Most of us don’t think about the intricate network of wireless systems that influence our world unless and until our cell phones leave service range. But at the Drexel Wireless Systems Lab (DWSL), a combination of interdisciplinary research and hardware prototyping is finding new ways that wireless can be used in a number of applications. Kapil R. Dandekar, PhD, E. Warren Colehower Chair Professor in Electrical and Computer Engineering and Director of DWSL, shared some updates on what the lab has been up to lately.
Medical Internet of Things
Together with collaborators in the Drexel Center for Functional Fabrics, Ursinus College, and the Children’s Regional Hospital at Cooper, the DWSL is working to develop new wearables for biomedical applications. The primary device being tested is a wearable sensor that can monitor a baby’s respiration and control an external ventilator to assist with their breathing. The same technology is also being applied to make wearables with other types of sensors that can be used for diverse applications including COVID-19 patient monitoring and contact tracing.
“When these wearable monitors are successful, they will enable patients to move about their homes or medical facilities instead of being confined to beds,” Dandekar explains. “To be sure that we can continue to read the output of the monitors as patients move about, we are also developing a smart reconfigurable radio frequency identification (RFID) reader that would be capable of dynamically changing its coverage area based on the location of the user. This research is currently supported by the National Institutes of Health and the National Science Foundation.”
Large Scale Wireless Emulation through Drexel Grid SDR Testbed
Working with Prof. Geoffrey Mainland in the College of Computing and Informatics and supported by the National Science Foundation, DWSL is developing the Grid Software Defined Radio (SDR) testbed for use in research and education.
“Unlike conventional cell phones, local area networking, and sensor devices whose functionality is fixed in hardware, a SDR makes use of general-purpose hardware that can be re-programmed to act like different devices through software,” Dandekar says. “The Grid testbed is made up of a large network of SDRs on both a ceiling-based scaffolding network as well as in server racks in the DWSL. Some of these radios are equipped with new reconfigurable antenna technologies being developed in the lab. The Grid is integrated with a large-scale wireless channel emulation system that provides a way to create realistic, reproducible, and software-definable propagation channels between the radios - in essence making it appear to the radios that they aren’t inside a lab, but out in the field in different applications.”
The testbed has been used for research in diverse areas including deep reinforcement learning for cognitive radio, a concept that programs radios to find the best signal in the area to avoid interference. The Grid has also been used to create digital twins for evaluating medical Internet of Things (IoT) systems, multi-target tracking radar, unmanned aerial vehicle (UAV) communication networks, more. It is also a hub for undergraduate and graduate coursework in communications and networking to students both in the College of Engineering and the College of Computing and Informatics. The testbed is now available publicly for users off campus at dwslgrid.ece.drexel.edu.
Reconfigurable Antennas for 5G / mmWave applications
Electrically reconfigurable antennas are capable of changing their radiation characteristics in response to the needs of the overlying communication system and network, allowing for beams to be dynamically steered towards or away from certain locations. Many people have encountered situations where it appears like their WiFi or cell phones don’t work in a specific location. Reconfigurable antennas, coupled with machine-learning based control algorithms, allow the cellular base station or local area networking access point to “learn” how to communicate with users more effectively. This technology has been developed for local area networking applications in the past and is now being developed for 5G and beyond cellular communication systems. DWSL is developing new reconfigurable antenna technologies in fabric, and for conformal integration with different devices, for future cellular communications operating at millimeter wave frequencies. A recent new reconfigurable conformal antenna was developed by a senior design team, and the resulting paper just appeared in an IEEE conference.
Campus-Scale Internet of Things Testbed
Through a Drexel Areas of Research Excellence (DARE) project, DWSL is leading the development of a campus-wide solution for the Internet of Things, enabling new applications in biomedical monitoring, smart buildings, public safety, industrial monitoring and environmental sensing for a future smart campus and city. The system being developed is called VarIoT, and it is built on an open source IoT platform called ThingsBoard. The system will support a wide variety of long range and short range wireless IoT protocols that include WiFi, Zigbee, LoRa, Bluetooth low energy, NB-IoT, Sigfox, and RFID.
“We envision deploying this system around campus similarly to what is currently done with campus WiFi, with a modular hardware and software interface that will enable a diverse set of applications and using our campus and city as a living laboratory for future technologies,” Dandekar says. “DWSL is currently seeking Drexel stakeholders who would be interested in using these capabilities for research or educational purposes.”
In a related effort, Dandekar also sits on the SmartCityPHL advisory board of the City of Philadelphia looking at how the city can effectively and equitably deploy future smart city technologies.
MXene Antennas and Radio Frequency Devices
Working with researchers in Materials Science and Engineering and supported by the National Science Foundation, DWSL is developing new MXene antennas that are flexible, conformal, and ultra-thin for potential new applications in various flexible electronic devices.
“We have demonstrated how thin MXene radio frequency devices can perform comparably to thicker antennas made from conventional materials providing the potential for greater flexibility and lower weight devices,” Dandekar says. “These antennas have been demonstrated to work at frequencies appropriate for commercial local area networking, RFID, and for 5G cellular communication systems.”
“The Wireless Systems Lab is fortunate to have a group of talented, dedicated engineers and scientists within its own walls, but also to find strategic partnerships at Drexel and beyond to further our research,” Dandekar shares. “Interdisciplinary cooperation leads to the kind of broad thinking needed to solve complex problems, and the DWSL is committed to exactly that.”