Radijska pokritost decentraliziranega omrežja Meshtastic

Paradiž, Tjaš (avtor), Batagelj, Boštjan (mentor), Blatnik, Aljaž (komentor)

Decentralizirana brezžična omrežja, kot je odprtokodni sistem Meshtastic, ne zahtevajo obstoječe infrastrukture, mobilnih omrežij ali povezave v internet, zato so uporabna tudi ob izpadu komunikacijske infrastrukture. Osnovna enota sistema je vozlišče, naprava z LoRa radijskim modulom in mikroprocesorjem, ki poleg lastnega prometa posreduje tudi sporočila drugih vozlišč. Uporabniki do omrežja dostopajo s povezavo na bližnje vozlišče prek mobilne aplikacije in si izmenjujejo kratka besedilna sporočila, podobna klasičnim SMS-om. Parametri LoRa so v sistemu združeni v konfiguracijske profile, na primer LongFast, MediumFast, ShortSlow in ShortFast, ki določajo kompromis med dosegom in hitrostjo prenosa. Naloga obravnava radijsko pokritost sistema Meshtastic z dveh vidikov: dejanskega dosega v realnem okolju ter mejne sprejemne občutljivosti pri različnih profilih LoRa. V sklopu terenskega preizkusa je bil s pomočjo dveh vozlišč, RAK4631 kot fiksne bazne postaje in Heltec V3 kot mobilnega vozlišča, ter modula RangeTest izmerjen doseg profila LongFast po treh trasah: skozi naselje, po urbanem območju z delom neposredne vidljivosti ter skozi gozd. Izmerjeno slabljenje poti je bilo primerjano z modeloma FSPL in Okumura-Hata. V laboratorijskem delu je bila s kaskado RF slabilnikov in generatorjem šuma simulirana radijska pot med vozliščema, s čimer je bila za profile LongFast, MediumFast, ShortSlow in ShortFast določena mejna vrednost bilance zveze (link budget) ter primerjana s teoretičnimi vrednostmi proizvajalca. Izmerjeno slabljenje je na terenu preseglo napoved modela FSPL za 40 do 70 dB, medtem ko se je model Okumura-Hata dobro ujemal z meritvami v pogojih neposredne vidljivosti. V nobenem od treh scenarijev signal ni dosegel meje zanesljivega dekodiranja, kar pomeni, da je bil doseg omejen z dolžino izbranih tras in ne z zmogljivostjo sprejemnika. Laboratorijske meritve so pokazale ujemanje izmerjenega bilance zveze s teoretičnimi vrednostmi proizvajalca na 0,7 do 3,0 dB natančno, vrstni red profilov glede na doseženo bilanco zveze pa je v celoti sledil pričakovanemu vrstnemu redu glede na faktor razširitve SF. Primerjava obeh delov naloge kaže, da bi sistem pri profilu LongFast in realnih pogojih dosegel doseg reda nekaj kilometrov, kar sicer precej presega razdalje, preizkušene s terensko meritvijo.

• Jezik: Slovenski jezik
• Ključne besede: Meshtastic, LoRa, faktor razširitve, doseg radijskega signala, model FSPL, model Okumura-Hata, sprejemna občutljivost, bilanca zveze
• Vrsta gradiva: Diplomsko delo/naloga
• Tipologija: 2.11 - Diplomsko delo
• Organizacija: FE - Fakulteta za elektrotehniko
• Leto izida: 2026
• PID: 20.500.12556/RUL-186229
• COBISS.SI-ID: 290033155
• Datum objave v RUL: 28.08.2026

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Radio Coverage of a Meshtastic Network

Izvleček

Decentralized wireless networks, such as the open-source Meshtastic system, do not require existing infrastructure, mobile networks or connection to the internet, which makes them useful even when communication infrastructure fails. The basic unit of the system is a node, a device with a LoRa radio module and a microcontroller that, besides its own traffic, also forwards messages from other nodes. Users access the network by connecting to a nearby node through a mobile application and exchange short text messages similar to classic SMS. The LoRa parameters are combined in the system into configuration profiles, such as LongFast, MediumFast, ShortSlow, and ShortFast, which determine the trade-off between range and data rate. The thesis addresses the radio coverage of the Meshtastic system from two perspectives: the actual range in a real-world environment and the receiver sensitivity threshold for different LoRa profiles. In the field test, the range of the LongFast profile was measured using the RAK4631 base station, the Heltec V3 mobile node, and the RangeTest module along three routes (a residential area, an urban area with a section of line of sight, and a forest), and compared with the FSPL and Okumura-Hata models. In the laboratory test, the radio path was simulated using a cascade of RF attenuators and a noise generator, which was used to determine the limiting link budget for the LongFast, MediumFast, ShortSlow, and ShortFast profiles and to compare it with the manufacturer's theoretical values. The measured path loss in the field exceeded the FSPL model prediction by 40 to 70 dB, while the Okumura-Hata model agreed well with the measurements under line-of-sight conditions. In none of the three scenarios did the signal reach the reliable decoding threshold, meaning that the range was limited by the length of the chosen routes rather than by the receiver's performance. The laboratory measurements showed agreement between the measured link budget and the manufacturer's theoretical values to within 0.7 to 3.0 dB, and the ranking of the profiles by achieved link budget fully matched the expected order based on the spreading factor SF. Comparing both parts of the thesis shows that, under real-world conditions, the system with the LongFast profile would achieve a range on the order of several kilometers, considerably exceeding the distances tested in the field measurement.

• Ključne besede: Meshtastic, LoRa, spreading factor, radio signal range, FSPL model, Okumura-Hata model, receiver sensitivity, link budget