Wsn basics

IEEE 802.15.4

IEEE802 15 4.png

• IEEE 802.15.4 at Wikipedia is the basis of many wsn protocols
  
  
  
• TI CC2520 2.4 GHZ IEEE 802.15.4/ZIGBEE® RF TRANSCEIVER DATASHEET
  
  
  
• Freescale MC13192: 2.4 GHz, Low Power Transceiver for 802.15.4 Ref Manual
  
  
  
  
  

6LoWPAN

• 6LoWPAN From Wikipedia

The 6lowpan group has defined encapsulation and header compression mechanisms that allow (internet)IPv6 packets to be sent to and received from over IEEE 802.15.4 based networks

• TI CC1101 Low-Power Sub-1GHz RF Transceiver page

RF Networks

• Wireless ad hoc network at Wikipedia
• Ad hoc http://en.wikipedia.org/wiki/Ad_hoc
• CSMA Carrier Sense Multiple Access http://en.wikipedia.org/wiki/Carrier_Sense_Multiple_Access
• The first implementation of CSMA was Ethernet http://en.wikipedia.org/wiki/Ethernet
• CSMA/CA Carrier sense multiple access with collision avoidance at Wikipedia
• TDMA Time division multiple access http://en.wikipedia.org/wiki/Time_division_multiple_access
• Wireless mesh network at Wikipedia
• The earliest wireless ad hoc networks were the "packet radio" networks (PRNETs) from the 1970s, sponsored by DARPA after the ALOHAnet project.
• ISM bands http://en.wikipedia.org/wiki/ISM_band

Low power wsn

• Example of Total Low Power using low Duty-Cycle

0.5sec active time every 300sec(5min) is 1/600

30mA with duty-cycle 1/600 is 50uA

50 uA with battery 1.2Ah(Alkaline D-cell) is 24000hours = 1000days

With better battery and more conservative power handling the battery life expectancy of 5 years is possible.

• Sub 1% Duty cycle of operation is considered necessary for Low Power Wireless Sensor Networks (WSN).