Showing papers on "Routing protocol published in 2010"

Improving the Scalability of Data Center Networks with Traffic-aware Virtual Machine Placement

Abstract: The scalability of modern data centers has become a practical concern and has attracted significant attention in recent years. In contrast to existing solutions that require changes in the network architecture and the routing protocols, this paper proposes using traffic-aware virtual machine (VM) placement to improve the network scalability. By optimizing the placement of VMs on host machines, traffic patterns among VMs can be better aligned with the communication distance between them, e.g. VMs with large mutual bandwidth usage are assigned to host machines in close proximity. We formulate the VM placement as an optimization problem and prove its hardness. We design a two-tier approximate algorithm that efficiently solves the VM placement problem for very large problem sizes. Given the significant difference in the traffic patterns seen in current data centers and the structural differences of the recently proposed data center architectures, we further conduct a comparative analysis on the impact of the traffic patterns and the network architectures on the potential performance gain of traffic-aware VM placement. We use traffic traces collected from production data centers to evaluate our proposed VM placement algorithm, and we show a significant performance improvement compared to existing general methods that do not take advantage of traffic patterns and data center network characteristics.

Design and implementation of smart home energy management systems based on zigbee

Abstract: Today, organizations use IEEE802.15.4 and ZigBee to effectively deliver solutions for a variety of areas including consumer electronic device control, energy management and efficiency home and commercial building automation as well as industrial plant management. The Smart home energy network has gained widespread attentions due to its flexible integration into everyday life. This next generation green home system transparently unifies various home appliances, smart sensors and wireless communication technologies. The green home energy network gradually forms a complex system to process various tasks. Developing this trend, we suggest a new Smart Home Energy Management System (SHEMS) based on an IEEE802.15.4 and ZigBee (we call it as a "ZigBee sensor network"). The proposed smart home energy management system divides and assigns various home network tasks to appropriate components. It can integrate diversified physical sensing information and control various consumer home devices, with the support of active sensor networks having both sensor and actuator components. We develop a new routing protocol DMPR (Disjoint Multi Path based Routing) to improve the performance of our ZigBee sensor networks. This paper introduces the proposed home energy control system's design that provides intelligent services for users. We demonstrate its implementation using a real environment.

DV-CAST: A distributed vehicular broadcast protocol for vehicular ad hoc networks

Abstract: The potential of infrastructureless vehicular ad hoc networks for providing safety and nonsafety applications is quite significant. The topology of VANETs in urban, suburban, and rural areas can exhibit fully connected, fully disconnected, or sparsely connected behavior, depending on the time of day or the market penetration rate of wireless communication devices. In this article we focus on highway scenarios, and present the design and implementation of a new distributed vehicular multihop broadcast protocol, that can operate in all traffic regimes, including extreme scenarios such as dense and sparse traffic regimes. DV-CAST is a distributed broadcast protocol that relies only on local topology information for handling broadcast messages in VANETs. It is shown that the performance of the proposed DV-CAST protocol in terms of reliability, efficiency, and scalability is excellent.

A Survey of BGP Security Issues and Solutions

Abstract: As the Internet's de facto interdomain routing protocol, the Border Gateway Protocol (BGP) is the glue that holds the disparate parts of the Internet together. A major limitation of BGP is its failure to adequately address security. Recent high-profile outages and security analyses clearly indicate that the Internet routing infrastructure is highly vulnerable. Moreover, the design of BGP and the ubiquity of its deployment have frustrated past efforts at securing interdomain routing. This paper considers the current vulnerabilities of the interdomain routing system and surveys both research and standardization efforts relating to BGP security. We explore the limitations and advantages of proposed security extensions to BGP, and explain why no solution has yet struck an adequate balance between comprehensive security and deployment cost.

