ISEP – CISTER – Comunicações em eventos científicos
URI permanente para esta coleção:
Navegar
Percorrer ISEP – CISTER – Comunicações em eventos científicos por autor "Aguiar, Ana"
A mostrar 1 - 5 de 5
Resultados por página
Opções de ordenação
- Characterization and Modeling of the Bicycle-Antenna System for the 2.4GHz ISM BandPublication . Pinto, Luis; M. Santos, Pedro; Almeida, Luis; Aguiar, AnaVehicular communication is rapidly becoming a standard reality, and precise models are necessary for accurate performance estimates. Alongside cars and trucks, smaller vehicles such as scooters and bicycles are also set to participate in V2X networking, but have received considerably less attention. In this work, we present an extensive characterization of the gain pattern of a bicycle and antenna system for the IEEE 802.11g standard. We measure the radiation patterns of the antenna of a commodity 2.4 GHz WiFi module mounted on six distinct positions on the body of six archetypal bicycles in an anechoic chamber. The RSSI sample set per angle and antenna position is characterized statistically and input into an empirical model of the gain pattern of the bicycle-antenna system. We define a bicycle-to-X propagation model that pairs the proposed bicycle-antenna gain and a log-distance shadowing path loss model, and conduct outdoor measurement campaign for evaluation. We observe that the gain model measured in chamber matches the measured RSSI at small distances, whereas at larger distances it provides less accuracy.
- Cooperative Bicycle Localization System via Ad Hoc Bluetooth NetworksPublication . Santos, Pedro Miguel; Rosa, Vera; Pinto, Luis; Aguiar, AnaBicycles are becoming increasingly more equipped with embedded connected devices, by design or through after market products, to support applications such as fitness monitoring and tracking. Bluetooth (BT) and BT Low Energy (BLE) technology is often embedded in such devices to support connectivity to a personal mobile device or a dock, when parked. BT/BLE transmit periodic beacons for node discovery that can be explored for V2X applications, such as safety and fleet management. We present a distributed system that explores periodic BT beacons sent by a module embedded in a bicycle to opportunistically locate nodes of interest (NOI). We address the particular application of stolen bicycle detection. In a scenario in which a bicycle is stolen and has its communication system tampered with but BLE remains functional, a service provider (e.g., fleet operator, authorities) is informed of this new NOI and shares an updated NOI list with the NOI detection-enabled bicycles. In turn, the bicycles flag contacts with stolen bicycles to the provider backoffice, at the earliest convenience (depending on available communications interfaces: immediately if cellular is available, or opportunistically when passing by a dock). We describe the operation and software architecture of the system, and an actual implementation in COTS equipment. Experimental measurements of the communication range and a demonstration of the system for oroof-of-concept are also reported.
- Experimental Evaluation of Urban Points-of-Interest as Predictors of I2V 802.11 Data TransfersPublication . Santos, Pedro M.; M. Sousa, Luís; Aguiar, AnaSmart Cities will leverage the Internet-of-Things (IoT) paradigm to enable cyber-physical loops over urban processes. Vehicular backhauls contribute to IoT platforms by allowing sensor/actuator nodes near roads to explore opportunistic connections to passing vehicles when other communication backhauls are unavailable. A placement process of nodes that includes vehicular networks as a connectivity backhaul requires estimates of infrastructure-to-vehicle (I2V) wireless service at potential deployment sites. However, carrying out I2V measurement campaigns at all potential locations can be very expensive; so, predictive models are necessary. To this end, qualitative characteristics of a potential site, such as infrastructural points-of-interest (POI) relating to traffic (i.e., traffic lights, crosswalks) and fleet activities (i.e., bus stops, garbage bins) can inform about the vehicles' mobility patterns and quality of the I2V service. In this paper, we show the contribution of POI (and site-specific information) to I2V transfers, leveraging a real-world dataset of geo-referenced I2V WiFi link measurements in urban settings. We present the distributions of throughput with respect to distance per POI class and site, and apply exponential regression to obtain practical throughput/distance models. We then use these models to compare I2V transfer estimation methodologies with different levels of POI-specific data and data resolution. We observe that I2V transfer estimate accuracy can improve from an average over-estimation of 18.3% with respect to measured values, if site or POI-specific information metrics are not used, to 9.3% in case such information is used.
- Feasibility of Gateway-Less IoT E-Health ApplicationsPublication . Pereira, Carlos; Guimarães, Diana; Mesquita, João; Santos, Frederico; Almeida, Luis; Aguiar, AnaMachine-to-Machine (M2M) communications are a key enabler of Internet of Things (IoT) applications. One domain with growing interest in M2M/IoT is e-health, either for self-monitoring, home monitoring, or hospital systems. However, current sensing devices in this domain rely on short-range communication protocols that require a gateway (GW) for Internet connection. Smartphones have been proposed as GWs in mobile M2M communications due to their enhanced connectivity and sensing capabilities. However, the GW functionality impacts on the smartphone usability, causing undesirable battery depletion and the smartphone itself increases the overall cost of e- health solutions. In this work, we propose converging e-health devices and Wi-Fi towards direct Internet access through the existing Wi-Fi infrastructure and by-passing current GWs. We use recent low-cost ultra low-power Wi-Fi modules and feature them with M2M capabilities supporting their integration in an interoperable e-health framework. We present results on end-to-end latency and power requirements within a concrete e-health use case that show the feasibility of the proposed GW-less solution.
- A Glimpse at Bicycle-to-Bicycle Link Performance in the 2.4GHz ISM BandPublication . Santos, Pedro M.; Pinto, Luis; Aguiar, Ana; Almeida, LuisBicycle-to-bicycle (Bi2Bi) communication can be implemented by well-established technologies in the 2.4GHz ISM band: IEEE 802.11, Bluetooth or IEEE 802.15.4. These technologies have distinct performance due to different physical and data link layers. In this paper, we characterize the mentioned 2.4 GHz-operating technologies over opportunistic links established between bicycles using commodity hardware. We find that, in Bi2Bi links, Blue-tooth, IEEE 802.11 at 24 Mbit/s, and IEEE 802.11 with automatic rate adaptation can communicate only in the immediate surroundings (under 15m of range), to maxima of 1.5 Mbit/s, 17 Mbit/s and 25 Mbit/s, respectively. IEEE 802.15.4 and IEEE 802.11 at 1 Mbit/s sustain connectivity up to 30 and 40 meters and peak transfer rates of 50 kbit/s and 800 kbit/s respectively. In addition, we observed that, in all measurement scenarios, link performance depended strongly on whether bicycles were approaching or moving away, rather than on whether one was at the front or back of the other.