WPAN IEEE 802.15.4 (ZigBee)

1. WPAN IEEE 802.15.4 (ZigBee)

2. WWAN < 15 km 802.20, GSM, GPRS, CDMA, 2.5G, 3G, 4G WMAN < 5 km 802.16 – 70 Mbps LMDS – 38 Mbps WLAN < 150 m 11 – 54 Mbps 802.11 HiperLAN/2 WPAN < 10 m Bluetooth、UWB、Zigbee 无线通信网络分类图

3. Common Aliases for Wireless Standards

4. IEEE 802.15 Working Group for Wireless Personal Area Networks • The 802.15 WPAN effort focuses on the development of consensus standards for Personal Area Networks (PAN) or short distance wireless networks • WPANs address wireless networking of portable and mobile computing devices such as: PCs, Personal Digital Assistants (PDAs), peripherals, cell phones, pagers, and consumer electronics; allowing these devices to communicate and interoperate with one another.

5. Example of home equipment demanding network operations

6. IEEE Project 802 Standards WPAN WLAN WMAN LR-WPAN

7. IEEE 802.15 Working Group

8. IEEE 802.15 Protocol Architecture

9. Wireless Local Networks

10. Bluetooth • In 1998 – Ericsson, IBM, Toshiba, Nokia and Intel form Bluetooth Special Interest Group (SIG). • Harald Bluetooth – Danish king who lived more than 1000 years ago • Universal short-range wireless capability • Uses 2.4-GHz band • Available globally for unlicensed users • Devices within 10 m can share up to 720 kbps of capacity • Supports open-ended list of applications • Data, audio, graphics, video • Data rate – 1 Mbps

11. Landline Data/Voice Access Points …and combinations! Personal Ad-hoc Networks Bluetooth Applications Cable Replacement - Synchronization - Cordless Headset It is reported that more than two billion Bluetooth-ready devices were shipped during 2012 – over 50 millions every day.

12. Radio Specification • Classes of transmitters (on which Bluetooth products are available): • Class 1: Outputs 100 mW for maximum range • Power control mandatory • Provides greatest distance – up to 100 m • Products: still available • Class 2: Outputs 2.4 – 2.5 mW at maximum • Power control optional • Transmission distance – 10 m • Products: most common • Class 3: Nominal output is 1 mW • Lowest power • Transmission distance – 10 cm – 1 m • Products - rare

13. Bluetooth Standards Documents • Core specifications • Details of various layers of Bluetooth protocol architecture • Profile specifications • Use of Bluetooth technology to support various applications

14. Bluetooth Protocol Stack

15. Applications IP SDP RFCOMM Control Data Audio L2CAP Link Manager Baseband RF Bluetooth Protocol Stack Composed of protocols to allow Bluetooth devices to locate each other and to create, configure and manage both physical and logical links that allow higher layer protocols and applications to pass data through these transport protocols Transport Protocol Group

16. Applications IP SDP RFCOMM Control Data Audio L2CAP Link Manager Baseband RF Bluetooth Protocol Stack Additional transport protocols to allow existing and new applications to operate over Bluetooth. Packet based telephony control signaling protocol also present. Also includes Service Discovery Protocol. Middleware Protocol Group

17. Applications IP SDP RFCOMM Control Data Audio L2CAP Link Manager Baseband RF Bluetooth Protocol Stack Consists of Bluetooth aware as well as un-aware applications. Application Group

18. Applications IP SDP RFCOMM Control Data Audio L2CAP LMP Link Manager Baseband RF Link Manager Protocol • Setup and management • of Baseband connections • Piconet Management • Link Configuration • Security

19. IP L2CAP Applications L2CAP - Logical Link Control and Adaptation Protocol SDP RFCOMM Data • L2CAP provides • Protocol multiplexing • Segmentation and • Re-assembly • Quality of service negotiation Audio L2CAP Link Manager Baseband RF

20. IP RFCOMM (Radio Frequency Communication)-- Serial Port Emulation using RFCOMM Applications SDP Serial Port RFCOMM Data • Serial Port emulation on top of a packet oriented link • Similar to HDLC (High level • Data Link Control protocol) • RS232 • For supporting legacy apps Audio L2CAP Link Manager Baseband RF

21. Usage Models • File transfer • Internet bridge • LAN access • Synchronization • Three-in-one phone • Headset

22. Piconets and Scatternets • Piconet • Basic unit of Bluetooth networking • Master and one to seven slave devices • Master determines channel and phase • Scatternet • Device in one piconet may exist as master or slave in another piconet • Allows many devices to share same area • Makes efficient use of bandwidth

23. Physical Links between Master and Slave • Synchronous connection oriented (SCO) • Allocates fixed bandwidth between point-to-point connection of master and slave • Master maintains link using reserved slots • Master can support three simultaneous links • Asynchronous connectionless (ACL) • Point-to-multipoint link between master and all slaves • Only single ACL link can exist

