Communication. Wireless multi-hop communication. Short range wireless communication

Transcription

1 Distributed systems and middleware : Distributed pervasive systems (2) Communication 2 3 Short range wireless communication IEEE IEEE IEEE Frequency 2.4GHz, 5GHz 2.4GHz 2.4GHz (800MHz, 900MHz) Radio range 10 to 75m Bandwidth 11n: up to 70m (indoor) up to 250m (outdoor) 54Mbps (802.11a/g) 300Mbps (802.11n) over 1Gbps (802.11ac) 1m (class3, 1mW) 10m (class2, 2.5mW) 100m (class1, 100mW) 1Mbps (ver. 1.2) 3Mbps (ver. 2.0+EDR) 24Mbps (ver. 3.0+HS) 1Mbps (ver. 4) Kbps 4 Wireless multi-hop communication Network with one hop wireless communication Nodes communicate via a base station Cellular network Wireless LAN Wired network Network with multi-hop wireless communication Nodes receive and forward packets Called ad hoc network node Radio range Receive and forward packets

2 Ad hoc networks Self-configuring network consisting of devices (nodes) connected by wireless links No communication infrastructure (e.g., base station or wireless access point) is required ad hoc = for the special purpose, temporary constructed Source node 5 forward forward forward Destination node Nodes located even beyond radio transmission range can communicate via multi-hop communication When nodes move, path will be broken need dynamic path search 6 Applications of ad hoc networks Emergency communication Ad hoc communication infrastructure in disaster areas Communication means for rescue activities Wireless sensor networks (WSNs) Environmental monitoring, surveillance, etc Vehicular ad hoc network (VANET) Safety navigation: pedestrian detection in intersections and notification to drivers Information gathering/dissemination: autonomously collect and disseminate information on traffic jam, accidents, and number of free parking spots among vehicles Low cost communication infrastructure Communication means for exchanging local, word of mouth information among users Auxiliary means enhancing existing communication infrastructure (e.g., off-loading for 3G cellular network) 7 Routing in mobile ad hoc networks Need to update routing information In mobile ad hoc network (MANET), communication path may be broken as network topology changes due to node mobility Reactive routing (AODV, DSR, etc) Search a path to destination when communication is needed Effective for dynamic networks with less frequent communications Proactive routing (DSDV, OLSR, etc) Keep each node updating routing table by periodically exchanging control information with neighboring nodes Effective for less dynamic networks with frequent communications Others: hybrid routing, energy-aware routing, etc 8 S Example of reactive routing: AODV: Ad hoc on-demand distance vector routing Search a shortest path to destination node based on flooding (1) Node S floods a RREQ (Route Request) message Each node receiving RREQ adds its sender ID in the msg, broadcasts it It also stores the sequence number of RREQ to discard the same RREQ received from other nodes (2) Node D sends back to S a RREP (Route Reply) msg with route info (S D) in the first RREQ received by D (3) Remove a route in the routing table if it is not used for a specified duration Flooding RREQ message D Dest next D 6 S Dest Next D Configuring routing table by RREP message D

3 Delay/disruption tolerant network Examples of DTNs In MANET routing (e.g., AODV), two nodes can communicate only when an end-to-end path exists between them Space networks Satellites, Deep space Trinity College Dublin 9 In sparse MANETs, there may be no continuous connectivity between nodes (e.g., VANET) Store, Carry, and Forward strategy for DTN (delay/disruption tolerant network) (1) A car has a message to send, but no other cars in its radio range (2) moves with the message by retaining it in its buffer (3) Sends the message when meeting another car 10 Military networks, tactical networks No consistent network infrastructure and frequent disruptions Sensor networks for wildlife tracking Coordinating the activities of multiple sensors to monitor science and hazard events Vehicular ad hoc networks Intermittent Autonomous (Opportunistic ) Communications Underwater networks Environmental Monitoring, Assisted Disaster Prevention, Assisted Navigation Battlefield-Online.Net NASA ZebraNet 11 Middleware and applications Functions required for context-aware systems Selecting information and services Navigation systems avoiding traffic jams Constraints for the context must be met Showing information and services Showing a route, location-dependent information (restaurants, spots, persons) Automatically executing services Systems and environments adapt to users presence and preference (smart spaces) User interface moves to the nearest device as the user moves (follow-me type application, seamless video session handoff,..) Attaching context to information (for future retrieval) Attaches spatiotemporal constraint (visible area in the physical world 12 and time period for existence) to information

4 13 Examples of context-aware systems Medical applications Emergency medical care, health care, etc Applications supporting our daily lives Smart space, smart environment, smart home, etc 14 Context-aware medical applications WBAN (Wireless Body Area Network) Consists of a set of mobile and small sensors capable of wireless communication, wearable or implanted into human body Monitors vital signs such as ECG, pulse, blood pressure, SPO2 and movements Transmits collected data to base station (in hospital) Applications of WBAN Emergency medical care prioritizes the ordering of treatments of patients by using electronic Triage in MCI (Masscasualty incident) Healthcare for chronic disease patients Collects information from sensors and provides adequate menus for meals and exercises Example: Electronic Triage System Many patients in MCI (mass-casualty incident) Determining the ordering of medical treatments for those patients in very short time is essential called Triage Currently, paper-based Triage tag is used to categorize patients into four categories (black, red, yellow, green) Problems: patients conditions will change as time goes E-triage ( Senses vital signs such as Pulse and SPO2 in real time Transmits data via ZigBee, determines position via localization Smart spaces What is a smart space? A physical space in which context-aware system (consisting of devices, actuators, and sensors) is embedded How smart space behaves? Collect information from sensors, determine current context Control devices (actuators) appropriately according to a scenario (specified based on user s preference) If Alice is in a room, turn on TV with channel CNN and set temperature CNN ON 15 Paper-based Triage tag Electronic Triage tag 25C for air conditioner Alice 25C 16 Example of a scenario ON

