• An Analytical Model for On-Chip Interconnects in Multimedia Embedded Systems

      Wu, Y.; Min, Geyong; Zhu, D.; Yang, L.T. (2013)
      The traffic pattern has significant impact on the performance of network-on-chip. Many recent studies have shown that multimedia applications can be supported in on-chip interconnects. Driven by the motivation of evaluating on-chip interconnects in multimedia embedded systems, a new analytical model is proposed to investigate the performance of the fat-tree based on-chip interconnection network under bursty multimedia traffic and nonuniform message destinations. Extensive simulation experiments are conducted to validate the accuracy of the model, which is then adopted as a cost-efficient tool to investigate the effects of bursty multimedia traffic with nonuniform destinations on the network performance.
    • Detecting k-Balanced Trusted Cliques in Signed Social Networks

      Hao, F.; Yau, S.S.; Min, Geyong; Yang, L.T. (2014)
      k-Clique detection enables computer scientists and sociologists to analyze social networks' latent structure and thus understand their structural and functional properties. However, the existing k-clique-detection approaches are not applicable to signed social networks directly because of positive and negative links. The authors' approach to detecting k-balanced trusted cliques in such networks bases the detection algorithm on formal context analysis. It constructs formal contexts using the modified adjacency matrix after converting a signed social network into an unweighted one. Experimental results demonstrate that their algorithm can efficiently identify the trusted cliques.
    • Energy efficient indoor tracking on smartphones

      Yao, D.Z.; Yu, C.; Dey, A.K.; Koehler, C.; Min, Geyong; Yang, L.T.; Jin, H. (2014-10)
      Continuously identifying a user’s location context provides new opportunities to understand daily life and human behavior. Indoor location systems have been mainly based on WiFi infrastructures which consume a great deal of energy mostly due to keeping the user’s WiFi device connected to the infrastructure and network communication, limiting the overall time when a user can be tracked. Particularly such tracking systems on battery-limited mobile devices must be energy-efficient to limit the impact on the experience of using a phone. Recently, there have been a lot of studies of energy-efficient positioning systems, but these have focused on outdoor positioning technologies. In this paper, we propose a novel indoor tracking framework that intelligently determines the location sampling rate and the frequency of network communication, to optimize the accuracy of the location data while being energy-efficient at the same time. This framework leverages an accelerometer, widely available on everyday smartphones, to reduce the duty cycle and the network communication frequency when a tracked user is moving slowly or not at all. Our framework can work for 14 h without charging, supporting applications that require this location information without affecting user experience.
    • Energy-Efficient Distributed Relay and Power Control in Cognitive Radio Cooperative Communications

      Luo, C.; Min, Geyong; Yu, F.R.; Chen, M.; Yang, L.T.; Leung, V.C.M. (2013)
      In cognitive radio cooperative communication (CR-CC) systems, the achievable data rate can be improved by increasing the transmission power. However, the increase in power consumption may cause the interference with primary users and reduce the network lifetime. Most previous work on CR-CC did not take into account the tradeoff between the achievable data rate and network lifetime. To fill this gap, this paper proposes an energy-efficient joint relay selection and power allocation scheme in which the state of a relay is characterized by the channel condition of all related links and its residual energy. The CR-CC system is formulated as a multi-armed restless bandit problem where the optimal policy is decided in a distributed way. The solution to the restless bandit formulation is obtained through a first-order relaxation method and a primal-dual priority-index heuristic, which can reduce dramatically the on-line computation and implementation complexity. According to the obtained index, each relay can determine whether to provide relaying or not and also can control the corresponding transmission power. Extensive simulation experiments are conducted to investigate the effectiveness of the proposed scheme. The results demonstrate that the power consumption is reduced significantly and the network lifetime is increased more than 40%.
    • Energy-efficient dynamic network selection in heterogeneous wireless networks

      Qian, C.; Luo, C.; Hao, F.; Yang, L.T.; Min, Geyong (2013)
      The complementary features of various wireless access technologies in heterogeneous wireless networks make it attractive and challenging to offer users an always best connected (ABC) service. To achieve this goal, the dynamic network selection has received many research efforts. However, most of the existing work have focused on the network layer performance and ignored the consideration of energy efficiency. To fill this gap, an energy-efficient network selection scheme is proposed in this paper to improve the energy efficiency of wireless network access in heterogeneous wireless networks environment. The dynamics of network selection is formulated as the process of an evolutionary game. The users in different service areas complete for the data rate from different wireless networks (i.e., WMAN, cellular networks, and WLAN), and the network selection made by a user is based on its payoff that is a function of the data rate and power consumption. The addressed problem is then modelled by the replicator dynamics. Simulation results are presented to demonstrate the significant performance improvement compared to the existing scheme.
    • MobiFuzzyTrust: An Efficient Fuzzy Trust Inference Mechanism in Mobile Social Networks

      Hao, F.; Min, Geyong; Lin, M.; Luo, C.; Yang, L.T. (2014)
      Mobile social networks (MSNs) facilitate connections between mobile users and allow them to find other potential users who have similar interests through mobile devices, communicate with them, and benefit from their information. As MSNs are distributed public virtual social spaces, the available information may not be trustworthy to all. Therefore, mobile users are often at risk since they may not have any prior knowledge about others who are socially connected. To address this problem, trust inference plays a critical role for establishing social links between mobile users in MSNs. Taking into account the nonsemantical representation of trust between users of the existing trust models in social networks, this paper proposes a new fuzzy inference mechanism, namely MobiFuzzyTrust, for inferring trust semantically from one mobile user to another that may not be directly connected in the trust graph of MSNs. First, a mobile context including an intersection of prestige of users, location, time, and social context is constructed. Second, a mobile context aware trust model is devised to evaluate the trust value between two mobile users efficiently. Finally, the fuzzy linguistic technique is used to express the trust between two mobile users and enhance the human's understanding of trust. Real-world mobile dataset is adopted to evaluate the performance of the MobiFuzzyTrust inference mechanism. The experimental results demonstrate that MobiFuzzyTrust can efficiently infer trust with a high precision.
    • Performance Analysis of Hybrid Wireless Networks Under Bursty and Correlated Traffic

      Wu, Y.; Min, Geyong; Yang, L.T. (2013)
      Wireless local area networks (WLANs) have risen in popularity for in-car networking systems that are designed to make driving safer. Wireless mesh networks (WMNs) are widely deployed to expand the coverage of high-speed WLANs and to support last-mile connectivity for mobile users anytime and anywhere at low cost. Many recent measurement studies have shown that the traffic arrival process in wireless networks exhibits the bursty and correlated nature. A new analytical model is developed in this paper as a cost-effective performance tool to investigate the quality-of-service (QoS) of the WMN that interconnects multiple WLANs in the presence of bursty and correlated traffic. After validating its accuracy via extensive simulation experiments, the analytical model is then used to investigate the performance of the hybrid wireless networks.