Rajin Darko 1 Ca CarT rTel: el: A Distributed Mobile Sensor - PowerPoint PPT Presentation

Rajin Darko 1

Ca CarT rTel: el: A Distributed Mobile Sensor Computing System Bret Hull, Vladimir Bychkovsky, Yang Zhang, Kevin Chen, Michel Goraczko, Allen Miu, Eugene Shih, Hari Balakrishnan and Samuel Madden MIT Computer Science and Artificial Intelligence Laboratory, Cambridge 2

Context 1. Motivation 2. Overview and Contribution 3. ICEDB 4. CafNet 5. The Portal 6. Case Studies 7. The Implementation 3

Introduction  Over 600 milion cars in the world  More than100 sensors per car  Source of sensor data 4

Introduction - What is a CarTel  CarTel - mobile sensor computing system designed to collect, process, deliver and visualize data from sensors located on mobile units such as cars, trains...  It is a mobile embedded computer connected to a set of sensors. 5

Motivation Overview and contribution Motivation ICEDB CafNet The Portal Case Studies The implementation  CarTel is motivated by the hypothesis that an important and emerging category of sensor networks is mobile and involves heterogeneous sensor data  That motivation comes from “technology push” and “application pull” 6

Motivation Overview and contribution Motivation ICEDB CafNet The Portal Case Studies The implementation  Technology push is rapidly making the underlying hardware components available  Application pull generates demands for such systems. 7

Motivation Overview and contribution Motivation ICEDB CafNet The Portal Case Studies The implementation  When sensor equipped computers or mobile phones are connected to cars or carried by people they form sensor network system, which can sense the environment at the much finer fidelity then any other static sensors 8

Motivation Overview and contribution Motivation ICEDB CafNet The Portal Case Studies The implementation 9

Motivation Motivation - Example Overview and contribution ICEDB CafNet The Portal Case Studies The implementation  If we would want to monitor the delays on some roads around the city, one solution would be to deploy static sensor network on all the major roads.  This solution is possible but considering expansion of backroads that many drivers use this solution would come across as expensive and impractical way of covering roads around the city.  Better way would be to equip each car with a GPS sensor to obtain info about traffic delays so we can use that information for route planning and traffic monitoring applications 10

Motivation Overview and contribution ICEDB Motivation – usage of sensors CafNet The Portal Case Studies The implementation  Except traffic monitoring, mobile sensors can be used for other purposes such as  Environmental monitoring (mobile chemical and pollution sensors)  Civil infrastructure monitoring (vibration sensors for monitoring state of roads)  Automotive diagnostics (system is obtaining info from cars on-board sensors, or can detect road rage)  Geo-imaging  Data muling 11

Motivation Overview and contribution Overview and contribution ICEDB CafNet The Portal Case Studies The implementation  CarTel provides a reusable software platform that can be used to build many mobile sensing applications. Each node is a mobile, embedded, computer coupled to a set of sensors 12

Motivation Overview and contribution Overview and contribution ICEDB CafNet The Portal Case Studies The implementation Goals of CarTel technical design:  Provide a simple programming interface CarTel applications should be as easy to write as standard Web applications, and application developers should not have to deal with distribution or mobility.  Handle large amounts of heterogeneous sensor data. CarTel should not constrain sensor data types, and should make it easy to integrate new kinds of sensors, new mobile nodes, and new data types into the system. 13

Motivation Overview and contribution Overview and contribution ICEDB CafNet The Portal Case Studies The implementation Goals of CarTel technical design: Handle intermittent connectivity   CarTel systems connect to the network using different types of opportunistic wireless (Wi-Fi, Bluetooth..)  Internet users in their homes and other locations can allow CarTel nodes to communicate with Internet hosts.  In most cases those networks will go from good connectivity to no connectivity at all, thus making those connection intermittent for some period of time.  CarTel node can also use other mobile devices, such as mobile phones, or usb keys and flash memory to deliver data as mules 14

Motivation Overview and Contribution Overview and contribution ICEDB CafNet - CarTel Components The Portal Case Studies The implementation The system is designed to have three main components: 1. The portal - central location that hosts CarTel applications and functions as the point of control and configuration for the distributed system.  It’s a software that requests data from remote nodes, and aggregates reports arriving from those nodes into a coherent picture of current conditions, and visualizes that data. 15

Motivation Overview and Contribution Overview and contribution ICEDB CafNet - CarTel Components The Portal Case Studies The implementation ICEDB – intermittently connected database - 2. a delay-tolerant continuous query processor, and CafNet - carry-and-forward network , a delay- 3. tolerant network stack.  The CarTel programming model is centralized and simple.  Applications running on the portal issue continuous queries using an API exported by ICEDB. These queries cause mobile nodes to stream responses using CafNet’s data delivery mechanism. 16

Motivation Overview and Contribution Overview and contribution ICEDB CafNet - CarTel Components The Portal Case Studies The implementation Queries specify: 1.  What sensor data must be acquired  At what rate should they be acquired  How the data should be sub-sampled , filtered and summarized on the mobile node  On what order should the results be prioritized for returning back to the portal. The ICEDB continuous query interface allows an application to express intra and inter query priorities. Query results stream in across an intermittently connected 2. network and populate a relational database at the portal. Application issue SQL queries on the portal’s relational database 3. to retrieve data they need for further analysis, visualization, etc. These are snapshot queries that run on whatever data is currently available. 17

Motivation Overview and Contribution Overview and contribution ICEDB CafNet - Contributions The Portal Case Studies The implementation  CarTel handles heterogeneous sensor data, allowing the set of sensors to be expanded without requiring major software changes on the remote nodes.  Each sensor has an adapter running on the node  Adapter handles  the details of configuring  extracting information from that sensor  converting it into a normalized form.  To ease management and deployment, when a new sensor is added, or when the functions of an adapter need to be modified, only the adapter module needs to change. 18

Motivation Overview and contribution ICEDB - Introduction ICEDB CafNet The Portal Case Studies The implementation  ICEDB distributes query execution and result delivery between the ICEDB server on the portal and the remote nodes .  The ICEDB server holds a list of continuous queries, submitted by applications, that are sent to the remote nodes using CafNet  The nodes in the field run ICEDB remote, to process the sensor data and return the query results using CafNet, prioritizing the result streams in order of importance.  Finally, when ICEDB server receives results from remote nodes, it places them into a per-query result table in the relational database at the portal. 19

Motivation Overview and contribution ICEDB – Data model ICEDB CafNet The Portal Case Studies The implementation  ICEDB supports heterogeneous data types  Makes the addition and removal of sensors relatively easy.  Because all results are eventually stored in a relational database, this requirement implies that the system  must be able to parse and store information that sensors produce and  must be able to evolve schemas as users add new sensors and application developers introduce new data types.  Adapter is a meta-data package used for adding new sensor types and managing schemas  Adapter has attributes of a sensor and executable program that interfaces with a sensors and triggers data collection 20

Motivation Overview and contribution ICEDB – Data model ICEDB CafNet The Portal Case Studies The implementation  Purpose of attributes is to provide information to ICEDB to: automatically create local tables to store 1. sensor readings acquire tuples from the sensor, and 2. parse sensor readings to store them in the 3. database and process them as specified by subsequent continuous queries. 21