The increasing importance of localizing objects in indoor environments is the motivation for much research on localization algorithms. This paper focuses on the maximum achievable resolution for... Show More

The increasing importance of localizing objects in indoor environments is the motivation for much research on localization algorithms. This paper focuses on the maximum achievable resolution for Angle of Arrival as a means to position objects inside rooms using equipment within the field of wireless sensor networks, thus dealing with restricted resources. A clear view on beamforming using antenna arrays is represented and is proven to be useful in Angle of Arrival measurements. A detailed overview of a dedicated algorithm, leads the authors to draw conclusions concerning the resolution. A reference value is defined, which allows the authors to calculate the realistic resolution for all room dimensions. In order to verify these theoretical outcomes with practical results, the development of a quadrature demodulation based antenna array architecture, operating at 2.4 GHz, is presented. The latter is based on a study of different phase shifting technologies.

To communicate within disaster scenarios, different devices/systems need to cooperate with specific protocols. The key communication protocol needs to provide interoperability among these systems... Show More

To communicate within disaster scenarios, different devices/systems need to cooperate with specific protocols. The key communication protocol needs to provide interoperability among these systems and provide the solution for emergency services. The paper studies the hybrid network disaster recovery (HNDR) systems and classifies its communication scenarios and requirements. The authors propose a new networking protocol for the hybrid network, with ability to forward sessions and messages through different transport protocols, and copes with node mobility and node failure. The paper considers heterogeneous network disaster recovery scenario and proposes a cost effective and easy to deploy hybrid network emergency communication protocol (HNEC). This internetwork protocol is a specific model of the inter-domain messaging (IDM) protocol for emergency communications. The routing protocol procedure is similar to the reactive AODV procedure but is different in maintaining routes from unpredicted link breaks or node failure. A detailed simulation model with the designed network layer model is used to investigate network delivery rate and end-to-end delay performance. The performance results are analyzed using varying node load, mobility speed, and network size.

In this paper a high throughput, low latency, mobility adaptive and energy efficient medium access protocol (MAC) called Mobility Adaptive (MA) for wireless sensor networks. MA-MAC ensures that... Show More

In this paper a high throughput, low latency, mobility adaptive and energy efficient medium access protocol (MAC) called Mobility Adaptive (MA) for wireless sensor networks. MA-MAC ensures that transmissions incur no collisions, and allows nodes to undergo sleep mode whenever they are not transmitting or receiving. It uses delay allocation scheme based on traffic priority at each node and avoids allocating same backoff delay for more than one node unless they are in separate clusters. It also allows nodes to determine when they can switch to sleep mode during operation. MA-MAC for mobile nodes provides fast association between the mobile node and the cluster coordinator. The proposed MAC performs well in both static and mobile scenarios, which shows its significance over existing MAC protocols proposed for mobile applications. The performance of MA-MAC is evaluated through extensive simulation, analysis and comparison with other mobility aware MAC protocols. The results show that MA-MAC outperforms significantly the existing CSMA/CA, Sensor Mac (S-MAC), Mobile MAC (MOB-MAC), Mobility aware Delay sensitive MAC (MD-MAC) and Dynamic Sensor MAC (DS-MAC) protocols including throughput, latency and energy consumption.

Wireless local area networks (WLANs) are commonplace in many universities. Understanding the trends in the usage of these networks is becoming more important. Interesting results can be extracted... Show More

Wireless local area networks (WLANs) are commonplace in many universities. Understanding the trends in the usage of these networks is becoming more important. Interesting results can be extracted about association patterns by analyzing WLAN traces from real scenarios. In this work, the library in the main campus of the Technical University of Catalonia (UPC) in Barcelona has been studied. Daily and weekly patterns of the WLAN connections are shown. The population accessing the network is mostly composed of infrequent users: half of the population accesses the WLAN once during each month. Many users associate to only one of the twelve possible access points, which means that, despite the widespread use of lightweight devices, many users are static. The results of this analysis provide general tools for characterizing campus-wide WLAN and a better understanding of usage and performance issues in a mature wireless network.

Few technical details are available about the various sensors embedded in modern smartphones, and what details are available can be hard to assemble and interpret by the broader technical community... Show More

Few technical details are available about the various sensors embedded in modern smartphones, and what details are available can be hard to assemble and interpret by the broader technical community that uses these devices. Since the physical and electromagnetic aspects of the sensors' operation can significantly affect the analysis and use of their data, it is essential for those who rely on these data to understand these details. As such, the authors provide a simplified and yet technically precise explanation of some of the sensors found on the Motorola Droid, which are representative of sensors found in most smartphones. The authors specifically explain its proximity sensor, Hall effect magnetometer, capacitive accelerometer, orientation sensor, and light sensor. Each sensor is described using illustrations and experiments that are provided to demonstrate some unexpected behaviors.