24. Connection Setup • Inquiry（查询消息） • Master 查找附近的蓝牙设备，以便通过收集来自从节点响应查询消息中得到该节点的设备地址（48b）和时钟 • Inquiry – scan（查询扫描） • Slave设备周期地监听来自其他设备的查询消息，以便自己能被发现,并在监听到后发送它的地址和时钟信息。

25. Master Active Slave • Parked Slave • Connected • Not in Pico Standby Connection Setup • Page （寻呼） • Master 通过在不同的跳频序列发送消息，来激活一个从节点, 并建立连接。调频序列由slaver的地址码计算出 • Page – scan（寻呼扫描） • Slaver 周期性地在扫描窗间隔时间内唤醒自己，并监听自己的访问码， Slaver节点每隔1.28s在这个扫描窗上根据寻呼跳频序列选择一个扫描频率

26. Bluetooth Packet Fields • Access code – used for timing synchronization, offset compensation, paging, and inquiry • Header – used to identify packet type and carry protocol control information • Payload – contains user voice or data and payload header, if present

27. 72 54 0-2745 bits access code packet header payload 4 64 (4) 3 4 1 1 1 8 preamble sync. (trailer) S address type flow ARQN SEQN HEC Frame Format of Bluetooth Packets • The 48 bit address unique to every Bluetooth device is used as the seed to derive the sequence for hopping frequencies of the devices. • Four types of access codes: • Type 1: identifies a “M” terminal and its piconet address • Type 2: identifies a “S” identity used to page a specific “S”. • Type 3: Fixed access code reserved for the inquiry process • Type 4: dedicated access code reserved to identify specific set of devices such as fax machines, printers, or cell phones. • Header: 18 bits repeated 3 times with a 1/3 FEC code bits

28. WPAN: IEEE 802.15 • 802.15-2: Coexistence • Coexistence of Wireless Personal Area Networks (802.15) and Wireless Local Area Networks (802.11), quantify the mutual interference • 802.15-3: High-Rate • Standard for high-rate (20Mbit/s or greater) WPANs, while still low-power/low-cost • Quality of Service isochronous protocol • Ad hoc peer-to-peer networking • Security • Low power consumption • Low cost • Designed to meet the demanding requirements of portable consumer imaging and multimedia applications

29. ZigBee • ZigBee - a specification set of high level communication protocols designed to use small, low power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs) • This technology is designed to be simpler and cheaper than other WPANs (such as Bluetooth) • ZigBee uses the IEEE 802.15.4 Low-Rate Wireless Personal Area Network (WPAN) standard to describe its lower protocol layers—the physical layer (PHY), and the medium access control (MAC) portion of the data link layer (DLL).

30. INDUSTRIAL & COMMERCIAL ZigBee Applications CONSUMER ELECTRONICS monitors sensors automation control TV VCR DVD/CD remote PC & PERIPHERALS PERSONAL HEALTH CARE monitors diagnostics sensors ZigBee LOW DATA-RATE RADIO DEVICES mouse keyboard joystick TOYS & GAMES HOME AUTOMATION consolesportables educational security HVAC lighting closures Reference from ZigBee Alliance Inc.

31. ZigBee Alliance 50+ companies Defining upper layers of protocol stack: from network to application, including application profiles IEEE 802.15.4 Working Group Defining lower layers : MAC and PHY Development of the Standard Customer APPLICATION ZIGBEE STACK ZigBee Alliance SILICON IEEE 802.15.4

32. IEEE 802.15.4 Overview • Wireless Personal Area Networks (WPANs) • short distance • small (ultra low complexity) • low duty-cycle (<0.1%) • power efficient (the most important factor) • inexpensive (ultra low cost) solutions. • Typically operating in the Personal Operating Space (POS) of 10 meters. • Supporting star and peer-to-peer topologies • controlled by the PAN coordinator

33. IEEE 802.15.4 standard • Includes layers up to and including Link Layer Control • LLC is standardized in 802.1 • Supports multiple network topologies including Star, Cluster Tree and Mesh • Channel scan for beacon is included, but it is left to the network layer to implement dynamic channel selection • Low complexity: 26 service primitives versus 131 service primitives for 802.15.1 (Bluetooth) ZigBee Application Framework 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

34. IEEE 802.15.4 Features • Media access is contention based. • Using carrier sense multiple access with collision avoidance (CSMA/CA) MAC protocol • Similar to IEEE 802.11 CSMA/CA protocol, but not the same • Provide the optional Superframe structure • The PAN coordinatorperiodically allocatesguaranteed time slots(GTS) to low latency devices • Dynamic device addressing • Two kinds of address of a device • 16-bit Short Address • 64-bit Extended Address • Fully acknowledged protocol for transfer reliability.

