Connectivity and time stamps tracking in MQTT protocol

Cilj magistrske naloge je gradnja sistema za povezljivost in sledenje časovnih žigov različnih naprav s pomočjo interneta stvari v protokolu MQTT. Področji interneta stvari in brezžična komunikacija postajata vse bolj priljubljeni področji v komunikacijskem svetu za povezljivost raznolikih naprav. V sodobnih aplikacijah je časovna sinhronizacija eden ključnih elementov in predstavlja proces sledenja ter strategijo prilagoditve notranjih ur naprav, povezanih v določenem omrežju. Zato smo se odločili, da to področje podrobneje raziščemo in analiziramo s pomočjo sledenja časovnih žigov različnih naprav ter ocenimo zgornjo mejo napake časovnih žigov glede na linearno interpolacijo izmerjenih časov. V nalogi je najprej podrobneje predstavljena arhitektura izdelanega sistema ter uporabljene tehnologije. Nato so predstavljeni vsi senzorji in naprave ter programska orodja, ki jih uporabljamo pri gradnji sistema. Sledi predstavitev opravljenih meritev, poskusov in delovanje sistema. Za vsak poskus je predstavljena arhitektura, shema in potek poskusa, uporabljeni gradniki ter način shranjevanja izmerjenih podatkov. Sledi interpretacija in ovrednotenje rezultatov ter primerjava točnosti in natančnosti časovnih žigov različnih naprav. Pri testiranju smo preverili rezultate za vse uporabnike, predstavili pa smo le tiste, ki so se najbolj natančno približali ciljni vrednosti. Za zaključek smo na kratko primerjali rezultate ter izpostavili glavne težave in pomanjkljivosti. Podali smo tudi navodila za nadaljnje delo ter smernice, kako lahko sistem še izboljšamo.The goal of this master’s thesis is to build a system for connectivity and tracking timestamps of various devices using the Internet of Things with the MQTT protocol. The fields of the Internet of Things and wireless communication are becoming increasingly popular in the communication world for connectivity of various devices. In modern applications, time synchronization is one of the key elements and represents the tracking process and the strategy of adjusting the internal clocks of devices connected in certain network. Therefore, we decided to investigate this area in detail, analyses it through tracking the timestamps of various devices and try to estimate the upper limit of the timestamps error according to the linear interpolation of the measured times. The master’s thesis first presents the architecture of the system and the technologies used. Then the sensors, devices and software tools are presented, which are used for building the system. Next, we present the performed measurements, experiments and the operation of the system. For each experiment, the architecture, scheme and flow of the experiment, the used components and the method of storing the measured data are presented. What follows is the actual interpretation and evaluation of the results and a comparison of the accuracy and precision of timestamps for various devices. We have examined the results obtained from all the participated users, but we present only those that gave best results. In conclusion, we briefly compare the results and highlight the main issues and weaknesses. We present possible directions for future work and give guidance on how the system can be further improved