Bidirectional Forwarding Detection (BFD)

Abstract: This document describes a protocol intended to detect faults in the bidirectional path between two forwarding engines, including interfaces, data link(s), and to the extent possible the forwarding engines themselves, with potentially very low latency. It operates independently of media, data protocols, and routing protocols. [STANDARDS-TRACK]

QELAR: A Machine-Learning-Based Adaptive Routing Protocol for Energy-Efficient and Lifetime-Extended Underwater Sensor Networks

Abstract: Underwater sensor network (UWSN) has emerged in recent years as a promising networking technique for various aquatic applications. Due to specific characteristics of UWSNs, such as high latency, low bandwidth, and high energy consumption, it is challenging to build networking protocols for UWSNs. In this paper, we focus on addressing the routing issue in UWSNs. We propose an adaptive, energy-efficient, and lifetime-aware routing protocol based on reinforcement learning, QELAR. Our protocol assumes generic MAC protocols and aims at prolonging the lifetime of networks by making residual energy of sensor nodes more evenly distributed. The residual energy of each node as well as the energy distribution among a group of nodes is factored in throughout the routing process to calculate the reward function, which aids in selecting the adequate forwarders for packets. We have performed extensive simulations of the proposed protocol on the Aqua-sim platform and compared with one existing routing protocol (VBF) in terms of packet delivery rate, energy efficiency, latency, and lifetime. The results show that QELAR yields 20 percent longer lifetime on average than VBF.

A Survey of BGP Security Issues and Solutions The Border Gateway Protocol (BGP) controls much of Internet traffic, but is vulnerable to communications interruptions and failures; finding suitable improved security measures with acceptable costs is difficult.

Abstract: As the Internet's de facto interdomain routing protocol, the Border Gateway Protocol (BGP) is the glue that holds the disparate parts of the Internet together. A major limitation of BGP is its failure to adequately address security. Recent high-profile outages and security analyses clearly indicate that the Internet routing infrastructure is highly vulnerable. Moreover, the design of BGP and the ubiquity of its deployment have frustrated past efforts at securing inter- domainrouting.Thispaperconsidersthecurrentvulnerabilities of the interdomain routing system and surveys both research and standardization efforts relating to BGP security. We explore the limitations and advantages of proposed security extensions to BGP, and explain why no solution has yet struck an adequate balance betweencomprehensive security anddeployment cost.

Routing without routes: the backpressure collection protocol

Abstract: Current data collection protocols for wireless sensor networks are mostly based on quasi-static minimum-cost routing trees. We consider an alternative, highly-agile approach called backpressure routing, in which routing and forwarding decisions are made on a per-packet basis. Although there is a considerable theoretical literature on backpressure routing, it has not been implemented on practical systems to date due to concerns about packet looping, the effect of link losses, large packet delays, and scalability. Addressing these concerns, we present the Backpressure Collection Protocol (BCP) for sensor networks, the first ever implementation of dynamic backpressure routing in wireless networks. In particular, we demonstrate for the first time that replacing the traditional FIFO queue service in backpressure routing with LIFO queues reduces the average end-to-end packet delays for delivered packets drastically (75% under high load, 98% under low load). Further, we improve backpressure scalability by introducing a new concept of floating queues into the backpressure framework. Under static network settings, BCP shows a more than 60% improvement in max-min rate over the state of the art Collection Tree Protocol (CTP). We also empirically demonstrate the superior delivery performance of BCP in highly dynamic network settings, including conditions of extreme external interference and highly mobile sinks.

DistressNet: a wireless ad hoc and sensor network architecture for situation management in disaster response

Abstract: Situational awareness in a disaster is critical to effective response. Disaster responders require timely delivery of high volumes of accurate data to make correct decisions. To meet these needs, we present DistressNet, an ad hoc wireless architecture that supports disaster response with distributed collaborative sensing, topology-aware routing using a multichannel protocol, and accurate resource localization. Sensing suites use collaborative and distributed mechanisms to optimize data collection and minimize total energy use. Message delivery is aided by novel topology management, while congestion is minimized through the use of mediated multichannel radio protocols. Estimation techniques improve localization accuracy in difficult environments.

