A Holistic Assessment of Efficient and Secure Cellular Machine-Type Communications for Low Power Wide Area Network Applications

In the area of cellular Machine-Type Communications (MTC) for Low Power Wide Area Network (LPWAN), namely Long-Term Evolution (LTE) for Machines (LTE-M) and Narrowband IoT (NB-IoT), the communication system design is essential to deploy and operate applications efficiently and securely. In particular, the constraints imposed by limitations in energy supply and device complexity, coupled with the need to provide extensive coverage and ensure security within a heterogeneous network, present a significant challenge in optimizing the utilization and consumption of resources efficiently. Consequently, the research evaluates individual aspects and features of the LPWAN communication system by rating their impact based on Key Performance Indicators (KPIs) like coverage, data rate, and energy consumption of the device. However, the relative merits and limitations of each design aspect in relation to the entire communication system are typically not demonstrated, thereby necessitating a holistic assessment. This thesis assesses the communication system aspects holistically by performing analytical evaluations to provide a reasonable understanding of the respective interdependencies. Therefore, the individual components of heterogeneity in the cellular MTC system are first analyzed individually before the insights gained are integrated into the perspective of the overall system. This ranges from trade-offs in the User Equipment (UE) hardware domain, the individual design options in the protocol stack to a detailed description regarding security, header compression, and Location Based Services (LBS) features. Finally, the findings are discussed by referring to specific LPWAN applications: smart metering, smart city, smart farming, wearables, and logistics. A particular focus is placed on the composition of the protocol stack concerning its overhead size in LTE-M and NB-IoT. The analysis illustrates that protocol headers of typical stack setups occupy a significant portion of the available Transport Block Size (TBS). In critical environments, where LTE-M and NB-IoT support a maximum of 1000 bits per TBS, the actual available payload portion can fall even below 40%. Consequently, it is concluded that optimization in the form of header compression schemes is required to enable the deployment in these situations. The holistic assessment indicates that for each application the adaptation of the design choices is needed on a case-by-case basis as there is no universal LPWAN solution.