Wooguil Pak

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In a wireless sensor network, the routing control overhead is prohibitive because mostly many nodes are involved in routing. To overcome the overhead problem, tier based anycast protocol was proposed in (Kulkarni et al., 2006). However, it has a shortcoming of using much more energy compared to other competitors of deterministic routing protocols in(More)
duty cycle of a wireless sensor node is a key factor that determines the life time of a wireless sensor network. In general, sensor medium access control protocols reduce the duty cycle to achieve longer lifetime. However, we found out that their performance improvements substantially decrease under extremely low duty cycles (<0.1%). Our proposed W-MAC(More)
—Policy lookup is a very essential function in packet forwarding and network security. As it is becoming a main cause of bottleneck in many network systems, this letter introduces a new policy lookup algorithm called FRFC (Fast table building for Recursive Flow Classification). Although it is based on RFC which shows the best policy lookup speed but the(More)
Keywords: Wireless sensor network Routing protocol Ultra low duty cycle Network lifetime Multi-hop wakeup time estimation a b s t r a c t Although various medium access control (MAC) and routing protocols have been designed for WSNs (wireless sensor networks) to extend the network lifetime, their performances are significantly aggravated under extremely low(More)
In this paper, we propose a new routing protocol named WRP to maximize a network lifetime. WRP needs no packet flooding for routing recovery and it also solves high energy consumption caused by a clock drift. It can achieve a long network lifetime independently with a node density because the number of a control message is not increased with the density.(More)
Cognitive radio is a key to resolve scarcity of radio spectrum. To exploit unused spectrum bands, cognitive capable devices called secondary users should perform spectrum sensing; but need to vacate the band, when a licensee of the band, i.e. a primary user, appears. For seamless communication in this case, they should discover a free channel to switch to;(More)
To support various services in the current Internet, QoS routing was proposed. QoS routing finds a path to meet the requested QoS specification for a user, reserves network resource, thereby guaranteeing the QoS for the user. Many works have been done for QoS routing in an autonomous system (AS) to make it feasible in large networks. For a large network,(More)
—In this paper, we propose a new centralized routing protocol named WRP that aims at maximizing the network lifetime. In WRP, the sink node is assumed to be with more capabilities and basically collects each node's estimated wakeup time. This enables the sink node to estimate the wakeup times of all sensor nodes even if some of them are multi-hops away from(More)
For security of Android operating systems, permission-based solutions are one of popular approaches but still exposed to two problems. First, there is coarse-grained relationship between a permission and its associated methods. Second, mobile users do not have rights to control the permissions of their applications. To solve these problems, we propose(More)