In Europe there are a number of license-free bands that can be used by anyone. However, there are restrictions on the use of these bands, both in terms of the application and the transmitted power. In particular, the manufacturer of transmitters operating in these bands must certify the equipment as meeting the required emission limits.
49.82 to 49.98 MHz – general purpose
173.2 to 173.35 MHz – telemetry. Note: 173.225 MHz is for short range alarms only
433.05 to 434.79 MHz – telemetry and vehicle security
458.5 to 458.95 MHz – industrial or commercial telemetry
868 to 870 MHz – general purpose.
Worldwide agreement has resulted in two bands, at 2.4 GHz and 5 GHz, being allocated to wireless LANs. Both of these bands are for industrial, scientific and medical (ISM) use.
The 2.4 GHz allocation covers 2.4 to 2.4835 GHz. Restrictions on the use of this ISM band include the use of carrier frequency hopping in step multiples of 1 MHz. This band is used by wireless LANs operating under IEEE802.11B and Bluetooth.
The IEEE802.11B standard uses 5 MHz carrier frequency steps, with some international variations. Europe allows the use of 13 channels (channel 1 to 13, with centre frequencies 2412 MHz to 2472 MHz), but the USA only allows the use of 11 channels (channel 1 to 11, with centre frequencies 2412 MHz to 2462 MHz). In Japan only channel 14 is allowed (no hopping), using a carrier centre frequency of 2477 MHz.
Bluetooth uses 79 hop frequencies, with multiples of a 1 MHz step size. The lowest carrier frequency is at 2402 MHz (channel 0) and the highest is 2480 MHz (channel 78). The frequency hopping pattern is psuedo-random, with 1600 hops per second.
The 5 GHz allocation is actually two sub-bands, one covering 5.15 to 5.35 GHz and the other covering 5.47 GHz to 5.725 GHz. The higher frequency ISM band allows 1 watt radiated power, rather than the 200 mW limit of the lower frequency band. As with the 2.4 GHz ISM band, sources in the 5 GHz band must use carrier frequency hopping with 5 MHz steps.