• ETRI Journal
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• v.35 no.3
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• pp.406-413
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• 2013

In this paper, an orthogonal frequency division multiple access (OFDMA)-based minimum end-to-end delay (MED) distributed routing scheme for mobile backhaul wireless mesh networks is proposed. The proposed scheme selects routing paths based on OFDMA subcarrier synchronization control, subcarrier availability, and delay. In the proposed scheme, OFDMA is used to transmit frames between mesh routers using type-I hybrid automatic repeat request over multipath Rayleigh fading channels. Compared with other distributed routing algorithms, such as most forward within radius R, farthest neighbor routing, nearest neighbor routing, and nearest with forwarding progress, simulation results show that the proposed MED routing can reduce end-to-end delay and support highly reliable routing using only local information of neighbor nodes.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.11
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• pp.385-392
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• 2016

Recently, Expectation Area-based Real-time Routing (EAR2) protocol has been proposed to support real-time routing in wireless sensor networks. EAR2 considers the expectation area of a mobile sink and uses flooding within the expectation area. However, flooding leads to excessive energy consumption and causes long delay against real-time routing. Moreover, since EAR2 uses single path to the expectation area, it is difficult to support reliable routing in sensor networks with high link failures. Thus, to overcome these limitation of EAR2, this paper proposes a reliable and real-time routing protocol based on virtual grids and multipath for mobile sinks. To support real-time routing, the proposed protocol considers expectation grids belonged to the expectation area. Instead of flooding within the expectation area, the proposed protocol uses multicasting to the expectation grids and single hop forwarding in an expectation grid because the multicasting can save much energy and the single hop forwarding can provide short delay. Also, the proposed protocol uses multipath to the expectation grids to deal with link failures for supporting reliable routing. Simulation results show that the proposed protocol is superior to the existing protocols.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.190-197
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• 2011

In industrial distributed control systems, sensors collect data from the physical environment periodically and transmit them to the actuators, which process the control operations based on the received data. For the effective operation of the control systems, the data transmitted by the sensors has to be delivered to the actuators reliably within the deadline, and if the message reception rate of the actuators becomes lower than a threshold, then the performance of the control systems drops greatly. This paper suggests a message routing protocol to transmit periodic messages reliably in a distributed control system based on wireless sensor networks. For reliable message transmission, the proposed protocol selects a routing path whose end-to-end message reception rate is the highest before transmitting data messages. The proposed protocol has the capability of maintaining a target message reception rate for each flow. To maintain the required target reception rate, each destination monitors the actual message reception rate periodically and transmits a feedback message to the source if it drops below the target reception rate. On receiving the feedback message, the source tries to find a new path which can satisfy the target rate. The performance of the proposed protocol has been evaluated using simulation and compared with other protocols in terms of the message reception rate, the message delay and delay jitter, and so on. The simulation results show that the proposed protocol has a higher message reception rate and comparable message delay and delay jitter to other protocols. The simulation results also show that the proposed protocol has an ability to adapt well to the dynamic network traffic change.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.4
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• pp.43-50
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• 2010

Vehicle-to-Vehicle (V2V) is a special type of vehicle ad-hoc network (VANET), and known as a solution to provide communication among vehicles and reduce vehicle accidents. Geographical routing protocols as Greedy Perimeter Sateless Routing (GPSR) are very suitable for the V2V communication due to special characters of highway and device for vehicles. However, the GPSR has problem that appears local maximum by some stale neighbor nodes in the greedy mode of the GPSR. It can lose transmission data in recovery mode, even if the problem is can be solved by the recovery mode of the GPSR. We therefore propose a Greedy Perimeter Reliable Routing (GPRR), can provide more reliable data transmission, to resolve the GPSR problem in the V2V environment. Simulation results using ns-2 shown that the GPRR reveals much better performance than the GPSR by remarkably reducing the local maximum rate in the greedy mode.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.136-138
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• 2006

The high-rate Wireless Personal Area Networks (WPANs) which IEEE 802.15.3 standard support, foster the Digital Home Network (DHN) scenarios with high rate multimedia data transmission. Actually, there are a few routing protocols for ad-hoc networks which considered the terminal location information and routing metric to reduce the energy consumption and optimize the routing path in mobile system. Based on other routing protocols, this paper presents the reliable location-based routing algorithm which is an adaptation to these networks.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.79-90
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• 2015

