Multi-hop Communication Network Research Articles

Fault Tolerant Control of Multi-Hop Control Networks

A multi-hop control network (MCN) consists of a plant where the communication between sensors, actuators, and computational units is supported by a (wireless) multi-hop communication network, and data flow is performed using scheduling and routing of sensing and actuation data. We address the control design problem on a MCN where the plant is a SISO LTI system and links are subject to permanent failures. We first characterize controllability and observability of a MCN: we provide necessary and sufficient conditions on the plant dynamics and on the communication scheduling, and we provide a design methodology to satisfy such conditions for any failure configuration. Then we address the problem of detecting the failure of links of the radio connectivity graph: we provide necessary and sufficient conditions on the plant dynamics and on the communication protocol, and we provide a design methodology to satisfy the above conditions.

Research on Topology Property for Wireless Multi-hop Communication Network

The random movement of nodes makes the topology structure be one of the most important characteristics in wireless multi-hop communication network, which makes the description and quantization of the dynamic property the very foundation of the design, simulation and measurement for this kind of network. Wireless Ad hoc network as a typical multi-hop network will be focused on in this paper. The distributions of the link duration and the topology duration will be derived and verified by simulations. Then, the topology flapping sensing method has been put forward based on TTL. Finally, the probability model of the topology stability in the measurement time has been established and calculated based on network tomography for wireless ad hoc network in this paper. Simulating results verify the correctness and efficiency of the approach, which will provide the technique basis of research on the dynamic property and end-to-end measurement for wireless multi-hop communication network. DOI: http://dx.doi.org/10.11591/telkomnika.v11i1.1907

Performance Evaluation of Multi-Hop Communication Based on a Mobile Multi-Robot System in a Subterranean Laneway

For disaster exploration and surveillance application, this paper aims to present a novel application of a multi-robot agent based on WSN and to evaluate a multi-hop communication caused by the robotics correspondingly, which are used in the uncertain and unknown subterranean tunnel. A Primary-Scout Multi-Robot System (PS-MRS) was proposed. A chain topology in a subterranean environment was implemented using a trimmed ZigBee2006 protocol stack to build the multi-hop communication network. The ZigBee IC-CC2530 modular circuit was adapted by mounting it on the PS-MRS. A physical experiment based on the strategy of PS-MRS was used in this paper to evaluate the efficiency of multi-hop communication and to realize the delivery of data packets in an unknown and uncertain underground laboratory environment.

Fault Tolerant Stabilizability of MIMO Multi-Hop Control Networks

A MIMO Multi-hop Control Network (MCN) consists of a MIMO LTI plant where the communication between sensors, actuators and computational units is supported by a (wireless) multi-hop communication network and data flow is performed using scheduling and routing of sensing and actuation data. We explicitly characterize by means of necessary and sufficient conditions the set of network configurations that invalidate controllability and observability of the plant. We show that checking such necessary and sufficient conditions can be solved with a complexity that is combinatorial with respect to the number of input and output signals. To overcome this difficulty, we propose an efficient algorithm to design the network configuration in linear time still guaranteeing controllability and observability.

Socially-Competent Computing Implementing Social Sensor Design

The paper presents a conceptual model for social sensor design in socially-competent computing systems. The model is based on theories of social behavior being driven by the underlying attitudes, rather than on models predicting behavior in response to behavior representing people as physical objects in dynamic interactions. It is proposed to increase the ability of the systems to extract relevant features and to achieve better social competence, similar to the kind that is underlying human interactions by implementing algorithms, capable of predicting behavior in response to attitude. The paper presents an account of the social level of understanding human interactions in the context of three application scenarios – multi-hop communication networks, embedded systems for support of medical interventions and information systems supporting educational activities. Patterns of real data are discussed in terms of the proposed model of social sensor design for enhanced socially-competent computing.

