ZigBee 802.15.4 and the ZigBee Alliance Motorola 802.15.4/ZigBee Platform Contents 1. The ZigBee Alliance and 802.15.4 2. Features of Protocol Stack 3. ZigBee and Bluetooth 4. Reliability Throughout the Stacks 5. Robustness Throughout the Stacks 6. 802.15.4/ZigBee vs. Bluetooth 7. Motorola 802.15.4/ZigBee Platform 8. An Application Example
The ZigBee Alliance and 802.15.4 1. The ZigBee Alliance is A consortium of end users and solution providers, primarily responsible for the development of the 802.15.4 standard Developing applications and network capability utilizing the 802.15.4 packet delivery mechanism Addresses application and interoperability needs of a substantial part of the market 2. IEEE 802.15.4 Composed of many of the individuals and companies that make up the ZigBee Alliance Developed the basic PHY and MAC standard with the requirement that 15.4 be simple and manageable and that high level functionality (networking, security key management, applications) be considered ZigBee (1/2) 1. ZigBee is designed to be a low power, low cost, low data rate, wireless solution. 2. ZigBee relies upon the robust IEEE 802.15.4 PHY/MAC to provide reliable data transfer in noisy, interference rich environments 3. ZigBee layers on top of 15.4 with Mesh Networking, Security, and Applications control
ZigBee (2/2) 1. ZigBee Value Propositions Addresses the unique needs of most remote monitoring and control network applications 1) Infrequent, low rate and small packet data Enables the broad based deployment of wireless networks with low cost & low power solutions 1) Example: Lighting, security, HVAC, 2) Supports peer to peer, star and mesh networks Monitor and sensor applications that need to have a battery life of years on alkaline batteries 1) Example security systems, smoke alarms What is the ZigBee Alliance? 1. Organization defining global standards for reliable, cost effective, low power wireless applications 2. A rapidly growing, worldwide, non profit industry consortium of Leading semiconductor manufacturers Technology providers OEMs End users 3. Sensors are one of the reasons for ZigBee!
What is ZigBee technology? 1. Cost effective, standards based wireless networking solution 2. Developed for and targets applications that need Low to moderate data rates and low duty cycles Low average power consumption / long battery life Security and reliability Flexible and dynamic network topologies 1) Star, cluster tree and mesh networks Interoperable application frameworks controlled by an industry alliance to ensure interoperability/compatibility The ZigBee Alliance Solution 1. Targeted at Industrial and Commercial control/monitoring systems Wireless sensor systems Home and Building automation and controls Medical monitoring Consumer electronics PC peripherals 2. Industry standard through application profiles running over IEEE 802.15.4 radios 3. Primary drivers Simplicity Long battery life Networking capabilities Reliability Low cost 4. Alliance member companies provide interoperability and certification testing
Why do we need ZigBee technology? 1. ONLY standards based technology that Addresses the unique needs of most remote monitoring and control and sensory network applications Enables the broad based deployment of wireless networks with low cost, low power solutions Provides the ability to run for years on inexpensive primary batteries for a typical monitoring application ZigBee Alliance 1. Submission Title: [What You Should Know about the ZigBee Alliance] 2. Date Submitted: [24 September 2003 3. Source: [Jon Adams] Company [Motorola] 4. Address [2100 E Elliott Rd, Tempe AZ 85254] 5. Voice:[480 413 3439], FAX: [480 413 4433], E Mail:[jta@motorola.com] 6. Re: [Sensors Expo Workshop] 7. Abstract: [Description of measures used to enhance reliability in IEEE 802.15.4/ZigBee] 8. Purpose: [Point of discussion for the Sensors Expo] 9. Notice: This document has been prepared to assist the ZigBee Alliance. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. 10. Release: The contributor acknowledges and accepts that this contribution will be posted in the member area of the ZigBee web site.
ZigBee Stack Release Matrix Stack Version ZigBee V1.0, r06 (sometimes referred to as Home Controls V0) ZigBee stack (formerly known as Home Controls V1) Release date and status Spec: December 2004 Platform test: March 2005 Currently shipped by all platform suppliers! Spec: August 2006 (est) Platform test: August 2006 (est) Feature summary 8 bit clusters, KVP/MSG services Joint routing CSKIP addresses Coordinator binding 16 bit clusters, KVP/MSG services removed Joint routing with CSKIP addresses Coordinator binding optional ZigBee cluster library Application Profiles Supported Home Controls Lighting (since abandoned) Commercial Building Automation Industrial Plant Monitoring Home Automation Compatibility No frame compatibility with ZigBee or ZigBee Pro Frame compatibility with ZigBee Pro expected No frame compatibility with ZigBee V1.0 No compatibility with ZigBee Pro networks ZigBee Pro stack (formerly known as Commercial, Industrial, Institutional) Spec: December 2006 (est) Platform test: January 2007 (est) Please note: Past experience would say this is 6 months after the specification is complete, June 2007 Same as ZigBee stack, plus or minus: Mutlicast (+) Many to one (source) routing (+) Fragmentation (+) AODV jr routing only ( ) New address assignment Commercial Building Automation Industrial Plant Monitoring Home Automation Frame compatibility with ZigBee expected without optional new features No frame compatibility with ZigBee V1.0 No compatibility with ZigBee networks Architecture Objectives ZigBee Architecture Objectives 1. Enables cost effective, low power, reliable devices for monitoring and control 2. ZigBee sarchitecture developed to target environments and applications best suited to the technology 3. Provide a platform and implementation for wirelessly networked devices 4. Ensure interoperability through the definition of application profiles 5. Define the ZigBee network and stack models 6. Provide the framework to allow a separation of concerns for the specification, design, and implementation of ZigBee devices 7. Allow future extension of ZigBee
