INTERFACE MODE ASSIGNMENT METHOD FOR SELF-RECONSTRUCTION OF WIRELESS MESH NETWORKS

The key features of computer networks available for disaster situation is reliable, fault tolerance and self-configurable. Therefore, using wireless mesh network for disaster prevention and recover system has gain much attention from the research community in last decades. In addition, from the practical aspects of the network infrastructures of the disaster system, we should assume the core capabilities such as wireless connectivity in wide range, ease of use, and low cost so on. In this paper, we propose an interface mode assignment method for reconstructing a route from an isolated router to a gateway (GW) router in a wireless mesh network based on IEEE 802.11 infrastructure mode after a disaster occurrance. The proposed method assigns an adequate mode to each interface in an isolated router to recover the network reachability in distributed manner. Simulation results show the effectiveness of the proposed method via two different scenarios

Joint Bandwidth Assignment and Routing for Power Saving on Large File Transfer with Time Constraints

The increase in network traffic in recent years has led to increased power consumption. Accordingly, many studies have tried to reduce the energy consumption of network devices. Various types of data have become available in large quantities via large high-speed computer networks. Time-constrained file transfer is receiving much attention as an advanced service. In this model, a request must be completed within a user-specified deadline or rejected if the requested deadline cannot be met. Some bandwidth assignment and routing methods to accept more requests have been proposed. However, these existing methods do not consider energy consumption. Herein, we propose a joint bandwidth assignment and routing method that reduces energy consumption for time-constrained large file transfer. The bandwidth assignment method reduces the power consumption of mediate node, typically router, by waiting for requests and transferring several requests at the same time. The routing method reduces the power consumption by selecting the path with the least predicted energy consumption. Finally, we evaluate the proposed method through simulation experiments

A ZigBee/Wi-Fi Cooperative Channel Control Method and Its Prototyping

Coexistence between ZigBee and Wi-Fi technologies, which operate within the same frequency band, is increasing with the widespread use of the IoT (Internet of Things). ZigBee devices suffer significant decrease in the sink arrival rate of packets in the presence of Wi-Fi interference. To overcome this problem, many channel control methods have been proposed. These existing methods switch only ZigBee channels to avoid interference with Wi-Fi. In contrast, we propose a cooperative channel control method for improving ZigBee packet arrival rate by controlling both the Wi-Fi and ZigBee channels. Specifically, the proposed method not only controls ZigBee devices and channels but also requests a temporary pause in the use of specific Wi-Fi channels. Finally, we show the effectiveness of the proposed method from the viewpoints of ZigBee’s packet arrival rate and applications’ satisfaction using computer simulations. In addition, the effective action of the proposed method is also demonstrated by experiments with prototyping

A Spectrum Sharing Method Based on Users' Behavior and Providers' Profit

In recent years, spectrum sharing has received much attention as a technique for more efficient spectrum use. In the case in which all providers are cooperative, spectrum sensing can easily be realized and can improve user throughput (on average). If that is not the case, providers are not cooperative, i.e., spectrum trading, spectrum bands are rented to promote spectrum sharing. To ensure more profit, however, non-cooperative providers must correctly estimate the fluctuation of the number of connected users to be able to determine the offered channel price. In this paper, we propose a spectrum sharing method to achieve both higher throughput and provider profit via appropriate pricing using a disaggregate behavioral model. Finally, we confirm the effectiveness of the proposed method using simulation experiments

Joint Bandwidth Scheduling and Routing Method for Large File Transfer with Time Constraint and Its Implementation

In recent years, the number of requests to transfer large files via large high-speed computer networks has been increasing rapidly. Typically, these requests are handled in the “best effort” manner which results in unpredictable completion times. In this paper, we consider a model where a transfer request either must be completed by a user-specified deadline or must be rejected if its deadline cannot be satisfied. We propose a bandwidth scheduling method and a routing method for reducing the call-blocking probability in a bandwidth-guaranteed network. Finally, we show their excellent performance by simulation experiments

Fair Routing for Overlapped Cooperative Heterogeneous Wireless Sensor Networks

In recent years, as WSNs (Wireless Sensor Networks) are diffused widely, multiple overlapping WSNs constructed on the same area become more common. In such a situation, their lifetime is expected to be extended by cooperative packet forwarding. Although some researchers have studied about cooperation in multiple WSNs, most of them do not consider the heterogeneity in characteristics of each WSN such as battery capacity, operation start time, the number of nodes, nodes locations, energy consumption, packet size and/or data transmission timing, and so on. In a heterogeneous environment, naive lifetime improvement with cooperation may not be fair. In this paper, we propose a fair cooperative routing method for heterogeneous overlapped WSNs. It introduces an energy pool to maintain the total amount of energy consumption by cooperative forwarding. The energy pool plays a role of broker for fair cooperation. Finally, simulation results show the excellent performance of the proposed method

Dkk3/REIC Deficiency Impairs Spermiation, Sperm Fibrous Sheath Integrity and the Sperm Motility of Mice

The role of Dickkopf-3 (Dkk3)/REIC (The Reduced Expression in Immortalized Cells), a Wnt-signaling inhibitor, in male reproductive physiology remains unknown thus far. To explore the functional details of Dkk3/REIC in the male reproductive process, we studied the Dkk3/REIC knock-out (KO) mouse model. By examining testicular sections and investigating the sperm characteristics (count, vitality and motility) and ultrastructure, we compared the reproductive features between Dkk3/REIC-KO and wild-type (WT) male mice. To further explore the underlying molecular mechanism, we performed RNA sequencing (RNA-seq) analysis of testicular tissues. Our results showed that spermiation failure existed in seminiferous tubules of Dkk3/REIC-KO mice, and sperm from Dkk3/REIC-KO mice exhibited inferior motility (44.09 +/- 8.12% vs. 23.26 +/- 10.02%, p 0.05) nor the difference in the sperm vitality rate (72.83 +/- 1.55% vs. 72.50 +/- 0.71%, p > 0.05) were statistically significant. The RNA-seq and GO (Gene Oncology) enrichment results indicated that the differential genes were significantly enriched in the GO terms of cytoskeleton function, cAMP signaling and calcium ion binding. Collectively, our research demonstrates that Dkk3/REIC is involved in the process of spermiation, fibrous sheath integrity maintenance and sperm motility of mice