4 GHz ISM band Table 12.5 Summary of different Bluetooth standard releases Version Data rate (Mbps) interfering pairs in a small area increases, the overall probability of interference also increases, ultimately resulting in unacceptable performance. However, the probability of many devices transmitting at the same time in close proximity (within a room or an office) is not very high. Interference from other equipment is also similarly mitigated by the frequency hopping process. A Bluetooth device's maximum transmission rate is limited by the carrier bandwidth of 1 MHz. Several versions of Bluetooth standard have been released and the transmission rate varies between releases. Bluetooth 1.0 specifies a 1 mega symbol/s transmission rate in combination with frequency shift keying technique to deliver a maximum data rate (including channel coding and other overheads) of 1 Mbps. The actual application level data rate however is in the order of 700 kbps. Bluetooth 2.0 uses enhanced data rates through higher order modulation techniques differential QPSK and differential 8-PSK. The latter increase the transmission rate to 3 Mbps. Again application level data rate is smaller and in the order of 2.1 Mbps. Bluetooth 3.0 uses media access and call set-up technologies of Bluetooth in combination with transmission technologies associated with wireless LAN to increase trans- mission rates to 24 Mbps [10, 11]. Bluetooth 4.0, released in 2010, combines a number of features from previous versions including high speed and low energy protocols. It is mainly intended for long range, low transmis- sion power, low transmission rate applications, such as sensor networking, telemetry and automa- tion. It still maintains a maximum transmission rate of 24 Mbps by incorporating features from Bluetooth 3.0. Transmission rates for different Bluetooth releases are summarised in Table 12.5. Bluetooth Networking Bluetooth devices pair and communicate in an ad-hoc manner. Two peer user devices form what is known as a piconet with one device acti