ZigBee Feature Set 1. ZigBee V1.0 Ad hoc self forming networks 1) Mesh, Cluster Tree and Star Logical Device Types 1) Coordinator, Router and End Device Applications 1) Device and Service Discovery 2) Messaging with optional responses 3) Home Controls Lighting Profile 4) General mechanism to define private Profiles Security 1) Symmetric Key with AES 128 2) Authentication and Encryption at MAC, NWK and Application levels 3) Master Keys, Network Keys and Link Keys Qualification 1) Conformance Certification (Platform and Profile) 2) Interoperability Events How A ZigBee Network Forms 1. Devices are pre programmed for their network function Coordinator scans to find an unused channel to start a network Router (mesh device within a network) scans to find an active channel to join, then permits other devices to join End Device will always try to join an existing network 2. Devices discover other devices in the network providing complementary services Service Discovery can be initiated from any device within the network 3. Devices can be bound to other devices offering complementary services Binding provides a command and control feature for specially identified sets of devices
ZigBee Address Architecture 1. Addressing Every device has a unique 64 bit MAC address Upon association, every device receives a unique 16 bit network address Only the 16 bit network address is used to route packets within the network Devices retain their 16 bit address if they disconnect from the network, however, if the LEAVE the network, the 16 bit address is re assigned NWK broadcast implemented above the MAC: 1) NWK address 0xFFFF is the broadcast address 2) Special algorithm in NWK to propagate the message 3) Best Effort or Guaranteed Delivery options 4) Radius Limited Broadcast feature Packet Structure 1. Packet Fields Preamble (32 bits) synchronization Start of Packet Delimiter (8 bits) specifies one of 3 packet types PHY Header (8 bits) Sync Burst flag, PSDU length PSDU (0 to 127 bytes) Data Preamble Start of Packet Delimiter PHY Header PHY Service Data Unit (PSDU) 6 Bytes 0 127 Bytes
General Data Packet Structure Preamble sequence Start of Packet Delimiter PRE SPD LEN PC ADDRESSING DSN Link Layer PDU CRC CRC 16 Data sequence number Addresses according to specified mode Flags specify addressing mode Length for decoding simplicity ZigBee Network Model ZigBee Coordinator (FFD) ZigBee Router (FFD) ZigBee End Device (RFD or FFD) Mesh Link 1. Star networks support a single ZigBee coordinator with one or more ZigBee End Devices (up to 65,536 in theory) 2. Mesh network routing permits path formation from any source device to any destination device
Wireless Networking Basics 1. Network Scan Device scans the 16 channels to determine the best channel to occupy. 2. Creating/Joining a PAN Device can create a network (coordinator) on a free channel or join an existing network 3. Device Discovery Device queries the network to discover the identity of devices on active channels 4. Service Discovery Device scans for supported services on devices within the network 5. Binding Devices communicate via command/control messaging Network Pieces PAN Coordinator 1. PAN Coordinator owns the network PAN Coordinator 1) Starts it 2) Allows other devices to join it 3) Provides binding and address table services 4) Saves messages until they can be delivered 5) And more could also have i/o capability A full function device FFD Mains powered
Network Pieces Router 1. Routers Routes messages Does not own or start network 1) Scans to find a network to join Given a block of addresses to assign A full function device FFD Mains powered depending on topology Could also have i/o capability Routers Network Pieces End Device 1. End Device Communicates with a single device Does not own or start network 1) Scans to find a network to join Can be an FFD or RFD (reduced function device) Usually battery powered End Device
Battery Life 1. ZigBee protocol was designed from the ground up to support very long life battery applications 2. Users can expect Near shelf life in a typical monitoring application 3. Battery life is ultimately a function of battery capacity and application usage 4. Many industrial applications are in harsh thermal environments Batteries may include alkalines or Li primaries Other forms of power generation might include solar, mechanical, piezoelectric ZigBee Membership Classes 1. Promoters founding members of ZigBee, who form the Board of Directors. There are currently 5 promoters + 1 chairperson 2. Participants members who generally wish to make technical contributions and/or serve on the Technical Group committees. These members have early access to specifications, and they may also chair working group subcommittees. They are in a position to help shape the ZigBee technology for industrial applications and the connected home.
