Associate Professor Qi Zhang (right) and PhD student Mohammad Sadegh Mohammadi are working on new solutions to improve Body Area Network Technology. They want to make it more reliable, secure, lightweight and energy efficient.
Researchers at Aarhus University are working on new solutions for Wireless Body Area Networks, making them reliable, secure, lightweight and energy efficient so it will not be necessary to change the batteries so often.
The idea of Wireless Body Area Networks (WBAN) is close to becoming reality. Before long it will be possible to wear electronic devices with multiple sensors, computing capability and radio transmitters.
This can be used to record and report details of your movements, your health or your surroundings in a wireless network carried on your body – or even implanted into your body, for that matter.
The technology is predicted to play an important role in the health services of the future, as well as elderly care, the entertainment industry, sport and a wide range of professions.
Using WBAN, doctors can keep an eye on a heart patient’s vital signs even while the patient is at home, a diabetic can be notified immediately if blood sugar levels are too low or too high, athletes can optimise their training, and a fireman’s uniform can send an alarm to both the firefighter and the commander about high temperatures and hazardous gases.
WBAN also provides numerous options for interaction with machines. Computer games, robots and drones can be controlled by body movements and provide feedback that can be felt by the operator or player on their bodies.
A hot topic
It is only close to becoming a reality, however. Using current technology, it is certainly possible to build WBANs, but they still demand so much energy that they are not particularly practicable. They either require large batteries or they have to be recharged too often. In addition, when electronic components use a lot of power, they get hot so called tissue heating problem– so no one wants to have them close to or inside their bodies.
In order to develop truly applicable WBANs, the researchers must meet the crucial requirements of optimal energy efficiency and low complexity – and at the same time overcome the challenges of a highly dynamic channel with inconsistent propagation characteristics due to body tissue, mobility and randomness.
Those are the problems that the researchers at Aarhus University are trying to solve. Their tools are primarily mathematical equations, formulae and algorithms.
“We address the algorithmic and theoretical part of the problem while we are concerned about the practical and technological constraints. We try to make everything as efficient, agile and simple as possible without compromising the system’s fidelity or consuming extra resources such as spectrum, energy and computational power at the sensor nodes,” says Associate Professor Qi Zhang.
The researcher’s solutions span in both physical and medium access control layers in the network protocol stack, as well as the sensor’s hardware such as analogue to digital converters.
Fewer errors mean less power
The project is focused on subjects from coding theory, signal processing and wireless communications.
“The conventional methods in designing wireless systems are based on assumptions that do not fit well to WBANs. They are usually not designed for optimal energy efficiency and minimum complexity and do not take into account channel issues imposed by near-body operation,” says Associate Professor Zhang.
Together with her research group she is trying to develop advanced coding techniques to boost the system’s performance, combined with the latest techniques in signal processing such as Compressive Sensing. Basically, the aim is to send data packets through the network as efficiently as possible.
“We propose a system that reconstructs an accurate picture of the sent information, although some of the received packets are damaged or missing bits due to for example noise and interference. A conventional system discards such packets and asks for re-transmission, which reduces the speed and costs energy. Our system, on the other hand, only needs to receive enough coded packets to fix the damaged parts and recover the whole “picture”. The recovery procedure is the main challenge,” explains Zhang.
The right transmitter
The researchers' work is not completely limited to the theoretical work. The new protocols and ideas are of course tested in models and computer simulations or implemented using the available software defined radio platforms.
“We are looking at all the ways we can optimise WBANs. We have, for example, developed techniques to improve Ultra Wideband systems (UWB). This is interesting because the UWB transmitter is very simple, its signal is low energy, almost immune to fading, and provides excellent ranging capabilities,” says PhD student Mohammad Sadegh Mohammadi.
It is still too early to say when the technology will become a reality.
“This is an emerging field of research. We’re discovering new challenges all the time,” he says.