Byungseok Kang

Effective route maintenance and restoration schemes in mobile ad hoc networks.

This study proposes a location-based hybrid routing protocol to improve data packet delivery and to reduce control message overhead in mobile ad hoc networks. In mobile environments, where nodes move continuously at a high speed, it is generally difficult to maintain and restore route paths. Therefore, this study suggests a new flooding mechanism to control route paths. The essence of the proposed scheme is its effective tracking of the destination’s location based on the beacon messages of the main route nodes. Through experiments based on an NS-2 simulator, the proposed scheme shows improvements in the data packet delivery ratio and reduces the amount of routing control message overhead compared with existing routing protocols such as AODV, LAR, ZRP and AODV-DFR.

Developing Route Optimization-Based PMIPv6 Testbed for Reliable Packet Transmission

Proxy Mobile IPv6 (PMIPv6) allows a mobile node to communicate directly to its peers while changing the currently used IP address. This mode of operation is called route optimization (RO). In the RO process, the peer node learns a binding between the home address and its current temporary care-of-address. Many schemes have been proposed to support RO in PMIPv6. However, these schemes do not consider the out-of-sequence problem, which may happen between the existing path and the newly established RO path. In this paper, we propose a scheme to solve the out-of-sequence problem with low cost. In our scheme, we use the additional packet sequence number and the time information when the problem occurs. We then run experiments on a reliable packet transmission (RPT) laboratory testbed to evaluate the performance of the proposed scheme, and compare it with the well-known RO-supported PMIPv6 and the out-of-sequence time period scheme. The experimental results show that for most of the cases, our proposed scheme guarantees RPT by preventing the out-of-sequence problem.

Internet of Everything: A Large-Scale Autonomic IoT Gateway

Gateways are emerging as a key element of bringing legacy and next generation devices to the Internet of Things (IoT). They integrate protocols for networking, help manage storage and edge analytics on the data, and facilitate data flow securely between edge devices and the cloud. Current IoT gateways solve the communication gap between field control/sensor nodes and customer cloud, enabling field data to be harnessed for manufacturing process optimization, remote management, and preventive maintenance. However, these gateways do not support fully-automatic configuration of newly added IoT devices. In this paper, we proposed a self-configurable gateway featuring real time detection and configuration of smart things over the wireless networks. This novel gateway’s main features are: dynamic discovery of home IoT device(s), automatic updates of hardware changes, connection management of smart things connected over AllJoyn. We use the ‘option’ field for automatic configuration of IoT devices rather than modify standard format of CoAP protocol. Proposed gateway functionality has been validated over the large-scale IoT testbed.

A Distributed Delay-Efficient Data Aggregation Scheduling for Duty-Cycled WSNs

With the growing interest in wireless sensor networks (WSNs), minimizing network delay and maximizing sensor (node) lifetime are important challenges. Since the sensor battery is one of the most precious resources in a WSN, efficient utilization of the energy to prolong the network lifetime has been the focus of much of the research on WSNs. For that reason, many previous research efforts have tried to achieve tradeoffs in terms of network delay and energy cost for such data aggregation tasks. Recently, duty-cycling technique, i.e., periodically switching ON and OFF communication and sensing capabilities, has been considered to significantly reduce the active time of sensor nodes and thus extend network lifetime. However, this technique causes challenges for data aggregation. In this paper, we present a distributed approach, named distributed delay efficient data aggregation scheduling (DEDAS-D) to solve the aggregation-scheduling problem in duty-cycled WSNs. The analysis indicates that our solution is a better approach to solve this problem. We conduct extensive simulations to corroborate our analysis and show that DEDAS-D outperforms other distributed schemes and achieves an asymptotic performance compared with centralized scheme in terms of data aggregation delay.

An SDN-enhanced load-balancing technique in the cloud system

The vast majority of Web services and sites are hosted in various kinds of cloud services, and ordering some level of quality of service (QoS) in such systems requires effective load-balancing policies that choose among multiple clouds. Recently, software-defined networking (SDN) is one of the most promising solutions for load balancing in cloud data center. SDN is characterized by its two distinguished features, including decoupling the control plane from the data plane and providing programmability for network application development. By using these technologies, SDN and cloud computing can improve cloud reliability, manageability, scalability and controllability. SDN-based cloud is a new type cloud in which SDN technology is used to acquire control on network infrastructure and to provide networking-as-a-service (NaaS) in cloud computing environments. In this paper, we introduce an SDN-enhanced Inter cloud Manager (S-ICM) that allocates network flows in the cloud environment. S-ICM consists of two main parts, monitoring and decision making. For monitoring, S-ICM uses SDN control message that observes and collects data, and decision-making is based on the measured network delay of packets. Measurements are used to compare S-ICM with a round robin (RR) allocation of jobs between clouds which spreads the workload equitably, and with a honeybee foraging algorithm (HFA). We see that S-ICM is better at avoiding system saturation than HFA and RR under heavy load formula using RR job scheduler. Measurements are also used to evaluate whether a simple queueing formula can be used to predict system performance for several clouds being operated under an RR scheduling policy, and show the validity of the theoretical approximation.

