ZigBee and IEEE

Transcription

1 n overview of ZigBee and IEEE IEEE Standard for Information technology Telecommunications and information exchange between systems Local and metropolitan area networks Specific requirements Part 5.4: Wireless Medium ccess Control (MC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal rea Networks (WPNs) IEEE Computer Society Sponsored by the LN/MN Standards Committee I E E E IEEE Std Park venue New York, NY , US Martijn 8 September van 006 Eenennaam, UT (Revision of IEEE Std ) / 9

2 ZigBee is: Spans entire protocol stack (PHY to ppl.layer) Complexity, cost and energy consumption < BT Low data rate Long battery life (duty cycle) Secure, robust networking Self organising / self healing network Martijn van Eenennaam, UT / 9

3 pplications: Wireless Control (home, office, industry) Wireless Monitoring Home utomation Wireless Personal rea Networks (WPN) Wireless Sensor Networks (WSN) Martijn van Eenennaam, UT 3/ 9

4 Martijn van Eenennaam, UT 4/ 9

5 ZigBee protocol stack Layered like OSI model pplication Layer Network Layer (routing) Medium ccess Control Physical layer, Radio Profiles defined by ZigBee lliance [] MC and PHY defined in IEEE [] Martijn van Eenennaam, UT 5/ 9

6 Defines several profiles (similar to BT) Profiles enable interoperability With vendor-specific implementations Provides security (8 bit ES symmetric key encryption) ll very nice... but out of the scope of this talk Martijn van Eenennaam, UT 6/ 9

7 ZigBee knows three types of nodes: ZigBee Coordinator () - per network ZigBee Router () - * ZigBee End Device () - * IEEE knows two: Full Function Device (FFD) Reduced Function Device (RFD) but... defines a PN-coordinator (which is a FFD) Martijn van Eenennaam, UT 7/ 9

8 Network Topologies Routing with d hoc On-demand Distance Vector (ODV): build routes only when needed llows multiple network toplogies, depending on application star mesh tree Martijn van Eenennaam, UT 8/ 9

9 !! ODV Routing (RFC 356 [4]). Node wants to send data to Node 3 RRE 4 Flood RR Martijn van Eenennaam, UT 9/ 9

10 ODV Routing (RFC 356 [4]). Node floods for ZE 4 Flood 3 from via: Martijn van Eenennaam, UT 9/ 9

11 ODV Routing (RFC 356 [4]) 3. receives EQ from via: Martijn van Eenennaam, UT 9/ 9

12 ODV Routing (RFC 356 [4]) 4. unicasts RREP to over shortest route R 4 Flood RRE 3 RREP RREP RREP 3 DT DT 4 4 RREP from via 3 send DT Martijn van Eenennaam, UT 9/ 9

13 ODV Routing (RFC [4]) 5. sends DT over shortest part Flood from via: 3 4 RREP RREP 3 DT DT DT 4 4 EP from via 3 send DT via Martijn van Eenennaam, UT 9/ 9

14 D 3 ODV Routing (RFC 356 [4]) 4 D RREP via 3 Flood 3 DT DT 4 DT send DT via 3 from via: 3 4 Benefits: 3 4 Routes built when needed (no comm. otherwise) Route in RREP is accurate Low setup delay Drawbacks: Can have stale routes Flooding can be burden on network Martijn van Eenennaam, UT 9/ 9

15 Ensures every node gets an opportunity to use the medium Two modes: Coordinated ( beacon-enabled ) and uncoordinated ( beaconless ) Martijn van Eenennaam, UT 0/ 9

16 beacon-enabled - (Slotted TDM) sends beacons, s Z sync. to beacons, wake up during beacon time. Sleeping star enables longmesh duty cycles. tree star mesh t!!!!!!!! beaconless - (CSM/C)!! Communication!! can occur at any time.!!!!!!!! RRE 3 3 Overview pplication Layer Network Layer Medium ccess Control Layer Physical Layer Martijn van Eenennaam, 3 UT 4 / 9 4