ZigBee Alliance Member Promoters Participants And more each month IEEE 802.15.4 IEEE 802.15 Working Group
Comparison between WPAN IEEE 802.15.4 Basics (1/2) 1. Simple packet data protocol for lightweight wireless networks Released in May 2003 Channel Access is via Carrier Sense Multiple Access with collision avoidance and optional time slotting Message acknowledgement and an optional beacon structure Multi level security Works well for 1) Long battery life, selectable latency for controllers, sensors, remote monitoring and portable electronics Configured for maximum battery life, has the potential to last as long as the shelf life of most batteries
IEEE 802.15.4 Basics (2/2) Frequency Band License Required? Geographic Region Data Rate Channel Number (s) 868.3 MHz No Europe 20 kbps 0 902 928 MHz No Americas 40 kbps 1 10 2405 2480 MHz No Worldwide 250 kbps 11 26 Normal Channel Occupancy 2.412 2.437 2.462 2.4835 (end of ISM Band) 2.40 2.41 2.42 2.43 2.44 2.45 2.46 2.47 2.48 802.11 DSSS Possible 802.11 Channel (North America) 802.11 Spectrum Occupancy (Typical) IEEE 802.15.4 Standard (1/2) Introduction to The IEEE 802.15.4 Standard 1. IEEE 802.15.4 standard released May 2003 Semiconductor manufacturers 1) Sampling Transceiver ICs and platform hardware/software to Alpha Customers now Users of the technology 1) Defining application profiles for the first products, an effort organized by the ZigBee Alliance 2. Includes layers up to and including Link Layer Control LLC is standardized in 802.1 3. Supports multiple network topologies including Star, Cluster Tree and Mesh
IEEE 802.15.4 Standard (2/2) 1. Features of the MAC: ZigBee Application Framework Association/dissociation ACK frame delivery channel access mechanism frame validation guaranteed time slot management beacon management channel scan Low complexity: 1) 26 primitives versus 131 primitives for 802.15.1 (Bluetooth) Networking App Layer (NWK) Data Link Controller (DLC) IEEE 802.2 IEEE 802.15.4 LLC LLC, Type I IEEE 802.15.4 MAC IEEE 802.15.4 IEEE 802.15.4 868/915 MHz PHY 2400 MHz PHY IEEE 802.15.4 PHY overview 1. PHY functionalities: Activation and deactivation of the radio transceiver Energy detection within the current channel Link quality indication for received packets Clear channel assessment for CSMA CA Channel frequency selection Data transmission and reception
PHY frame structure 1. PHY packet fields Preamble (32 bits) synchronization Start of packet delimiter (8 bits) shall be formatted as 11100101 PHY header (8 bits) PSDU length PSDU (0 to 127 bytes) data field Sync Header PHY Header PHY Payload Preamble Start of Packet Delimiter Frame Length (7 bit) Reserve (1 bit) PHY Service Data Unit (PSDU) 4 Octets 1 Octets 1 Octets 0 127 Bytes Operating frequency bands 868MHz/ 915MHz PHY Channel 0 Channels 1 10 868.3 MHz 902 MHz 2 MHz 928 MHz 2.4 GHz PHY Channels 11 26 5 MHz 2.4 GHz 2.4835 GHz
Frequency bands and data rates 1. The standard specifies two PHYs : 868 MHz/915 MHz direct sequence spread spectrum (DSSS) PHY (11 channels) 1) 1 channel (20Kb/s) in European 868MHz band 2) 10 channels (40Kb/s) in 915 (902 928)MHz ISM band 2450 MHz direct sequence spread spectrum (DSSS) PHY (16 channels) 1) 16 channels (250Kb/s) in 2.4GHz band IEEE 802.15.4 MAC 1. Employs 64 bit IEEE & 16 bit short addresses Ultimate network size can be >> nodes (more than we ll probably need ) Using local addressing, simple networks of more than 65,000 (2^16) nodes can be configured, with reduced address overhead 2. Three devices specified Network Coordinator Full Function Device (FFD) Reduced Function Device (RFD) 3. Simple frame structure
IEEE 802.15.4 MAC 1. Reliable delivery of data 2. Association/disassociation 3. AES 128 security 4. CSMA CA channel access 5. Optional super frame structure with beacons 6. Optional GTS mechanism MAC/PHY Frame Format IEEE 802.15.4 MAC/PHY Frame Format Four frame types: 1. Beacon 2. Data 3. MAC command 4. Acknowledge MAC sub layer Frame control Sequence Address number info MAC Header Max 127 Bytes Bytes: 2 1 0 20 variable 2 Payload MAC service data unit MAC protocol data unit Bytes: 4 1 1 Max 127 Bytes Frame check sequence MAC footer MAC frame Preamble SFD Length PHY service data unit PHY protocol data unit
Superframe (1/3) Beacon CAP CFP Beacon GTS 0 GTS 1 Inactive 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 SD = abasesuperframeduration*2 SO symbols (Active) BI = abasesuperframeduration*2 BO symbols 1. A superframe is divided into two parts Inactive: all devices sleep Active: 1) Active period will be divided into 16 slots 2) 16 slots can further divided into two parts Contention access period Contention free period Superframe (2/3) 1. Beacons are used for starting superframes synchronizing with associated devices announcing the existence of a PAN informing pending data in coordinators 2. In a beacon enabled network, Devices use the slotted CAMA/CA mechanism to contend for the usage of channels FFDs which require fixed rates of transmissions can ask for guarantee time slots (GTS) from the coordinator 3. The structure of superframes is controlled by two parameters: beacon order (BO) and superframe order (SO) BO decides the length of a superframe SO decides the length of the active potion in a superframe
Superframe (3/3) 1. For a beacon enabled network, the setting of BO and SO should satisfy the relationship 0 SO BO 14 2. For channels 11 to 26, the length of a superframe can range from 15.36 msec to 215.7 sec. which means very low duty cycle 3. Each device will be active for 2 (BO SO) portion of the time, and sleep for 1 2 (BO SO) portion of the time 4. In IEEE 802.15.4, devices duty cycle follow the specification BO-SO 0 1 2 3 4 5 6 7 8 9 10 Duty cycle (%) 100 50 25 12 6.25 3.125 1.56 0.78 0.39 0.195 < 0.1 Device to Coordinator Data Transfer Model (Device to Coordinator) 1. Data transferred from device to coordinator In a beacon enable network, device finds the beacon to synchronize to the superframe structure. Then using slotted CSMA/CA to transmit its data. In a non beacon enable network, device simply transmits its data using unslotted CSMA/CA Communication to a coordinator In a beacon enabled network Communication to a coordinator In a non beacon enabled network
Coordinator to Device (1/2) Data Transfer Model (Coordinator to Device ) 1. Data transferred from coordinator to device In a beacon enable network, the coordinator indicates in the beacon that the data is pending. Device periodically listens to the beacon and transmits a MAC command request using slotted CSMA/CA if necessary. Communication from a coordinator In a beacon enabled network Coordinator to Device (2/2) Data Transfer Model (Coordinator to Device ) 1. Data transferred from coordinator to device In a non beacon enable network, a device transmits a MAC command request using unslotted CSMA/CA. If the coordinator has its pending data, the coordinator transmits data frame using unslotted CSMA/CA. Otherwise, coordinator transmits a data frame Communication from a coordinator in a non beacon enabled network with zero length payload.
