Ultra-wideband (UWB) wireless has been around for many years in multiple forms. Though it’s found numerous niches, UWB has never caught on like Bluetooth, Wi-Fi, and others. It seems to come and go as the technology develops and new applications are found.
Well, here it comes again. Semiconductor company Decawave recently introduced a UWB product to address a new IEEE wireless standard.
According to the FCC, a wireless signal is said to be UWB if it occupies a minimum of 500 MHz of spectrum or a bandwidth of at least 20% of its center operating frequency. The allocated spectrum is for unlicensed applications in the 3.1- to 10.6-GHz range. The power level is restricted to −41.3 dBm/MHz or 75 nW. Many other wireless services exist in that spectrum, but because of the very low operating power and the extremely wide bandwidth, the UWB signal looks more like noise than an interfering signal.
That broad definition has resulted in several forms of UWB. The original form is an impulse scheme where the serial data to be transmitted is converted into short pulses that are modulated by pulse-position modulation or binary phase-shift keying. Direct sequence spread spectrum (DSSS) is also used. The pulse width determines the center frequency and is approximately equal to the reciprocal. A pulse width of 150 ps gives an approximate center frequency of 6.67 GHz.
Another form of UWB developed by the WiMedia Alliance leverages orthogonal frequency-division multiplexing (OFDM). The UWB spectrum is divided into bands or channels that are 528 MHz wide; the format was able to achieve a data rate of 480 Mb/s. Several companies developed chips for this version of UWB. The maximum range of this or any other method of UWB is about 10 meters because of the very low power.
Other UWB variations have also been developed over the years. No killer app ever seemed to emerge, though. UWB has been used for radar, wireless USB, video transmission, digital cameras, and some military uses. It has been a solution looking for a problem. Now that may finally be changing.
A New IEEE Standard
One of the many objectives of the Institute of Electrical and Electronic Engineers is to develop standards for a wide range of components and systems. It has established a variety of wireless standards, the most well-known, of course, being Wi-Fi designated IEEE 802.11. It exists in many variations. The newest Wi-Fi versions are 802.11ac and 802.11ax, both featuring data rates well above 1 GHz. Its main application is wireless local-area networks for internet access. The IEEE also established a UWB standard called 802.15.4a.
A new UWB standard under development is 802.15.4z. It expands and improves upon the 802.15.4a version. Final ratification of the standard is expected sometime during 2019.
The emerging application for this UWB version is real-time location services (RTLS). This is a technology that’s used to locate and track assets. It uses impulse UWB to locate a mobile node with respect to an application point. Each has the appropriate UWB transceiver that uses the time-of-flight (TOF) or time-of-arrival (TOA) algorithm called trilateration. It determines the distance between the two devices by measuring the time of signal transmission to locate the intersection of three circles. Its accuracy is in the 2- to 10-cm range.
RTLS ability makes possible a new UWB application: wireless payment. It would compete with NFC for smartphone space, but offers the benefit of highly increased mobile transaction security. The standard creates a “digital twin” and the user’s location is utilized for authentication.
Decawave recently announced plans to develop 802.15.4z products. The company’s current UWB product is the DW1000 transceiver, which is 802.15.4a-compliant. The new standard 4z isn’t backward-compatible with 4a. But future Decawave chips will support both 4a and 4z, making them backward-compatible with current existing chips.
The new 4z chips are expected by the end of the year. Check the Decawave website for details.
Maybe this new security application will finally establish UWB as a “must-have” technology. The UWB Alliance works to support and promote UWB worldwide. Take a look at their efforts and plans when you get the chance.