Server-Driven Scheduling for Scalable and Collision-Free LoRaWAN Networks
Authors
Juhl, Simon Kaalund ; Ejsing, Christoffer
Term
4. semester
Education
Publication year
2025
Submitted on
2025-06-04
Pages
42
Abstract
I mange IoT-udrulninger, som LoRaWAN, sender batteridrevne enheder små målinger med faste mellemrum. Hvis to enheder sender samtidig med samme radioparametre, kolliderer signalerne, beskeder går tabt, og sendetid spildes. Denne afhandling undersøger en serverstyret, tidsbaseret planlægning, hvor en central server tildeler hver enhed sit eget tidsvindue (tidslot) til at sende i, så der opstår en kollisionfri tidsplan. Der præsenteres tre planlægningsprotokoller, som hver har deres egen måde at tildele tidsvinduer og omlægge dem på, når enheder kommer til, forsvinder eller glider ud af plads. En specialbygget simulator bruges til at afprøve protokollerne ved forskellige netværksstørrelser og rapporteringsintervaller. Resultaterne viser, at ved periodisk trafik på én kanal og med én spredningsfaktor kan alle tre protokoller holde de tilgængelige tidsvinduer næsten fuldt udnyttet, forudsat at klokkedrift korrigeres, og omlægning håndteres omhyggeligt. Selvom evalueringen sker i en enkel LoRaWAN-opsætning, er planlægningsstrukturen tænkt til at kunne udvides til flere kanaler og blandede spredningsfaktorer. Arbejdet fremhæver, at tydelig slotstruktur, robust omlægning og aktiv håndtering af klokkedrift er afgørende for pålidelig drift i stor skala i LoRaWAN.
In many Internet of Things deployments, such as LoRaWAN, battery-powered devices send small measurements at regular intervals. If two devices transmit at the same time with the same radio settings, their signals collide, messages are lost, and airtime is wasted. This thesis studies a server-driven, time-based scheduling approach in which a central server gives each device its own time slot for transmission, creating a collision-free timetable. Three scheduling protocols are presented, each using a different method to assign slots and to reschedule them when devices join, leave, or drift out of place. A custom simulator is used to test these protocols under different network sizes and device reporting periods. The results show that, for periodic traffic on a single channel with a single spreading factor, all three protocols can keep the available time slots almost fully utilized, provided that clock drift is corrected and rescheduling is handled carefully. Although evaluated in a simple LoRaWAN setting, the scheduling design is intended to extend to multi-channel and mixed spreading-factor deployments. Overall, the work highlights that clear slot structure, robust rescheduling, and active drift management are key to reliable, large-scale LoRaWAN operation.
[This summary has been rewritten with the help of AI based on the project's original abstract]
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