Prof. Jong-Won Yu KAIST

Transcription

1 Prof. Jong-Won Yu KAIST

2 WSN (Wireless Sensor Network) WSN : A network of (possibly low-size and low complex) devices denoted as nodes that can sense the environment and communicate the information gathered from the monitored field through wireless links. Homes and office Industrial applications Logistics Environmental monitoring Transportation WSN (Wireless Sensor Network) Health Care Entertainment Positioning and animals tracking Mood-base services Tom s ceremony Tom s friends Danger s warning Personal coaching Mental counseling Daily travel 2

3 Cost/Complexity Wireless Sensor System UWB (WLAN/Wi-Fi) Bluetooth ZigBee RFID Short-range, high-speed networking solution Long-range networking solution Short-range networking solution Networking solution for home/industrial automation Active/Passive tags for inventory tracking UWB (Ultra-Wideband, IEEE a, IEEE a) Mbps ( < 2m), 110Mpbps (> 10m) - low power, high speed Wi-Fi(IEEE ) - 11 Mbps(2.4GHz), 54Mbps(5GHz) - Range : < 150m - high power (<1W, multi-hours) ZigBee (IEEE ) kbps@2.4 GHz, 40 kbps@915 MHz, 20 kbps@868 MHz - Range : 10 ~ 100 m - low power (multi-month ~ years) Bluetooth (IEEE ) - 1 Mbps - Range : 10 ~ 100m - medium power (multi-days) RFID (140 different ISO standards) - < GHz - Range : < 1m (passive tag) - unpowered tag (passive tag) 3

4 IEEE (Wi-Fi) Wireless Local Area Network (WLAN) 2.4 GHz ISM band (2.4GHz ~ GHz) : IEEE b/g - DSSS (Direct Seuence Spread Spectrum) - 1Mbps(DBPSK), 2Mbps(DQPSK), 5.5Mbps(CCK), 11Mbps(PBCC) 5GHz band(5.15ghz ~ GHz) : IEEE a - OFDM (orthogonal freuency-division multiplexing) - 6 Mbps (BPSK) ~ 54 Mbps(64QAM) Operation Range of 100m 10-5 bit -80dBm 4

5 IEEE b/g Radio Block Diagram Direct Conversion 5

6 IEEE a Radio Block Diagram Superheterodyne Conversion OFDM (Orthogonal Freuency Division Multiplexing) OFDM Symbol Assembly for N = 8 Subcarriers 6

7 IEEE (Wi-Fi) Freuency vs. Channel Allocation IEEE b/g(2.4GHz band) IEEE a(5GHz band) 7

8 Bluetooth Data/Voice Access Points Cable Replacement Personal Ad-hoc Connectivity A Short Range Wireless Communication Technology Intended to create Personal Area Network (PAN) Operating Range : 100m (class 1, 100mW), 10m (class 2, 2.5mW), 10 cm (class 3, 1mW) Operates in ISM Band (1MHz 79 channel, GHz to GHz) Freuency Hopping Gaussian Minimum Shift Keying (GMSK) 0.1% bit error -70dBm Targeted at all types of Devices Wireless Telephones (Cellular, Portables, Satellite, etc.) Computers, PDAs, Peripherals, etc. Set-top Boxes, Audio Systems, Cameras and Camcorders, etc. Consumer Electronics, Headsets, Remote controls, etc. 8

9 Bluetooth Transceiver RF Transceiver Baseband Processor FLASH GMSK modulation 0 : phase no change 1 : phase change 0 to p reducing sideband power(continuous phase) 9

10 Bluetooth Freuency Hopping Freuency Hopping : 1600hops/sec fre master slave time 10

11 Comparison of Wi-Fi and Bluetooth Wi-Fi (2.4 GHz band) DSSS( Direct Seuence Spread Spectrum) Use only 22MHz X 3 (channel) = 66 MHz Max data rate 56 Mbps at close range, 5.9 Mbps < 175 ft, 5.5 Mbps at 250 ft Bluetooth FHSS (Freuency Hopping Spread Spectrum) Use 1MHz X 79 (channel) = 79 MHz The hop rate is 1600 hops/sec Max data rate 550 kbps at 250 ft. Range up to 100 m, depends on power and environment Power range; 100 m (class 1), 10 m (class 2), 10 cm (class 3) Each Wi-Fi network uses 1 channel, max 3 nonoverlapping networks FCC reuires BT devices to hop > 75 channels up to max 79 channels 11

