UWB Tutorial: Basics, Working, and Applications

This Ultra Wideband (UWB) tutorial covers UWB basics including UWB working, benefits, modulation schemes, specifications, and UWB applications. UWB (Ultra Wideband) is a high-speed short-range wireless technology. It was initially introduced in the IEEE 802.15.3a standard.

The latest release defining specifications of UWB is specified in IEEE 802.15.4a. This standard mentions three frequency bands: below 1GHz, 3 - 5GHz, and 6-10GHz.

How it works?

UWB uses a time-shifting mechanism to transmit binary data at millions of pulses per second. Here, zero is transmitted at short time intervals, and one is transmitted at long time intervals.

The UWB waveform is shown in the figure above. At the receiver, the time interval between pulses defines whether one or zero has been received. The figure below depicts a UWB transmitter, which consists of a binary data source, conversion of bits to symbols, symbols to pulses using a pulse generator, and an RF part.

The figure above depicts a UWB receiver consisting of a front-end part and symbols-to-bits conversion. The front-end part does acquisition, tracking, and conversion of pulses to symbols. After bits conversion, data conversion takes place based on the application’s needs.

Modulation Schemes

UWB uses various modulation schemes based on application needs. There are time-based techniques and shape-based techniques.

Pulse position modulation (PPM) is used as time-based modulation. PPM is a simple technique but needs fine time resolution in the receiver. BPM (Bi-phase modulation), OOK (On-Off Keying), PAM (Pulse Amplitude modulation), OPM (Orthogonal Pulse Modulation), etc., are used as shaped-based modulation techniques.

PAM and OOK are also simple binary-only techniques, but they have poor noise immunity. OPM is complex but carries the advantage of being orthogonal.

Benefits of UWB system

• As the UWB operates at a low noise level, conventional receivers will not be able to decode the signal, and hence it is one of the major technologies used for military communication.
• Being a very low-power signal, it will not interfere with other wireless systems in the same frequency band.
• They can easily penetrate into walls.
• The battery of UWB devices can last for a longer duration due to its low-power operation.

Typical specifications

• Frequency spectrum: 3.1 - 5.15 and 5.825 to 10.6 GHz (DS-UWB), 4 bands (MB-OFDM)
• Bandwidth: 1.368 GHz and 2.736GHz (for DS-UWB) and 528 MHz for MB-OFDM
• Range: 10-30 meters
• Physical layers: MB-OFDM or Direct Sequence UWB (DS-UWB)
• Data rate: 1Gbps
• No. of simultaneous piconets: 8 (DS-UWB), 4 (MB-OFDM)

Applications

• Consumer electronics for home entertainment networks and home networking
• Asset tracking in hospitals such as wheelchairs and beds
• Health care
• Military
• Medicine

UWB in Medicine

UWB is widely used in medicine for various applications. These include cardiology, respiratory medicine, obstetrics and Gynecology, in the emergency room and for acute care, assistance for disabled people, throat and vocal cord monitoring, etc.