ZigBee IEEE 802.15.4 PHY Layer - SoC: soc

1 Universit Pierre et Marie Curie, Paris 6. Outline ZigBee : Applications and Perspective. ZigBee ZigBee Standard. ieee PHY Layer ieee PHY Layer . Nicolas Beilleau, Post-Doc. Hassan Aboushady, Associate Professor N. Beilleau and H. Aboushady 2. ZigBee Where Does ZigBee Fit ? ZigBee for applications with modest transmission data Wireless Video Applications Faster requirements, and demanding secure communication. Named after Zig-zag movements of bees when UWB. Wireless Data Applications pollinating low-power = long life (+2 y.) with small batteries. IrDA. Peak Data Rate Wi-Fi . low-cost and low-area = widely deployed in wireless control and monitoring applications. wireless mesh networking = high reliability and larger Bluetooth.

2 Range (+65000 nodes) = Wireless Sensors Networks Wireless (WSN). Slower Wireless Sensors ZigBee Networking vs Bluetooth = simpler, less expensive and more Sources: WRH + Co Closer Range Farther network capabilities. (Freescale). N. Beilleau and H. Aboushady 3 N. Beilleau and H. Aboushady 4. ieee Applications Sensors Sensors & Controls: Humidity Home Automation Industrial Automation Remote Metering Pressure sensor Accelerometer Automotive Networks Interactive Toys Active RFID/ asset tracking Medical Temperature Force Chemical Heterogenous devices communicate through the Bio same protocole. Magnetometer Gyroscope ( ZigBee Alliance) (CEA LETI). N. Beilleau and H. Aboushady 5 N. Beilleau and H. Aboushady 6. ZigBee : Building Automation ZigBee : Asset Management Advance Transformer Within each container, sensors Wireless lighting control form a mesh network.

3 Dimmable ballasts Multiple containers in a ship form Light switches anywhere a mesh to report sensor data Customizable lighting schemes Increased security through on- Energy savings on bright days Building Management System truck and on-ship tamper BMS (DALI) detection Extendable networks Faster container processing. Additional sensors Manifest data and sensor data are Other networks known before ship docks at port. ( ZigBee Alliance) ( ZigBee Alliance). N. Beilleau and H. Aboushady 7 N. Beilleau and H. Aboushady 8. ZigBee : Home RF ZigBee : Agriculture (Freescale) (Journal of Computers and Electronics in Agriculture, Elsevier). N. Beilleau and H. Aboushady 9 N. Beilleau and H. Aboushady 10. ZigBee : Agriculture ZigBee Perspective 2007: 7 millions units shipped.

4 2012: 292 millions units shipped (much higher ?). Bluetooth: 2007: 800 millions units shipped. 2012: 1850 millions units shipped. (In-Stat previsions). Wireless Sensor Network: R&D: billions $ in 2012. Science Found.: #400 projects in 2008. EU funding: 1 billion $ 2008/2012. (Journal of Computers and Electronics in Agriculture, Elsevier) (ON World report). N. Beilleau and H. Aboushady 11 N. Beilleau and H. Aboushady 12. Outline ZigBee Features Set ZigBee (2003). Application Customer Ad-hoc self forming networks ZigBee : Applications and Perspective. Mesh, Cluster Tree and Star API Logical Device Types Coordinator, Router and End Device Security ZigBee Standard. 32- / 64- / 128-bit encryption ZigBee Applications Alliance Device and Service Discovery Network Messaging with optional responses.

5 Star / Mesh / Cluster-Tree ieee PHY Layer . Security MAC Symmetric Key with AES-128. Authentication and Encryption at MAC, NWK. channel access, data reliability ieee and Application levels . PHY Qualification 868 MHz / 915 MHz / Conformance Certification (Platform and Profile). Silicon Stack App Interoperability Events N. Beilleau and H. Aboushady 13 N. Beilleau and H. Aboushady 14. ZigBee Network Topologies ZigBee Nodes Communication Star Mesh Based on ieee standard: Transmission Range of 30-100+ Meters Channel Access is via CSMA-CA or optional time slotting. Message acknowledgement or an optional beacon structure. Multi-level security. Network Coordinator: 3 bands, 27 channels specified: Maintains overall network knowledge; most sophisticated of the 3 types; most memory and computing power GHz: 16 channels, 250 kbps Router (Full Function Device: FFD): MHz : 1 channel, 20 kbps Carries full functionality; additional Cluster Tree 902-928 MHz: 10 channels, 40 kbps memory, computing power for routing Works well for End Device (Reduced Function Device: RFD): Carries limited functionality to reduce Long battery life, selectable latency for controllers, cost and complexity sensors, remote monitoring and portable electronics N.

