Distributed systems and middleware 20137: Distributed pervasive systems (2)

Communication

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Short range wireless communication

IEEE 802.11 IEEE 802.15.1 IEEE 802.15.4Frequency 2.4GHz, 5GHz 2.4GHz 2.4GHz (800MHz,

900MHz)

Radio range

11n: up to 70m (indoor)up to 250m (outdoor)

1m (class3, 1mW)10m (class2, 2.5mW)100m (class1, 100mW)

10 to 75m

Bandwidth 54Mbps (802.11a/g)300Mbps (802.11n)over 1Gbps (802.11ac)

1Mbps (ver. 1.2)3Mbps (ver. 2.0+EDR) 24Mbps (ver. 3.0+HS) 1Mbps (ver. 4)

20 - 250Kbps

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Wireless multi-hop communicationNetwork with one hop wireless communication

Nodes communicate via a base stationCellular networkWireless LAN

Network with multi-hop wireless communicationNodes receive and forward packetsCalled ad hoc network

Wired network

Receive and forwardpackets

Radio range

node4

Ad hoc networksSelf-configuring network consisting of devices (nodes) connected by wireless links

No communication infrastructure (e.g., base station or wireless access point) is requiredad hoc = for the special purpose, temporary constructed

forward forward

forward

Source node

Destinationnode

•Nodes located even beyond radio transmission range can communicate via multi-hop communication•When nodes move, path will be broken need dynamic path search5

Applications of ad hoc networksEmergency communication

Ad hoc communication infrastructure in disaster areasCommunication 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 driversInformation gathering/dissemination: autonomously collect and disseminate information on traffic jam, accidents, and number of free parking spots among vehicles

Low cost communication infrastructureCommunication means for exchanging local, word of mouth information among usersAuxiliary means enhancing existing communication infrastructure (e.g., off-loading for 3G cellular network)6

Routing in mobile ad hoc networksNeed 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 neededEffective 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 nodesEffective for less dynamic networks with frequent communications

Others: hybrid routing, energy-aware routing, etc7

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 1 6 10 14 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

1313

99

1212

33

22

55 88

11S

66

D

14141010

Flooding RREQ message

13131111

99

1212

33

4422

77

55 88

11S

66

D

14141010

Dest nextD 6

Dest NextD 14

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Configuring routing table by RREP message8

Delay/disruption tolerant networkIn MANET routing (e.g., AODV), two nodes can communicate only when an end-to-end path exists between themIn sparse MANETs, there may be no continuous connectivity between nodes (e.g., VANET)Store, Carry, and Forward strategy for DTN (delay/disruption tolerant network)

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(3) Sends the message when meeting another car

(2) moves with the message by retaining it in its buffer

(1) A car has a message to send, but no other cars in its radio range

Examples of DTNs Space networks

Satellites, Deep space

Military networks, tactical networksNo consistent network infrastructure and frequent disruptions

Sensor networks for wildlife trackingCoordinating the activities of multiple sensors to monitor science and hazard events

Vehicular ad hoc networksIntermittent Autonomous (Opportunistic ) Communications

Underwater networks Environmental Monitoring, Assisted Disaster Prevention, Assisted Navigation

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© Battlefield-Online.Net

© ZebraNet

© NASA

© Trinity College Dublin

Middleware and applications

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Functions required for context-aware systems

Selecting information and servicesNavigation systems avoiding traffic jamsConstraints for the context must be met

Showing information and servicesShowing a route, location-dependent information (restaurants, spots, persons)

Automatically executing servicesSystems 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 and time period for existence) to information12

Examples of context-aware systemsMedical applications

Emergency medical care, health care, etc

Applications supporting our daily livesSmart space, smart environment, smart home, etc

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Context-aware medical applicationsWBAN (Wireless Body Area Network)

Consists of a set of mobile and small sensors capable of wireless communication, wearable or implanted into human bodyMonitors vital signs such as ECG, pulse, blood pressure, SPO2 and movementsTransmits collected data to base station (in hospital)

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Applications of WBAN

for meals and exercises

Applications of WBAN • Emergency medical careprioritizes the ordering of treatments of patients by using electronic Triage in MCI (Mass-casualty incident)•Healthcare for chronic disease patientsCollects information from sensors and provides adequate menus for meals and exercises

Example: Electronic Triage SystemMany patients in MCI (mass-casualty incident)

Determining the ordering of medical treatments for those patients in very short time is essential called TriageCurrently, paper-based Triage tag is used to categorize patients into four categories (black, red, yellow, green)

Problems: patients conditions will change as time goesE-triage (http://etriage.jp)

Senses vital signs such as Pulse and SPO2 in real timeTransmits data via ZigBee, determines position via localization

15 Paper-based Triage tag Electronic Triage tag

Smart spacesWhat 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 contextControl devices (actuators) appropriately according to a scenario (specified based on user’s preference)

Alice

ON

CNNIf Alice is in a room, turn on TV with channel CNN and set temperature 25C°for air conditioner 25C°

ONExample of a scenario16

Network for connecting devices/sensorsWireless: ZigBee, Bluetooth, IEEE802.11Wired: PLC, Ethernet

Framework for device communicationUPnP (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/middlewareSoftware for appropriately controlling devices according to context determined by data collected from sensors and user preference

Technologies for realizing smart spacesApplications/middleware

UPnP, Jini, etc

ZigBee，Bluetooth，PLC, etc

Upperlayers

Middlelayers

Lowerlayers

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Rule-based device controlScenario for controlling appliances at living room

Time: 5 to 6 PMIllumination: dimStereo: FM radio with small volumeAir cond.: temp. 25C°, hum. 60%

Time: 9 to 10 PMIllumination: brightTV: News with medium volumeAir cond.: temp. 28C°

Control scenario can be described as a set of rulesEach rule consists of condition for context and action for deviceCondition: Alice is in living room and time is between 5 and 6 PMAction: Turn on left lamp, stereo for FM radio with volume level 10, and air conditioner with 25C° temperature setting

TV

Air cond.

