01775nas a2200157 4500008004100000245006700041210006700108260001800175300001400193520120800207100002101415700002301436700001901459700002401478856011501502 2016 eng d00aEvaluation of Power Control Mechanism on OLSR Routing Protocol0 aEvaluation of Power Control Mechanism on OLSR Routing Protocol cMarch 23 - 25 a766 - 7713 a

The mobility that characterizes the wireless networks, is leading to the use of ad hoc networks for wireless communications. Due to the constant motion of wireless devices, infrastructure wireless networks cannot provide connectivity at all times, in comparison with ad hoc networks, which are more easy to use and are based on abstract and continuously altering topologies. The use of specialized routing protocols is improving the performance of these networks, concluding to lower power consumption and faster communication. However, routing is not enough to preserve the battery power of the mobile devices. By using a power control mechanism on top of the routing protocols, further power savings can be achieved. In this paper, we present a power control mechanism which relies on the routing protocol in
order to make decisions about power management and the behavior and the performance of the network. The mechanism is based on using SNR (Signal-to-Noise Ratio) as a metric for adjusting the transmission power accordingly and eventually saving a respectable amount of energy to prolong life time of mobile devices and benefit the performance ad hoc networks.

1 aBouras, Christos1 aKapoulas, Vaggelis1 aStamos, Kostas1 aStathopoulos, Nikos uhttps://telematics.upatras.gr/telematics/publications/evaluation-power-control-mechanism-olsr-routing-protocol01707nas a2200157 4500008004100000245007600041210006900117260002100186300001000207520112600217100002101343700002301364700002401387700002201411856011601433 2016 eng d00aMechanisms for enhancing the performance of routing protocols in VANETs0 aMechanisms for enhancing the performance of routing protocols in cNovember 13 - 17 a11-183 a

Vehicular Ad Hoc Networks (VANETs) are considered as a special case of Mobile Ad Hoc Networks (MANETs) and are recently gaining a great attention from the research community. Routing in VANETs has to adapt to special characteristics such as high speed and road pattern movement as well as high linkage break probability. In an urban setting the problem becomes more difficult as the existence of buildings blocks the wireless signal and hinders communication, resulting in only few nodes with increased connectivity (mostly in the intersections) that can act as true routing nodes rather than just forwarding nodes. In this paper, we compare the performance of GPCR (Greedy Perimeter Coordinator Routing), GPSR (Greedy Perimeter Stateless Routing) as well as the modified GPSR (GPSR-M) routing protocols. GPSR-M is an enhancement for the GPSR protocol that focuses on routing a message to an intermediate vehicle moving in the line of movement of the final destination, as soon as possible. Based on the performance evaluation we propose enhancements to GPSR-M in order to improve performance.

1 aBouras, Christos1 aKapoulas, Vaggelis1 aStathopoulos, Nikos1 aGkamas, Apostolos uhttps://telematics.upatras.gr/telematics/publications/mechanisms-enhancing-performance-routing-protocols-vanets01497nas a2200169 4500008004100000245008200041210006900123260002000192300001200212520085900224100002101083700002301104700001901127700002401146700002501170856013201195 2015 eng d00aPower Management and Rate Control Mechanism for Wi-Fi Infrastructure Networks0 aPower Management and Rate Control Mechanism for WiFi Infrastruct cOctober 26 - 28 a731-7363 a

The advances in wireless networks have encouraged the use of mobile devices in everyday life. However, one of the main problems of these devices is the limited amount of energy they have available to use in order to function and the extended energy consumption of wireless adapters. A lot of research has been done to reduce the amount of energy spent on wireless communications. On the other hand, the extended use of wireless networks causes interference problems in communications, which affect the overall performance of each network. The purpose of this work is to provide a mechanism, which can reduce the power consumption on the station side and increase the mobile devices’ operation time, and in combination with a rate adaptation mechanism on the access point side, improve the overall performance of the network.