35. Device Classes • There are two different device types : • A full function device (FFD) • A reduced function device (RFD) • The FFD can operate in three modes serving • Device • Coordinator • PAN coordinator • The RFD can only operate in a mode serving: • Device • Coordinator provides synchronization information to other devices

36. FFD vs RFD • Full function device (FFD) • Any topology • Network coordinator capable • Talks to any other device • Reduced function device (RFD) • Limited to star topology • Cannot become a network coordinator • Talks only to a network coordinator • Very simple implementation

37. Network Topologies • Star and Peer2Peer Topologies

38. Network Topologies • Star network formation: • An FFD may establish its own network and become the PAN coordinator. • All star networks operate independently. • Choosing a PAN identifier, which is not currently used by any other network within the radio sphere of influence. • Both FFDs and RFDs may join the network. • Peer-to-peer network formation: • Each device is capable of communicating with any other device. • One FFD device will be nominated as the PAN coordinator.

39. Star Topology • Home Application FFD FFD RFD RFD FFD FFD PAN coordinator RFD RFD RFD RFD RFD RFD FFD FFD

40. Cluster Tree Topology • Only one PAN coordinator • No detail yet Cluster Head PAN coordinator

41. Cluster Tree Establishment • The PAN coordinator forms the first cluster by establishing itself as the cluster head (CLH) with a cluster identifier (CID) of zero. • Choosing an unused PAN identifier(PANID) and broadcasting beacon frames to neighboring devices. • A candidate device receiving a beacon frame may request to join the network at the CLH. • If the PAN coordinator permits the device, it will add the new device as a child device in its Access Control List (ACL). • The newly joined device will add the CLH as its parent in its ACL, and begin transmitting periodic beacons. • Other candidate devices may then join the network at that device. A larger network (PAN) is possible by forming a mesh of multiple neighboring clusters. • The PAN coordinator may instruct a device to become the CLH of a new cluster adjacent to the first one. • Other devices gradually connect and form a multi-cluster network structure.

42. Addressing Methods • Two or more devices with a POS communicating on the same physical channel constitute a WPAN which includesat least one FFD (PAN coordinator) • Each independent PAN will select a unique PAN identifier • All devices operating on a network shall have unique 64-bit extended address. This address can be used for direct communication in the PAN • The address can use a 16-bit short address, which is allocated by the PAN coordinator when the device associates • Addressing modes: • Network + device identifier (star) • Source/destination identifier (peer-peer) • Source/destination cluster tree + device identifier (cluster tree)

43. MAC/PHY Functions • Functions in PHY sublayer • activation and deactivation of the radio transceiver • energy detection • link quality indication • clear channel assessment (CCA) - carrier sense • transmitting/receiving bit stream • Functions in MAC sublayer • beacon management • channel access (slotted or unslotted CSMA/CA) • guarantee time slot management (QoS) • frame validation • acknowledged frame delivery • association • disassociation • security mechanisms (AES)

44. PHY Specifications • The standard specifies two PHYs : • 868 MHz/915 MHzdirect sequence spread spectrum (DSSS) PHY (11 channels) • 1 channel (20Kb/s)inEuropean 868MHz band • 10 channels (40Kb/s)in915 (902-928)MHz ISM band • 2450 MHzdirect sequence spread spectrum (DSSS) PHY (16 channels) • 16 channels (250Kb/s)in 2.4GHz band

45. PHY Specification • 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

46. PHY Specification

47. Operating Frequency Range BAND COVERAGE DATA RATE CHANNEL(S) 2.4 GHz ISM Worldwide 250 kbps 16 868 MHz Europe 20 kbps 1 915 MHz ISM Americas 40 kbps 10 • A total of 27 channels, numbered 0 to 26, are available across the three frequency bands. • 16channels are for 2450 MHz, 10 are for 915 MHz an 1 is for 868 MHz.

48. PHY Parameters • Transmit Power • Capable of at least 1 mW • Power reduction capability required if > 16 dBm (reduce to < 4 dBm in single step) • Transmit Center Frequency Tolerance •  40 ppm • Receiver Sensitivity • -85dBm (2450 MHz) • -92dBm (868/915 MHz) • 1% Packet Error Rate in PSDU = 20 Bytes) • RSSI Measurements • Packet strength indication • Clear channel assessment • Dynamic channel selection

49. PHY PDU Format (PPDU) • PHY Packet Fields • A synchronization header • Preamble (32 bits) – 32 binary zeros used forsynchronization • Start of Packet Delimiter (8 bits) – 10100111 • A PHY header • PHY Header (8 bits)– 7-bit frame length (0-127) and 1-bit reserved • A payload • PSDU (0 to 127 bytes)– Data field 4 Bytes 1 Byte 1 Byte Start of Packet Delimiter PHY Header PHY Service Data Unit (PSDU) Preamble 6 Bytes 0-127 Bytes

50. MAC Options • Two channel access mechanisms • Non-beacon network • Standard CSMA-CA communications + ACK • Non-beacon mode is useful in situations where only light traffic is expected • Beacon-enabled network • Superframe structure • Set up by network coordinator to transmit beacons at predetermined intervals • 15ms to 252sec, slotted CSMA-CA • In general, the ZigBee protocols minimize the time the radio is on, so as to reduce power use. • In beaconing networks, nodes only need to be active while a beacon is being transmitted. • In non-beacon-enabled networks, power consumption is decidedly asymmetrical: some devices are always active, while others spend most of their time sleeping.