UWB is the acronym for Ultra-Wideband, a 132-year-old communications technology. Engineers are revitalizing this old technology for connecting wireless devices over short distances. Although more modern technologies like Bluetooth are available for the purpose, industry observers are of the opinion that UWB can prove to be more versatile and successful than Bluetooth is. According to them, UWB has superior speed, uses less power, is more secure, provides superior device ranging and location discovery, and is cheaper than Bluetooth is.
Therefore, companies are researching and investing in UWB technology. This includes names like Xtreme Spectrum, Bosch, Sony, NXP, Xiaomi, Samsung, Huawei, Apple, Time Domain, and Intel. As such, Apple is already using UWB chips in their iPhone 11. This is allowing Apple obtain superior positioning accuracy and ranging, as it uses time of flight measurements.
Marconi’s first man-made radio using spark-gap transmitters used UWB for wireless communication. The government banned UWB signals for commercial use in 1920. However, since 1992, the scientific community started paying greater attention to the UWB technology.
UWB or Ultra-Wideband technology offers a protocol for short-range wireless communications, similar to what Wi-Fi or Bluetooth offer. It uses short pulse radio waves over a spectrum of frequencies that range from 3.1 to 10.5 GHz and does not require licensing for its applications.
In UWB, the bandwidth of the signal is equal to or larger than 500 MHz or is fractionally greater than 20% of the fractional bandwidth around the center frequency. Compared to conventional narrowband systems, the very wide bandwidth of UWB signals leads to superior performance indoors. This is because the wide bandwidth offers significantly greater immunity from channel effects when used in dense environments. It also allows very fine time-space resolutions resulting in highly accurate indoor positioning of the UWB devices.
As its spectral density is low, often below environmental noise, UWB ensures the security of communications with a low probability of signal detection. UWB allows transmission at high data rates over short distances. Moreover, UWB systems can comfortably co-exist with other narrowband systems already under deployment. UWB systems allow two different approaches for data transmission.
The first approach uses ultra-short pulses—often called Impulse radio transmission—in the picosecond range, covering all frequencies simultaneously. The second approach uses the OFDM or orthogonal frequency division multiplexing for subdividing the entire UWB bandwidth to a set of broadband channels.
While the first approach is cost-effective, there is a degradation of the signal-to-noise ratio. Impulse radio transmission does not involve a carrier; therefore, it uses a simpler transceiver architecture as compared to traditional narrowband transceivers. For instance, the UWB antenna radiates the signal directly. An example of an easy to generate UWB pulse is using a Gaussian monocycle or one of its derivatives.
The second approach offers better performance as it significantly uses the spectrum more effectively. Although the complexity is higher as the system requires more signal processing, it substantially improves the data throughput. However, the higher performance comes at the expense of higher power consumption. The application defines the choice between the two approaches.