Multipath routing technique is recognized as one of the effective approaches to improve the reliability of data forwarding. However, the traditional multipath routing focuses only on how many paths are needed to ensure a desired reliability. For this purpose, the protocols construct additional paths and thus cause significant energy consumption. These problems have motivated the study for the energy-efficient and reliable data forwarding. Thus, this paper proposes an energy-efficient concurrent multipath routing protocol with a small number of paths based on interaction between paths. The interaction between paths helps to reinforce the multipath reliability by making efficient use of resources. The protocol selects several nodes located in the radio overlapped area between a pair of paths as bridge nodes for the path-interaction. In order to operate the bridge node efficiently, when the transmission failure has detected by overhearing at each path, it performs recovery transmission to recover the path failure. Simulation results show that proposed protocol is superior to the existing multipath protocols in terms of energy consumption and delivery reliability.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.69-77
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• 2006

Geocasting is a form of communication that transmits messages to all nodes within a given geographical region(i.e., the geocasting region). Most of conventional onery aware protocols were based on shortest-hop routing that is, they minimized the cost in terms of the distance and total transmission energy not considering both the residual energy at each node and the link error ratio when selecting the routes for communication. In this paper we propose a MLRG(Maximum Lifetime Reliable Geocast) protocol for energy-efficient and reliable geocasting in Ad-hoc networks. The proposed MLRG, a position-based and routing-based geocasting algorithm, maximizes the network lifetime using newly defined cost function and selecting the energy balanced routes on the basis of each node's residual energy, and provides a reliable communication considering the link error ratio.

• Korean Journal of Hydrosciences
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• v.1
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• pp.1-14
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• 1990

The analytical diffusion model is first formulated and its characteristics are critically reviewed. The flood events during the 1985-1986 flood seasons in the IHP Pyungchang Representative Basin are routed by this model and are compared with those routed by the kinematic wave model. The present model is proven to be an excellent means of taking the backwater effects due to lateral inflow or downstream river stage variations into consideration in channel routing of flood flows. It also requires much less effort and computing time at a desired station compared to any other reliable flood routing methods.

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.4
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• pp.243-253
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• 2010

Multihop data delivery in vehicular ad hoc networks (VANETs) suffers from the fact that vehicles are highly mobile and inter-vehicle links are frequently disconnected. In such networks, for efficient multihop routing of road safety information (e.g. road accident and emergency message) to the area of interest, reliable communication and fast delivery with minimum delay are mandatory. In this paper, we propose a multihop vehicle-to-infrastructure routing protocol named Vertex-Based Predictive Greedy Routing (VPGR), which predicts a sequence of valid vertices (or junctions) from a source vehicle to fixed infrastructure (or a roadside unit) in the area of interest and, then, forwards data to the fixed infrastructure through the sequence of vertices in urban environments. The well known predictive directional greedy routing mechanism is used for data forwarding phase in VPGR. The proposed VPGR leverages the geographic position, velocity, direction and acceleration of vehicles for both the calculation of a sequence of valid vertices and the predictive directional greedy routing. Simulation results show significant performance improvement compared to conventional routing protocols in terms of packet delivery ratio, end-to-end delay and routing overhead.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.2
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• pp.504-527
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• 2015

Underwater wireless sensor networks (UWSNs) are similar to the terrestrial sensor networks. Nevertheless, there are different characteristics among them such as low battery power, limited bandwidth and high variable propagation delay. One of the common major problems in UWSNs is determining an efficient and reliable routing between the source node and the destination node. Therefore, researchers tend to design efficient protocols with consideration of the different characteristics of underwater communication. Furthermore, many routing protocols have been proposed and these protocols may be classified as location-based and location-free routing protocols. Pressure-based routing protocols are a subcategory of the location-free routing protocols. This paper focuses on reviewing the pressure-based routing protocols that may further be classified into non-void avoidance protocols and void avoidance protocols. Moreover, non-void avoidance protocols have been classified into single factor based and multi factor based routing protocols. Finally, this paper provides a comparison between these protocols based on their features, performance and simulation parameters and the paper concludes with some future works on which further study can be conducted.