100 mW, Minimum capability 2.5 mW, or 1 mW, 0.5 mW; maximum These will lend themselves to wide-scale use embedded depending on class as allowed by local in consumer electronics, home and building automation regulations and security systems, industrial controls, PC peripherals, Minimum sensitivity -70 dBm for medical and industrial sensor applications, toys and -85 dBm (2.4GHz) or 0.1% BER -92 dBm (915/868 games and similar applications. It's natural to compare MHz) for packet error Zigbee with the other WPAN standard, Bluetooth, and rate <1% there will be some overlap in implementations. However, the two systems are quite different, as is evident from Network topology Master-Slave Star or Peer-Peer 255 8 active nodes active nodes the comparison in Table 5.2-6. Short-range wireless applications and technologies CHAPTER 5.2 being specified for three unlicensed bands-2.4 GHz, APPLICATION LAYERS 915 MHz and 868 MHz; the latter two being included in the same physical layer. Those two bands are generally mutually exclusive, their use being determined by geo- graphic location and regional regulations. The following LOGICAL LINK CONTROL 27 transmitting channels are defined: DATA LINK LAYER MEDIUM ACCESS CONTROL Channel number Center frequency Channel width range 868.3 MHz 600 kHz PHYSICAL LAYER 1 to 10 906 to 924 MHz 2 MHz 868/915MHZ 2450MHZ 11 to 27 2405 to 2480 5 MHz Data rates and modulation types for each of the bands are shown in Table 5.2-7. TRANSMISSION MEDIUM In both physical layers, the modulation is DSSS (direct sequence spread spectrum). The spreading pa- rameters are defined to meet communication authority Figure 5.2-21 Zigbee architecture. regulations in the various regions as well as desired data rates. For example, the chip rate of 600 kbps on the is applied. Just above the physical layers is the data link 902-928 band allows the transmission to meet the FCC layer, consisting of two sublayers: medium access control, paragraph 15.247 requirement of minimum 500 kHz or MAC, and the logical link control, LLC. 