VIEWS: 30 PAGES: 50 POSTED ON: 3/11/2011
Presented By : AJAR ZigBee/IEEE 802.15.4 Origin Of Name ZigBee The domestic honeybee, a colonial insect, lives in a hive that contains a queen, a few male drones, and thousands of worker bees. The survival, success, and future of the colony is dependent upon continuous communication of vital information between every member of the colony. The technique that honey bees use to communicate new-found food sources to other members of the colony is referred to as the ZigBee Principle. Using this silent, but powerful communication system, whereby the bee dances in a zig- zag pattern, she is able to share information such as the location, distance, and direction of a newly discovered food source to her fellow colony members. Instinctively implementing the ZigBee Principle, bees around the world industriously sustain productive hives and foster future generations of colony members. What is ZigBee ZigBee is a Ad-hoc networking technology for LR-WPAN Based On IEEE 802.15.4 standard that defines the PHY and Mac Layers for ZigBee. Intended for 2.45 Ghz , 868 Mhz and 915 Mhz Band. Low in cost ,complexity & power consumption as compared to competing technologies. Intended to network inexpensive devices Data rates touch 250Kbps for 2.45Ghz ,40 Kbps 915Mhz and 20Kbps for 868Mhz band. ZigBee Alliance Worlds Most Common Frequency Bands Market Requirements-I Global licence free ISM band operation Unrestricted geographic use RF penetration through walls & ceilings Automatic/semi-automatic installation Ability to add or remove devices Possible voice support Market Requirements-II 10k-115.2kbps data throughput 10-75m coverage range (home/garden) Support for 32-255 nodes Support for 4 critical devices 4-100 co-located networks 0.5-2 year battery life Up to 5m/sec. (18kmph) permitted mobility Module cost: $1.5-$2.5 in 2004/5! Home/Light Commercial spaces Industrial Environment Warehouses, Fleet management, Factory, Supermarkets, Office complexes Gas/Water/Electric meter, HVAC Smoke, CO, H2O detector Refrigeration case or appliance Equipment management services & Preventative maintenance Security services Lighting control Assembly line and work flow, Inventory Materials processing systems (heat, gas flow, cooling, chemical) Application Sectors monitors TV sensors VCR automation DVD/CD control INDUSTRIAL & CONSUMER remote COMMERCIAL ELECTRONICS ZigBee LOW DATA-RATE RADIO DEVICES PC & PERSONAL HEALTH CARE PERIPHERALS security consoles HVAC portables lighting educational TOYS & HOME GAMES AUTOMATION closures ZigBee Market Shares ZigBee General Characteristics Data rates of 20 kbps and up to 250 kbps Star or Peer-to-Peer network topologies Support for Low Latency Devices CSMA-CA Channel Access Handshaking Low Power Usage consumption 3 Frequencies bands with 27 channels Extremely low duty-cycle (<0.1%) ZigBee Statistics BAND COVERAGE DATA RATE CHANNELS 2.4 GHz ISM Worldwide 250 kbps 16 915 MHz ISM Americas 40 kbps 10 868 MHz Europe 20 kbps 1 868MHz/ Channel 0 Channels 1-10 2 MHz 915MHz PHY 868.3 MHz 902 MHz 928 MHz 2.4 GHz PHY Channels 11-26 5 MHz 2.4 GHz Low Power Statistics Today’s definition: Low power: Battery operation for several years Some figures • 1 year is 365*24 hours = 8760 hours • AAA battery capacity is about 1300mAh • AA battery capacity is about 3100mAh • Coin cell lithium CR2032 capacity is about 230mAh Note that peak current,(internal resistance) and leakage are also issues, but not today An average consumption of 10uA will last • AAA:15 years, AA: 35 years and CR2032: 2.6 years Comparison Chart Bluetooth ZigBee Comparison fo PAN networks ZigBee Protocol was developed to serve very different applications than Bluetooth and leads to tremendous optimizations in power consumption. Some of the key protocol differentiators are: ZigBee: • Very low duty cycle, very long primary battery life, • Static and dynamic star and mesh networks, >65,000 nodes, with low latency available, • Ability