Backoff-stage synchronization in three-hop string-topology wireless networks with hidden nodes

In IEEE 802.11 wireless multi-hop networks, each node works individually and their individual operations generate entire network dynamics. It is important to clarify the network dynamics in wireless multi-hop networks for designing and constructing multi-hop communication networks. This paper presents the network-dynamics investigations for three-hop string-topology wireless network in detail. From the investigations, a “backoff-stage synchronization” phenomenon, which is mutuality between hidden nodes, is found. The mechanism of the backoff-stage synchronization is expressed and the sufficient conditions for the synchronization occurrence are given. This phenomenon gives some impacts on the IEEE 802.11 multi-hop-network communications.

Applying dynamic reconfiguration in the mobile robotics domain

Mobile robots are widely used in industrial environments and are expected to be widely available in human environments in the near future, for example, in the area of care and service robots. This article proposes an implementation for a highly customizable color recognition module based on Field Programmable Gate Array (FPGA) hardware to accomplish tasks like real-time frame processing for image streams. In comparison to a pure software solution on a CPU, an attached FPGA-based hardware accelerator enables real-time image processing and significantly reduces the required computing power of the CPU. Instead, the CPU can be used for tasks that cannot be efficiently implemented on FPGAs, for example, because of a large control overhead. We concentrate on a multirobot scenario where a group of robots follows a human team member by keeping a specific formation in order to support the human in exploration and object detection. Additionally, the robots provide a communication infrastructure to maintain a stable multihop communication network between the human and a base station recording all actions and evaluating the captured images and transmitted data. Depending on the current operating conditions, the robot system has to be able to execute a wide variety of different tasks. Since only a small number of tasks have to be executed concurrently, dynamic reconfiguration of the FPGA can be used to avoid the parallel implementation of all tasks on the FPGA. Within this context, this article discusses application fields where dynamic reconfiguration of FPGA-based coprocessors significantly reduces the CPU load and presents examples of how dynamic reconfiguration can be used in exploration.

Rate Control for Network-Coded Multipath Relaying with Time-Varying Connectivity

This paper presents techniques for achieving high throughput in delay-constrained, multihop wireless communication networks with time-varying link connectivity. We develop a rate-controlled, multipath strategy using network coding, and compare its performance with that of multipath flooding and with the performance of traditional single-path strategies. These performance comparisons include both theoretical benchmarks and simulation results from cooperative relay scenarios, which incorporate different sets of link connectivity statistics that are drawn from field tests of mobile satellite communication terminals. The results indicate that with appropriate rate-control, network coding can provide throughput performance comparable to multipath flooding of the network while utilizing bandwidth nearly as efficiently as single-path routing.

Targeted coupon distribution using social networks

We propose to exploit online social networks in order to reveal user preferences such that goods and services might be targeted appropriately. We consider goods and services that are consumed periodically, and a user model where users could buy different numbers of goods at a marked ("high") price and at a discounted ("low") price. The problem is to identify users who are interested in the good, and to discount them sufficiently that the entire demand is realized, but not so much that revenue is compromised. Using techniques from "backpressure routing" used for control of multihop communication networks, we develop a multi-hop coupon forwarding scheme in which users are incentivized to forward the right number of coupons to appropriate neighbors such that the above target is achieved. We also develop a simple delay-based heuristic algorithm that also shows a near-optimal performance.

Compositional Modeling and Analysis of Multi-Hop Control Networks

We propose a mathematical framework for modeling and analyzing multi-hop control networks designed for systems consisting of multiple control loops closed over a multi-hop (wireless) communication network. We separate control, topology, routing, and scheduling and propose formal syntax and semantics for the dynamics of the composed system, providing an explicit translation of multi-hop control networks to switched systems. We propose formal models for analyzing robustness of multi-hop control networks, where data is exchanged through a multi-hop communication network subject to disruptions. When communication disruptions are long, compared to the speed of the control system, we propose to model them as permanent link failures. We show that the complexity of analyzing such failures is NP-hard, and discuss a way to overcome this limitation for practical cases using compositional analysis. For typical packet transmission errors, we propose a transient error model where links fail for one time slot independently of the past and of other links. We provide sufficient conditions for almost sure stability in presence of transient link failures, and give efficient decision procedures. We deal with errors that have random time span and show that, under some conditions, the permanent failure model can be used as a reliable abstraction. Our approach is compositional, namely it addresses the problem of designing scalable scheduling and routing policies for multiple control loops closed on the same multi-hop control network. We describe how the translation of multi-hop control networks to switched systems can be automated, and use it to solve control and networking co-design challenges in some representative examples, and to propose a scheduling solution in a mineral floatation control problem that can be implemented on a time triggered communication protocols for wireless networks.