Channel Access Mechanism 1. Two type channel access mechanism: In non beacon enabled networks unslotted CSMA/CA channel access mechanism In beacon enabled networks slotted CSMA/CA channel access mechanism CSMA/CA Algorithm 1. In slotted CSMA/CA The backoff period boundaries of every device in the PAN shall be aligned with the superframe slot boundaries of the PAN coordinator 1) i.e. the start of first backoff period of each device is aligned with the start of the beacon transmission The MAC sublayer shall ensure that the PHY layer commences all of its transmissions on the boundary of a backoff period 2. Each device shall maintain three variables for each transmission attempt NB: number of time the CSMA/CA algorithm was required to backoff while attempting the current transmission CW: contention window length, the number of backoff periods that needs to be clear of channel activity before transmission can commence (initial to 2 and reset to 2 if sensed channel to be busy) BE: the backoff exponent which is related to how many backoff periods a device shall wait before attempting to assess a channel
IEEE 802.15.4 MAC Options 1. Two channel access mechanisms Non beacon network 1) Standard ALOHA CSMA CA communications 2) Positive acknowledgement for successfully received packets Beacon enabled network 1) Super frame structure For dedicated bandwidth and low latency Set up by network coordinator to transmit beacons at predetermined intervals 15ms to 252sec (15.38ms*2n where 0 n 14) 16 equal width time slots between beacons Channel access in each time slot is contention free Three security levels specified 1) None 2) Access control lists 3) Symmetric key employing AES 128 IEEE 802.15.4 Device Types 1. Three device types Network Coordinator 1) Maintains overall network knowledge; most sophisticated of the three types; most memory and computing power Full Function Device 1) Carries full 802.15.4 functionality and all features specified by the standard 2) Additional memory, computing power make it ideal for a network router function 3) Could also be used in network edge devices (where the network touches the real world) Reduced Function Device 1) Carriers limited (as specified by the standard) functionality to control cost and complexity 2) General usage will be in network edge devices 2. All of these devices can be no more complicated than the transceiver, a simple 8 bit MCU and a pair of AAA batteries!
Data Frame Format 1. One of two most basic and important structures in 15.4 2. Provides up to 104 byte data payload capacity 3. Data sequence numbering to ensure that all packets are tracked 4. Robust frame structure improves reception in difficult conditions 5. Frame Check Sequence (FCS) ensures that packets received are without error Acknowledgement Frame Format 1. The other most important structure for 15.4 2. Provides active feedback from receiver to sender that packet was received without error 3. Short packet that takes advantage of standards specified quiet time immediately after data packet transmission
MAC Command Frame Format 1. Mechanism for remote control/configuration of client nodes 2. Allows a centralized network manager to configure individual clients no matter how large the network Beacon Frame Format 1. Beacons add a new level of functionality to a network 2. Client devices can wake up only when a beacon is to be broadcast, listen for their address, and if not heard, return to sleep 3. Beacons are important for mesh and cluster tree networks to keep all of the nodes synchronized without requiring nodes to consume precious battery energy listening for long periods of time
Frequencies and Data Rates 1. The two PHY bands (UHF/Microwave) have different physical, protocol based and geopolitical characteristics Worldwide coverage available at 2.4GHz at 250kbps 900MHz for Americas and some of the Pacific 868MHz for European specific markets ISM Band Interference and Coexistence 1. Potential for interference exists in every ISM band, not just 2.4GHz 2. IEEE 802.11 and 802.15.2 committees are addressing coexistence issues 3. ZigBee/802.15.4 Protocol is very robust Clear channel checking before transmission Backoff and retry if no acknowledgement received Duty cycle of a ZigBee compliant device is usually extremely low It s the cockroach that survives the nuclear war 1) Waits for an opening in otherwise busy RF spectrum 2) Waits for acknowledgements to verify packet reception at other end
IEEE 1451.5 Sensor Group IEEE 1451.5 Sensor Group Wireless Criteria 1. A survey was conducted mid 2002 on the characteristics of a wireless sensor network most important to its users 2. In order of importance, these characteristics are Data Reliability Battery Life Cost Transmission Range Data Rate Data Latency Physical Size Data Security 3. How would you modify these requirements, if at all? Freescale 802.15.14 Radio Example 1. Key Features IEEE 802.15.4 Compliant 1) 2.4GHz 2) 16 selectable channels 3) 250Kbps Data Rate 4) 250Kbps 0 QPSK DSSS Multiple Power Saving Modes 1) Hibernate 2.3uA 2) Doze 35uA 3) Idle 500uA RF Data Modem Up to 7 GPIO SPI Interface to Micro Analog Receiver Frequency Generator Analog Transmitter Power Management MC13191/2/3 Digital Transceiver GPIO SPI Timers Control Logic Buffer RAM IRQ RAM Arbiter Arbiter Voltage Regulators MC9S08GT Family HCS08 CPU Flash Memory RAM SPI LVI COP Internal Clock Generator BDM 8-ch 10-Bit ADC 2xSCI IIC 4-ch 16-bit Timer Up to 36 GPIO Sensors MMA Series Accelerometers MPX Series Pressure Sensors MC Series Ion and Smoke Photo Sensors
