Version 2.x Bluetooth
Added two modulations:
Pi/4~DQPSK (2 Mbps) and 8-DPSK (3 Mbps)
8-DPSK at 3 Mbps can only be used in ideal conditions
Version 3.0 Bluetooth
Added low power modes
3.0+HS added an alternate MAC/PHY (AMP)
AMP uses separate radio module for 802.11-like transmissions for high speed transmission
Version 4.0 introduced Bluetooth low energy (BLE)