2. RF Communication in TinyOS2X ㈜한백전자

3. Background

4. IEEE 802 LAN/MAN Standards Committee802.1Higher 802.1 Higher Layer LAN Protocols Working Group 802.11 Wireless Local A rea Network Wor king Group 802.15 Wireless Personal A rea Network Wor king Group 802.20 MBWA W orking Gr oup TG1 WPAN/Bluetooth Task Group TG2 Coexistence Task Group TG3 WPAN High Rate Task Group TG4 WPAN Low Rate Task Group ………… + ZigBee IEEE 802.15.4 TG4

5. Low Rate Wireless Personal Area Networks  LR-WPAN A LR-WPAN is a simple, low-cost communication network that allows wireless connectivity in applications with limited power  Main objectives of an LR-WPAN Easy installation Reliable data transfer Short-range operation Low cost Reasonable battery life, Simple protocol. Table1 cited in 29 of standard BAND COVERAGE DATARATE CHANNELS 2.4 GHz ISM Worldwide 250 kbps 16 915 MHz ISM Americas 40 kbps 10 868 MHz Europe 20 kbps 1

6. The IEEE Standard 802.15.4  A low-rate wireless personal area network low-cost, very low-power short-range wireless communication LR-WPAN’s important goal “cost” “power consumption”  Applications Industry controlling Home automation, networking Personal healthcare Vehicle communication

7. IEEE 802.15.4a  Scope Detecting distance (<1m) / low power / low-cost  Alternative PHY UWB CSS: Chirp Spread Spectrum

8. IEEE 802.15.4b  Scope Extension previous IEEE 802.15.4-2003 Beacon mode, beacon schedule Security Remove unnecessary descriptions Current Beacon IEEE 802.15.4-2006 (publish)

9. 6LoWPAN (IPv6 over Low Power Wireless PAN)  Implement IPv6 technology on USN  Issue 15.4 PDU -> 102 byte, IPv6 MTU -> 1280byte Shim layer for fragmenting and assembling MTU

10. 802.15.4 and Zigbee  802.15.4 Define PHY and MAC  ZigBee Define Network, Security and Applications PHY 868MHz / 915MHz / 2.4GHz MAC Network Star / Mesh / Cluster-Tree Security 32- / 64- / 128-bit encryption Application API ZigBee Alliance IEEE 802.15.4 Customer Silicon Stack App

11. CC2420

12. About Chipcon CC2420  CC2420 Features Support 2.4 GHZ IEEE 802.15.4 DSSS modem, 250 kbps, 50 registers, 368 byte RAM Low power consumption (RX: 19.7mA, TX:17.4mA) Separate transmit and receive FIFOs (each 128 byte) Easy configuration interface (4-wire SPI interface) 802.15.4 MAC hardware support: Automatic preamble generator, Synchronization word insertion/detection CRC-16 computation and checking over the MAC payload Clear Channel Assessment Energy detection / digital RSSI Link Quality Indication Full automatic MAC security

13. About Chipcon CC2420  CC2420 power consumption and switch delay StateConsumption Voltage Off1 uA Power Down20 uA IDLE Mode426 uA Receive Mode19.7 mA Transmit Mode P = -25 dBm P = -15 dBm P = -10 dBm P = −5 dBm P = 0 dBm 8.5 mA 9.9 mA 11 mA 14 mA 17.4 mA statesDelay Startup time300 ~ 500 uS Startup time (V on)100 uS Setting time2 uS

14. CC2420 Receive Mode 1  Receive Mode Set SRXON register RX check by SFD, FIFO, FIFOP pin In TinyOS, use FIFOP pin SFLUSHRX command flush RX RAM

15. CC2420 Receive Mode 2  Data in RXFIFO Data in RXFIFO includes MPDU as well as RSSI and QLI RSSI and QLI are inserted instead of CRC filed

16. CC2420 Transmit Mode  Transmit Mode Set STXON register TX check by SFD pin In TinyOS, do not use interrupt pin SFLUSHTX command flush TX RAM

17. CC2420 Radio Chip

18. RSSI, LQI, CCA  RSSI (Received Signal Strength Indicator) 8 bit values in RSSI_VAL register (need 8 symbol) P = RSSI_VAL – RSSI_OFFSET (-45) [dBm]  LQI (Link Quality indication) LQI is limited from 0 to 255, however CC2420 support 0~110 correlation base on the incoming packets LQI = (CORR – a) x b  CCA (Clear Channel Assessment) CS threshold level is programmed by CCA_THR register CCA 3 modes are assigned CCA_POLARITY register

19. RF Communication

20. RF functions in TinyOS2X

21. Flooding Protocol  Flooding Flooding is that all nodes participate with data forwarding without fixed routing path. Firstly, source node broadcasts its data packet including destination address, and other neighbor nodes forward it. Finally, destination node can receive the data packet

22. Drawback of Flooding  Flooding’s limitations Nodes can receive same packets because of broadcast All nodes should participate flooding for transmitting one data packet Even if the destination node received data packet, the flooding protocol is not finished It has serious collision problem because all nodes participate flooding

23. Other approach for overcoming flooding  LAR By using location information, flooding region is limited  Gossiping By using probability, data forwarding decision is changed  Hierarchical Routing Select coordinator Only coordinator participate flooding

24. p.2323 Gradient-Based or Tree-Based Routing  GBR (Gradient-Based Routing) or Tree Routing The interest packet is required to record the number of hops from the sink. Each node calculates the minimum number of hops, called height. A gradient is defined as the difference between a node's height and that of its neighbor. Data packet is forwarded on the link with the largest gradient.

25. Homework  Ubi-HomeNet Exercise Hanback_TestTree. Read 15 chapter (ZigbeX’s textbook) Understand 15 chapter example Experiment 15 chapter tests  Report Searching some special codes to force multihop in Hanback TestTree Changing the example not to work forced multihop in Hanback TestTree Draw function diagram of tree routing components

26. Q & A