Wireless Sensor Networks

Transcription

1 Wireless Sensor Networks Office Hours: Tuesday 3 5 Main Building, third floor Credits: 6

2 Standard Solutions for Wireless Networks 2

3 Standard Solutions for WSN 3

4 DEI, University Università of di Bologna Standard Solutions for WSN / IoT

5 The IEEE

6 IEEE Main Features Thought for low-cost, low-rate, low-power consumption wireless communications Used for Low Rate W-PAN composed of battery charged devices Standard de-facto for WSNs It defines the PHY and MAC Layers protocols

7 Protocol Stack Architecture / 1

8 Protocol Stack Architecture / 2 Application Objects End Manufacturer Application Layer Network Layer Zigbee Alliance MAC Layer IEEE Physical Layer

9 Protocol Stack Architecture / 3

10 IEEE / 1 IEEE , 2006, 2011 IEEE a Different PHY (UWB) IEEE c Alternative PHY to support Chinese bands IEEE e MAC Enhancements for Industrial Applications - Time Synchronized Channel Hopping (TSCH) MAC protocol, IEEE f Active Radio Frequency Identification (RFID) IEEE g Smart Utility Networks (SUN) - PHY amendment (OFDM)

11 IEEE / 2 IEEE j Medical Body Area Networks IEEE k Low Energy Critical Infrastructure Monitoring (LECIM) IEEE m Operations in TV White Space IEEE n China Medical Band IEEE p Positive Train Control (PTC) IEEE q Ultra Low Power (ULP) Alternative PHY to support Japanese bands

12 The IEEE PHY 12

13 Protocol Stack Time Synchronization Energy Management Localization Application Layer Network Layer MAC Layer PHY Layer

14 PHY Layer PHY is responsible for: Activation and deactivation of the radio transceiver Data Transmission and Reception Channel Frequency selection ED within the current channel CCA for CSMA/CA PAN Formation (Handouts 5) MAC Layer (Handouts 4)

15 IEEE Bands PHY Frequency Band Channels Chip rate parameters Modulation Bit rate parameters Symbol rate From bits to symbols 800/915 MHz MHz MHz 0 From 1 to kchip/s 600 kchip/s BPSK BPSK 20 kb/s 40 kb/s 20 kbaud 40 kbaud Binary Binary 2.4 GHz GHz From 11 to Mchip/s O-QPSK 250 kb/s 62.5 kbaud 16-ary Orthogonal 16 channels, 5 MHz each 80 MHz 2.45 GHz ISM Band MHz frequency

16 IEEE Bands

17 IEEE PHY PHY Frequency Band Channels Chip rate parameters Modulation Bit rate parameters Symbol rate From bits to symbols 800/915 MHz MHz MHz 0 From 1 to kchip/s 600 kchip/s BPSK BPSK 20 kb/s 40 kb/s 20 kbaud 40 kbaud Binary Binary 2.4 GHz GHz From 11 to Mchip/s O-QPSK 250 kb/s 62.5 kbaud 16-ary Orthogonal

18 IEEE PHY - Modulation MSK Modulation

19 IEEE PHY

20 IEEE PHY Hamming distance between each pair of 32-chip sequences Probability of error on a symbol when n chips are wrong (n errors on chips)

21 IEEE PHY Performance BER SNR [db]

22 IEEE PHY - Performance

23 IEEE PHY - Performance db

24 IEEE PHY - Band 80 MHz 2.45 GHz ISM Band 5 MHz frequency 5 MHz 3 MHz

25 IEEE Data Block (PHY PDU) n bytes Preamble (4) SFD (1) FLI (1) MHR (3 + (4 to 20)) FCS (2) Start of Frame Delimiter Frame Length MAC Header Data Payload Frame Check Sequence PHY Payload (PSDU) Max 127 bytes PHY Layer Protocol Data Unit (PPDU)

26 Wireless Sensor Networks