Forwarding Capability Research Articles

Proactively Placing Static Relays With Social-Link Awareness in Mobile Social Networks

Mobile social networks have been exploited for data forwarding due to its low cost and better robustness. Existing data forwarding strategies in mobile social networks rely on the pairwise contacts among mobile users. However, these pairwise contacts only provide limited forwarding capabilities and most data fail to be delivered before the expiration time. In this paper, we improve the performance of data forwarding by proactively placing low-cost static relays to increase the opportunistic contacts among the mobile nodes. Based on this idea, an important question is where to place the static relays in the network to best facilitate data forwarding among nodes. To answer this question, we first analyze four real-world datasets of mobile social networks, and identify that data forwarding only appears in a small group of social links. Then, we formalize the problem of static relay placement as an optimization problem, and propose a heuristic based solution to improve the data forwarding performance along these social links. Considering the fact that the social links may evolve over time, we also propose an efficient relay replacement algorithm which replaces the outdated relays with new relays to further improve the data forwarding performance. Evaluation results show that the proposed relay based solutions can significantly improve the performance of data forwarding in mobile social networks.

Exploration of Wireless Multimedia Sensor Network Based on Joint Photographic Experts Group Image Coding Algorithm

to study the performance of image coding and image transmission of wireless video sensor node in wireless multimedia sensor network, the challenges and design objectives of image coding technology in wireless multimedia sensor network are discussed, and the classification and exploration are carried out from two aspects: individual source coding and distributed source coding. The compression of video monitoring image sequence in wireless multimedia sensor network is studied and a low complexity image coding scheme based on change detection and improved Joint Photographic Experts Group (JPEG) algorithm is proposed. The moving target in the monitoring image is located with the change detection algorithm, that is, the area of interest. Only the region of interest is transmitted to reduce the quantity of data transmission and adapt to the limited storage and forwarding capability of wireless sensor nodes; The Discrete Cosine Transform (DCT) and quantization processes in Joint Photographic Experts Group (JPEG) algorithm are improved to reduce the computational complexity and adapt to the limited computing power of wireless sensor nodes.The analysis of algorithm complexity and the results of simulation experiment show that the proposed method can effectively reduce the data communication amount of wireless sensor nodes and the energy consumption in the calculation process while ensuring the image quality required by the application.Wireless multimedia sensor network is a new and interdisciplinary subject.The study of it is also multidirectional and multi-angle.The image coding algorithm of wireless multimedia sensor network is studied deeply.Although some achievements have been made, there are still a lot of problems that need to be further studied.

A Transmission Prediction Mechanism Exploiting Comprehensive Node Forwarding Capability in Opportunistic Networks

Opportunistic network enables users to form an instant network for data sharing, which is a type of Ad-hoc network in nature, thus depends on cooperation between nodes to complete message transmission. Because of intermittent communication and frequent changes of topology structure in opportunistic networks, the duration of node encounters is limited, as well as the length of established connections. If the amount of interactive data is large and the communication bandwidth is small, the messages that need to be transmitted are not guaranteed to be delivered successfully every time. In this regard, this paper establishes a transmission prediction mechanism exploiting comprehensive node forwarding capability (TPMEC) in opportunistic networks. When quantifying the forwarding capability of nodes, the algorithm not only considers the cooperative tendency but also discusses the encounter strength between nodes. At the same time, in order to find out all key nodes during the transmission process, the algorithm adopts the theory of matrix decomposition to predict and supplement the missing forwarding capability value of nodes, thus improving the efficiency of message transmission. Simulation results show that compared with ITPCM algorithm, ETNS algorithm, Spray and Wait algorithm, and PRoPHET algorithm, the proposed scheme has the highest transmission success ratio and the lowest routing overhead.

