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IEEE 802.15.4. Slide 2 Content Overview Topologies Superframe structure Frame formatting Data service Management service Interframe spacing CSMA procedure.

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Presentation on theme: "IEEE 802.15.4. Slide 2 Content Overview Topologies Superframe structure Frame formatting Data service Management service Interframe spacing CSMA procedure."— Presentation transcript:

1 IEEE 802.15.4

2 Slide 2 Content Overview Topologies Superframe structure Frame formatting Data service Management service Interframe spacing CSMA procedure

3 Introduction Until recently the main concentration In wireless was on high throughput. Some applications for home automation, security, agriculture,industrial etc. have relaxed throughput requirements with low power consumption and low cost. Existing standards are not suitable because of high complexity, power implications and high cost. 3

4 Applications Home automation heating, ventilation, and air conditioning, security, lighting, and the control of objects. Industrial detecting emergency situations, monitoring machines Automotive automotive sensing, such as tire pressure monitoring; Agriculture sensing of soil moisture, pesticide, herbicide, and pH levels. Others Controlling consumer electronics, PC peripherals etc. Data rate needed ranges from 115.2 kb/s to less than 10 kb/s. 4

5 IEEE 802.15.4 MAC Upper Layers IEEE 802.15.4 SSCS IEEE 802.2 LLC, Type I IEEE 802.15.4 2400 MHz PHY IEEE 802.15.4 868/915 MHz PHY 802.15.4 Architecture 5

6 Slide 6 Protocol Drivers  Extremely low cost  Ease of installation  Reliable data transfer  Short range operation Reasonable battery life

7 Slide 7 802.15.4 Overview Star and peer-to-peer topologies Optional frame structure Association CSMA-CA channel access mechanism Packet validation and message rejection Optional guaranteed time slots Guaranteed packet delivery Facilitates low-power operation Security

8 Slide 8 IEEE 802.15.4 Device Classes Full function device (FFD) – Any topology – PAN coordinator capable – Talks to any other device – Implements complete protocol set Reduced function device (RFD) – Limited to star topology or end-device in a peer-to-peer network. – Cannot become a PAN coordinator – Very simple implementation – Reduced protocol set

9 Slide 9 IEEE 802.15.4 Definitions Network Device: An RFD or FFD implementation containing an IEEE 802.15.4 medium access control and physical interface to the wireless medium. Coordinator: An FFD with network device functionality that provides coordination and other services to the network. PAN Coordinator: A coordinator that is the principal controller of the PAN. A network has exactly one PAN coordinator.

10 Slide 10 Low-Power Operation Duty-cycle control using superframe structure – Beacon order and superframe order – Coordinator battery life extension Indirect data transmission Devices may sleep for extended period over multiple beacons Allows control of receiver state by higher layers

11 11 Typical Network Topologies

12 Slide 12 Star Topology FFD RFD Communications flow Master/slave PAN coordinator

13 Slide 13 Peer-Peer Topology Communications flow Point to point Cluster tree FFD RFD PAN coordinators

14 Slide 14 Combined Topology FFD RFD Communications flow Clustered stars - for example, cluster nodes exist between rooms of a hotel and each room has a star network for control.

15 Technical Characteristics Physical layer – 20 kbps over 1 channel @ 868-868.6 MHz – 40 kbps over 10 channels @ 905 – 928 MHz – 250 kbps over 16 channels @ 2.4 GHz MAC protocol – Single channel at any one time – Combines contention-based and schedule-based schemes – Asymmetric: nodes can assume different roles 15

16 Physical Frequencies and Channels 16 868MHz / 915MHz PHY 2.4 GHz 868.3 MHz Channel 0 Channels 1-10 Channels 11-26 2.4835 GHz 928 MHz902 MHz 5 MHz 2 MHz 2.4 GHz PHY

17 2.4 GHz PHY 250 kb/s (4 bits/symbol, 62.5 kBaud) Data modulation is 16-ary orthogonal modulation 16 symbols are ~orthogonal set of 32-chip PN codes Chip modulation is MSK at 2.0 Mchips/s 868MHz/915MHz PHY Symbol Rate 868 MHz Band: 20 kb/s (1 bit/symbol, 20 kBaud) 915 MHz Band: 40 kb/s (1 bit/symbol, 40 kBaud) Data modulation is BPSK with differential encoding Spreading code is a 15-chip m-sequence Chip modulation is BPSK at 868 MHz Band: 300 kchips/s 915 MHz Band: 600 kchips/s 17 IEEE 802.15.4 PHY Overview Modulation/Spreading

18 Transmit Power Capable of at least 1 mW Transmit Center Frequency Tolerance  40 ppm Receiver Sensitivity (Packet Error Rate <1%) -85 dBm @ 2.4 GHz band -92 dBm @ 868/915 MHz band RSSI Measurements Packet strength indication Clear channel assessment Dynamic channel selection 18 IEEE 802.15.4 PHY Overview Common Parameters

19 IEEE 802.15.4 PHY Overview Packet Structure Preamble Start of Packet Delimiter PHY Header PHY Service Data Unit (PSDU) PHY Packet Fields Preamble (32 bits) – synchronization Start of Packet Delimiter (8 bits) PHY Header (8 bits) – PSDU length PSDU (0 to 1016 bits) – Data field 6 Octets0-127 Octets 19

