Remote Data
Acquisition for Wireless
Sensor Networks

Changfei Chen
Steve Distasi
Sarah Greenberg
Topics

 Methods of RDA


 Possible WSN RDA Configurations


 Physical Concerns of RDA
Methods of Remote Data
Acquisition

 Wired System


 Radio Modem (point-to-point)


 Cellular Modem
Wired System

 Gateway node connected directly to
  established Internet connection
Wired System Example

 City Sniff
    In-home pollution sensing kit
    Sends environmental data to public database
   ...
City Sniff cont.

 Connects Tmote Sky to
  embedded linux gateway
     BaseStation Tmote
      connected via USB to
    ...
Radio Modem
 Transmit data over long distance (point-to-point)
 Useful for…
       Remote Locations
       No wired ac...
Radio Modem Example

 Volcanic Monitoring
      Uses FreeWave Radio Modem
Cellular Modem

 Send/receive data via cellular communication
    SMS—text message
    Email
    Direct internet conne...
Cell Modem Example

 Temperature
  monitoring on fish
  boats in Ireland
 Users can access the
  data via web server or
...
Cell Modem Example
 Klimat
      Monitoring effects of global warming on the Baltic
       Sea
      RDA using GPRS sat...
Limitations

 Power
 Memory
 Frequency
 Transmission Distance
Power

 Wired
     Usually inside, just plug it in!
 Radio/Cell/Satellite modems
     Large batteries
     Energy har...
XTend-PKG 900 MHz USB RF
Modem

•Receive current: 110mA
•Transmit current (1mW-1W transmit power):
   110-900mA
•Three Mod...
MultiModem GPRS
•Three Modes:
  •Always-on
  •Wake-up on ring
  •Dial-on demand
Memory

 Dependant on gateway device
     Tmotes have little onboard memory, so
      they have limited gateway capabili...
Operating Frequencies of
modems
 Radio Modem – 900 MHz
 Cellular Modem
     GSM:
       900MHz, 1800MHz;
       850MH...
Transmission Distance

 XTend RF Modem & MultiModem GPRS
     Transmission Power can be up to 1 Watt
     Indoor/Urban ...
Possible WSN RDA
Configurations
 Gateway Concept
     WTF


 Possible Orientations


 Current Solutions
     Cell Mod...
Gateways

    Provide the connection to the
     communication medium

    Can be a node, or any device with access
    ...
Gateway Challenges

 Is it just a router?


      Do we want the ability to address individual
       nodes?

      Goe...
Gateway Challenges

 Application-level gateway


     Requester sends properly formatted
      message to the gateway no...
Possible Orientations

 WSN to Internet

                    INTERNET
 Internet to WSN


 WSN to WSN
  Tunneling
Possible Configurations
 WSN to Internet
     A sensor node in your house wants to send an
      alert that your house i...
Possible Configurations
 Internet to WSN
     You wish to access the Votey WSN from
      your home terminal
     Gatew...
Possible Configurations
 WSN to WSN Tunneling
     Gateways act as simple extensions from
      one WSN to another
    ...
Cell Modems!<3

 GSM/GPRS


     Some Definitions

     Services
Global System for Mobile
communications (GSM)
 Implements 2 Circuit-Switching data
  protocols
     Circuit Switched Dat...
General Packet Radio Service
(GPRS)
 Packet-Switching data protocol
     Sends data in packets along channels not
      ...
Current Solutions

 lwIP & µIP


 lwIP
     Designed for 16-bit microcontrollers
     Uses only tens of kbs of RAM
  ...
Current Solutions

 lwIP & µIP


 µIP
     Designed for 8-bit and 16-bit
      microcontrollers
     Ram usage on the ...
Serial Communication

 RS-232


 USB


 Synchronous and Asynchronous
Serial Communication
Hardware
 UART (Universal Asynchronous
  Receiver Transmitter) -- Translates data
  between parallel...
Serial Communication
Parameters
 Baud Rate
 Start Bit
 Data Bits – 5 to 8
 Parity – Error check (Even, Odd, none)
 St...
Serial Communication
Example Parameters