12 WiFi and Bluetooth can Coexist 12

13 ZigBee IEEE LR-WPAN (Wireless Personal Aria Network) Data Rates : GHz, MHz, MHz ( < 1mW) 255 devices per network Low Power Consumption (Battery life multi-month to nearly infinity) Range : 10m nominal(1~100m) DSSS (Direct Seuence Spread Spectrum), O-QPSK (2.4GHz Band) 13

14 2.4GHz ZigBee Transceiver Direct Conversion DSSS O-QPSK O-QPSK (Offset uadrature phase-shift keying) Offset Ts/2 at Q data Phase Shift lower than 90 o (QPSK 180 o ) 14

15 Comparision of Zigbee and Bluetooth Transmission Scheme Modulation Bluetooth FHSS (Freuency Hopping Spread Spectrum) GFSK (Gaussian Freuency Shift Keying) Zigbee DSSS (Direct Seuence Spread Spectrum) QPSF (Quadrature Phase Shift Keying) or BPSK (Binary Phase Shift Keying) Freuency Band 2.4 GHz 2.4GHz, 915MHz, 868 MHz Raw Data Bit Rate Power Output Minimum Sensitivity 1 Mbps Maximum 100mW, 2.5mW, or 1mW (depending on class) -70 dbm for 0.1% BER 250 kbps, 40 kbps, 20 kbps (depends on freuency band) Maximum capability 0.5 mw; Maximum as allowed by local regulation -85 dbm (2.4 GHz) or -92 dbm (915/868 MHz) for packet error rate < 1% Network topology Master-Slave 8 active nodes Star or Peer-Peer 255 active nodes 15

16 UWB (Ultrawideband) DS-UWB, MB-UWB : IEEE a(PAN), IR-UWB : IEEE a(WSN) Data Rates : > 100 Mbps ~ 400 Mbps (BW > 500 MHz) 3.1~10.6GHz indoor power limit < dbm/mhz (noise floor) * DS-UWB (direct seuence UWB), MB-UWB (multiband UWB), IR-UWB (impulse radio-uwb) 16

17 MB-OFDM UWB & DS-UWB MB-OFDM UWB OFDM(128FFT)/QPSK 55 ~ 480 Mbps DS-UWB 4-ary biorthogonal symbols CDMA/MBOK(M-ary biorthogonal keying) or BPSK 28.5 Mbps ~ 1.2Gbps 17

18 MB-OFDM UWB & DS-UWB Transceiver MB-OFDM UWB DS-UWB transceiver 18

19 Impulse Radio UWB Pulse Position Modulation UWB Radio Pulse Shape & spectrum (pulse width = ns) 19

20 RFID : Radio-Freuency Identification The lowest cost of identifying an object The fastest growing sector of the radio technology industry. 20

21 Range & Operating Freuency of RFID System Operating Freuency Interrogation zones 21

22 Inductive Coupling Transponder Magnetic field H Binary Code Signal, subcarrier fre. (fs) 22

23 Electric field backscattering 23

24 Passive, Semi-passive, and Active RFID u Passive RFID - no independent source of electrical power to drive the circuitry in tag - no radio transmitter of their own - Reading range is limited u Semi-passive RFID - Incorporating a battery to power the passive tag (battery assisted passive tag) - Long reading range (~ 100m) - wake-up signal from reader u Active RFID - Synthesizes a carrier signal using a local oscillator and crystal reference - communicate by using different freuency channel 24

25 Components of RFID System Transponder, which is located on the object to be identified Interrogator or reader, which may be a read or write/read device 25

26 UHF RFID Transmitter & Receiver 26

27 Elements of a Passive UHF Tag 27