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The IEEE 802.15.4 (Low Rate Wireless Personal Area Network) Standard

The IEEE 802.15.4 (Low Rate Wireless Personal Area Network) Standard. Lance Hester Ken Cornett Florida Communication Research Lab Motorola Labs May 20, 2002. IEEE What?. IEEE 802 LAN/MAN Standards Committee. …. …. …. 802.1 Higher Layer LAN Protocols Working Group. 802.17 Resilient

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The IEEE 802.15.4 (Low Rate Wireless Personal Area Network) Standard

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  1. The IEEE 802.15.4 (Low Rate Wireless Personal Area Network) Standard Lance Hester Ken Cornett Florida Communication Research Lab Motorola Labs May 20, 2002

  2. IEEE What? IEEE 802 LAN/MAN Standards Committee … … … 802.1 Higher Layer LAN Protocols Working Group 802.17 Resilient Packet Ring Working Group 802.11 Wireless Local Area Network Working Group 802.15 Wireless Personal Area Network Working Group … … … TG4 WPAN Low Rate Task Group TG1 WPAN/Bluetooth Task Group TG2 Coexistence Task Group TG3 WPAN High Rate Task Group Formed in November, 2000

  3. What it is: An WPAN standard optimized for low (0.01-115.2 kb/s) data throughput applications with simple QoS requirements Lower power, lower cost than other WPANs (e.g., Bluetooth) Capable of multiple network types (star, cluster tree, etc.) Using ZigBee Consortium for marketing and compliance (like WECA/Wi-Fi/802.11b) What it is not: A WLAN A Bluetooth™ replacement (e.g., no isochronous voice capability) Optimized for multimedia, TCP/IP, or other high data rate applications A system, network, or application set IEEE 802.15.4--

  4. 802.15.4 Physical Layers • 2.4 GHz: • 250 kb/s raw data rate, 1 Mc/s chip rate • Chips: O-QPSK with half-sine shaping (a.k.a. MSK) • Data: 16-ary orthogonal modulation • 16 channels; 5 MHz channel separation • -85 dBm sensitivity @ 1% PER (20 byte packets) • Variable length payload size dependent upon addressing • 868 (915- U.S.) MHz: • 20 (40) kb/s raw data rate, 300 (600) kc/s chip rate • Chips: BPSK with raised-cosine shaping • Data: differential BPSK • 1 (10) channels; 2 MHz channel separation @ 915 MHz • -92 dBm sensitivity @ 1 % PER (20 byte packets)

  5. 802.15.4 Physical Characteristics • Transmission Range • ~ 10 meters indoors; ~ 30 meters outdoors @ Tx-Power = - 3 dBm (0.5 mW) • Maximum regulated transmit power levels • Power Consumption < 100 A • Expected duty cycle of 1% and low power operation (under 0 dBm [1mW]) • Power Supply • AA battery • Lifetime approx. 1 year

  6. 802.15.4 Physical Characteristics • Bi-directional communication supported • Uni-directional communication not supported • All messages are acknowledged • DSSS modulation mitigates multipath interference • “1000 ns” chip length >> 30 ns propagation delay

  7. Chip Set information • Yes! There is IC development for the 802.15.4

  8. 802.15.4 Medium Access Control (MAC) Features • Extremely flexible support: • Star, cluster tree, other network topologies, with optional network beacon • Application flexibility • Slotted Access CSMA-CA • Superframe period switchable from 15 ms to > 4 minutes • Trade power consumption, message latency, and throughput • Optional guaranteed time slots in superframe • Low-latency applications (e.g., mice, wireless gaming) • Low duty cycle: • Can be < 0.1% • Low power consumption • Good coexistence with other services

  9. 802.15.4 MAC Super Frame Structure Beacon Beacon Contention Free Period Contention Access Period GTS 1 GTS 2 Super Frame Duration Network Beacon Transmitted by nodes. Contains network information, super frame structure, and notification of pending messages Contention Period Access by any node using CSMA-CA Allocated slot Reserved for nodes requiring guaranteed bandwidth

  10. Node Types Supported • Distribution node • Controls the network topology at that node • Master/coordinator or mediation device • Stores routing information • Talks to other distribution and slave nodes • Slave node • Cannot control the network • Very simple implementation • Does not store routing information • Talks only to a distribution node

  11. 100 High 802.11x 802.3 10 802.15.3 802.11a 4G 802.11b Transitions from Wired to Wireless Data Rate (Mbps) Moderate 1 “Bluetooth” 3G 802.15.1 Evolution Path with Sustaining Innovation Variable w/ Duty Cycle 2.5G 0.1 PSTN Low 2G 1G 100 102 104 106 802.15.4 2010 1980 1990 2000 Related technology Network Scalability Low latency intensive Intended for high power apps Fixed 802.3 - ‘Wired Ethernet’ Cost Fixed & Wireless 802.11b - ‘Wi-Fi’ Bluetooth 802.15.4 M2M Area (meters2) To complex for low-rate low-power apps

  12. How Does 802.15.4 Match Up?

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