Browsing by Author "Liu, Dan"

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    Connected Dominating Sets in Wireless Networks with Different Transmission Ranges
    (2005-11-21) Thai, My T.; Wang, Feng; Liu, Dan; Zhu, Shiwei; Du, Ding-Zhu
    Since there is no fixed infrastructure or centralized management in wireless ad hoc networks, a Connected Dominating Set (CDS) has been proposed as the virtual backbone. The CDS of a graph representing a network has a significant impact on an efficient design of routing protocols in wireless networks. This problem has been studied extensively in Unit Disk Graphs (UDG), in which each node has the same transmission range. However, in practice, the transmission ranges of all nodes are not necessary equal. In this paper, we model a network as a disk graph and introduce the CDS problem in disk graphs. We present three constant approximation algorithms to obtain a minimum CDS of a given network. These algorithms can be implemented as distributed algorithms. Furthermore, we show the size relationship between a maximal independent set and a CDS as well as the bound of the maximum number of independent neighbors of a node in disk graphs. The theoretical analysis and simulation results are also presented to verify our approaches.
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    Process variation and scaling effects on embedded DRAMs.
    (2012-08) Liu, Dan
    Embedded DRAM has been an important branch of embedded memories recently. The scaling trend in the power comparison between SRAM and eDRAM is conducted. To improve the performance of eDRAM various kinds of eDRAM cells are introduced. The scaling trend of major leakage currents affecting eDRAM performance is presented, as well as their impact on the behavior of various cells. A method to evaluate the effect from the process variation is introduced. The comparison on 28nm and 65nm 2T & 2T1C cell's performance is applied to verify the conclusions made on the leakage scaling. Finally, the technology full of potential for eDRAM, FinFET, is introduced.