to remain quiescent for long periods without communications, • Direct Sequence Spread Spectrum allows devices to sleep without the requirement for close synchronization. Bluetooth: • Moderate duty cycle, secondary battery lasts same as master, • Very high QoS and very low, guaranteed latency, • Quasi-static star network up to seven clients with ability to participate in more than one network, • Frequency Hopping Spread Spectrum is extremely difficult to create extended networks without large synchronization cost. Basic Network Charachteristics • 65,536 network (client) nodes • Optimized for timing-critical applications – Network join time: 30 ms (typ) – Sleeping slave changing to active: 15 ms (typ) Network coordinator Full Function node – Active slave channel access Reduced Function node time: 15 ms (typ) Communications flow Virtual links ZigBee Layers Typical Implementation’s What are the RAM/ROM requirements for the FFD and RFD MAC ? ZigBee requires a small amount of system resources substantially simplifying the process of designing wireless communications into products while reducing time to market and product cost. While still in the definition phase, the estimated MAC size is as follows: RFD = 12KB to 16KB FFD = 16KB to 20KB. Device Addressing All devices have IEEE addresses Short addresses can be allocated Addressing modes: • Network + device identifier (star) • Source/destination identifier (peer-peer) • Source/destination cluster tree + device identifier (cluster tree) IEEE 802.15.4 Device Definitions 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 ZigBee Network Devices Star and Peer to Peer Networks Cluster Tree Network Network Architecture Types of PAN Non-Beacon Enabled PAN Un-slotted CSMA/CA Beacon Enabled PAN Slotted CSMA/CA SuperFrame Structures A superframe is formed by the PAN coordinator to synchronize network reception and transmission. Communication Mechanisms-I Communication Mechanisms-II PHY/MAC Framing Network Layer Network Layer Framing Beacon Frame Data Frame Acknowledgement Frame MAC Command Frame Primitives for PHY Layer Mac Layer Primitives Robustness of Architecture CSMA/CA Frame Acknowledgement Data Verification Security Access control Data Encryption Frame Integrity Sequential Freshness Security Modes Unsecured Mode ACL Mode Secured Mode PHY Layer Modulation and Spreading 2.45 Ghz Band Characteristics 16-ary quasi-orthogonal modulation technique (4 information bits are used to select one out of 16 PN sequences. ) Concatenated PN sequences transmitted using O-QPSK Bit to Symbol mapping Symbol to chip mapping (32 chip) Half-sine wave pulse shaping In-Phase (I) carrier even chips Quadrature Phase (Q) carrier odd chips -85dbm minimum receiver sensitivity 62.5 k symbols/sec +/- 40ppm Adjacent channel rejection 0dbm Alternate channel rejection 30dbm PHY Layer Modulation and Spreading 868 and 915Mhz bands DSSS with BPSK Differential Encoding Bit to Chip Mapping (15 chip) BPSK Modulation Pulse Shaping Symbol rate 20ksymbols/sec Receiver sensitivity -94dbm Turn-around time=12 symbols Clear Channel Assessment parameters Energy Detection(10dbm threshold) Link Quality Indication • Receiver ED • Signal to Noise ration estimation Carrier sense Chipset Comparisons 800/9 Standb Trans Reciev Othe 2400 Vdd Interf Encr Packag Manuf Chip 00 y mit e r Remarks MHz (V) . ypt e acurer MHz (µA) (mA) (mA) Iface AT86RF21 1.8 - 60 (3.3 48 Atmel yes no 1 14.5 SPI no no PHY 0 3.6 V) QFN Freesc 2.0 - 32 MC13192 no yes 3 34 37 SPI no no PHY ale 3.4 QFN Chipco 2.1 - 7 x 7 48 CC2420 no yes ? 17.4 19.7 SPI no yes PHY n 3.6 QLP 2.1 - 7 x 7 48 Ember EM2420 no yes 0.5 20.7 19.7 SPI no yes PHY 3.6 QLP ZMD4410 Paral PHY + Thin 48 ZMD yes no 2.4 4 20 19 SPI no 1 lel MAC MLF Comp CX1540 no yes 3.0 1 56 57 SPI no no PHY + MAC 48 XS OKI ML7065 no yes 3.0 1 56 57 SPI no no PHY + MAC 48 48 UBEC UZ2400 no yes 1.8 5 ? ? SPI no ? PHY + MAC QFN Thank You !
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