A Survey of Energy-Efficient Hierarchical Cluster-Based Routing in Wireless Sensor

Abstract: ------------------------------------------------------------------------------------------------------------------------------------Recent technological advances in communications and computation have enabled the development of low-cost, low-power, small in size, and multifunctional sensor nodes in a wireless sensor network. Since the radio transmission and reception consumes a lot of energy, one of the important issues in wireless sensor network is the inherent limited battery power within network sensor nodes. Therefore, battery power is crucial parameter in the algorithm design to increase lifespan of nodes in the network. In addition to maximizing the lifespan of sensor nodes, it is preferable to distribute the energy dissipated throughout the wireless sensor network in order to maximize overall network performance. Much research has been done in recent years, investigating different aspects like, low power protocols, network establishments, routing protocol, and coverage problems of wireless sensor networks. There are various routing protocols like location-aided, multi-path, datacentric, mobility-based, QoS based, heterogeneity-based, hierarchical routing, hybrid routing, etc., in which optimal routing can be achieved in the context of energy. In this paper, the focus is mainly driven over the survey of the energy-efficient hierarchical cluster-based available routings for Wireless Sensor Network.

Greening backbone networks: reducing energy consumption by shutting off cables in bundled links

Abstract: In backbone networks, the line cards that drive the links between neighboring routers consume a large amount of energy. Since these networks are typically overprovisioned, selectively shutting down links during periods of low demand seems like a good way to reduce energy consumption. However, removing entire links from the topology often reduces capacity and connectivity too much, and leads to transient disruptions in the routing protocol. In this paper, we exploit the fact that many links in core networks are actually 'bundles' of multiple physical cables and line cards that can be shut down independently. Since identifying the optimal set of cables to shut down is an NP-complete problem, we propose several heuristics based on linear optimization techniques. We evaluate our heuristics on topology and traffic data from the Abilene backbone as well as on two synthetic topologies. The energy savings are significant, our simplest heuristic reduces energy consumption by 79% on Abilene under realistic traffic loads and bundled links consisting of five cables. Our optimization techniques run efficiently using standard optimization tools, such as the AMPL/CPLEX solver, making them a practical approach for network operators to reduce the energy consumption of their backbones.

Routing Protocols in Vehicular Ad Hoc Networks: A Survey and Future Perspectives

Abstract: Vehicular Ad hoc Network (VANET), a subclass of mobile ad hoc networks (MANETs), is a promising approach for the intelligent transportation system (ITS). The design of routing protocols in VANETs is important and necessary issue for support the smart ITS. The key difference of VANET and MANET is the special mobility pattern and rapidly changeable topology. It is not effectively applied the existing routing protocols of MANETs into VANETs. In this investigation, we mainly survey new routing results in VANET. We introduce unicast protocol, multicast protocol, geocast protocol, mobicast protocol, and broadcast protocol. It is observed that carry-and-forward is the new and key consideration for designing all routing protocols in VANETs. With the consideration of multi-hop forwarding and carry-and-forward techniques, min-delay and delay-bounded routing protocols for VANETs are discussed in VANETs. Besides, the temporary network fragmentation problem and the broadcast storm problem are further considered for designing routing protocols in VANETs. The temporary network fragmentation problem caused by rapidly changeable topology influence on the performance of data transmissions. The broadcast storm problem seriously affects the successful rate of message delivery in VANETs. The key challenge is to overcome these problems to provide routing protocols with the low communication delay, the low communication overhead, and the low time complexity. The challenges and perspectives of routing protocols for VANETs are finally discussed.

Symbiotic routing in future data centers

Abstract: Building distributed applications that run in data centers is hard. The CamCube project explores the design of a shipping container sized data center with the goal of building an easier platform on which to build these applications. CamCube replaces the traditional switch-based network with a 3D torus topology, with each server directly connected to six other servers. As in other proposals, e.g. DCell and BCube, multi-hop routing in CamCube requires servers to participate in packet forwarding. To date, as in existing data centers, these approaches have all provided a single routing protocol for the applications.In this paper we explore if allowing applications to implement their own routing services is advantageous, and if we can support it efficiently. This is based on the observation that, due to the flexibility offered by the CamCube API, many applications implemented their own routing protocol in order to achieve specific application-level characteristics, such as trading off higher-latency for better path convergence. Using large-scale simulations we demonstrate the benefits and network-level impact of running multiple routing protocols. We demonstrate that applications are more efficient and do not generate additional control traffic overhead. This motivates us to design an extended routing service allowing easy implementation of application-specific routing protocols on CamCube. Finally, we demonstrate that the additional performance overhead incurred when using the extended routing service on a prototype CamCube is very low.