 Baud rate = 115200 bps
 8 Data Bits
 No parity
 1 Stop Bit
 No Flow Control
Serial Communication
Signals

 Transmitted Data (TxD)


 Received Data (RxD)


 Ground (GND)
Serial Communication
Signals

   Request To Send (RTS)
      Asserted (set to 0) by sender to prepare receiver to receiv...
Flow Control

 Flow control avoids overflow
 Can Eliminate the need for flow control
  by…
     Regulating speeds
    ...
Demo

 Configure parameters
 Transmit data through modem
 Polling vs. event driven
Thanks! Any Questions???
Remote Data Acquisition for Wireless Sensor Networks
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Remote Data Acquisition for Wireless Sensor Networks

  1. 1. Remote Data Acquisition for Wireless Sensor Networks Changfei Chen Steve Distasi Sarah Greenberg
  2. 2. Topics  Methods of RDA  Possible WSN RDA Configurations  Physical Concerns of RDA
  3. 3. Methods of Remote Data Acquisition  Wired System  Radio Modem (point-to-point)  Cellular Modem
  4. 4. Wired System  Gateway node connected directly to established Internet connection
  5. 5. Wired System Example  City Sniff  In-home pollution sensing kit  Sends environmental data to public database  Connects to existing wired internet connection
  6. 6. City Sniff cont.  Connects Tmote Sky to embedded linux gateway  BaseStation Tmote connected via USB to gateway  Gateway is then connected to home’s router
  7. 7. Radio Modem  Transmit data over long distance (point-to-point)  Useful for…  Remote Locations  No wired access  No cell access
  8. 8. Radio Modem Example  Volcanic Monitoring  Uses FreeWave Radio Modem
  9. 9. Cellular Modem  Send/receive data via cellular communication  SMS—text message  Email  Direct internet connection  GSM/GPRS most commonly used standard, CDMA also used  Useful for…  Remote location with cell access  Mobile sources—cars and boats  Immediate updates or alerts sent to specific person/location
  10. 10. Cell Modem Example  Temperature monitoring on fish boats in Ireland  Users can access the data via web server or SMS server  SMS warning system
  11. 11. Cell Modem Example  Klimat  Monitoring effects of global warming on the Baltic Sea  RDA using GPRS satellite modem
  12. 12. Limitations  Power  Memory  Frequency  Transmission Distance
  13. 13. Power  Wired  Usually inside, just plug it in!  Radio/Cell/Satellite modems  Large batteries  Energy harvesting  Energy saving techniques  Cyclic sleep modes
  14. 14. XTend-PKG 900 MHz USB RF Modem •Receive current: 110mA •Transmit current (1mW-1W transmit power): 110-900mA •Three Modes: •Pin sleep: 17mA •Serial port sleep: 45mA •Cyclic sleep (Various intervals): 19-39mA
  15. 15. MultiModem GPRS •Three Modes: •Always-on •Wake-up on ring •Dial-on demand
  16. 16. Memory  Dependant on gateway device  Tmotes have little onboard memory, so they have limited gateway capabilities.
  17. 17. Operating Frequencies of modems  Radio Modem – 900 MHz  Cellular Modem  GSM:  900MHz, 1800MHz;  850MHz, 1900MHz. (US., Canada)  Uses 1900MHz  Uplink:1850-1910MHz  Downlink: 1930-1990MHz
  18. 18. Transmission Distance  XTend RF Modem & MultiModem GPRS  Transmission Power can be up to 1 Watt  Indoor/Urban range (2.1 dB dipole antenna): Up to 3000 feet (900m)  Outdoor RF line-of-sight range (High gain antenna): Up to 40 miles (64 km)  Outdoor RF line-of-sight range (2.1 dB dipole antenna): Up to 14 miles (22 km)
  19. 19. Possible WSN RDA Configurations  Gateway Concept  WTF  Possible Orientations  Current Solutions  Cell Modems!<3  lwIP & µIP
  20. 20. Gateways  Provide the connection to the communication medium  Can be a node, or any device with access to the WSN.
