 Bluetooth for example, use the normal 79 channel hopping-sequence based on a simplified representation of which is shown in the master's address and timing. Figure 5.2-21. On the bottom are the physical layers, showing two alternative options for the RF transceiver 5.2.3 Zigbee functions of the specification. Both of these options are never expected to exist in a single device, and indeed their transmission characteristics-frequencies, data Zigbee is the name of a standards-based wireless network rates, modulation system-are quite different. However, technology that addresses remote monitoring and control the embedded firmware and software layers above them applications. Its promotion and development is being will be essentially the same no matter what physical layer handled on two levels. A technical specification for the physical and data link layers, IEEE 802.15.4, was drawn up by a working group of the IEEE as a low data rate Table 5.2-6 Comparison of Zigbee and Bluetooth WPAN (wireless personal area network). An association of committed companies, the Zigbee Alliance, is defining Bluetooth Zigbee the network, security, and application layers above the Transmission FHSS (frequency DSSS (direct 802.15.4 physical and medium access control layers, and scheme hopping spread sequence spread will deal with interoperability certification and testing. spectrum) spectrum) The distinguishing features of Zigbee to which the Modulation GFSK (gaussian IEEE standard addresses itself are QPSK (quadrature frequency shift phase shift keying) or Low data rates-throughput between 10 and keying) BPSK (binary phase shift keying) 115.2 kbps Low power consumption-several months up to two Frequency band 2.4 GHz 2.4 GHz, 915 MHz, years on standard primary batteries 868 MHz Network topology appropriate for multisensor Raw data bit rate 1 Mbps 250 kbps, 40 kbps or monitoring and control applications 20 kbps (depends on Low complexity for low cost and lease of use frequency band) Very high reliability and security Power output Maximum 