Dataset: Enabling Ofline Tuning of Fat Channel Communication Konrad-Felix Krentz, Madhushanka Padmal, Bappaditya Mandal, Robin Augustine, and Thiemo Voigt Uppsala universitet {konrad.krentz,madhushanka.padmal,thiemo.voigt}@it.uu.se {bappaditya.mandal,robin.augustine}@angstrom.uu.se ABSTRACT Though fat channel communication has advantages over earlier intra-body communication (IBC) technologies based on galvanic or capacitive coupling, the development of a protocol stack on top of fat channel communication is still at its infancy. In this paper, we consider Krentz’s denial-of-sleep-resilient multi-channel medium access control (MAC) layer for IEEE 802.15.4 networks as a starting point for such a protocol stack. In brief, we conducted the follow- ing experiment with a phantom that mimics human tissues. Two devices exchanged IEEE 802.15.4 radio frames in a ping-pong man- ner on the phantom’s fat tissue using Krentz’s MAC layer. The data collected from this experiment lends itself to two purposes. First, it can serve to benchmark and tune algorithms for select- ing radio channels. Second, it can also serve to benchmark and tune schemes for deriving cryptographic keys from received signal strength indicator (RSSI) readings. We made the data available at https://uppsala.box.com/s/z2a6jpigswpoifd5l73yophokcfwd88b. CCS CONCEPTS · Networks → Network experimentation;· Applied comput- ing → Health informatics;· Security and privacy → Embed- ded systems security. KEYWORDS intra-body communication, channel hopping, PHY key generation ACM Reference Format: Konrad-Felix Krentz, Madhushanka Padmal, Bappaditya Mandal, Robin Au- gustine, and Thiemo Voigt. 2021. Dataset: Enabling Ofine Tuning of Fat Channel Communication. In The 19th ACM Conference on Embedded Net- worked Sensor Systems (SenSys’21), November 15–17, 2021, Coimbra, Portugal. ACM, New York, NY, USA, 2 pages. https://doi.org/10.1145/3485730.3494112 1 INTRODUCTION The development of intra-body communication (IBC) technologies is driven by innovative medical applications, such as automatic in- sulin delivery, electroceuticals, neuroprosthetics, remote treatment, or remote health monitoring. Fat channel communication is a very recent IBC technology, which has the main advantage of achieving higher data rates than earlier IBC technologies based on galvanic or capacitive coupling [1]. Its approach is to transmit radio waves Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for proft or commercial advantage and that copies bear this notice and the full citation on the frst page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specifc permission and/or a fee. Request permissions from permissions@acm.org. SenSys’21, November 15–17, 2021, Coimbra, Portugal © 2021 Association for Computing Machinery. ACM ISBN 978-1-4503-9097-2/21/11. . . $15.00 https://doi.org/10.1145/3485730.3494112 into the fat tissue of the human body. Since the fat tissue has a low dielectric coefcient and is surrounded by radio wave guiding muscles and skin tissues, fat channel communication requires only low transmission power. That said, the development of a protocol stack on top of fat channel communication is still at an early stage. Previous results do suggest that the 2.4 GHz ofset quadrature phase-shift keying (O-QPSK) physical layer (PHY) of IEEE 802.15.4 is suitable [1], but upper layers remained unexplored. Among the medium access control (MAC) layers available for IEEE 802.15.4 networks, the one developed by Krentz has the unique feature of comprehensive resilience against denial-of-sleep attacks [5]. Such attacks deprive battery-powered devices of entering energy-saving sleep modes temporarily or permanently. Since denial-of-sleep vulnerabilities would threaten the health of a patient, we investigate Krentz’s MAC layer for use with fat channel communication. Our main contribution is an open-access dataset of our results of applying Krentz’s MAC layer to fat channel communication inside a phantom. The dataset is geared towards two purposes. On the one hand, it enables ofine comparisons and tuning of algorithms for selecting radio channels. Presently Krentz’s MAC layer uses blind channel hopping. However, simulations have shown that delivery ratios improve when employing a multi-armed bandit (MAB) algorithm for channel selection [3]. On the other hand, our dataset enables ofine comparisons and tuning of schemes for deriving shared keys from received signal strength indicator (RSSI) readings. Such schemes are useful for key refreshment [7], key provisioning [6], and key establishment [4]. 2 METHODOLOGY On the hardware side, our experimental setup is similar to that of Bappaditya et al. [2]. An 18cm long phantom with four layers rep- resenting bone, muscle, fat, and skin was laid on a fat surface. Two special antennas, whose design is detailed in [2], were implanted into the fat layer through the topmost 2mm thick skin layer, as shown in Figure 1. The two antennas were then connected to two OpenMote-B sensors labeled Alice and Bob. On the software side, Alice and Bob ran Contiki-NG with Krentz’s MAC layer on top of the 2.4 GHz O-QPSK PHY layer of IEEE 802.15.4. Figure 1: Phantom with two implanted antennas 524