Wireless Protocols for IoT Part III: ZigBee . Overview 1. ZigBee Features, Versions, Device Types, Topologies 2. ZigBee Protocol Architecture 3. ZigBee Application, ZigBee Application Support Layer 4. Network Layer, Routing: AODV, DSR Raj Jain 5. ZigBee Smart Energy V2 Washington University in Saint Louis Saint Louis, MO 63130 rd [email protected] Note: This is the 3 lecture in series of class lectures on IoT. Bluetooth, Bluetooth Smart, IEEE 802.15.4 were covered in These slides and audio/video recordings of this class lecture are at: http://www.cse.wustl.edu/~jain/cse574-16/ the previous lectures.. Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-1 13-2 ZigBee Overview ZigBee Overview (Cont) Industrial monitoring and control applications requiring small IEEE 802.15.4 MAC and PHY. amounts of data, turned off most of the time (<1% duty cycle), Higher layer and interoperability by ZigBee Alliance e.g., wireless light switches, meter reading, patient monitoring Up to 254 devices or 64516 simpler nodes Ultra-low power, low-data rate, multi-year battery life Named after zigzag dance of the honeybees Power management to ensure low power consumption. Direction of the dance indicates the location of food Less Complex. 32kB protocol stack vs 250kB for Bluetooth Multi-hop ad-hoc mesh network Range: 1 to 100 m, up to 65000 nodes. Multi-Hop Routing: message to non-adjacent nodes Tri-Band: Ad-hoc Topology: No fixed topology. Nodes discover each other ¾ 16 Channels at 250 kbps in 2.4GHz ISM Mesh Routing: End-nodes help route messages for others ¾ 10 Channels at 40 kb/s in 915 MHz ISM band Mesh Topology: Loops possible ¾ One Channel at 20 kb/s in European 868 MHz band Ref: ZigBee Alliance, http://www.ZigBee.org Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-3 13-4 PRO Features Pro Features (Cont) Stochastic addressing: A device is assigned a random address Power Management: Routers and Coordinators use main and announced. Mechanism for address conflict resolution. power. End Devices use batteries. Parents don’t need to maintain assigned address table. Link Management: Each node maintains quality of links to Security: Standard and High neighbors. Link quality is used as link cost in routing. End-Devices get new security key when they wake up. Frequency Agility: Nodes experience interference report to channel manager (e.g., trust center), which then selects another channel Multicast Many-to-One Routing: To concentrator Asymmetric Link: Each node has different transmit power and sensitivity. Paths may be asymmetric. Fragmentation and Reassembly Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-5 13-6 ZigBee Device Types ZigBee Topologies Coordinator: Selects channel, starts the network, assigns short addresses to other nodes, transfers packets to/from other nodes Star Tree Cluster Tree Mesh Router: Transfers packets to/from other nodes C C C Full-Function Device: Capable of being coordinator or router E E E E Reduced-Function Device: Not capable of being a coordinator C E R R E E E R or a router Þ Leaf node R E E E E ZigBee Trust Center (ZTC): Provides security keys and E E E E authentication E R ZigBee Gateway: Connects to other networks, e.g., WiFi C Coordinator R E E R R Router Self-Healing E E E E End-Device E E Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-7 13-8 ZigBee Protocol Architecture ZigBee Protocol Architecture (Cont) Application Objects: e.g., Remote control application. Also referred to as End-Point (EP). ZigBee Switch EP1 EP6 Light Application Framework Device End-Node: End device. Each node can have up to 250 application objects. App App App Object Interface (ZDO) ZigBee Device Object (ZDO): Control and management of Object Object Object ZDO Public application objects. Initializes coordinator, security service, Application Support Sublayer (APS) device and service discovery Application Support Layer (APS): Serves application ZDO Service Security Network Layer objects. Management Network Layer: Route Discovery, neighbor discovery Media Access Control (MAC) ZDO Management Physical Layer Security Service Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-9 