Browsing Engineering and Informatics by Author "Ma, X."
A Novel Verification Scheme for Fine-Grained Top-k Queries in Two-Tiered Sensor NetworksMa, X.; Song, H.; Wang, J.; Gao, J.; Min, Geyong (2014)A two-tiered architecture with resource-rich master nodes at the upper tier and resource-poor sensor nodes at the lower tier is expected to be adopted in large scale sensor networks. In a hostile environment, adversaries are more motivated to compromise the master nodes to break the authenticity and completeness of query results, whereas it is lack of light and secure query processing protocol in tiered sensor networks at present. In this paper, we study the problem of verifiable fine-grained top- queries in two-tiered sensor networks, and propose a novel verification scheme, which is named Verification Scheme for Fine-grained Top- Queries (VSFTQ). To make top- query results verifiable, VSFTQ establishes relationships among data items of each sensor node using their orders, which are encrypted together with the scores of the data items and the interested time epoch number using distinct symmetric keys kept by each sensor node and the network owner. Both theoretical analysis and simulation results show that VSFTQ can not only ensure high probability of detecting forged and/or incomplete query results, but also significantly decrease the amount of verification information when compared with existing schemes.
Congestion control based on cross-layer game optimization in wireless mesh networksMa, X.; Xu, L.; Min, Geyong (2013)Due to the attractive characteristics of high capacity, high-speed, wide coverage and low transmission power, Wireless Mesh Networks become the ideal choice for the next-generation wireless communication systems. However, the network congestion of WMNs deteriorates the quality of service provided to end users. Game theory optimization model is a novel modeling tool for the study of multiple entities and the interaction between them. On the other hand, cross-layer design is shown to be practical for optimizing the performance of network communications. Therefore, a combination of the game theory and cross-layer optimization, named cross-layer game optimization, is proposed to reduce network congestion in WMNs. In this paper, the network congestion control in the transport layer and multi-path flow assignment in the network layer of WMNs are investigated. The proposed cross-layer game optimization algorithm is then employed to enable source nodes to change their set of paths and adjust their congestion window according to the round-trip time to achieve a Nash equilibrium. Finally, evaluation results show that the proposed cross-layer game optimization scheme achieves high throughput with low transmission delay.