17 Only four frametypes are specified: Beacon - sent by coordinator s MC, function is to coordinate Data - encapsulates upper-layer data cknowledgement - used to signal correct reception at MC MC Command - MC management info Martijn van Eenennaam, UT / 9

18 Manages the radio (off to safe power) Selects channel Performs energy detection (CC, Carrier Sense) Most important: transmits and receives information Martijn van Eenennaam, UT 3/ 9

19 Spectrum IEEE Std LOCL ND METROPOLITN RE NETWORKS PRT 5.4: Table Frequency bands and data rates PHY (MHz) Frequency band (MHz) Spreading parameters Chip rate Modulation (kchip/s) Bit rate (kb/s) Data parameters Symbol rate (ksymbol/s) Symbols 868/95 868/95 (optional) BPSK 0 0 Binary BPSK Binary SK bit PSSS SK bit PSSS 868/ O-QPSK ary Orthogonal (optional) O-QPSK ary Orthogonal O-QPSK ary Orthogonal Modulated This standard using is intended DSSS, to conform 868/95 with established can regulations alsoin Europe, use Parallel Japan, Canada, and Sequence the United States. The regulatory documents listed below are for information only and are subject to change and Spread revisions Spectrum at any time. [3] Devices = conforming tradeoff to this between standard shall data also comply rate, with energy specific regional legislation. dditional regulatory information provided in nnex F. efficiency and multipath fading resistance at a low electronic Europe: complexity. Overview pproval standards: European Telecommunications Standards Institute (ETSI) pplication Layer Network Layer Medium ccess Control Layer Physical Layer Documents: ETSI EN [B6], ETSI EN [B7], ETSI EN [B5], ERC Recommendation [B4] pproval authority: National type approval authorities Martijn van Eenennaam, UT 4/ 9

20 Transmit power mw Communication range 0-75m depending on environment and modulation Few analog stages, digital circuits whenever possible Radio and microcontroller (and sometimes antenna) often integrated in single chip Martijn van Eenennaam, UT 5/ 9

21 Questions? Martijn van Eenennaam, UT 6/ 9

22 Backup Slides Martijn van Eenennaam, UT 7/ 9

23 Beacon frame Figure 0 shows the structure of the beacon frame, which originates from within the MC sublayer. coordinator can transmit network beacons in a beacon-enabled PN. The MC payload contains the superframe specification, GTS fields, pending address fields, and beacon payload (see 7...). The MC payload is prefixed with Frame a MC header (MHR) structures and appended with a MC [] footer (MFR). The MHR contains the MC Frame Control field, beacon sequence number (BSN), addressing fields, and optionally the auxiliary security header. The MFR contains a 6-bit frame check sequence (FCS). The MHR, MC payload, and MFR together form the MC beacon frame (i.e., MPDU). Beacon frame Octets: MC sublayer 0, 5, 6, 0 or 4 or 0 4 k m Frame Control Sequence Number MHR ddressing Fields uxiliary Security Header Superframe Specification GTS Fields Pending ddress Fields MC Payload n Beacon Payload FCS MFR Octets: PHY layer Preamble Sequence PHY dependent (see clause 6) Start of Frame Delimiter SHR Frame Length / Reserved PHR 7 + (4 to 4) + k + m + n PSDU PHY Payload (see clause 6) (4 to 4) + k + m + n Figure 0 Schematic view of the beacon frame and the PHY packet The MC beacon frame is then passed to the PHY as the PHY service data unit (PSDU), which becomes the Overview PHY payload. pplication The PHY Layer payload is prefixed Networkwith Layer a synchronization Mediumheader ccess(shr), Controlcontaining Layer the Preamble Physical Layer Sequence and Start-of-Frame Delimiter (SFD) fields, and a PHY header (PHR) containing the length of the PHY payload in octets. The SHR, PHR, and PHY payload Martijn together van Eenennaam, form the PHY UT packet (i.e., PPDU). 8/ 9