Fault Tolerant Stabilizability of Multi-Hop Control Networks

AbstractA Multi-hop Control Network (MCN) consists of a plant where the communication between sensor, actuator and computational unit is supported by a wireless multi-hop communication network, and data flow is performed using scheduling and routing of sensing and actuation data. We address the problem of characterizing controllability and observability of a MCN, by means of necessary and sufficient conditions on the plant dynamics and on the communication scheduling and routing. We provide a methodology to design scheduling and routing, in order to satisfy controllability and observability of a MCN for any fault occurrence in a given set of failures configurations.

Convex Optimization, Game Theory, and Variational Inequality Theory

In this article, we have provided a unified view of some basic theoretical foundations and main techniques in convex optimization, game theory, and VI theory. We put special emphasis on the generality of the VI framework, showing how it allows to tackle several interesting problems in nonlinear analysis, classical optimization, and equilibrium programming. In particular, we showed the relevance of the VI theory in studying Nash and GNE problems. The first part of the article was devoted to provide the (basic) theoretical tools and methods to analyze some fundamental issues of an equilibrium problem, such as the existence and uniqueness of a solution and the design of iterative distributed algorithms along with their convergence properties. The second part of the article made these theoretical results practical by showing how the VI framework can be successfully applied to solve several challenging equilibrium problems in ad hoc wireless (peer-to-peer wired) networks, in the emerging field of CR networks, and in multihop communication networks. We hope that this introductory article would serve as a good starting point for readers to apply VI theory and methods in their applications, as well as to locate specific references either in applications or theory.

A Sensor Network Configuration Considering Priori Estimation Error and Communication Energy

This paper deals with a network configuration considering priori estimation error variance and communication energy in sensor networked feedback system. Each sensor transmits information to a fusion center via multi-hop communication network. We propose a novel network configuration algorithm that each sensor node transmits information with a same dimension. The transmitted information is merged in each sensor node and consists of measurement data with time delay. Then the priori estimate can be minimum variance estimation. The proposed algorithm achieves sub-***optimal network topology with minimum energy and a desired variance. Experimental results show an effectiveness of the proposed method.

An evolutionary programming algorithm for finding constrained optimal disjoint paths for multihop communication networks

We present an evolutionary programming algorithm (EP) for finding hop count and bandwidth constrained cost optimal disjoint paths in multihop communication networks. In general, multi-constrained path selection is an NP complete problem. Our proposed algorithm can be used for real-time online network applications, which can initiate and process a number of calls simultaneously on disjoint paths, without overloading the network. This algorithm also requires a small memory space and low execution time. The proposed algorithm, which maintains a balance between finding an optimal shortest path and CPU mean execution time, also generates parallel suboptimal paths during the process of generating the best path. One of these suboptimal paths can be used as a backup path if it is link disjoint with all the primary paths (best paths) of the concurrent requests. Thus, the proposed algorithm provides a limited degree of reliability for routing of packets as well.

Fuzzy Logic Mobility Prediction Routing Algorithm for Mobile Ad Hoc Networks

The mobile ad hoc network (MANET) is a temporarily organized computer multi-hop communication network which is composed of mobile hosts equipped with wireless transmitters and receivers. These hosts can move at will, which results in a highly dynamic topology and imposes significant effect on the route stability and overall performance of the network. Based on the observation of the velocity and direction of these mobile hosts, this paper proposes a routing algorithm which can predict the link stability with fuzzy logic. The simulation results have proven that this protocol works well in extending the average lifetime of data connections, in increasing the data rate as well as the end-to-end throughput, and in decreasing the end-to-end latency and overhead substantially.