1 aBouras, Christos1 aKapoulas, Vaggelis1 aStamos, Kostas1 aStathopoulos, Nikos1 aTavoularis, Nikolaos uhttps://telematics.upatras.gr/telematics/publications/power-management-and-rate-control-mechanism-wi-fi-infrastructure-networks01712nas a2200181 4500008004100000245007800041210006900119300001000188490000900198520106100207100002101268700002301289700002701312700001901339700002401358700002501382856012301407 2015 eng d00aA Signal Adaptation Mechanism for power optimization of wireless adapters0 aSignal Adaptation Mechanism for power optimization of wireless a a48-720 v4(3)3 a

This manuscript introduces, implements and evaluates a feedback-based adaptation mechanism that adjusts the transmission power of a wireless card on commodity mobile devices. Main focus of this work is to minimize the power consumption by adjusting the transmission power of the wireless card, thus extending the battery life, while negative effects on connection quality are avoided. To achieve that, a mechanism that optimizes the power depending on the quality of the connection is presented, which measures the quality of the transmission and adjusts the transmission power, by utilizing an expanded array of metrics, for more accurate estimation. The mechanism has been implemented and tested on actual wireless adapters. In order to evaluate, fine-tune and improve the mechanism, a list of real environment experiments has been performed. The results indicate that power consumption can be significantly reduced for nodes that are either almost stationary or slowly moving, without any significant increase in packet loss.

1 aBouras, Christos1 aKapoulas, Vaggelis1 aKioumourtzis, Georgios1 aStamos, Kostas1 aStathopoulos, Nikos1 aTavoularis, Nikolaos uhttps://telematics.upatras.gr/telematics/publications/signal-adaptation-mechanism-power-optimization-wireless-adapters01615nas a2200169 4500008004100000245007500041210006900116260001500185300001200200520099900212100002101211700002301232700001901255700002401274700002201298856012501320 2014 eng d00aPower management for wireless adapters using multiple feedback metrics0 aPower management for wireless adapters using multiple feedback m c4-8 August a262-2673 a

The main focus of this work is the effort to minimize the power consumption on mobile devices such as notebooks, netbooks, tablets, tablets, smartphones, etc. by adjusting the transmission power of the wireless card, thus extending the battery life. In order to achieve that, we provide a mechanism (which we call Signal Adaptation Mechanism – SAM) that optimizes the power depending on the quality of the connection. This mechanism measures the quality of the transmission and adjusts the transmission power accordingly, by utilizing an expanded array of metrics along the Received Signal Strength Indicator (RSSI), for more accurate estimation. It also aims at easy implementation on various wireless adapters. In order to evaluate, fine-tune and improve the mechanism, a list of experiments has been performed. These experiments were conducted on a real (as opposed to simulated) ad-hoc network, where the nodes of the networks followed varying moving patterns.

1 aBouras, Christos1 aKapoulas, Vaggelis1 aStamos, Kostas1 aStathopoulos, Nikos1 aTavoularis, Nikos uhttps://telematics.upatras.gr/telematics/publications/power-management-wireless-adapters-using-multiple-feedback-metrics02064nas a2200181 4500008004100000245006100041210006000102260001800162300001600180520144600196100002101642700002301663700001901686700002001705700002201725700002401747856011101771 2013 eng d00aFeedback-based Adaptation for Improved Power Consumption0 aFeedbackbased Adaptation for Improved Power Consumption cMarch 25 - 28 a 562 - 568 3 aIn this paper we present a feedback-based adaptation mechanism that adjusts the transmission power of a wireless card on commodity PCs depending on the quality of the connection. Our purpose is to manage the available power in order to achieve lower power consumption without negatively affecting the user?s perception of connection quality. We based our implementation on an existing theoretical model and focused on resolving problems and removing assumptions which made it inefficient in real life implementation. The initial model manages to minimize the power consumption in networks with exactly two nodes. In this paper, we extend the model to consider the possibility of the existence of a base station, where any number of nodes can be connected. Our objectives for the base station are to minimize the power consumption and guarantee continuous connectivity for all mobile nodes. We implement the adaptation mechanism for a specific adapter with open sources drivers thus allowing necessary modifications. We conduct a number of real world experiments. The results indicate that power consumption can be significantly reduced for nodes that are either almost stationary or slowly moving (e.g. at walking speed), without any significant increase in packet loss. The results are quite important as nowadays mobile devices with limited battery life time use tethering to become base stations for other devices like in ad-hoc networks.1 aBouras, Christos1 aKapoulas, Vaggelis1 aStamos, Kostas1 aKioumourtzis, G1 aTavoularis, Nikos1 aStathopoulos, Nikos uhttps://telematics.upatras.gr/telematics/publications/feedback-based-adaptation-improved-power-consumption