Pressure Routing for Underwater Sensor Networks

Abstract: A SEA Swarm (Sensor Equipped Aquatic Swarm) is a sensor "cloud" that drifts with water currents and enables 4D (space and time) monitoring of local underwater events such as contaminants, marine life and intruders. The swarm is escorted at the surface by drifting sonobuoys that collect the data from underwater sensors via acoustic modems and report it in real-time via radio to a monitoring center. The goal of this study is to design an efficient anycast routing algorithm for reliable underwater sensor event reporting to any one of the surface sonobuoys. Major challenges are the ocean current and the limited resources (bandwidth and energy). In this paper, we address these challenges and propose HydroCast, a hydraulic pressure based anycast routing protocol that exploits the measured pressure levels to route data to surface buoys. The paper makes the following contributions: a novel opportunistic routing mechanism to select the subset of forwarders that maximizes greedy progress yet limiting co-channel interference; and an efficient underwater "dead end" recovery method that outperforms recently proposed approaches. The proposed routing protocols are validated via extensive simulations.

MR-LEACH: Multi-hop Routing with Low Energy Adaptive Clustering Hierarchy

Abstract: In this paper, we present a Multi-hop Routing with Low Energy Adaptive Clustering Hierarchy (MR-LEACH) protocol. In order to prolong the lifetime of Wireless Sensor Network (WSN), MR-LEACH partitions the network into different layers of clusters. Cluster heads in each layer collaborates with the adjacent layers to transmit sensor’s data to the base station. Ordinary sensor nodes join cluster heads based on the Received Signal Strength Indicator (RSSI). The transmission of nodes is controlled by a Base Station (BS) that defines the Time Division Multiple Access (TDMA) schedule for each cluster-head. BS selects the upper layers cluster heads to act as super cluster heads for lower layer cluster heads. Thus, MR-LEACH follows multi-hop routing from cluster-heads to a base station to conserve energy, unlike the LEACH protocol. Performance evaluation has shown that MR-LEACH achieves significant improvement in the LEACH protocol and provides energy efficient routing for WSN.

Routing for disruption tolerant networks: taxonomy and design

Abstract: Communication networks, whether they are wired or wireless, have traditionally been assumed to be connected at least most of the time. However, emerging applications such as emergency response, special operations, smart environments, VANETs, etc. coupled with node heterogeneity and volatile links (e.g. due to wireless propagation phenomena and node mobility) will likely change the typical conditions under which networks operate. In fact, in such scenarios, networks may be mostly disconnected, i.e., most of the time, end-to-end paths connecting every node pair do not exist. To cope with frequent, long-lived disconnections, opportunistic routing techniques have been proposed in which, at every hop, a node decides whether it should forward or store-and-carry a message. Despite a growing number of such proposals, there still exists little consensus on the most suitable routing algorithm(s) in this context. One of the reasons is the large diversity of emerging wireless applications and networks exhibiting such "episodic" connectivity. These networks often have very different characteristics and requirements, making it very difficult, if not impossible, to design a routing solution that fits all. In this paper, we first break up existing routing strategies into a small number of common and tunable routing modules (e.g. message replication, coding, etc.), and then show how and when a given routing module should be used, depending on the set of network characteristics exhibited by the wireless application. We further attempt to create a taxonomy for intermittently connected networks. We try to identify generic network characteristics that are relevant to the routing process (e.g., network density, node heterogeneity, mobility patterns) and dissect different "challenged" wireless networks or applications based on these characteristics. Our goal is to identify a set of useful design guidelines that will enable one to choose an appropriate routing protocol for the application or network in hand. Finally, to demonstrate the utility of our approach, we take up some case studies of challenged wireless networks, and validate some of our routing design principles using simulations.

