[3] IEEE 802.15.4a specifies two additional PHYs using ultra-wideband (UWB) and chirp spread spectrum (CSS).
[4] The IEEE 802.15 Low Rate Alternative PHY Task Group (TG4a) for wireless personal area networks (WPANs), as its name implies, was tasked with amending the 802.15 standard to provide alternate PHY standards that would allow for high aggregate throughput (much throughput over time) communications with a precision ranging capability (within 1 meter accuracy) and low power usage within the scope of the WPAN.
Direct Sequence UWB is spectrally efficient, can support precision ranging, and is very robust even at low transmit powers.
The standard has been consolidated into and superseded by IEEE Standard 802.15.4-2011. nanotron Technologies developed their first Chirp Spread Spectrum (CSS) smart RF module Smart nanoLOC RF with ranging capabilities certified in Europe and Japan in February 2008.
[6] IMEC made the first UWB transmitter that is compliant to the new standard[7] which they plan to use in wireless autonomous transducer systems used in healthcare, lifestyle and process automation applications.