Freescale 802.15.14 Radio Example cont d Internal Timer comparators (reduce MCU resources) 16.6dBm to +3.6dBm output power 1) Software selectable 2) On chip regulator Up to 92 Rx sensitivity at 1% PER 2V to 3.4 operating voltage 40 C to +85 C operating temperature Low external component count 1) Requires single 16Mhz Xtal (Auto Trim) 5mmx5mm QFN 32 1) Lead Free IEEE 802.15.4 MC13201 MC13202 MC13203 Overview Network Topology Software Transfer Mode Throughput Tx/Rx Switch Low Power Modes Sensitivity Power Supply MCU Support MCU Interface Power Output Operating Temp Package 10K SRP Low cost 2.4 GHz transceiver for proprietary applications Point to Point and Star Simple MAC (SMAC) Packet 91 dbm 8 bit MCU, ColdFire, S12, DSC $2.35 IEEE 802.15.4 Compliant 2.4 GHz transceiver Buffered transmit and receive data packets for use with low cost MCUs Low component count reduces complexity and cost Programmable clock output available to MCU IEEE 802.15.4 MAC Integrated on chip 5x5x1 mm 32 pin QFN (Meets RoHS requirements) $2.75 Peer to Peer, Star and Mesh Packet and Streaming 250 Kbps, O QPSK Modulation, DSSS Energy Spreading Scheme Off, Hibernate, Doze and Idle 2.0 to 3.4 V SPI Interface to MCU 27 dbm to +4 dbm (software selectable) 40º to +85ºC Operating Temperature 94 dbm Optimized for 8 bit HCS08 Family ZigBee Ready 2.4 GHz transceiver ZigBee Stack $3.28
The 802.15.4 / Zigbee Sandbox Wireless Video Applications Slower Faster Peak Data Rate IrDA ISM Link Closer UWB Bluetooth ZigBee 802.15.4 802.11a 802.11g 802.11b HomeRF Range WiFi Wireless Data Applications 2.5G/3G Farther
The Application Space The Application Space for 802.15.4/ZigBee BUILDING AUTOMATION Security, HVAC, AMR, Lighting Control, Access Control CONSUMER ELECTRONICS Remote Control PC & PERIPHERALS Mouse, Keyboard, Joystick RESIDENTIAL/ LIGHT COMMERCIAL CONTROL Security, HVAC, Lighting Control, Access Control INDUSTRIAL CONTROL Asset Mgt, Process Control, Energy Mgt PERSONAL HEALTH CARE Patient monitoring The Wireless Market TEXT GRAPHICS INTERNET HI FI AUDIO STREAMING VIDEO DIGITAL VIDEO MULTI CHANNEL VIDEO PAN < RANGE > LAN ZigBee Bluetooth 2 Bluetooth1 802.11b 802.11a/HL2 & 802.11g LOW < DATA RATE > HIGH
Market Size 802.15.4/ZigBee Market Size 1. Strong growth in areas such as wireless sensors will help fuel the growth of 802.15.4 and ZigBee Harbor Research reports that by 2008, 100 million wireless sensors will be in use On World reports that by 2010, more then 500 million nodes will ship for wireless sensor applications 2. ABI Research forecasts shipments of ZigBee devices in 2005 at about 1 million, growing to 80 million units by the end of 2006 3. In Stat 2004 report has an aggressive forecast of over 150 million annual units of 802.15.4 and ZigBee chipsets by 2008 Features of Protocol Stack Development of the Standard 1. ZigBee Alliance 50+ companies: semiconductor mfrs, IP providers, OEMs, etc. Defining upper layers of protocol stack: from network to application, including application profiles First profiles published mid 2003 2. IEEE 802.15.4 Working Group Defining lower layers of protocol stack: MAC and PHY scheduled for release in April APPLICATION Customer ZIGBEE STACK SILICON IEEE 802.15.4 ZigBee Alliance
Frequencies and Data Rates BAND COVERAGE DATA RATE # OF CHANNEL(S) 2.4 GHz ISM Worldwide 250 kbps 16 868 MHz Europe 20 kbps 1 915 MHz ISM Americas 40 kbps 10 Stack Reference Model (1/2) End developer applications, designed using application profiles ZA1 ZA2 ZAn IA1 IAn Application interface designed Using general profile API UDP Topology management, MAC management, routing, discovery protocol, security management Channel access, PAN maintenance, reliable data transport Transmission & reception on the physical radio channel ZigBee NWK IEEE 802.15.4 MAC (CPS) IEEE 802.15.4 PHY IP 802.2 LLC MAC (SSCS)
Stack Reference Model (2/2) 1. Microcontroller utilized 2. Full protocol stack <32 k 3. Simple node-only stack ~4k 4. Coordinators require extra RAM Node device database Transaction table Pairing table APPLICATIONS APPLICATION INTERFACE SECURITY NETWORK LAYER Star/Cluster/Mesh MAC LAYER MAC LAYER PHY LAYER 2.4 GHz 915MHz 868 MHz Customer IEEE 802.15.4 ZigBee Alliance Application ZigBee Stack Silicon ZigBee and Bluetooth Optimized for different applications ZigBee Bluetooth Smaller packets over large network Larger packets over small network Ad hoc networks Mostly Static networks with many, infrequently used devices Home automation, toys, remote controls, etc. File transfer Screen graphics, pictures, handsfree audio, Mobile phones, headsets, PDAs, etc.