Cross-Layer Routing and Dynamic Spectrum Allocation in Cognitive Radio Ad Hoc Networks

Abstract: Throughput maximization is one of the main challenges in cognitive radio ad hoc networks, where the availability of local spectrum resources may change from time to time and hop by hop. For this reason, a cross-layer opportunistic spectrum access and dynamic routing algorithm for cognitive radio networks is proposed, which is called the routing and dynamic spectrum-allocation (ROSA) algorithm. Through local control actions, ROSA aims to maximize the network throughput by performing joint routing, dynamic spectrum allocation, scheduling, and transmit power control. Specifically, the algorithm dynamically allocates spectrum resources to maximize the capacity of links without generating harmful interference to other users while guaranteeing a bounded bit error rate (BER) for the receiver. In addition, the algorithm aims to maximize the weighted sum of differential backlogs to stabilize the system by giving priority to higher capacity links with a high differential backlog. The proposed algorithm is distributed, computationally efficient, and has bounded BER guarantees. ROSA is shown through numerical model-based evaluation and discrete-event packet-level simulations to outperform baseline solutions, leading to a high throughput, low delay, and fair bandwidth allocation.

Rethinking Indoor Wireless Mesh Design: Low Power, Low Frequency, Full-Duplex

Abstract: Existing indoor WiFi networks in the 2.5GHz and 5 GHz use too much transmit power, needed because the high carrier frequency limits signal penetration and connectivity. Instead, we propose a novel indoor wireless mesh design paradigm, based on Low Frequency, using the newly freed white spaces previously used as analogue TV bands, and Low Power - 100 times less power than currently used. Preliminary experiments show that this maintains a similar level of connectivity and performance to existing networks. It also yields more uniform connectivity, thus simplifies MAC and routing protocol design. We also advocate full-duplex networking in a single band, which becomes possible in this setting (because we operate at low frequencies). It potentially doubles the throughput of each link and eliminates hidden terminals.

MobiCent: a Credit-Based Incentive System for Disruption Tolerant Network

Abstract: When Disruption Tolerant Network (DTN) is used in commercial environments, incentive mechanism should be employed to encourage cooperation among selfish mobile users. Key challenges in the design of an incentive scheme for DTN are that disconnections among nodes are the norm rather than exception and network topology is time varying. Thus, it is difficult to detect selfish actions that can be launched by mobile users or to pre-determine the routing path to be used. In this paper, we propose MobiCent, a credit-based incentive system for DTN. While MobiCent allows the underlying routing protocol to discover the most efficient paths, it is also incentive compatible. Therefore, using MobiCent, rational nodes will not purposely waste transfer opportunity or cheat by creating non-existing contacts to increase their rewards. MobiCent also provides different payment mechanisms to cater to client that wants to minimize either payment or data delivery delay.

Joint sink mobility and routing to maximize the lifetime of wireless sensor networks: the case of constrained mobility

Abstract: The longevity of wireless sensor networks (WSNs) is a major issue that impacts the application of such networks. While communication protocols are striving to save energy by acting on sensor nodes, recent results show that network lifetime can be prolonged by further involving sink mobility. As most proposals give their evidence of lifetime improvement through either (small-scale) field tests or numerical simulations on rather arbitrary cases, a theoretical understanding of the reason for this improvement and the tractability of the joint optimization problem is still missing. In this paper, we build a framework for investigating the joint sink mobility and routing problem by constraining the sink to a finite number of locations. We formally prove the NP-hardness of the problem. We also investigate the induced subproblems. In particular, we develop an efficient primal-dual algorithm to solve the subproblem involving a single sink, then we generalize this algorithm to approximate the original problem involving multiple sinks. Finally, we apply the algorithm to a set of typical topological graphs; the results demonstrate the benefit of involving sink mobility, and they also suggest the desirable moving traces of a sink.

