces are proposed and evaluated. Performance evaluation for several different network topologies indicates that CSR significantly outperforms the existing VCR scheme, Logical Coordinate Routing (LCR), while being competitive with geographic coordinate based Greedy Perimeter Stateless Routing (GPSR), even though latter makes use of node location information.     

Routing in wireless sensor networks for wind turbine monitoring

Smart wireless sensor devices are rapidly emerging as key enablers of the next evolution in wind turbine monitoring. The potential for in-situ monitoring of turbine elements, employing methodologies that are not possible with existing wired technology, make it possible to attain new levels of granularity and autonomy in the monitoring of these structures. Wireless sensor devices are limited in terms of communication by the range of their radio modules and, thus, need to form networks in order to transfer data from distant points. Routing protocols are primary enablers of such ad hoc wireless sensor networks and these require the implementation of reliable and energy-efficient mechanisms to maximize network reliability and availability. Existing routing protocols cannot be directly applied to the monitoring of wind turbines without addressing the unique context and operational characteristics of these structures in multi-hop wireless communication. This work identifies the potential effects associated with the operation, environment and structure of wind turbines in wireless sensor network multi-hop communication, and proposes and evaluates a reliable routing protocol for wireless sensor networks employed in these domains.     

Ad Hoc网络基于能量消耗的动态源路由协议

为了节省路由能耗,增加网络中节点生存时间,提出一种基于能量消耗的Ad Hoc网络动态源路由协议（ECDSR）。该协议以路由剩余能量、路由能耗预测、路由能量延时3个参数作为路径能量评价的参数。其中剩余能量参数反映了节点当前的剩余能量状态,能耗预测参数反映了节点能量的变化情况,能量延时参数能够保护低能量节点,屏蔽能量状况差的路由路径。仿真结果表明该协议相对于动态源路由（DSR）可以在网络时延和协议开销增加不明显的前提下,提高网络的生存时间等网络性能。     

Routing Internet traffic in heterogeneous mesh networks: Analysis and algorithms

In practical wireless mesh networks (WMNs), gateways are subject to hard capacity limits on the aggregate number of flows (in terms of bit rate) that they can support. Thus, if traffic is routed in the mesh network without considering those constraints, as well as the traffic distribution, some gateways or intermediate mesh routers may rapidly get overloaded, and the network resources can be unevenly utilized. To address this problem, in this paper we firstly develop a multi-class queuing network model to analyze feasible throughput allocations, as well as average end-to-end delay, in heterogeneous WMNs. Guided by our analysis, we design a Capacity-Aware Route Selection algorithm (CARS), which allocates network paths to downstream and upstream Internet flows so as to ensure a more balanced utilization of wireless network resources and gateways’ fixed connections. Through simulations in a number of different network scenarios we show that the CARS scheme significantly outperforms conventional shortest path routing, as well as an alternative routing method that distributes the traffic load on the gateway nodes to minimize its variance.     

移动Ad Hoc网络路由协议综述

1 引言无线网络由于其移动性和灵活性给人们的生活带来了极大的方便,因此日益广泛地进入我们的日常生活。近年来,一种新型的无线网络即移动Ad Hoc网络(MANET)诞生了。移动Ad Hoc网络是由一组移动节点(带有多个终端的路由器、移动通讯设备等)形成一个多跳的、临时性的自治系统。这     

Proactive Highly Ambulatory Sensor Routing (PHASeR) protocol for mobile wireless sensor networks

This paper presents a novel multihop routing protocol for mobile wireless sensor networks called PHASeR (Proactive Highly Ambulatory Sensor Routing). The proposed protocol uses a simple hop-count metric to enable the dynamic and robust routing of data towards the sink in mobile environments. It is motivated by the application of radiation mapping by unmanned vehicles, which requires the reliable and timely delivery of regular measurements to the sink. PHASeR maintains a gradient metric in mobile environments by using a global TDMA MAC layer. It also uses the technique of blind forwarding to pass messages through the network in a multipath manner. PHASeR is analysed mathematically based on packet delivery ratio, average packet delay, throughput and overhead. It is then simulated with varying mobility, scalability and traffic loads. The protocol gives good results over all measures, which suggests that it may also be suitable for a wider array of emerging applications.     

Interval Routing Schemes

Interval routing was introduced to reduce the size of routing tables: a router finds the direction where to forward a message by determining which interval contains the destination address of the message, each interval being associated to one particular direction. This way of implementing a routing function is quite attractive but very little is known about the topological properties that must satisfy a network to support an interval routing function with particular constraints (shortest paths, limited number of intervals associated to each direction, etc.). In this paper we investigate the study of the interval routing functions. In particular, we characterize the set of networks which support a linear or a linear strict interval routing function with only one interval per direction. We also derive practical tools to measure the efficiency of an interval routing function (number of intervals, length of the paths, etc.), and we describe large classes of networks which support optimal (linear) interval routing functions. Finally, we derive the main properties satisfied by the popular networks used to interconnect processors in a distributed memory parallel computer. Received February 7, 1996; revised November 25, 1996.     