Capacity Improvement of Multihop Inter-Vehicle Communication Networks by STBC Cooperative Relaying

In this paper, we evaluate the effect of space-time coded cooperative relaying technique in multihop inter-vehicle communication (IVC) networks. The IVC systems have an issue that communication links are often blocked by obstacles such as heavy vehicles. The breakage of a radio link in multihop connections may significantly decrease the system throughput in multihop IVC networks. It is demonstrated through system-level evaluations that the cooperative relaying can offer remarkable capacity enhancement by exploiting multi-route diversity and overcoming accidental link breakage resulting from frequent topological changes.

Maintaining weakly-connected dominating sets for clustering ad hoc networks

An ad hoc network is a multihop wireless communication network supporting mobile users. Network performance degradation is a major problem as the network becomes larger. Clustering is an approach to simplify the network structure and thus alleviate the scalability problem. One method that has been proposed to form clusters is to use weakly-connected dominating sets [Y.P. Chen, A.L. Liestman, Approximating minimum size weakly-connected dominating sets for clustering mobile ad hoc networks, in: The Third ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc’02), 2002, pp. 165–172; Y.P. Chen, A.L. Liestman, A zonal algorithm for clustering ad hoc networks, International Journal of Foundations of Computer Science 14(2) (2003) 305–322]. Here, we present a zonal distributed algorithm to maintain weakly-connected dominating sets as the network structure changes. When the zones are small, the algorithm is essentially localized; when the zones are large, it behaves more globally. The size of the weakly-connected dominating set obtained also varies depending on the choice of zone size, with larger zones generally resulting in smaller weakly-connected dominating sets. Experiments provide evidence that this maintenance algorithm keeps the size of the weakly-connected dominating set approximately the same as its initial size and does not compromise the network connectivity.

An efficient primary-segmented backup scheme for dependable real-time communication in multihop networks

Several distributed real-time applications (e.g., medical imaging, air traffic control, and video conferencing) demand hard guarantees on the message delivery latency and the recovery delay from component failures. As these demands cannot be met in traditional datagram services, special schemes have been proposed to provide timely recovery for real-time communications in multihop networks. These schemes reserve additional network resources (spare resources) a priori along a backup channel that is disjoint with the primary. Upon a failure in the primary channel, its backup is activated, making the real-time connection dependable. In this paper, we propose a new method of providing backups called segmented backups, in which backup paths are provided for partial segments of the primary path rather than for its entire length, as is done in the existing schemes. We show that our method offers: 1) improved network resource utilization; 2) higher average call acceptance rate; 3) better quality-of-service guarantees on propagation delays and failure-recovery times; and 4) increased flexibility to control the level of fault tolerance of each connection separately. We provide an algorithm for routing the segmented backups and prove its optimality with respect to spare resource reservation. We detail necessary extensions to resource reservation protocol (RSVP) to support our scheme and argue that they increase the implementation complexity of RSVP minimally. Our simulation studies on various network topologies demonstrate that spare resource aggregation methods such as backup multiplexing are more effective when applied to our scheme than to earlier schemes.

A note on dependable real-time communication in multihop networks

The issue of providing fault-tolerance in real-time communication has been a problem of growing importance. There are two basic approaches for satisfying fault-tolerant requirements in real-time communication: (i) forward error recovery approach and (ii) detect and recovery approach. The first approach is well-suited for hard real-time communication, whereas the second approach is well-suited for soft real-time communication. Neither of these basic approaches is well-suited for supporting both hard and soft real-time communication. In this paper, we propose an integrated scheme that not only supports such a mixed communication requirements, but also improves the call acceptance rate significantly due to its efficient resource allocation mechanisms such as traffic dispersion and backup multiplexing. The effectiveness of the proposed scheme has been evaluated through extensive simulation studies.

Fundamental characteristics of multi-hop wireless communication networks

This paper discusses stochastic characteristics of hierarchical multi?hop wireless networks. It is assumed that terminals and base stations are distributed according to specific distributions, respectively. It is also assumed that a multi?hop wireless network is logically divided into clusters by a clustering algorithm. In this paper, the Lowest ID Cluster algorithm and another simple clustering algorithm are considered. Using theoretical techniques based on the stochastic geometry, this paper analyzes fundamental characteristics of the multi?hop wireless networks with the clustering algorithms.