DCAR: Distributed Coding-Aware Routing in Wireless Networks

Abstract: Recently, there has been a growing interest of using network coding to improve the performance of wireless networks, for example, authors of proposed the practical wireless network coding system called COPE, which demonstrated the throughput gain achieved by network coding. However, COPE has two fundamental limitations: (1) the coding opportunity is crucially dependent on the established routes and (2) the coding structure in COPE is limited within a two-hop region only. The aim of this paper is to overcome these limitations. In particular, we propose DCAR, the distributed coding-aware routing mechanism which enables: (1) the discovery for available paths between a given source and destination and (2) the detection for potential network coding opportunities over much wider network region. One interesting result is that DCAR has the capability to discover high throughput paths with coding opportunities, while conventional wireless network routing protocols fail to do so. In addition, DCAR can detect coding opportunities on the entire path, thus eliminating the ?two-hop? coding limitation in COPE. We also propose a novel routing metric called coding-aware routing metric (CRM) which facilitates the performance comparison between ?coding-possible? and "coding-impossible? paths. We implement the DCAR system in ns-2 and carry out extensive evaluation. We show that when comparing to the coding mechanism in, DCAR can achieve much higher throughput gain.

An Energy Saving Routing Algorithm for a Green OSPF Protocol

Abstract: In this paper we analyze the challenging problem of energy saving in IP networks. A novel network-level strategy based on a modification of current link-state routing protocols, such as OSPF, is proposed; according to this strategy, IP routers are able to power off some network links during low traffic periods. The proposed solution is a three-phases algorithm: in the first phase some routers are elected as "exporter" of their own Shortest Path Trees (SPTs); in the second one the neighbors of these routers perform a modified Dijkstra algorithm to detect links to power off; in the last one new network paths on a modified network topology are computed. Performance study shows that, in an actual IP network, even more than the 60% of links can be switched off.

Cognitive radios for dynamic spectrum access: from concept to reality

Abstract: This article provides a comprehensive survey of cognitive radio technology, focusing on its application to dynamic spectrum access, especially from the perspective of realizing consumer- oriented CR networks. We first overview the state of the art in CR technology and identify its key functions across the protocol stack, such as spectrum sensing, resource allocation, CR MAC protocol, spectrum-aware opportunistic routing, CR transport protocol, QoS awareness, spectrum trading, and security. We also review the various schemes proposed for each of these functions and discuss the suitability, advantages, and limitations of their usage in the future CR market. Finally, we introduce the activities in CR research communities and industry in terms of development of real-life applications, such as IEEE 802.22, Ecma 392, and IEEE 802.11af (also known as Wi-Fi 2.0 or White-Fi), and then identify necessary steps for future CR applications.

SourceSync: a distributed wireless architecture for exploiting sender diversity

Abstract: Diversity is an intrinsic property of wireless networks. Recent years have witnessed the emergence of many distributed protocols like ExOR, MORE, SOAR, SOFT, and MIXIT that exploit receiver diversity in 802.11-like networks. In contrast, the dual of receiver diversity, sender diversity, has remained largely elusive to such networks.This paper presents SourceSync, a distributed architecture for harnessing sender diversity. SourceSync enables concurrent senders to synchronize their transmissions to symbol boundaries, and cooperate to forward packets at higher data rates than they could have achieved by transmitting separately. The paper shows that SourceSync improves the performance of opportunistic routing protocols. Specifically, SourceSync allows all nodes that overhear a packet in a wireless mesh to simultaneously transmit it to their nexthops, in contrast to existing opportunistic routing protocols that are forced to pick a single forwarder from among the overhearing nodes. Such simultaneous transmission reduces bit errors and improves throughput. The paper also shows that SourceSync increases the throughput of 802.11 last hop diversity protocols by allowing multiple APs to transmit simultaneously to a client, thereby harnessing sender diversity. We have implemented SourceSync on the FPGA of an 802.11-like radio platform. We have also evaluated our system in an indoor wireless testbed, empirically showing its benefits.

Know Thy Neighbor: Towards Optimal Mapping of Contacts to Social Graphs for DTN Routing