24 Data frame Frame structures [] IEEE Std LOCL ND METROPOLITN RE NETWORKS PRT 5.4: Data frame Figure shows the structure of the data frame, which originates from the upper layers. MC sublayer Octets: PHY layer Preamble Sequence PHY dependent (see clause 6) Start of Frame Delimiter SHR Octets: Frame Length / Reserved PHR Frame Control 4 to 0 Sequence Number ddressing Fields MHR 0, 5, 6, 0 or 4 uxiliary Security Header 5 + (4 to 34) + n PSDU PHY Payload (see clause 6) (4 to 34) + n n Data Payload MC Payload FCS MFR Figure Schematic view of the data frame and the PHY packet The data payload is passed to the MC sublayer and is referred to as the MC service data unit (MSDU). The MC payload is prefixed with an MHR and appended with an MFR. The MHR contains the Frame Control field, data sequence number (DSN), addressing fields, and optionally the auxiliary security header. Overview The MFR is pplication composed Layer of a 6-bit FCS. Network The MHR, Layer MC payload, Mediumand ccess MFR Control together Layer form the MC Physical data Layer frame, (i.e., MPDU) Martijn van Eenennaam, UT 8/ 9

25 cknowledgment frame Figure shows the structure of the acknowledgment frame, which originates from within the MC sublayer. The MC acknowledgment frame is constructed from an MHR and an MFR; it has no MC payload. The MHR contains the MC Frame Control field and DSN. The MFR is composed of a 6-bit FCS. The MHR and MFR together form the MC acknowledgment frame (i.e., MPDU). Frame structures [] The MPDU is passed to the PHY as the PSDU, which becomes the PHY payload. The PHY payload is prefixed with the SHR, containing the Preamble Sequence and SFD fields, and the PHR containing the cknowledgement length of the PHY payload in octets. frame The SHR, PHR, and PHY payload together form the PHY packet, (i.e., PPDU). Octets: MC sublayer PHY layer Octets: PHY dependent (see clause 6) Preamble Sequence SHR Start of Frame Delimiter Frame Control Sequence Number MHR MFR 5 Frame Length / PSDU Reserved PHR PHY Payload (see clause 6) + 6 Figure Schematic view of the acknowledgment frame and the PHY packet FCS Copyright 006 IEEE. ll rights reserved Martijn van Eenennaam, UT 8/ 9

26 IEEE WIRELESS MC ND PHY SPECIFICTIONS FOR LR-WPNS Std MC command frame Command frame Frame structures [] Figure 3 shows the structure of the MC command frame, which originates from within the MC sublayer. The MC payload contains the Command Type field and the command payload (see 7...4). The MC payload is prefixed with an MHR and appended with an MFR. The MHR contains the MC Frame Control field, DSN, addressing fields, and optionally the auxiliary security header. The MFR contains a 6- bit FCS. The MHR, MC payload, and MFR together form the MC command frame, (i.e., MPDU). MC sublayer PHY layer Octets: PHY dependent (see clause 6) Preamble Sequence SHR Start of Frame Delimiter Octets: Frame Length / Reserved PHR Frame Control 4 to 0 Sequence Number ddressing Fields MHR 0, 5, 6, 0, or 4 uxiliary Security Header 6 + (4 to 34) + n PSDU PHY Payload (see clause 6) (4 to 34) + n Command Type n Command Payload MC Payload FCS MFR Figure 3 Schematic view of the MC command frame and the PHY packet The MPDU is then passed to the PHY as the PSDU, which becomes the PHY payload. The PHY payload is prefixed with an SHR, containing the Preamble Sequence and SFD fields, and a PHR containing the length Overview of the PHY pplication payload Layer in octets. The Network preamble Layer sequence Medium enables ccess the Control receiver Layer to achieve Physical symbol Layer synchronization. The SHR, PHR, and PHY payload together form the PHY packet, (i.e., PPDU) Martijn van Eenennaam, UT 8/ 9

27 References [] ZigBee lliance - [] IEEE Std [3] H. Schwetlick and. Wolf, PSSS - Parallel Sequence Spread Spectrum - Physical Layer for RF Communication, 004 [4] RFC 356, Martijn van Eenennaam, UT 9/ 9