Address Different Needs 1. Bluetooth is a cable replacement for items like Phones, Laptop Computers, Headsets 2. Bluetooth expects regular charging Target is to use <10% of host power 3. ZigBee is better for devices Where the battery is rarely replaced Targets are : 1) Tiny fraction of host power 2) New opportunities where wireless not yet used Air Interface ZigBee 1. DSSS 11 chips/ symbol 2. 62.5 K symbols/s 3. 4 Bits/ symbol 4. Peak Information Rate ~128 Kbit/second Bluetooth 1. FHSS 2. 1 M Symbol / second 3. Peak Information Rate ~720 Kbit / second
Protocol Stack Comparison Application Interface Silicon Application Network Layer Data Link Layer MAC Layer MAC Layer PHY Layer ZigBee Stack Zigbee Application Voice Intercom Headset Cordless Group Call vcard vcal vnote Telephony Control Protocol Silicon User Interface OBEX vmessage Dial-up Networking RFCOMM (Serial Port) L2CAP Host Control Interface Link Manager Link Controller Baseband RF Bluetooth Stack Bluetooth Fax Service Discovery Protocol Applications Timing Considerations ZigBee: Network join time = 30ms typically Sleeping slave changing to active = 15ms typically Active slave channel access time = 15ms typically Bluetooth: Network join time = >3s Sleeping slave changing to active = 3s typically Active slave channel access time = 2ms typically ZigBee protocol is optimized for timing critical applications
Comparison Overview Bluetooth ZigBee AIR INTERFACE FHSS DSSS PROTOCOL STACK 250 kb 28 kb BATTERY rechargeable non rechargeable DEVICES/NETWORK 8 255 LINK RATE 1 Mbps 250 kbps RANGE ~10 meters (w/o pa) ~30 meters Reliability Throughout the Stacks (1/8) 1. Consistently perform a given task to the desired result despite all changes of environmental behavior 2. Without fail 3. A necessary ingredient of trust 4. When the sensor measures its environment; the controller always knows that same value 5. The wireless medium is not a protected environment like the wired medium, but rather, it is fraught with degradations, disruptions, and pitfalls such as dispersion, multipath, interference, frequency dependent fading, sleeping nodes, hidden nodes, and security issues.
Reliability Throughout the Stacks (2/8) 1. Each of these degradations and disruptions can be mitigated by various mechanisms within the ISO layers; but not all mechanisms are compatible with all other mechanisms or may negatively impact critical performance attributes 2. The system must be optimized for the best performance in a realistic environment 3. In addition to the previous disruptions there is the case of sending messages to devices that are not receiving, e.g. they re in the sleep mode. When this happens the message needs to be buffered by another device that is able to send the message when the sleeping device wakes up. Reliability Throughout the Stacks (3/8) Interferer Router X X Multipath Sleeping Node Network Coordinator Hidden Node
Reliability Throughout the Stacks (4/8) 1. IEEE 802.15.4 has built upon the successes of previous IEEE 802 standards by selecting those mechanisms proven to ensure good reliability without seriously degrading system and device performance. ISO Layers: 1. PHY: Direct Sequence with Frequency Agility (DS/FA) 2. MAC: ARQ, Coordinator buffering 3. Network: Mesh Network (redundant routing) 4. Application Support Layer: Security Reliability Throughout the Stacks (5/8) PHY Layers: 1. Direct sequence: allows the radio to reject multipath and interference by use of a special chip sequence. The more chips per symbol, the higher its ability to reject multipath and interference. 2. Frequency Agility: ability to change frequencies to avoid interference from a known interferer or other signal source.
Reliability Throughout the Stacks (6/8) MAC: 1. ARQ (acknowledgement request) is where a successful transmission is verified by replying with an acknowledge (ACK). If the ACK is not received the transmission is sent again 2. Coordinator buffering is where the network coordinator buffers messages for sleeping nodes until they wake again Network: 1. Mesh Networking: allows various paths of routing data to the destination device. In this way if a device in the primary route is not able to pass the data, a different valid route is formed, transparent to the user. Reliability Throughout the Stacks (7/8) Application Support Sub layer(aps): 1. Security: supports reliability by keeping other devices from corrupting communications. 2. The APS configures the security emplaced in the MAC layer and also adds some of its own.
Reliability Throughout the Stacks (8/8) Reliability: Mesh Networking ZigBee Coordinator (FFD) ZigBee Router (FFD) ZigBee End Device (RFD or FFD) Mesh Link Star Link IEEE 802 Direct Sequence IEEE 802. 11 11b 15.4 (900) 15.4 (2.4) Chips/Symbol 11 11 15 32 1. As can be seen from above, IEEE802.15.4/ZigBee has more processing gain (chips/symbol) than its predecessors
Direct Sequence and Frequency Agility Interferer Desired Signal Over the Air After DS correlation 2.4 GHz PHY Channels 11 26 5 MHz 2.4 GHz 2.4835 GHz Robustness Throughout the Stacks (1/4) Robustness of IEEE 802.15.4 and ZigBee 1. Let s define robustness as the ability to tolerate significant degrading phenomena in the physical medium 2. Multipath and interference are probably the most significant degradations to the channel model.
