The IEEE 802.15 group was set up in March 1999 to reflect on wireless networks with a range of ten meters, or WPAN (Wireless Personal Area Network), with the aim of making connections between different portable one user or multiple users. This type of network can connect a laptop, cell phone, PDA or any other device of this type. Three service groups were defined, A, B and C.
Group A uses the band of unlicensed spectrum use (2.4GHz) targeting a low cost of implementation and use. The size of the cell around the point of emission is of the order of one meter. Power consumption should be particularly low for the terminal to keep several months without electric charging. The selected transmission mode is connectionless. The network must be able to work in parallel with an IEEE 802.11 network. On a single physical location, it may therefore be simultaneously a network of each type, both of which can possibly function degraded way.
Group B shows performance increase, with a MAC level up to a rate of at least 100 Mbit / s. The core network must be able to interconnect at least six machines and offer a QoS algorithm, or quality of service, to authorize the operation of some applications, such as telephone speech, which requires a fairly strict QoS. The range between the transmitter and receiver reaches ten meters, and the maximum time to connect to the network must not exceed the second. Finally, this network class must have bridges with other categories of 802.15 networks.
Group C introduces important new features for individuals or businesses, such as communication security, video transmission and the possibility of roaming or roaming between wireless networks.
To meet these objectives, industrial groups have set up, such as Bluetooth or WiMedia Alliance. Bluetooth brings together more than 800 companies that have made an open specification for wireless connection between personal devices. Bluetooth is based on a radio link between two devices, while the WiMedia Alliance is interested in very high speed connections over a short range.
The IEEE 802.15 working group was divided into four subgroups:
• IEEE 802.15.1, for Class C networks;
• IEEE 802.15.3 for Class B networks;
• IEEE 802.15.4 for Class A networks;
• IEEE 802.15.2 for dealing with interference problems with other networks using the 2.4 GHz band.
The IEEE 802.15 group created new groups, including TG3c (Task Group 3c), to explore possibilities of a personal network in the ranges 57-64 GHz unused, which would rise to several transmission speeds gigabits per second, and the TC5, which aims mesh networks, which can cover a much larger geographic area than a personal network.
The choice of the first group turned to Bluetooth, presented in detail in the next section. The second group is facing broadband and UWB (Ultra Wide Band). This radio interface has been recovered by the WiMedia Alliance and the SIG (Bluetooth Special Interest Group). The group 802.15.4 defines a short-range network of a few meters, to interconnect all sensors and actuators that can be found everywhere, eg in toys.