13-10 ZigBee Application Layer ZigBee Application Layer (Cont) Application layer consists of application objects (aka end Clusters: A collection of attributes and commands on them. points) and ZigBee device objects (ZDOs) Each cluster is represented by a 16-bit ID. Commands could be 256 End Point Addresses: read/write requests or read/write responses ¾ 240 application objects: Address EP1 through EP240 Cluster Library: A collection of clusters. ZigBee forum has defined a number of cluster libraries, e.g., General cluster ¾ ZDO is EP0 library contains on/off, level control, alarms, etc. ¾ End Points 241-254 are reserved Binding: Process of establishing a logical relationship (parent, ¾ EP255 is broadcast child, ..) Each End Point has one application profile, e.g., light on/off ZDO: profile ¾ Uses device and service discovery commands to discover ZigBee forum has defined a number of profiles. details about other devices. Users can develop other profiles ¾ Uses binding commands to bind and unbind end points. Attributes: Each profile requires a number of data items. Each ¾ Uses network management commands for network data item is called an “attribute” and is assigned an 16-bit discover, route discovery, link quality indication, join/leave “attribute ID” by ZigBee forum requests Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-11 13-12 ZigBee Application Profiles ZigBee Address Assignment Smart Energy: Electrical, Gas, Water Meter reading Each node gets a unique 16-bit address Commercial Building Automation: Smoke Detectors, lights, Two Schemes: Distributed and Stochastic … Home Automation: Remote control lighting, heating, doors, … Distributed Scheme: Good for tree structure Personal, Home, and Hospital Care (PHHC): Monitor blood ¾ Each child is allocated a sub-range of addresses. pressure, heart rate, … ¾ Need to limit maximum depth L, Telecom Applications: Mobile phones Maximum number of children per parent C, and Maximum Remote Control for Consumer Electronics: In collaboration number of routers R with Radio Frequency for Consumer Electronics (RF4CE) alliance ¾ Address of the nth child is parent+(n-1)S(d) Industrial Process Monitoring and Control: temperature, pressure, position (RFID), … Many others Ref: A. Elahi and A. Gschwender, “ZigBee Wireless Sensor and Control Network,” Prentice Hall, 2009, 288 pp., ISBN:0137134851, Safari Book Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-13 13-14 Distributed Scheme Example Distributed Scheme Example (Cont) C d=0 Assume the address of coordinator is 10 (decimal) S(0)=4 10 Address of R1 = 10+1 = 11 Address of R2 = 10+1+S(0) = 11+4=15 R1 R2 R3 R4 d=1 Address of R3 = 10+1+2*S(0) = 11+8 = 19 11 15 19 23 S(1)=1 Address of R3 = 10+1+3*S(0) = 11+12 =23 Routers R1-R4 compute S(1): L L L L L L L L d=2 12 13 16 17 20 21 25 26 Children of R1 are assigned 12 and 13 Max depth L=2, Routers R=4, Children C=3 Children of R2 are assigned 16 and 17 C Coordinator: d=0. Skip 10 R4 R4 R4 R4 11 15 19 23 L L L L L L L L L L L L 12 13 14 16 17 18 20 21 22 24 25 26 Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-15 13-16 Stochastic Address Assignment ZigBee Routing Parent draws a 16 bit random number between 0 and 1. Ad-Hoc On-Demand Distance Vector (AODV) 16 2 -1 and assigns it to a new child. A new number is 2. Dynamic Source Routing (DSR) drawn if the result is all-zero (null) or all-one 3. Tree Hierarchical Routing (broadcast). So the assigned address is between 1 and 216-2. 4. Many-to-one routing Parent then advertises the number to the network If another node has that address an address conflict message is returned and the parent draws another number and repeats There is no need to pre-limit # of children or depth Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain Washington University in St. Louis http://www.cse.wustl.edu/~jain/cse574-16/ ©2016 Raj Jain 13-17 13-18 AODV AODV (Cont) Ad-hoc On-demand Distance Vector Routing Intermediate nodes can reply to RREQ only if they have a route On-demand Reactive Construct a route when needed to destination with higher destination sequence # Routing Table: Path is not stored.