Lamps

Stereo

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Middleware for context-aware device control

CADELRealizes rule-based context-aware control of UPnP-ready appliances

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Rule execution

Rule database

Communication interface (UPnP library)

Consistency check

Rule description support GUI

Device object Device object Device object…UPnP protocols (SOAP, SDDI, etc)

Example of a rule in CADEL

if (aliceBedroom1.Existence && sensorBedroom1.Temperature>=28){fanBedroom1.SetPower(true);

}

Names of devices and sensors are decided when they are configured as UPnP devices

Nishigaki, et al., Framework and Rule-based Language for Facilitating Context-aware Computing using Information Appliances, Proc. of SIUMI'05

Examples of distributed pervasive systems

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Position tracking sensor(ultrasound receiver）

Positioning sensor（ultrasound emitter）

power meter

power consum

ption (Wh)

(1) Smart home

Position tracking systemaccurately tracks user’s position (within 50cm error)

Power metermeasures power consumption of an appliance

Environment sensormeasures temperature, humidity, and illuminance

Door sensordetects open/close behavior by acceleration

Infrared remote controlleroperates appliances

Sensors are wirelessly connected to home networkAll sensor data are periodically collected at the server

Sensors in smart home

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Example scenario for context-aware control in a smart home

Inhabitant location time Illumina-tion

TV temperature Priority

Alice Living, bed rooms

anytime dim Music Channel

28 degree [C] Middle

Dave Living, bed rooms

anytime bright Sport Channel

24 degree [C] Low

Carol anywhere 9:00-10:00PMon Mondays

bright Drama Channel

26 degree [C] High

Condition for context

Action(appliance operation)

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Simulator for smart homes

UbiREAL

Network simulator

Physical quantity

Simulator

Visualizer& GUI

UPnP device 1 UPnP device n Rule-baseddevice control

middleware (CADEL)

Rule-basedscenario

UPnP middleware

．．

Application software24

Nishikawa, et al., UbiREAL: Realistic Smartspace Simulator for Systematic Testing, UbiComp2006 (http://ubireal.org/)

Smart home in UbiREAL

living room

kitchenbed rooms

bath room

toilet

entrance

corridor

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Simulating smart home with UbiREAL

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(2) Emergency medical support system

Developed as part of a government-funded project (JST CREST) by Osaka Univ., NAIST, Keio Univ., Shizuoka Univ. and Juntendo Univ.

Mizumoto et al., Emergency Medical Support System for Visualizing Locations and Vital Signs of Patients in Mass Casualty Incident, Proc. of PerNEM 2012

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Electronic triageElectronic triage tag (eTriage tag)

Vital sensors (spo2, pulse, breathing rate) ZigBee based communication functionCan wirelessly send vital signs of patients

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http://etriage.jp/

Technologies for efficient rescue operations

Estimate patients’ position using ZigBee-based localization techniqueSend vital sign to server using ad-hoc networking technologySupport medical-staffs using context-awareness technology

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Construction of ad-hoc network and disaster map

Monitoring vital sign of patients

Localization of patient’s location

System organization

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Inter-site view:Displaying overall situation on map

Displays information of each first-aid station

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The number of medical personnel

The number of patients per each triage category

Intra-site view:Displaying patients information on 3D map

3D View WindowDisplays patients/personnel as 3D objs

Vital Sign Window Displays vital signs, triage categories,

and other information of patients

Bird-Eye View Window

Event List WindowDisplays type and occurrence

time of events

Medical personnel

Patients with Triage

Categories

View Area

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Displays patient’s information on a tablet PCUses augmented reality to overlay the information

Individual view:Displaying each patient’s information

Patients’ Information

The number of patients existing in each direction

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Assignment 3: Deadline August 13th

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Design your own distributed pervasive system. Clarify the following items:

Name of your systemServices provided by your systemPhysical 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 informationNetwork architecture, communication protocols, algorithms that your system utilizesOther 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 e-mail to the instructor with attachment of the file.(3) Receive confirmation e-mail from the instructor.

Summary

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Communications in distributed pervasive systemsShort-range wireless communication (WiFi, Bluetooth, ZigBee)Ad hoc networks/MANETs/DTNs

Formed by mobile/embedded devices where they transfer data using wireless multi-hop communicationRouting in MANETs: AODV, etcStore-Carry-and-Forward for DTNs

Middleware/applications of pervasive systemsMiddleware: UPnP, rule-based device control middlewareApplication examples: Emergency medical support system, smart home