  21. 21. Gateway Challenges  Is it just a router?  Do we want the ability to address individual nodes?  Goes against the idea that and individual node is irrelevant
  22. 22. Gateway Challenges  Application-level gateway  Requester sends properly formatted message to the gateway node  Masks the data-centric exchange in the WSN behind an identity-centric exchange of the internet
  23. 23. Possible Orientations  WSN to Internet INTERNET  Internet to WSN  WSN to WSN Tunneling
  24. 24. Possible Configurations  WSN to Internet  A sensor node in your house wants to send an alert that your house is on fire.  Gateway must convert intra-WSN event notification message to an Internet application message.
  25. 25. Possible Configurations  Internet to WSN  You wish to access the Votey WSN from your home terminal  Gateway must translate this request into proper intra-sensor network protocols
  26. 26. Possible Configurations  WSN to WSN Tunneling  Gateways act as simple extensions from one WSN to another  Such tunnels need not be made of fixed gateways
  27. 27. Cell Modems!<3  GSM/GPRS  Some Definitions  Services
  28. 28. Global System for Mobile communications (GSM)  Implements 2 Circuit-Switching data protocols  Circuit Switched Data (CSD)  High Speed Circuit Switched Data(HSCSD)  Reserves a certain amount of bandwidth between two points for the life of a connection
  29. 29. General Packet Radio Service (GPRS)  Packet-Switching data protocol  Sends data in packets along channels not being used for circuit-switching  Multiple GPRS users share a single unused channel - using it only in short bursts
  30. 30. Current Solutions  lwIP & µIP  lwIP  Designed for 16-bit microcontrollers  Uses only tens of kbs of RAM  Code size of around 40 kbs
  31. 31. Current Solutions  lwIP & µIP  µIP  Designed for 8-bit and 16-bit microcontrollers  Ram usage on the order of a few hundred bytes  Code size on the order of a few kbs
  32. 32. Serial Communication  RS-232  USB  Synchronous and Asynchronous
  33. 33. Serial Communication Hardware  UART (Universal Asynchronous Receiver Transmitter) -- Translates data between parallel and serial forms  Included in Tmote microcontroller  RX, TX, and FIFO buffers  Line driver -- Converts circuit level voltages to line voltages and vice versa  USB controller
  34. 34. Serial Communication Parameters  Baud Rate  Start Bit  Data Bits – 5 to 8  Parity – Error check (Even, Odd, none)  Stop Bit(s)  Flow Control (DTR/DSR, RTS/CTS, Xon/Xoff, none)  Start and Stop bits not necessary for synchronous communication
  35. 35. Serial Communication Example Parameters  Baud rate = 115200 bps  8 Data Bits  No parity  1 Stop Bit  No Flow Control
  36. 36. Serial Communication Signals  Transmitted Data (TxD)  Received Data (RxD)  Ground (GND)
  37. 37. Serial Communication Signals  Request To Send (RTS)  Asserted (set to 0) by sender to prepare receiver to receive data.  Clear To Send (CTS)  Asserted by receiver to acknowledge RTS and allow transmission.  Data Terminal Ready (DTR)  Asserted by device to indicate that it is ready to be connected. If the device is a modem, this may "wake up" the modem, bringing it out of a power saving mode.  Data Set Ready (DSR)  Asserted by host to indicate an active connection.  Data Carrier Detect (DCD)  Asserted by host when a connection has been established with remote equipment.  Ring Indicator (RI)  Asserted by host when it detects ring signal from the telephone line
  38. 38. Flow Control  Flow control avoids overflow  Can Eliminate the need for flow control by…  Regulating speeds  Packet size smaller than buffers
  39. 39. Demo  Configure parameters  Transmit data through modem  Polling vs. event driven
  40. 40. Thanks! Any Questions???

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