Page 110 - ITU Journal, Future and evolving technologies - Volume 1 (2020), Issue 1, Inaugural issue
P. 110

ITU Journal on Future and Evolving Technologies, Volume 1 (2020), Issue 1




          shows that most Bluetooth-based contact tracing apps
          use just the received signal strength indicator (RSSI)
          of the Bluetooth for distance measurements.  Unfor-
          tunately, in practice, numerous factors can affect the
          RSSI that can make the distance measurement inaccu-
          rate, such as the power of the antenna used for broad-          Advertising
          casting (i.e., the TxPower) and the obstacles blocking         1
          transmission paths. Moreover, Bluetooth-based proxim-                   2  Connection
          ity tracing can also raise false positives because of the
          potential misinterpretation of various scenarios. For ex-
          ample, a proximity tracing system may interpret two            3  Ultrasound Signal
          users have contact even if they are separated by a solid
          wall, where the risk of infection is much lower than the                       4  Ultrasound Signal
          risk indicated by the measured distance.
                                                                                 5  Ultrasound Data
          Therefore, we would like to propose an improved ap-                       Exchange
          proach by combining as many data sources as possible
          in an integrated way, with the key objective of mini-                  6  Disconnection
          mizing false positives and false negatives in the contact
          tracing and meanwhile protecting user’s privacy. The
          contact tracing data we can collect includes (1) multi-  Fig. 1 – A Simplified Protocol for Improved Data Exchange.
          ple channels including both Bluetooth and ultrasound  2.  IMPROVED DATA COLLECTION
          (using both microphones and speakers available in the
          smartphone), and multiple sources including (2) WiFi  There are two fundamental objectives that a good digital
          and (3) cellular networks if they are available. We show  contact tracing system must satisfy: (1) it should be ef-
          how we can use improved methodology to collect data  fective in tracking an individual (e.g., few false positives
          that is privacy aware, transparent, and integrated in  and missed detections), and (2) it should protect the pri-
          Section 2.                                           vacy of users. For example, a CCTV footage would be
                                                               highly effective if (1) were the sole objective, however it
          Similarly, while testing followed by quarantining/iso-  does not meet (2) since it is too much privacy-invasive.
          lation is a powerful tool against a pandemic such as  Therefore, we must look for effective and privacy-aware
          COVID-19, testing capacity remains an issue, especially  digital contact tracing techniques.
          in hard hit areas where testing results could take multi-
          ple days, even up to a week, to arrive. While traditional  Since the outbreak of Covid-19, numerous techniques
          approaches have focused on testing individuals who ex-  based on Bluetooth, WiFi, and cellular networks have
          hibit symptoms or have come in contact with other in-  been developed for contact tracing. Each technique has
          fected individuals, these approaches miss out many po-  its own pros and cons. For instance, Bluetooth based
          tential areas of outbreak where asymptomatic or pre-  solutions can achieve reliable communication and a low
          symptomatic super-spreaders seed the virus, which gets  energy operation, but these suffer from a high rate of
          detected only after it has already spread significantly.  false positives due to a long communication range. WiFi
          Thus, testing capacity needs to be used judiciously to  based solutions do not require installation of apps on
          prevent widespread outbreaks. In Section 4, we argue  mobile phones, and they rely heavily on access point
          that the current myopic approach to testing focuses on  (AP) deployment, and its coverage. Therefore, in this
          identifying individuals with the highest probability of  paper, we aim to present an integrated approach that
          being infected, which does not help minimize the over-  improves the accuracy of a Bluetooth-based approach
          all number of infected individuals.                  with additional channels, and combines WiFi and cel-

          Organization. The rest of this paper is organized as  lular information if they are available. Furthermore by
                                                               utilizing clever algorithms that are provably optimal, it
          follows: In Section 2, we describe an improved and inte-  aims to increase the efficiency with which infected indi-
          grated methodology to collect contact tracing data. In  viduals are contained early without infecting too many
          Section 3, we describe techniques that enable us to effi-  of their “neighbors”.
          ciently integrate the data collected from various streams.
          This allows us to reduce the “error probabilities” asso-  Improving  Bluetooth-based  Contact  Tracing
          ciated with false alarms or missed detection of diseases,  with Ultrasound Signals. Since Bluetooth-signals
          and generate a dynamic susceptibility graph. In Sec-  can penetrate obstacles such as solid walls, and also
          tion 4, we address the practical problem of testing un-  have a long transmission range, we would like to leverage
          der constraints on resources. We perform simulations to  other sensors in a smartphone to improve its proximity
          show necessities of contact tracing and building a con-  accuracy. In particular, we can use the inaudible ultra-
          tact graph in Section 5, and conclude in Section 6.  sound generated from the speaker and recorded by the





          90                                 © International Telecommunication Union, 2020
   105   106   107   108   109   110   111   112   113   114   115