Robustness Throughout the Stacks (2/4) 1. Frequency hopping is a method that allows the radio to periodically change channels to over time minimize the effect of a bad channel. While this technique is very effective in some circumstances it creates other problems such as latency, network uncertainty for sleeping nodes, loss of the product bandwidth x time, etc. 2. Direct Sequence with Frequency Agility (DS/FA) combines the best features of DS and FH without most of the problems caused by frequency hopping because frequency changes aren t necessary most of the time, rather they re appropriate only on an exception basis. Robustness Throughout the Stacks (3/4) 1. The 802.11 Working Group couldn t agree upon which of the following PHYs was the best: FH, IR, or DS. So all three were standardized and left to the market to decide. 2. Of the three PHYs; DS was the clear market winner. DS provided sufficient robustness with higher overall performance. 3. Excess robustness does not achieve higher performance, rather it typically costs performance
Robustness Throughout the Stacks (4/4) Reliability and Robustness throughout the stacks of IEEE 802.15.4 and ZigBee 1. IEEE 802.15.4/ZigBee have addressed reliability throughout the ISO stack with proven mechanisms to minimize the uncertainty of the wireless medium 802.15.4/ZigBee vs Bluetooth 1. Bluetooth and 802.15.4 transceiver physical characteristics are very similar 2. Protocols are substantially different and designed for different purposes 3. 802.15.4 designed for low to very low duty cycle static and dynamic environments with many active nodes 4. Bluetooth designed for high QoS, variety of duty cycles, moderate data rates in fairly static simple networks with limited active nodes 5. Bluetooth costs and system performance are in line with 3 rd and 4 th generation products hitting market while 1 st generation 15.4 products will be appearing only late this year
Transceiver Comparisons 1. Instantaneous Power Consumption 15.4 Transceivers are similar to Bluetooth Transceivers 1) 802.15.4 OQPSK with shaping Max data rate 250kbps over the air 2Mchips/s over the air Direct Sequence Spread Spectrum (62.5ksps*32 spread) 90 dbm sensitivity 40ppm xtal 2) Bluetooth FSK Max data rate 720kbps over the air 1Msps over the air Frequency Hop Spread Spectrum (79 channels @ 1600 hps) 85dBm sensitivity 20ppm xtal 2. Instantaneous power consumption will be similar for the raw transceivers without protocol 3. Bluetooth s frequency hop makes it extremely difficult to create extended networks without large synchronization cost General Schematic Vcc 802.15.4 SPI XCVR IRQ/ RESET 4 Vcc SPI MCU INT IRQ OSC1 OSC2 3Vdc 16.000MHz 32.768kHz Plus about 10 12 small value capacitors, resistors excluding any special components for heartbeat sensor) Heartbeat Sensor
802.15.4/ZigBee Operation Mode 1. 802.15.4/ZigBee Mode Network environment using Guaranteed Time Slot (GTS) Network beacons occurring either every 1) 960ms or 61.44s (closest values to 1 and 60 s) 2) Guaranteed time slot occurs at some predetermined point in the beacon interval 2. Sensor has two ongoing processes Heartbeat time logging Transmit heartrate and other information (8 bytes total) 1) Instantaneous heartrate (1/timeinterval between last two pulses,1ms precision) 2) Running average heartrate (1/time interval between last twenty pulses, 1ms precision) 3) Sensor average temperature (0.1C precision) 4) Sensor average battery state (0.1V precision) heartbeat GTS Beacon time Protocol Makes the Difference 1. 15.4 Protocol was developed for very different reasons than Bluetooth 802.15.4 1) Very low duty cycle, very long primary battery life applications 2) Static and dynamic star and mesh network structures with potentially a very large number (>>65534) of client units, low latency available but not necessary 3) Ability to remain quiescent for long periods of time without communicating to the network Bluetooth 1) Moderate duty cycle, secondary battery operation where battery lasts about the same as master unit 2) Wire replacement for consumer devices that need moderate data rates with very high QoS and very low, guaranteed latency 3) Quasi static star network structure with up to 7 clients (and ability to participate in more than one network simultaneously) 4) Generally used in applications where either power is cycled (headsets, cellphones) or mains powered (printers, car kits) 2. Protocol differences can lead to tremendous optimizations in power consumption
Applications 1. Industrial Control/Monitoring Space Asset Management 1) Basic identification Device ID, Device PN/SN, Device source/destination, etc. 2) Asset health Temperature, humidity, shock, fuel levels, etc. Nearly any parameter can be monitored given an appropriate sensor Asset Tracking 1) Location tracking through two way communication Simplest form is communication/identification when passes a checkpoint Same as other RFID tagging systems More sophisticated what other devices can it hear/communicate with? Other options include ranging (time of flight) and SNR measurement Has the potential for very precise location measurement The wireless network uses protocol gateways to move command/monitor data between the end devices and the network data management center Product Examples Warehouses, Fleet management, Factory, Supermarkets, Office complexes Gas/Water/Electric meter, HVAC Smoke, CO, H 2 O detector Refrigeration case or appliance Equipment management services & PM Security services Lighting control Assembly line and work flow, Inventory Materials processing systems (heat, gas flow, cooling, chemical) Energy, diagnostics, e Business services Gateway or Field Service links to sensors & equipment Monitored to suggest PM, product updates, status changes Nodes link to PC for database storage PC Modem calls retailer, Service Provider, or Corp headquarters Corp headquarters remotely monitors assets, billing, energy management Field Service or mobile worker Mfg Flow Temp. Sensor Database Gateway Security Sensor Telephone Cable line Back End Server Materials handling HVAC Service Provider Corp Office Retailer
Home & Diagnostics Examples SOHO Retailer Dealer Customers Back End Server Telephone Cable line Gateway(s) Service Provider 1. Mobile clients link to PC for database storage PC links to peripherals, interactive toys PC Modem calls retailer, SOHO, Service Provider 2. Gateway links to security system, temperature sensor, AC system, entertainment, health. 3. Gateway links to field sales/service PC & peripherals Entertainment Field Service AC or heat Pump Body monitor Data Communication Two way Temp. Sensor White goods Security Sensor Motorola 802.15.4/ZigBee Platform System Simplicity and Flexibility Motorola RF Packet Radio Motorola 8 Bit MCU