5 17 Technologies for realizing smart spaces Network for connecting devices/sensors Wireless: ZigBee, Bluetooth, IEEE Wired: PLC, Ethernet Framework for device communication UPnP (Universal Plug and Play) A set of protocols that allow devices (PCs, appliances, phones, etc) to be easily connected to home network (zero-configuration) Jini (Java Intelligent Network Infrastructure) Similar to UPnP, but it uses JavaRMI Applications/middleware Upper layers Middle layers Lower layers Applications /middleware UPnP, Jini, etc ZigBee,Bluetooth, PLC, etc Software for appropriately controlling devices according to context determined by data collected from sensors and user preference Rule-based device control Scenario for controlling appliances at living room Time: 5 to 6 PM Illumination: dim Stereo: FM radio with small volume Air cond.: temp. 25C, hum. 60% Time: 9 to 10 PM Illumination: bright TV: News with medium volume Air cond.: temp. 28C Lamps Stereo Control scenario can be described as a set of rules Each rule consists of condition for context and action for device Condition: Alice is in living room and time is between 5 and 6 PM Action: Turn on left lamp, stereo for FM radio with volume level 10, and air conditioner with 25C temperature setting 18 TV Air cond. Middleware for context-aware device control Nishigaki, et al., Framework and Rule-based Language for Facilitating Context-aware Computing using Information Appliances, Proc. of SIUMI'05 CADEL Realizes rule-based context-aware control of UPnP-ready appliances Examples of distributed pervasive systems Rule database Rule description support GUI Rule execution Consistency check Communication interface (UPnP library) UPnP protocols (SOAP, SDDI, etc) Device object Device object Device object Names of devices and sensors are decided when they are configured as UPnP devices Example of a rule in CADEL 19 if (alicebedroom1.existence && sensorbedroom1.temperature>=28){ fanbedroom1.setpower(true); } 20

6 (1) Smart home Sensors in smart home Position tracking system Position tracking sensor (ultrasound receiver) power meter Positioning sensor (ultrasound emitter) power consumption (Wh) 22 accurately tracks user s position (within 50cm error) Power meter measures power consumption of an appliance Environment sensor measures temperature, humidity, and illuminance Door sensor detects open/close behavior by acceleration Infrared remote controller operates appliances Sensors are wirelessly connected to home network All sensor data are periodically collected at the server 23 Example scenario for contextaware control in a smart home Inhabitant location time Illumina -tion Alice Dave Living, bed rooms Living, bed rooms Carol anywhere 9:00-10:00PM on Mondays Condition for context anytime dim Music Channel anytime bright Sport Channel bright TV temperature Priority Drama Channel 28 degree [C] Middle 24 degree [C] Low 26 degree [C] High Action (appliance operation) 24 Simulator for smart homes Nishikawa, et al., UbiREAL: Realistic Smartspace Simulator for Systematic Testing, UbiComp2006 ( Physical quantity Simulator UbiREAL Network simulator UPnP middleware Visualizer &GUI Rule-based scenario UPnP device 1 UPnP device n Rule-based.. device control middleware (CADEL) Application software

7 Smart home in UbiREAL Simulating smart home with UbiREAL toilet entrance bath room corridor living room bed rooms kitchen (2) Emergency medical support system Mizumoto et al., Emergency Medical Support System for Visualizing Locations and Vital Signs of Patients in Mass Casualty Incident, Proc. of PerNEM 2012 Developed as part of a government-funded project (JST CREST) by Osaka Univ., NAIST, Keio Univ., Shizuoka Univ. and Juntendo Univ. Electronic triage Electronic triage tag (etriage tag) Vital sensors (spo2, pulse, breathing rate) ZigBee based communication function Can wirelessly send vital signs of patients

8 Technologies for efficient rescue operations System organization Estimate patients position using ZigBee-based localization technique Send vital sign to server using ad-hoc networking technology Support medical-staffs using context-awareness technology Construction of ad-hoc network and disaster map Localization of patient s location Monitoring vital sign of patients Inter-site view: Displaying overall situation on map Displays information of each first-aid station Intra-site view: Displaying patients information on 3D map 3D View Window Displays patients/personnel as 3D objs The number of medical personnel Medical personnel Vital Sign Window Displays vital signs, triage categories, and other information of patients 31 The number of patients per each triage category 32 Patients with Triage Categories Bird-Eye View Window View Area Event List Window Displays type and occurrence time of events

9 Individual view: Displaying each patient s information Assignment 3: Deadline August 13th 33 Displays patient s information on a tablet PC Uses augmented reality to overlay the information Patients Information The number of patients existing in each direction 34 Design your own distributed pervasive system. Clarify the following items: Name of your system Services provided by your system Physical components (e.g., sensor nodes, mobile phones, wireless AP, server, etc) and their organization (including their deployment positions) Information collected by sensors and contexts extracted from the information Network architecture, communication protocols, algorithms that your system utilizes Other information that characterizes your system NOTE: Submit your report by the following way: (1) Make your report as a PDF or a MS-word file. (2) Send to the instructor with attachment of the file. (3) Receive confirmation from the instructor. Summary Communications in distributed pervasive systems Short-range wireless communication (WiFi, Bluetooth, ZigBee) Ad hoc networks/manets/dtns Formed by mobile/embedded devices where they transfer data using wireless multi-hop communication Routing in MANETs: AODV, etc Store-Carry-and-Forward for DTNs Middleware/applications of pervasive systems Middleware: UPnP, rule-based device control middleware Application examples: Emergency medical support system, smart home 35