Energy-constrained transmission on hybrid communication networks

The real communication systems usually consist of different types of agents, e.g. computers, routers, base stations and mobile phones, forming various hybrid communication networks. Furthermore, in many cases, those agents are energy-constrained resulting in a limited lifetime of the communication networks. We proposed a hybrid communication network model composed of energy-constrained base stations and mobile users, and further gave a novel energy-aware gateway selection strategy to balance the energy consumption of base stations. We developed a new metric of nodes, called node forwarding strength, which measures the intrinsic forwarding capability of nodes and is basically dependent on the network structure and routing protocol. Based on this metric, we further derived the critical packet generation rate of traffic congestion, average number of transmission hops, and network lifetime. By investigating the influence of factors on the network lifetime, we obtained the optimal user moving speed and gateway selection parameter corresponding to the maximum network lifetime. Our work may provide some clues for the designing and optimization of real hybrid communication systems.

Multi-interface Gateway Protocol Conversion Method for Nearspace-air-vehicle-ground Dedicated Network

There are many kinds of monitoring and detecting load equipments in the Nearspace-air-vehicle-ground network, including visible light, infrared pods and various sensors, and there are various bus interfaces for communication and transmission of different types of loads, including network port, RS422, CAN, LVDS and so on. This paper proposes the use of FPGA and embedded Linux system software and hardware cooperation method to achieve interoperability between multi-bus interface and Ethernet, making full use of software flexibility and hardware fast forwarding capabilities. The test results show that this method realizes the data transmission between the multi-interface bus and Ethernet, and plays an important role in the transmission of information between the landing platform and ground in the Nearspace-air-vehicle-ground Dedicated Network

Connectivity Modeling and Analysis for Internet of Vehicles in Urban Road Scene

The connectivity of a large-scale heterogeneous Internet of Vehicles (IoV) is an important challenge for the environment of urban road scenes, which feature crossroads, buildings, and communication devices. The uneven density and wide distribution of vehicles in the city, the building barriers, and the interference of other communication technology will make the connectivity weaker. To the best of our knowledge, there is no formal method to model and analyze connectivity by considering the environment of urban road scenes. This paper presents such a theoretical method to investigate four connectivity properties- i.e., possibility, data forwarding time, link forwarding capability, and packet error rate-and deduce a connectivity model. Using experiments, we prove that the proposed model can ensure that the connectivity is effective and reliable in an urban road scene, and it can be used to accurately evaluate the network connectivity of a highly dynamic IoV.

CADD: connectivity-aware data dissemination using node forwarding capability estimation in partially connected VANETs

The recent development of the vehicular ad hoc networks (VANETs) has motivated an increasing interest in vehicular services and applications, such as active safety service and the infotainment service. Effective data Dissemination has become more and more important in vehicular services sharing. In this paper, the connectivity characteristics of VANETs are theoretically analyzed and implemented to show the partial connections in vehicle to vehicle communication. Hence, we propose the connectivity-aware data dissemination (CADD) in partially connected VANETs will improve the data transmission capacity. In the CADD protocol, a new metric of the node forwarding capability estimation is introduced. The metric is designed by the combination the throughput function and the active connection time estimation. And then, the high efficiency data dissemination protocol is designed by the new metric. Simulation results show that the CADD protocol outperforms existing solutions in terms of the packet delivery ratio, the transmission delay, and the protocol overhead under the condition of the intermittent network connectivity.

An Efficient DSR Protocol to Detect Blackhole Attacks in WMN Using Cross Layer Approach

Constructing an efficient and secured Wireless Mesh Network is a challenging issue due to its physical channel vulnerability and dynamic change of topology. In this network, attacks on network layer have vital significance since they may lead to disabling of larger scale network services. Secured Routing Protocol plays a major role in providing seamless network services. A Modified DSR protocol is proposed in this paper to overcome the blackhole attacks by detecting malicious nodes in the network. The proposed work computes the trust level of the path in the network layer by calculating the capability of the links. The link forwarding capability of the links is calculated at the link layer and node forwarding capability is calculated at network layer based on the behavior of the nodes. The nodes operate in the promiscuous mode to detect the misbehaving nodes. The performance of the modified DSR protocol is compared with DSR protocol and the simulation results show that the throughput and packet delivery ratio for the proposed work is better than DSR even in the presence of malicious nodes with minimal network overhead.

