Scylla: Interleaving Multiple IoT Stacks on a Single Radio Hassan Iqbal LUMS Lahore, Pakistan 16060023@lums.edu.pk Muhammad Hamad Alizai LUMS Lahore, Pakistan hamad.alizai@lums.edu.pk Ihsan Ayyub Qazi LUMS Lahore, Pakistan ihsan.qazi@lums.edu.pk Olaf Landsiedel Kiel University Kiel, Germany ol@informatik.uni-kiel.de Zartash Afzal Uzmi LUMS Lahore, Pakistan zartash@lums.edu.pk ABSTRACT IoT deployments often require communication between devices that employ heterogeneous wireless technologies. Traditionally, expensive gateways are used to relay packets between heteroge- neous nodes. Recent cross-technology communication ofers a low bandwidth alternative, which is only feasible when communica- tion between such nodes is limited to simple binary commands. In contrast, our work capitalizes on the increasing presence of multi-standard radio chips in mainstream IoT devices, to provide a new perspective on how to enable direct communication between heterogeneous nodes. We design ScyllaÐa software control layerÐ that allows multiple wireless stacks to coexist on top of a single radio chip, thereby simultaneously ofering multiple communica- tion interfaces. Uniquely, Scylla achieves near stack-native perfor- mance and requires no changes to the standards. CCS CONCEPTS · Networks → Network design principles; Network protocol design; Network resources allocation; ACM Reference Format: Hassan Iqbal, Muhammad Hamad Alizai, Ihsan Ayyub Qazi, Olaf Landsiedel, and Zartash Afzal Uzmi. 2018. Scylla: Interleaving Multiple IoT Stacks on a Single Radio. In CoNEXT ’18: International Conference on emerging Network- ing EXperiments and Technologies, December 4ś7, 2018, Heraklion, Greece. ACM, New York, NY, USA, 7 pages. https://doi.org/10.1145/3281411.3281412 1 INTRODUCTION Emerging applications in residential, business, automotive, and industrial domains have contributed to an enormous growth of IoT deployments in recent years. These deployments often comprise a wide range of devices, such as sensors, actuators, relays, and compound embedded boards, that communicate based on a variety 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. CoNEXT ’18, December 4ś7, 2018, Heraklion, Greece © 2018 Association for Computing Machinery. ACM ISBN 978-1-4503-6080-7/18/12. . . $15.00 https://doi.org/10.1145/3281411.3281412 GW GW 6 6 6 (a) The gateway ap- proach GW Scylla 6 6 6 (b) Scylla as in- network gateway Scylla 6 6 6 6 6 6 6 (c) Scylla for edge- computing Figure 1: Depicting Scylla Core Function. A traditional gateway approach is shown in (a). A Scylla node in (b,c) provides in-network gateway functionality and facilitates direct communications between heterogeneous devices. of wireless technology standards (or stacks) such as Zigbee, low- power IPv6 (6LoWPAN), Bluetooth low-energy (BLE), LoRaWAN, Z-Wave, WirelessHART, and IEEE 802.11ah, to name a few. Many IoT applications in present-day deployments require com- munication between heterogeneous IoT devices (i.e., those using difering communication stacks) 1 . Unfortunately, this is not readily possible today due to their incompatible communication interfaces. This is despite the fact that bulk of the IoT communication stacks operate in the unlicensed spectrum, often using even the same frequency bands. We present Scylla 2 ,a software control layer that enables commod- ity and inexpensive IoT devices to provide the functionality of a multi-radio gateway. Scylla achieves this by seamlessly interleaving multiple wireless stacks on a single radio. As a result, heterogeneous IoT nodes are able to communicate at stack-native speeds without requiring any changes in the wireless standards as shown in Fig. 1. Scylla’s design is based on two observations: • The increasing use of multi-standard radio chips, which are rapidly penetrating the IoT device market (cf. Table 1). • Radio duty-cycling support in IoT stacks to conserve energy by avoiding idle listening. This leaves time in between the transmis- sions from a single stack, allowing co-located stacks to interleave their transmissions as shown in Fig. 2. 1 A foor supervisor in a manufacturing unit might need to use their smartphone to collect sensor data and exchange control commands with a LoRaWAN-equipped device used for process tracking and control. 2 A multi-headed monster in Greek mythology.