Low Power Wireless Personal Area Network (LP-WPAN) IEEE 802.15.4 (Zigbee) Low Power Wireless Personal Area Network (LP-WPAN) 9/20/2018 Chao GAO, VAMK

IEEE 802.15.4 General Description 16 channels in the 2.4GHz band, 10 channels in the 915 MHz band, and 1 channel in the 868 MHz band; Over-the-air data rates of 250kb/s @2.4G, 40kb/s @915, and 20kb/s @868, respectively. Star or peer-to-peer topology Allocated 16-bit short or 64-bit extended addresses Allocation of guaranteed time slots (GTSs) CSMA-CA channel access with synchronized sleep mode (low power consumption) Energy detection (ED) Link quality indication (LQI) Aimed to a Low-Rate Wireless Personal Area Network (LR-WPAN) Standard. 9/20/2018 Chao GAO, VAMK

IEEE 802.15.4 Channels At 2.4GHz shared with WiFi 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 868.3MHz 902MHz 928MHz Channel spacing: 2MHz 26 25 2400MHz 2412MHz ch1 2417MHz ch2 2422MHz ch3 802.11 channel Spacing: 5MHz 2462MHz ch11 Tx power 11 16 17 12 18 20 13 21 23 14 19 22 15 bandwidth: 22MHz 24 2405 2410 802.15.4 channel 2470 Freq. (MHz) 9/20/2018 Chao GAO, VAMK

IEEE 802.15.4 Topology Two basic topologies are supported: star and peer-to-peer Two types of nodes: FFD (Full-Function Device), and RFD (Reduced- Function Device) Thus two MAC protocols are used: CSMA/CA (for p2p) and CSMA/CA with superframe synchronization (for star) Star topology Peer-to-peer topology Communication flow PAN coordinator Reduced function device (RFD) PAN coordinator Full function device (FFD) 9/20/2018 Chao GAO, VAMK

IEEE802.15.4 standard and ZigBee Stack Architecture Application Profile Application ZDO SSP App Support (APS) ZigBee Stack NWK Physical Radio (PHY) Medium Access (MAC) IEEE 802.15.4 9/20/2018 Chao GAO, VAMK

Need of MAC Collision may happen ??? Tonight I am free. Can you give me a hand? If you have a watch, tell me what the time is now? 9/20/2018 Chao GAO, VAMK

I have ordered some pizza. Do you want to eat? Need of Address In a network, address is critical. I have ordered some pizza. Do you want to eat? Is she talking to me? Is she talking to me? 9/20/2018 Chao GAO, VAMK

Need of Error Checking and ACK Verify data is error free and acknowledge it. Lets meet at 8pm tonight in front of cinema. (DATA) Ok, 8pm cinema. (ACK) 9/20/2018 Chao GAO, VAMK

PHY Service Data Unit (PSDU) IEEE802.15.4 Physical Layer Power: Transmitter power: 0dBm Receiver Sensitivity: ~-85dBm PHY Packet Fields Preamble (4 octets) – synchronization Start of Packet Delimiter (SPD, 1 octet) PHY Header (1 octet) – PSDU length PSDU (0 to 127 octets) – Data field 4 1 1 Pramble SPD PSDU LEN PHY Service Data Unit (PSDU) 6 octets 0-127 octets 9/20/2018 Chao GAO, VAMK

PHY Service Data Unit (PSDU) IEEE 802.15.4 Frames 4 types: DATA, BEACON, ACK, CONTROL In a P2P network, we only see DATA and ACK PHY Header Pramble (4) SPD (1) PSDU LEN (1) PHY Service Data Unit (PSDU) MHR: MAC Header MSDU: MAC Service Data Unit MFR: MAC Footer MHR MSDU MFR Frame control Seq. No. Addresses Data payload Frame Chksum DATA frame 2 1 4-20 2 Frame control Seq. No. Frame Chksum ACK frame 9/20/2018 Chao GAO, VAMK

Sequence Number in MHR Monotonically incrementing (00 – 01 – … – FF – 00) CSMA/CA supports retransmission. SN helps the receiver to avoid Run 20km Ok. Run 20km collision ??? Run 20km 9/20/2018 Chao GAO, VAMK

Frame Control & Address Depends on settings, address fields may contain 3 addresses: PAN address: 2 octets, indicating the specific PAN (multi-PAN co-existence) Destination and Source addresses: 2/6 octets (depends on settings) Frame control is 2 octets (first 2 bytes in MAC header) Frame TYPE: 001-DATA, 000-BEACON, 010-ACK, 011-Control, others-Reserved SE: 0 if no encryption is applied FP: 0 if no further frames are waiting for transmission AR: ACK required, usually set in a DATA frame PANID Compression: 1 if destination and source nodes are in the same PAN Address Mode: 00-no address, 01-reserved, 10 - 16bit short addr, 11 - 64bit extended addr 9/20/2018 Chao GAO, VAMK

IEEE 802.15.4 Frame Examples A sniffer capture (from out laboratory facility) 2 1 2 2 2 5 2 DATA 2 1 2 ACK DATA ACK What is the temperature? (DATA 01H) OK wait (ACK) Temperature is 0x16 (DATA 16H) OK thanks (ACK) PAN coordinator Sensor 9/20/2018 Chao GAO, VAMK

Power Consumption of Sensor Node It is desirable to put a sensor node into sleep mode. The question is: when it can sleep? From [Tsiatis et al, 2002] Can you come here? 9/20/2018 Chao GAO, VAMK Chao Gao, VAMK

Zigbee Programming XBee is a very popular 802.15.4-compatible module. The module requires 3.3V DC power. An regulator is needed if you want to work with Arduino or RPi. Working with PC, you can also use a USB adaptor. Arduino example: http://www.instructables.com/id/How-to-Use-XBee- Modules-As-Transmitter-Receiver-Ar/. Raspberry Pi example: https://www.cooking- hacks.com/documentation/tutorials/xbee-arduino-raspberry-pi-tutorial/. Xbee with whip and chip antenna Xbee on a regulator Xbee USB adapter 9/20/2018 Chao GAO, VAMK