Intermittent geocast routing in urban vehicular delay tolerant networks

Nowadays, both vehicular active safety service and user infotainment service have become two core applications for urban Vehicular Delay Tolerant Networks (uVDTNs). Both core applications require a high data transmission capacity over uVDTNs. In addition, the connection between any two vehicles in uVDTNs is intermittent and opportunistic. Intermittent data dissemination over uVDTNs is a stringent and challenging issue. In this paper, we propose Intermittent Geocast Routing (IGR). For the first step, IGR has to estimate the active connection time interval via the moving directions and velocities between any two vehicles. Second, the throughput function for uVDTNs is fitted by building a wavelet neural network traffic model. Third, the throughput function within the effective connection time interval is integrated to obtain the forwarding capability estimation of the node. Fourth, a high-efficiency geocast routing algorithm using the node forwarding capability for uVDTNs is designed. Finally, IGR is simulated on the opportunistic Network Environment simulator. Experimental results show that IGR can greatly improve the packet delivery ratio, transmission delay, delay jitter, and packet loss rate compared with the state of the art.

Exploiting Small World Properties for Message Forwarding in Delay Tolerant Networks

In Delay Tolerant Networks (DTNs), the connections between mobile nodes are always disrupted and constant end-to-end paths rarely exist. In order to cope with these communication challenges, most existing DTN routing algorithms favour the “multi-hop forwarding” fashion where a message can be forwarded by multiple relay nodes in the hope that one of the employed relay nodes can deliver the message to the destination node. Since aggressively employing relay nodes may incur the intolerable delivery cost in DTNs, it is meaningful to design a cost-efficient routing algorithm that can achieve a high delivery performance. In this paper, we first design a novel delivery metric to measure the forwarding capability of nodes. Then, we utilize small-world properties to design the principles of relay node selection, e.g., limiting the number of relays and finding the appropriate relay nodes, and further develop a cost-efficient social-aware forwarding algorithm called TBSF. Extensive simulations on real mobility traces are conducted to evaluate the performance of TBSF, and the results demonstrate its efficiency and usefulness.

CAMF: Context-Aware Message Forwarding in Mobile Social Networks

In mobile social networks (MSN), with the aim of conserving limited resources, egotistic nodes might refuse to forward messages for other nodes. Different from previous work which mainly focuses on promoting cooperation between selfish nodes, we consider it from a more pragmatic perspective in this paper. Be specific, we regard selfishness as a native attribute of a system and allow nodes to exhibit selfish behavior in the process of message forwarding. Apparently, selfishness has a profound influence on routing efficiency, and thus novel mechanisms are necessary to improve routing performance when self-centered nodes are considered. We first put forward a stateless approach to measure encounter opportunities between nodes, and represent forwarding capabilities of nodes by combining the acquired encounter opportunities with node selfishness. We then quantify receiving capabilities of nodes based on their available buffer size and energy. Taking both forwarding and receiving capabilities into account, we finally present a forwarding set mechanism, which could be deduced to a multiple knapsack problem to maximize the forwarding profit. Consequently, we take all the above studies into the design of a context-aware message forwarding algorithm (CAMF). Extensive trace-driven simulations show that CAMF outperforms other existing algorithms greatly. In fact, it achieves a surprisingly high routing performance while consumes low transmission cost and resource in MSN.

Emulation of Shortest Path Algorithm in Software Defined Networking Environment

The field of Computer network has evolved a lot since the last three decades from conventional static networks to dynamically programmed architecture. The main goal of Software Defined Networking (SDN) is for the network to be open and programmable. Traditional network devices like router and switches can take routing decision and forwarding of these packets, SDN separate these component into different planes by pulling different component apart called as Data plane and Control plane. Hence the switches only have packet forwarding capability and cannot make any routing decisions, while decision making is done by the controller. OpenFlow is the interface that helps the switches and the controller to communicate. It is a communication protocol that enables the controller to determine the route of the network packet via the switches. This project implements the Bellman – Ford algorithm to find the shortest path between two nodes in a network using SDN environment. POX API’s has been used to implement the Bellman – Ford Algorithm.

