 options are unavailable or undesired. A Tazzle device sets up the peer-to-peer networking con- nection using Bluetooth technology, and A single click sends the video transfers files using the Wi-Fi air inter- to the PC and auto-plays face. Applications range from printing to sharing files, pictures and videos from a smart phone with a laptop device. Tazzle claims one-click file transfer as its soft- ware is programmed to work with the Bluetooth interface. ZigBee The ZigBee system is a competitor technology to Content and services layer Bluetooth for short range communications and is simi- larly specified under the IEEE 802.15 family of stan- dards [12]. It is managed through ZigBee Alliance, a Connectivity retail layer consortium established in 2002 and consisting of more than 400 companies, including major global telecom- munications and control companies. ZigBee applica- Infrastructure layer tions focus on short to long range machine-to-machine (M2M) sensor networking, using the 900 MHz and 2.4 GHz ISM bands. In Europe ZigBee may operate in the Subscriber/end-user 860 MHz band, which is set aside for unlicensed sen- sor networking applications. The market for ZigBee devices has been growing at a very fast rate and it is expected that by 2019 there will be more than 220 million devices shipped worldwide [13] (Figure 12.11). Initial applications have been in the utility sector, with sensors used for telemetry, automated and connected home and energy management. The total market size is expected to be $4.3 billion according to the ZigBee Alliance. The ZigBee physical layer uses the same DSSS technology used in the 802.11b and Wideband CDMA (W-CDMA) systems. Frequency channel bandwidth is 5 MHz, and 16 channels may be used in the 2.4 GHz ISM band. BPSK modulation is used in the 868 and 915 MHz bands, and a form of QPSK in the 2.4 GHz band. Transmission rates are deliberately kept low as sensor networking and automation applications need longer battery life. 3 Photograph and illustration reproduced by permission of