Trail-Using Ant Behavior Based Energy-Efficient Routing Protocol in Wireless Sensor Networks

Swarm Intelligence (SI) observes the collective behavior of social insects and other animal societies. Ant Colony Optimization (ACO) algorithm is one of the popular algorithms in SI. In the last decade, several routing protocols based on ACO algorithm have been developed for Wireless Sensor Networks (WSNs). Such routing protocols are very flexible in distributed system but generate a lot of additional traffic and thus increase communication overhead. This paper proposes a new routing protocol reducing the overhead to provide energy efficiency. The proposed protocol adopts not only the foraging behavior of ant colony but also the trail-using behavior which has never been adopted in routing. By employing the behaviors, the protocol establishes and manages the routing trails energy efficiently in the whole network. Simulation results show that the proposed protocol has low communication overhead and reduces up to 55% energy consumption compared to the existing ACO algorithm.

Distributed Degree-Based Link Scheduling for Collision Avoidance in Wireless Sensor Networks

Wireless sensor networks (WSNs) consist of multiple sensor nodes, which communicate with each other under the constrained energy resources. Retransmissions caused by collision and interference during the communication among sensor nodes increase overall network delay. Since the network delay increases as the nodes waiting time increases, the network performance is reduced. Thus, the link scheduling scheme is needed to communicate without collision and interference. In the distributed WSNs environment, a sensor node has limited information about its neighboring nodes. Therefore, a comprehensive link scheduling scheme is required for distributed WSNs. Many schemes in the literature prevent collision and interference through time division multiple access (TDMA) protocol. However, considering the collision and interference in TDMA-based schedule increases the delay time and decreases the communication efficiency. This paper proposes the distributed degree-based link scheduling (DDLS) scheme, based on the TDMA. The DDLS scheme achieves the link scheduling more efficiently than the existing schemes and has the low delay and the duty cycle in the distributed environment. Communication between sensor nodes in the proposed DDLS schemes is based on collision avoidance maximal independent link set, which enables to assign collision-free timeslots to sensor nodes, and meanwhile decreases the number of timeslots needed and has low delay time and the duty cycle. Simulation results show that the proposed DDLS scheme reduces the scheduling length by average 81%, the transmission delay by 82%, and duty cycle by over 85% in comparison with distributed collision-free low-latency scheduling scheme.

A fast recovery scheme based on detour planning for in-band openflow networks

In SDN, a network can be controlled using in-band or out-of-band control networks. Most of current research for SDN focuses on an out-of-band network. In this network, the controller is directly connected to every router or switch in one-to-one manner. However, out-of-band networks are expensive to build due to the requirement of a separate network and cannot provide integration with previous network infrastructure such as legacy, DSL, and WSN, etc. Also, this network may not be feasible in realistic scenarios. To solve the above problem, SDN is required to be implemented for an in-band network. Because control and data traffics share the same network links, fast recovery is one of important problems in SDN. In this paper, we propose a fast recovery scheme for in-band OpenFlow networks. We design a detour planning to reduce the control message overhead. To evaluate performance of proposed scheme, we have developed laboratory scale in-band SDN testbed. The experimental results show that the proposed scheme reduces control overhead and guarantees the network QoS.

A Distributed Scheme for Broadcast Scheduling in Duty-cycled Wireless Sensor Networks

The paper investigates the minimum-transmission broadcast problem in duty-cycled wireless sensor networks in which each sensor node alternates between active and sleeping modes during its lifetime for energy saving. We propose a scheme, Distributed Broadcast Scheduling (DiBS), to construct a broadcast backbone together with a broadcast schedule for each backbone node such that a broadcast message is disseminated to all other nodes in the network with a minimum number of transmissions. The minimization of the total number of transmissions is achieved thanks to two factors. First, the nature of wireless communications enables a sender to distribute the message to multiple nodes with a single transmission. Second, DiBS exploits such a single transmission in constructing the broadcast backbone. A set of extensive simulations is conducted to show the performance of DiBS as well as its improvement over existing ones in terms of total number of transmissions.

A Transport Protocol for Multimedia Transmission in Overlay Networks

Overlay networks are opening up new ways for Internet usability, mainly by adding new services that are not available or cannot be implemented in the current Internet. Overlay networks use application level switches of intermediate nodes. However, the designs of overlay network are based on store-and-forward principles maintained by split TCP connections of hop-by-hop approaches and this can increase delay of packet delivery and cause unreliability of packet transmissions due to buffer overflow of the application level switch of each intermediate node, which has a limited buffer space. Also, hop-by-hop approaches for overlay networks cannot support end-to-end semantics. Thus, this study proposes a new Overlay Transport Protocol for overlay networks by considering management of end-to-end connection and congestion and flow control between source and destination nodes. By using a prototype implementation via simulation with MATLAB, We validate our analytical findings and evaluate the performance of proposed protocol which can provide end-to-end reliable data transfers, and also improve throughput in comparison with a network model where Overlay Transport Protocol layer is not available.