Optimized Inter-Landmark Routing by Dtn-Flow Algorithm

2 Abstract: This Paper focus on the well-organized routing of data in the middle of dissimilar areas in delay tolerant networks (DTN).In the current algorithm selects widely held places that nodes visit repeatedly as landmarks and splits the complete DTN area into subareas signified by landmarks. The number of node transfers between two landmarks is computed to represent the forwarding capability between them, relyupon which routing tables are created on each and every landmark to route the packet routing. However, there is more number of landmarks for a single path, throughput depends upon the traffic, the only static path is available, and no mobility nodes can be used. To overcome this problem, we suggest an Ad-hoc On Demand Distance Vector (AODV) routing technique in DTN flow algorithm to enhance node to node communication and for effective throughput is proposed. This technique can be used on all mobility nodes and efficient throughput can be obtained by the utilization of all nodes. The number of landmarks and the total cost is limited. Overall performance will be multiplied by increasing the N range of dynamic methods.

ML-SOR: Message routing using multi-layer social networks in opportunistic communications

Opportunistic networks are a generalization of DTNs in which disconnections are frequent and encounter patterns between mobile devices are unpredictable. In such scenarios, message routing is a fundamental issue. Social-based routing protocols usually exploit the social information extracted from the history of encounters between mobile devices to find an appropriate message relay. Protocols based on encounter history, however, take time to build up a knowledge database from which to take routing decisions. While contact information changes constantly and it takes time to identify strong social ties, other types of ties remain rather stable and could be exploited to augment available partial contact information. In this paper, we start defining a multi-layer social network model combining the social network detected through encounters with other social networks and investigate the relationship between these social network layers in terms of node centrality, community structure, tie strength and link prediction. The purpose of this analysis is to better understand user behavior in a multi-layered complex network combining online and offline social relationships. Then, we propose a novel opportunistic routing approach ML-SOR (Multi-layer Social Network based Routing) which extracts social network information from such a model to perform routing decisions. To select an effective forwarding node, ML-SOR measures the forwarding capability of a node when compared to an encountered node in terms of node centrality, tie strength and link prediction. Trace driven simulations show that a routing metric combining social information extracted from multiple social network layers allows users to achieve good routing performance with low overhead cost.

QoF: Towards Comprehensive Path Quality Measurement in Wireless Sensor Networks

Due to its large scale and constrained communication radius, a wireless sensor network mostly relies on multi-hop transmissions to deliver a data packet along a sequence of nodes. It is of essential importance to measure the forwarding quality of multi-hop paths and such information shall be utilized in designing efficient routing strategies. Existing metrics like ETX, ETF mainly focus on quantifying the link performance in between the nodes while overlooking the forwarding capabilities inside the sensor nodes. The experience on manipulating GreenOrbs, a large-scale sensor network with 330 nodes, reveals that the quality of forwarding inside each sensor node is at the least an equally important factor that contributes to the path quality in data delivery. In this paper we propose QoF, Quality of Forwarding, a new metric which explores the performance in the gray zone inside a node left unattended in previous studies. By combining the QoF measurements within a node and over a link, we are able to comprehensively measure the intact path quality in designing efficient multi-hop routing protocols. We implement QoF and build a modified Collection Tree Protocol (CTP). We evaluate the data collection performance in a testbed consisting of 50 TelosB nodes, and compare it with the original CTP protocol. The experimental results show that our approach takes both transmission cost and forwarding reliability into consideration, thus achieving a high throughput for data collection.

