Hiromu Asahina , Hisao Yamamoto, Kentaroh Toyoda and Iwao Sasase, "Path metrics for lower throughput fluctuation for video streaming service in wireless mesh networks," The 21st Asia-pacific Conference on Communications (APCC2015), Kyoto, Japan, October 13-16, 2015.
The video streaming service over Wireless Mesh Networks (WMNs) is an attractive feature for live streaming and video conversation when disaster occurs. The path construction with the conventional metrics e.g., throughput, latency, or packet loss rate, suffers from the repeated waiting time due to the CSMA/CA since paths are concentrated on nodes with good metric. As a consequence, it brings about throughput fluctuation of video streaming service. We propose two metrics that reflect on the magnitude of CSMA/CA interference around a node in order to select a path that the throughput of video streaming session will get stable. The first metric is calculated from the number of received Request To Send (RTS)/Clear To Send (CTS) frames. Since the number of RTS/CTS reflects on the frequency of the packet transmission around a node, a source node can chooses a path which does not make a node waiting for constant time due to the CSMA/CA on the existing path that might use streaming service. The second metric uses the number of neighbor nodes and we set the larger metric value as more nodes exist. The idea comes from the fact that a node which has few neighbor nodes does not much interfere other established paths. The proposed metrics can be easily installed into Hybrid Wireless Mesh Protocol (HWMP) which is a de facto standard path selection protocol defined in IEEE802.11s. We show that the proposed metrics can achieve lower rate of throughput fluctuation than that of conventional metric by using the networks simulator Qualnet.
Miho Kurata, Kentaroh Toyoda, and Iwao Sasase. "Two-stage SPIT detection scheme with betweenness centrality and social trust," The 21st Asia-pacific Conference on Communications (APCC2015), Kyoto, Japan, October 13-16, 2015.
Detecting SPIT (Spam over Internet Telephony) is an urgent demand with growing voice communication services. Chaisamran et al. proposed a trust-based SPIT detection scheme and it is superior to other trust-based schemes since it is valid for unknown users. However, this scheme might misdetect a call from low-frequent users as SPIT gradually in time, since they seldom call and thus their social trusts get decreased with time. In this paper, we propose a two-stage SPIT detection scheme using BC (Betweenness Centrality) and social trust to decrease misdetection of a call from low-frequent users as SPIT. BC indicates user’s centrality in the entire network and the value of BC against legitimate users gradually increases with time even if users seldom call, whereas it does not increase against spammers since the connection between a legitimate caller and a spammer is hardly established. As a first stage, we use BC as a feature to correctly identify a call request from a low-frequent user. Then we judge whether a call is from a legitimate caller or a spammer by using social trust. By the computer simulation, we show that our scheme improves the false positive rate while maintaining high true positive rate.
Kenji Iuchi, Takumi Matsunaga, Kentaroh Toyoda and Iwao Sasase, "Secure parent node selection scheme in route construction to exclude attacking nodes from RPL network," The 21st Asia-pacific Conference on Communications (APCC2015), Kyoto, Japan, October 13-16, 2015.
The IPv6 Routing Protocol for Low-power and Lossy networks (RPL) is a standard routing protocol to realize the Internet of Things (IoT). Since RPL is a tree-based topology network, an attacking node may falsely claim its rank towards neighbor nodes in order to be chosen as a parent of them and to collect more packets to tamper. In this paper, we propose a secure parent selection scheme so that each child node can select a legitimate node as its parent. In the proposed scheme, each node chooses a parent after excluding the best candidate if multiple parent candidatekuratas exist. Our scheme utilizes the fact that an attacking node claims falsely a lower rank than that of a legitimate nodes. We show that attacking nodes have no merits to claim lower ranks than true ones in a secure parent node selection scheme. By the computer simulation, we show that the proposed scheme reduces the total number of child nodes attached to attacking nodes in comparison with the conventional RPL scheme.