20 IEEE 802.15.4 MAC Overview General Frame Structure 4 Types of MAC Frames: Data Frame Beacon Frame Acknowledgment Frame MAC Command Frame 20

21 IEEE 802.15.4 MAC overview All devices have IEEE addresses Short addresses can be allocated Addressing modes: – Network + device identifier (star) – Source/destination identifier (peer-peer) 21

22 Slide 22 Optional Frame Structure 15ms * 2 n where 0  n  14 GTS 3 GTS 2 Network beacon Transmitted by PAN coordinator. Contains network information, frame structure and notification of pending node messages. Beacon extension period Space reserved for beacon growth due to pending node messages Contention period Access by any node using CSMA-CA Guaranteed Time Slot Reserved for nodes requiring guaranteed bandwidth [n = 0]. GTS 1 Slot Battery life extension Contention Access Period Contention Free Period

23 Slide 23 Optional Frame Structure Superframe may have inactive period 15ms * 2 BO where SO  BO  14 15ms * 2 SO where 0  SO  14 SO = Superframe order BO = Beacon order Inactive Period

24 IEEE 802.15.4 MAC overview Star networks: devices are associated with coordinators – Forming a PAN, identified by a PAN identifier Coordinator – Bookkeeping of devices, address assignment, generate beacons – Talks to devices and peer coordinators Beacon-mode superframe structure – GTS assigned to devices upon request b 24

25 Slide 25 General MAC Frame Format Frame control field

26 Slide 26 Beacon Frame Format

27 Slide 27 MAC Command Frame Command Frame Types – Association request – Association response – Disassociation notification – Data request – PAN ID conflict notification –Orphan Notification –Beacon request –Coordinator realignment –GTS request

28 Slide 28 Data Frame Format Acknowledgement Frame Format

29 Slide 29 Data Service Data transfer to neighboring devices – Acknowledged or unacknowledged – Direct or indirect – Using GTS service Maximum data length (MSDU) aMaxMACFrameSize (102 bytes)

30 Slide 30 Data Transfer Message Sequence Diagram

31 Slide 31 Indirect Data Transfer Message Sequence Diagram

32 Slide 32 Passive Scan

33 Slide 33 Active Scan

34 Slide 34 Orphaning Message Sequence Diagram

35 Slide 35 Inter-frame Spacing For frames ≤ aMaxSIFSFrameSize use short inter-frame spacing (SIFS) For frames > aMaxSIFSFrameSize use long inter-frame spacing (LIFS)

36 Slide 36 Slotted CSMA Procedure Used in beacon enabled networks.

37 Slide 37 Un-slotted CSMA Procedure Used in non-beacon networks.

38 802.15.4 Architecture IEEE 802.15.4 MAC Applications IEEE 802.15.4 2400 MHz PHY IEEE 802.15.4 868/915 MHz PHY Network Routing Address translation Packet Segmentation Profiles ZigBee 38

39 ZigBee Relation to 802.15.4 similar to Bluetooth / 802.15.1 Pushed by Chipcon (now TI), ember, freescale (Motorola), Honeywell, Mitsubishi, Motorola, Philips, Samsung… More than 260 members – about 15 promoters, 133 participants, 111 adopters – must be member to commercially use ZigBee spec ZigBee platforms comprise – IEEE 802.15.4 for layers 1 and 2 – ZigBee protocol stack up to the applications 39

40 ZigBee Stack Architecture 40

41 Typical ZigBee-Enabled Device Design Typical design consist of RF IC and 8-bit microprocessor with peripherals connected to an application sensor or actuators 41

42 Wireless Technology Comparison Chart 356  A 34KB /14KB 42

43 Competing/Similar Technologies Bluetooth – – X10 – Powerline protocol first introduced in the 1970's. – Z-wave – Proprietary protocol for wireless home control networking. – INSTEON – Peer-to-peer mesh networking product that features a hybrid radio/powerline transmission – nanoNET – Proprietary set of wireless sensor protocols, designed to compete with ZigBee. – 43

44 Bluetooth vs IEEE 802.15.4. Bluetooth based WPAN Few devices Data range is 10m to 100m Data rate is nearly 1Mb/s Power consumption is a low. Battery life is low. Star only. IEEE 802.15.4 LR-WPAN Many devices Data range is nearly 10m Data rate is 20 kb/s,40kb/s,250kb/s. Power consumption is ultra low. Battery lasts years. peer to peer,Star. 44

45 Summary 802.15.4: Low-Rate, Very Low-Power – Low data rate solution with multi-month to multi-year battery life and very low complexity – Potential applications are sensors, interactive toys, smart badges, remote controls, and home automation – Data rates of 20-250 kbit/s, latency down to 15 ms – Master-Slave or Peer-to-Peer operation – Up to 254 devices or 64516 simpler nodes – Support for critical latency devices, such as joysticks – CSMA/CA channel access (data centric), slotted (beacon) or unslotted – Automatic network establishment by the PAN coordinator – Dynamic device addressing, flexible addressing format – Fully handshaked protocol for transfer reliability – Power management to ensure low power consumption – 16 channels in the 2.4 GHz ISM band, 10 channels in the 915 MHz US ISM band and one channel in the European 868 MHz band – Basis of the ZigBee technology – 45

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