Quadrant Based DIR in CWin Adaptation Mechanism for Multihop Wireless Network

In Multihop Wireless Networks, traffic forwarding capability of each node varies according to its level of contention. Each node can yield its channel access opportunity to its neighbouring nodes, so that all the nodes can evenly share the channel and have similar forwarding capability. In this manner the wireless channel is utilize d effectively, which is achieved using Contention Window Adaptation Mechanism (CWAM). This mechanism achieves a higher end to - end throughout but consumes the network power to a higher level. So, a newly proposed algorithm Quadrant Based Directional Routing Protocol (Q-DIR) is implemented as a cross - layer with CWAM, to reduce the total network power consumption through limited flooding and also reduce the routing overheads, which eventually increases overall network throughput. This algorithm limits the broadcast region to a quadrant where the source node and the destination nodes are located. Implementation of the algorithm is done in Linux based NS-2 simulator.

Performance Analysis on Two-Way Relay System with Co-Channel Interference

In this paper, we investigate the performance of two-way relay system with co-channel interference in a Rayleigh fading environment. Due to the mathematical intractability of original expression of signal-to-interference and noise ratio (SINR) induced by the bi-directional forwarding, a couple of effective bounds are derived for important performance metrics such as outage probability and average bit error rate of modulation, with application of diverse physical layer network coding (PNC) schemes of two time slot (2TS) and three time slot (3TS). Some asymptotic solutions are also proposed to intuitively exhibit the trends of performance in high SINR regime. We demonstrate that the performance bounds have practical meaning corresponding to different forwarding capability of the relay. Numeric simulations validate our analysis by showing that the theoretic bounds match well with simulation results. Additionally, the effect of distance between relay and sources is discussed in our interference scenario, as well as the impact of relay's power allocation factor in 3TS PNC scheme.

Fair and optimal dynamic admission control of elastic flows

The task of assigning part of the forwarding capability of a router to different flows, usually called admission control, is considered and an algorithm to handle the requests is developed. The idea is to admit not only the acceptance and the rejection answers but also a third kind of answer that occurs when there is no available share of the resource at the instant of the request but there may be a quote of resource available in a determined time-window in the future, provided that the active flows are suitably decreased. The algorithm guarantees both the fair occupancy of the resource and the optimality of its usage. Moreover, the only information on which the algorithm relies is the number of flows, and for each one, the minimum bandwidth needed and the desired bandwidth.

GMPLS-enabled MPLS-TP/PWE3 node with integrated 10 Gbps tunable DWDM transponders: design and experimental evaluation

In this paper we propose a more cost-efficient alternative to current transport network technologies (SONET/SDH) based on the high-bandwidth transport and deterministic performance of the optical circuit technologies (i.e., WSON) along with the efficient aggregation and statistical multiplexing of a packet transport technology (i.e., MPLS-TP) to support IP and Ethernet services. The purpose is to achieve cost reductions, simplified operations and flexible scalability in transport networks. We present the architectural design, implementation and the performance evaluation of the forwarding capabilities of a MPLS-TP/PWE3 node with integrated 10Gbps tunable DWDM transponders, extending the GMPLS-enabled WSON transport network of the ADRENALINE Testbed. The node has been implemented using commercial off-the-shelf hardware and the forwarding engine has been implemented using open source software. An evaluation of the node is provided by means of analyzing the obtained throughput and CPU usage in different evaluation scenarios with different traffic grooming and traffic aggregation strategies.

MobiCom 2011 poster

Opportunistic networking is a mobile communication paradigm utilizing spontaneously arising networking options for data forwarding. Although node movement affects the forwarding capabilities of these nodes, the utilization of this knowledge for local forwarding decisions is still not sufficiently exploited and a major aim of our approach. We describe node heterogeneity along movement features capturing urban user movement and how to derive movement activities from these features. Hereby, we summarize main results of an experimental study based on real-world GPS data of 252 daily trips. In a second step, we explain how movement characteristics of mobile nodes may influence data dissemination and present first simulation results indicating that the heterogeneity in movement activities indeed influences the performance of opportunistic data dissemination.