无线传感器网络中的路由协议研究

无线传感器网络作为计算、通信和传感器三项技术相结合的产物,是一种全新的信息获取和处理技术.本文首先简要介绍无线传感器网络体系结构和性能标准,然后着重从路由协议方面比较分析无线传感器网络的多种典型的路由协议,指出了各自的特色,最后指出了下一步的研究趋势.     

Permutation Routing on Reconfigurable Meshes

In this paper we present efficient algorithms for packet routing on the reconfigurable linear array and the reconfigurable two-dimensional mesh. We introduce algorithms that are efficient in the worst case and algorithms that are better on average. The time bounds presented are better than those achievable on the conventional mesh and previously known algorithms. We present two variants of the reconfigurable mesh. In the first model, M _r , the processors are attached to a reconfigurable bus, the individual edge connections being bidirectional. In the second model, M _mr , the processors are attached to two unidirectional buses. In this paper we present lower bounds and nearly matching upper bounds for packet routing on these two models. As a consequence, we solve two of the open problems mentioned in [9]. Received August 17, 1998; revised November 3, 1999.     

基于蚁群优化的路由算法

针对移动自组网提出了一种基于蚁群优化的路由算法,该算法很好地利用了蚁群算法的自适应性,能有效地承载移动自组网的负载。在NS-2平台下的算法仿真表明,该算法在移动自组网环境下表现了较好的性能,从吞吐量、平均延迟、传送率三个指标比较来看,比AODV和DSR的性能都要好。     

传感器网络的路由机制

微电子技术和无线技术的进步推动传感器网络的发展,传感器网络实现分布式监测任务,能够应用于各种领域。由于传统网络路由协议重点在于提供高的服务质量,不能适用于存在能量约束的传感器网络。本文在说明传感器特点的基础上,对传感器网络的路由机制进行了简单的分类,并详细介绍和分析已提出的主要路由机制。     

无线传感器网络路由协议研究综述

无线传感器网络是一种新的计算模式,它对网络的路由协议提出了许多新挑战。首先简要介绍无线传感器网络的体系结构和性能标准,然后着重从路由协议方面比较分析无线传感器网络中多种典型的路由协议,指出了各自的特色,最后总结出未来的研究热点和发展趋势。     

Mesh网络耐故障虫孔路由

耐故障是互连网络设计中的一个重要问题。本文提出了一种新的耐故障路由算法,并将其应用于使用虫孔交换技术的Mesh网络。由于使用了较低的路由限制,这一算法具有很强的自适应性,可以在各种不同故障域的Mesh网络中保持路由的连通性和无死锁性;由于使用了最小限度的虚拟通道,这一算法所需的缓冲器资源很少,非常适宜构建低成本的耐故障互连网络;由于根据本地故障信息进行绕行故障节点的决策,这一算法的路由决策速度较快并且易于在互连网络中实现。最后网络仿真试验显示,这一算法具有良好的平滑降级使用的性能。     

基于网格和曲线转发的传感器网络路由算法

针对传感器网络节点稠密布置的特点，提出一种将网格结构和基于轨迹的转发方式相结合的路由算法。通过构造大小适当的网格，然后在网格中控制一个节点工作，其他节点暂停工作以便将来随时补充死亡的节点，工作节点基于曲线进行数据转发，以延长网络的生存时间。理论分析和模拟实验表明，算法具有较好的性能。     

三维水声传感器网络中高效路由协议的研究

近年来,三维水声传感器网络在学术界和工业界引起了极大的关注.在被监测海域部署三维水声传感器网络,可以解决二维水声传感器网络节点无法充分观测的问题.为了实现三维水声传感器网络在新环境中的水下监测,需要解决一系列的问题.其中,由于监测区域环境的限制以及水声传感器节点的特殊性,需要设计高效的路由协议来保证数据包在各节点之间正确转发.首先提出一种基本地理位置路由协议.在此基础上,设计一种自适应路由协议,以较好地适应三维水声传感器网络中部分节点失效的情况.通过仿真实验发现,自适应路由协议可以在数据包传送率、端到端延时和网络吞吐量指标上达到平衡,而基本地理位置路由协议在端到端延时指标上可获得更好的性能.     

一种考虑能量的自组网概率路由协议

从均衡消耗网络节点能量的角度出发，提出了一种考虑能量的自组网概率路由协议（Energy—Aware Probability Routing，EAPR）。EAPR在DSR（Dynamic Source Routing）路由发现过程中引入了概率模型。隐式地均衡通信流量，进而均衡消耗网络各节点能量。对概率模型中的系数α进行了分析，并使用仿真验证了系数α对于EAPR性能的影响。基于仿真结果对EAPR和LEAR（Local Energy-Aware Routing）进行了比较和分析。