6 Beilleau and H. Aboushady 15 N. Beilleau and H. Aboushady 16. Channel Access Mechanisms Integration of ieee / ZigBee CSMA-CA (Carrier Sense Multiple Access-Collision Avoidance): performs a clear channel assessment (CCA): measures the spectral energy in the frequency channel of interest (Energy Detection). or detects the type of the occupying signal (Carrier Sense). if no channel available, wait for a random time and retry. waits for ack. to verify packet reception at other end. BEACON-Enabled Networking Coordinator dedicates a specific time slot to a particular device (Guaranted Time Slot: GTS). 3 types of devices (Coordinator, FFD, RFD) can be implemented with this architecture Beacon is a message with specific format sent by the and powered by a AAA battery: coordinator to synchronize the nodes in the network.

7 Full protocol stack < 32 k Dedicated bandwidth and low latency Simple node-only stack 4k Wake-up only for synchronization Coordinators require extra 18 RAM (node device database, transaction table, pairing N. Beilleau and H. Aboushady 17. table) N. Beilleau and H. Aboushady 18. Freescale Radio Example TI CC2531: SoC Key Features MC13191/2/3. ieee Compliant Analog GPIO. MC9S08GT Family Digital Transceiver Receiver HCS08 CPU BDM. SPI. Flash 8-ch Sensors MMA Series Features: 16 selectable channels Frequency Generator Memory 10-Bit ADC. Accelerometers 250 Kbps Data Rate Timers Control RAM 2xSCI MPX Series Pressure Sensors ieee PHY/MAC. Analog Logic 250 Kbps 0-QPSK DSSS Transmitter SPI IIC. Buffer RAM LVI 4-ch 16-bit MC Series Ion and ZigBee Stack Multiple Power Saving Modes IRQ COP.

8 Timer Smoke Photo Hibernate Arbiter Power RAM Arbiter Voltage Internal Clock Up to 36 GPIO. Sensors USB controller Doze 35uA Management Regulators Generator Idle 500uA. RF Data Modem Performance: Up to 7 GPIO 2V to operating voltage SPI Interface to Micro -40 C to +85 C operating Power Cons. = 40 mA. Internal Timer comparators (reduce temperature RX Sensitivity = -97 dBm MCU resources) Low external component count to + output power Requires single 16 Mhz Xtal (Auto TX Power = dBm Trim). Software selectable surface = 6mm x 6mm On-chip regulator 5mmx5mm QFN-32. Up to -92 Rx sensitivity at 1% PER Lead-Free N. Beilleau and H. Aboushady 19 N. Beilleau and H. Aboushady 20. Outline ieee PHY Layer 3 bands, 27 channels specified: ZigBee : Applications and Perspective.

9 GHz (ISM/Worldwide) : 16 channels, 250 kbps MHz (ISM/Europe) : 1 channel, 20 kbps ZigBee Standard. 902-928 MHz(ISM/Americas): 10 channels, 40 kbps ieee PHY Layer . Channels spacing: 5 MHz Coding: Direct Sequence Spread Spectrum Modulation: Offset-QPSK. Tx Maximum Output Power > -3 dBm (adj. 30 dB). Rx Sensitivity < -85 dBm for a PER of 1%. N. Beilleau and H. Aboushady 21 N. Beilleau and H. Aboushady 22. PHY Layer Data Frame format Direct Sequence Spread Spectrum Improves the receiver sensitivity level, increases the jamming resistance, and reduces the effect of the multipath. 1 chips sequence/symbol (4 bits) => 16 chips sequences. minimize the similarity of each sequence to the other 15. sequences (quasi-orthogonals = low cross-correlation).

10 Data Rate = 250 kbps for GHz ISM band. sequences of 32 chips @ 2 Mcps => signal spectrum spread on Preamble sequence (32 binary 0) used for receiver timing recovery. a larger band then modulation performance based on it. SFD indicates end of the synchronization field. de-spreading at receiver concentrates signal energy on a Frame length indicates the size of the PSDU. smaller frequency band to increase the final SNR. Average size of PPDU = 22 bytes = 176 bits. Processing Gain = 10 log10(2M/250k) 9 dB. PER=1% => BER= N. Beilleau and H. Aboushady 23 N. Beilleau and H. Aboushady 24. Direct Sequence Spread Spectrum Offset Quadrature Phase Shift keying Q chips are delayed of a Tchip period from I chips. chips are processed by a half-sin filter.