Abstract: Delay Tolerant Networks (DTN) are networks of self-organizing wireless nodes, where end-to-end connectivity is intermittent. In these networks, forwarding decisions are generally made using locally collected knowledge about node behavior (e.g., past contacts between nodes) to predict future contact opportunities. The use of complex network analysis has been recently suggested to perform this prediction task and improve the performance of DTN routing. Contacts seen in the past are aggregated to a social graph, and a variety of metrics (e.g., centrality and similarity) or algorithms (e.g., community detection) have been proposed to assess the utility of a node to deliver a content or bring it closer to the destination. In this paper, we argue that it is not so much the choice or sophistication of social metrics and algorithms that bears the most weight on performance, but rather the mapping from the mobility process generating contacts to the aggregated social graph. We first study two well-known DTN routing algorithms - SimBet and BubbleRap - that rely on such complex network analysis, and show that their performance heavily depends on how the mapping (contact aggregation) is performed. What is more, for a range of synthetic mobility models and real traces, we show that improved performances (up to a factor of 4 in terms of delivery ratio) are consistently achieved for a relatively narrow range of aggregation levels only, where the aggregated graph most closely reflects the underlying mobility structure. To this end, we propose an online algorithm that uses concepts from unsupervised learning and spectral graph theory to infer this 'correct' graph structure; this algorithm allows each node to locally identify and adjust to the optimal operating point, and achieves good performance in all scenarios considered.

Indexing multi-dimensional data in a cloud system

Abstract: Providing scalable database services is an essential requirement for extending many existing applications of the Cloud platform. Due to the diversity of applications, database services on the Cloud must support large-scale data analytical jobs and high concurrent OLTP queries. Most existing work focuses on some specific type of applications. To provide an integrated framework, we are designing a new system, epiC, as our solution to next-generation database systems. In epiC, indexes play an important role in improving overall performance. Different types of indexes are built to provide efficient query processing for different applications. In this paper, we propose RT-CAN, a multi-dimensional indexing scheme in epiC. RT-CAN integrates CAN [23] based routing protocol and the R-tree based indexing scheme to support efficient multi-dimensional query processing in a Cloud system. RT-CAN organizes storage and compute nodes into an overlay structure based on an extended CAN protocol. In our proposal, we make a simple assumption that each compute node uses an R-tree like indexing structure to index the data that are locally stored. We propose a query-conscious cost model that selects beneficial local R-tree nodes for publishing. By keeping the number of persistently connected nodes small and maintaining a global multi-dimensional search index, we can locate the compute nodes that may contain the answer with a few hops, making the scheme scalable in terms of data volume and number of compute nodes. Experiments on Amazon's EC2 show that our proposed routing protocol and indexing scheme are robust, efficient and scalable.

LEACH-B: An Improved LEACH Protocol for Wireless Sensor Network

Abstract: Based on the analysis on the defect in LEACH including the fluctuation of the number of cluster heads and the ignorance of the node's residual energy, this paper presents a novel protocol called LEACH-B (LEACH-Balanced)At each round, after first selection of cluster head according to LEACH protocol, a second selection is introduced to modify the number of cluster head in consideration of node's residual energy As a result the number of cluster head is constant and near optimal per round The simulation by MATLAB shows that the improved protocol has balanced the system energy consumption and has better performance of prolonging the network lifetime than LEACH protocol

XLP: A Cross-Layer Protocol for Efficient Communication in Wireless Sensor Networks

Abstract: Severe energy constraints of battery-powered sensor nodes necessitate energy-efficient communication in Wireless Sensor Networks (WSNs). However, the vast majority of the existing solutions are based on the classical layered protocol approach, which leads to significant overhead. It is much more efficient to have a unified scheme, which blends common protocol layer functionalities into a cross-layer module. In this paper, a cross-layer protocol (XLP) is introduced, which achieves congestion control, routing, and medium access control in a cross-layer fashion. The design principle of XLP is based on the cross-layer concept of initiative determination, which enables receiver-based contention, initiative-based forwarding, local congestion control, and distributed duty cycle operation to realize efficient and reliable communication in WSNs. The initiative determination requires simple comparisons against thresholds, and thus, is very simple to implement, even on computationally constrained devices. To the best of our knowledge, XLP is the first protocol that integrates functionalities of all layers from PHY to transport into a cross-layer protocol. A cross-layer analytical framework is developed to investigate the performance of the XLP. Moreover, in a cross-layer simulation platform, the state-of-the-art layered and cross-layer protocols have been implemented along with XLP for performance evaluations. XLP significantly improves the communication performance and outperforms the traditional layered protocol architectures in terms of both network performance and implementation complexity.