Browsing by Subject "Sensor Networks"

Now showing 1 - 4 of 4

Open Access
E-sense : a wireless sensor network testbed and system for monitoring inbuilding environments
(2008) Berker, Berk
Wireless sensor networks consist of small, smart and battery-powered devices suitable for widespread deployment to monitor an environment by taking physical measurements. Wireless sensor nodes are deployed over an area in a random manner. They need to self-establish a wireless multi-hop network and routing paths from all sensor nodes to a central base station. In this thesis, we present our E-Sense system, a wireless sensor network testbed consisting of MICA2 sensor nodes which can be used to monitor an indoor environment like office buildings and homes. The testbed can be accessed through the Internet and provides a webbased interface to the sensor network. The users of the network can be located at any point in the Internet. Via the web based interface, the users can submit various types of queries to the sensor network and get the replies including the physical measurement results. The E-Sense system also includes a distributed and energy-aware routing protocol that we designed and implemented. The protocol aims efficient and balanced usage of energy in the sensor nodes to prolong the lifetime of the network. The routing protocol is based on a many-to-one routing tree where each node independently determines its next parent depending on the values of RSSI (Received Signal Strength Indicator). The protocol can also adjust the transmit power to further decrease the energy spent in each sensor node. The testbed will be useful for experimental studies at both application and network levels.
Open Access
EHPBS: Energy harvesting prediction based scheduling in wireless sensor networks
(IEEE, 2013) Akgun, B.; Aykın, Irmak
The clustering algorithms designed for traditional sensor networks have been adapted for energy harvesting sensor networks (EHWSN). However, in these algorithms, the intra-cluster MAC protocols to be used were either not defined at all or they were TDMA based. These TDMA based MAC protocols are not specified except for the fact that cluster heads assign time slots to their members in a random manner. In this paper, we will modify this TDMA based scheduling as follows: members will request a time slot depending on their energy prediction and the cluster heads will assign these slots to members. This method will increase the network lifetime. The proof will be given with simulations. © 2013 IEEE.
Open Access
Power efficient data gathering and aggregation in wireless sensor networks
(2004) Tan, Hüseyin Özgür
Recent developments in processor, memory and radio technology have enabled wireless micro-sensor networks which are deployed to collect useful information from an area of interest. The sensed data must be gathered and transmitted to a base station where it is further processed for end-user queries. Since the network consists of low-cost nodes with limited battery power, power efficient methods must be employed for data gathering and aggregation in order to achieve long network lifetimes. In an environment where each of the sensor nodes has data to send to a base station in a round of communication, it is important to minimize the total energy consumed by the system in a round so that the system lifetime is maximized. A near optimal data gathering and routing scheme can be achieved in terms of network lifetime, while minimizing the total energy per round with the use of data fusion and aggregation techniques, if power consumption per node can be balanced as well. So far, different routing protocols have been proposed to maximize the lifetime of a sensor network. In this thesis, we propose two new protocols PEDAP (Power Efficient Data gathering and Aggregation Protocol) and PEDAP-PA (PEDAPPower Aware), which are minimum spanning tree based routing schemes, where one of them is the power-aware version of the other. Our simulation results show that our protocols perform well both in systems where base station is far away from and where it is in the center of the field.
Open Access
Routing and scheduling approaches for energy-efficient data gathering in wireless sensor networks
(2011) Tan, Hüseyin Özgür
A wireless sensor network consists of nodes which are capable of sensing an environment and wirelessly communicating with each other to gather the sensed data to a central location. Besides the advantages for many applications, having very limited irreplaceable energy resources is an important shortcoming of the wireless sensor networks. In this thesis, we present effective routing and node scheduling solutions to improve network lifetime in wireless sensor networks for data gathering applications. Towards this goal, we first investigate the network lifetime problem by developing a theoretical model which assumes perfect data aggregation and power-control capability for the nodes; and we derive an upper-bound on the functional lifetime of a sensor network. Then we propose a routing protocol to improve network lifetime close to this upper-bound on some certain conditions. Our proposed routing protocol, called L-PEDAP, is based on constructing localized, self-organizing, robust and power-aware data aggregation trees. We also propose a node scheduling protocol that can work with our routing protocol together to improve network lifetime further. Our node scheduling protocol, called PENS, keeps an optimal number of nodes active to achieve minimum energy consumption in a round, and puts the remaining nodes into sleep mode for a while. Under some conditions, the optimum number can be greater than the minimum number of nodes required to cover an area. We also derive the conditions under which keeping more nodes alive can be more energy efficient. The extensive simulation experiments we performed to evaluate our PEDAP and PENS protocols show that they can be effective methods to improve wireless sensor network lifetime for data gathering applications where nodes have power-control capability and where perfect data aggregation can be used.