Browsing by Subject "Sleep mode"

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    Activity management algorithm for improving energy efficiency of small cell base stations in 5G heterogeneous networks
    (2014) Aykın, Irmak
    Heterogeneous networks (HetNets) are proposed in order to meet the increasing demand for next generation cellular wireless networks, but they also increase the energy consumption of the base stations. In this thesis, an activity management algorithm for improving the energy efficiency of HetNets is proposed. A smart sleep strategy is employed for the operator deployed pico base stations to enter sleep and active modes. According to that strategy, when the number of users exceeds the turn on threshold, the pico node becomes active and when the number of users drop below the turn off threshold, it goes into sleep mode. Mobile users dynamically enter and leave the cells, triggering the activation and deactivation of pico base stations. The performance of the system is examined for three different cellular network architectures: cell on edge (COE), uniformly distributed cells (UDC) and macro cell only network (MoNet). Two different user distributions are considered: uniform and hotspot. The effects of number of hotspot users and sleep energies of pico nodes on the energy efficiency are also investigated. The proposed activity management algorithm increases the energy efficiency, measured in bits/J, by 20%. The average bit rates achieved by HetNet users increase by 29% compared with the MoNet architecture. Thus, the proposed activity control algorithm increases the spectral efficiency of the network while consuming the energy more efficiently.
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    ItemOpen Access
    DSSP: A Dynamic Sleep Scheduling Protocol for prolonging the lifetime of wireless sensor networks
    (IEEE, 2007-05) Bulut, Eyüphan; Körpeoğlu, İbrahim
    This paper presents DSSP (Dynamic Sleep Scheduling Protocol), a centralized scheme for extending the lifetime of densely deployed wireless sensor networks by keeping only a necessary set of sensor nodes active. We present an algorithm for finding out which nodes should be put into sleep mode, and the algorithm preserves coverage and connectivity while trying to put as much nodes as possible into sleep mode. The algorithm is executed at the base station periodically. In this way, the network is reconfigured periodically, which also helps to a more even distribution of energy consumption load to sensor nodes. We evaluated our protocol via simulations and observed a significant increase in the lifetime, depending on the node density, while providing good coverage. © 2007 IEEE.