Motorola 802.15.4 / ZigBee Solution 1. Features 2.4 GHz Band, 90 dbm RX sensitivity at 1% PER 1) IEEE spec is 85 dbm Power supply 2.0 3.6 V w/ on chip regulator, logic interface 1.7 to 3.3 1) Runs off a single Li or 2 alkaline cells Complete RF transceiver data modem antenna in, fully packetized data out Data and control interface via standard SPI at 4 to 8 MHz 802.15.4 MAC A large number of Motorola s substantial line of HC08 MCUs will interoperate with the data modem chip 1) Often 802.15.4 functionality can be added to existing systems simply by including the modem chip and reprogramming an existing MCU that may already be in the application HC08 RAM/FLASH configurations from 384B/4kB to 2kB/60kB depending upon application SW needs RF Data Modem Transceiver (1/2) 1. Designed for the IEEE 802.15.4 and ZigBee standards Operates in the 2.4 GHz ISM band available worldwide Cost effective CMOS design Low external components, no T/R switch required On chip low noise amplifier 0dBm (1.0 mw) PA, step adjustable to 30dBm Integrated VCO, no external components Full spread spectrum encoding and decoding compatible with 802.15.4 RX sensitivity of 90 dbm at 1% PER, better than specification Engineered to support 250 kbit/s O QPSK data in 5.0 MHz channels, per the IEEE 802.15.4 specification No line of sight limitations as with infrared (IR)
RF Data Modem Transceiver (2/2) 1. Designed to run DIRECTLY off two alkaline AA or AAA cells, or one Lithium cell 2.0 to 3.6 V with on chip voltage regulator Can use the full capacity of the battery (to end of life ~1.0V per cell) 2. Buffered transmit and receive data packets for simplified use with lowend microcontrollers 3. SPI data and control interface, operates up to 8MHz 4. Designed to support peer to peer and star topologies 5. On board timers to support optional Superframe/Guaranteed Time Slots for low latency transfer 6. Will support optional Zigbee Network layer software 7. Application configurable power saving modes that take best advantage of battery operation RX/TX > Idle > Doze > Hibernate > Off Scalability to Address Specific Needs 802.15.4 is a guest in existing microcontrollers 802.15.4 PHY Compliant Transceiver RF Transceiver IC RF Receiver RF Transmitter RF Transceiver IC RF Receiver RF Transmitter RF Transceiver IC RF Receiver RF Transmitter RF Transceiver IC RF Receiver RF Transmitter Digital Processing Digital Processing Digital Processing Digital Processing SPI SPI SPI SPI Zigbee NWK 15.4 FFD MAC >32kB FLASH 8 Bit Microcontroller Application Zigbee NWK 15.4 RFD MAC 32kB FLASH 8 Bit Microcontroller Application 15.4 RFD MAC 12kB FLASH 8 Bit Microcontroller Application Application Direct SPI Calls 3kB FLASH (min) 8 Bit Microcontroller Applicationspecific interfaces System Complexity and Cost
Advantages 1. Total System Solution Single source for platform solution 1) Integrated Circuits, Reference Designs, Modules, Stack Software, Development Systems 2. Key technology enhancements provide for a superior solution Adjacent channel rejection 1) Improvements in noisy environment High Sensitivity Radio Solution 1) 5 dbm beyond spec longer range Extended Temperature Operating Range 1) 40 Cto +85 C for industrial and automotive applications Operating voltage range optimized for alkaline or lithium primary cells 1) 2.0 Vdc to 3.6 Vdc, disposable Adjustable TX Output power 1) Improved coexistence for short range applications, improved battery life 3. IEEE and ZigBee Alliance membership Technology and standards driver Early access to new technology An Application Example (1/7) Wireless Keyboard 1. Scenario Parameters Battery operated keyboard 1) Part of a device group including a mouse or trackball, sketchpad, other human input devices 2) Each device has a unique ID 3) Device set includes a USB to wireless interface dongle Dongle powered continuously from computer 4) Keyboard does not have ON/OFF switch 5) Power modes Keyboard normally in lowest power mode Upon first keystroke, wakes up and stays in a more aware state until 5 seconds of inactivity have passes, then transitions back to lowest power mode
An Application Example (2/7) Keyboard Usage 1. Typing Rates 10, 25, 50, 75 and 100 words per minute 2. Typing Pattern Theoretical: Type continuously until battery is depleted 1) Measures total number of hours based upon available battery energy An Application Example (3/7) Wireless Keyboard Using 802.15.4 1. 802.15.4 Operation Parameters Star network Non beacon mode (CSMA CA) USB Dongle is a PAN Coordinator Full Functional Device (FFD) Keyboard is a Reduced Function Device (RFD) Power Modes 1) Quiescent Mode used for lowest power state First keystroke latency is approx 25ms 2) Idle mode used for more aware state Keystroke latency 8 12 ms latency
An Application Example (4/7) Wireless Keyboard Using 802.15.4 1. 802.15.4 Chipset Parameters 1) Motorola 802.15.4 Transceiver and HCS08 MCU 2) Battery operating voltage 2.0 3.6 V All required regulation internal to ICs Nearly all available energy usable with end of life voltage at 2.0 volts An Application Example (5/7) Wireless Keyboard Using Bluetooth 1. Bluetooth Operation Parameters Piconet network USB Dongle is piconet Master Keyboard is a piconet Slave Power Modes 1) Park mode used for lowest power state 1.28 second park interval First keystroke latency is 1.28s 2) Sniff mode used for more aware state 15ms sniff interval 15ms latency
An Application Example (6/7) Wireless Keyboard Using Bluetooth 1. Bluetooth Chipset Parameters CSR BlueCore 2 External + Flash + Regulator Battery Operating Voltage 2.7 3.6 Vdc 1) Requires external regulator for best performance 2) Only 19 to 30 percent of available battery life usable with 2.7V cutoff voltage Power Consumption (estimated) 1) Park Mode @ 1.28 s interval: 0.05mA avg 2) Sniff Mode @ 15ms interval: 8mA avg 3) NOTE: I do not assume a deep sleep mode since wake up time of 4 to 30 seconds seems unacceptable An Application Example (7/7) Bluetooth vs. 15.4 Keyboard Comparison Bad Hunt n Peck 802.15.4: Approx 38 days BT: Approximately 5 operating days By the way, WirelessUSB looks much like BT
Q & A 1. 경청해주셔서감사합니다. 2. Q & A