Modeling Contention Behavior of Machine-Type Devices over Multiple Wireless Channels
Ahmadian, Amir Mehdi
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Machine-Type Communication (MTC) is expected to account for the largest proportion of the regular connected devices with a dramatic growth from 2 billion at the end of 2011 to 12 billion by the end of 2020. Leading the largest submarket within the Internet of Things (IoT) submarket, it has been one the most attractive research areas as it has received remarkable attention recently from both academic and industry. Deployments of unattended devices characterized by their small-size and infrequent data pattern over Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) have been focused in this Thesis. MTC devices may utilize contention-based random access to transmit over the LTE network to have their data delivered. However, there has been limited attention to analytical characterization of contention-based behavior when unsaturated MTC traffic is considered. Furthermore, the existing efforts lack the analytical model capturing MTC contention behavior and utilizing it for MTC over LTE transmission use cases and scenarios. Thus, in this Thesis we focus on proposing a novel mathematical model which characterizes contention behavior in a multi-channel environment being applicable to various MTC over LTE scenarios. Further, the proposed mathematical model has been confirmed by extensive protocol-level simulations. Regarding the performance evaluation, in this Thesis we have assessed two distinct variations of ALOHA-type algorithms to characterize the MTC contention behavior. Proposing a novel mathematical model which captures contention behavior based on the system attributes and entities, we have employed the ALOHA-type channel access methods and mathematical processes (e.g. Markov chain) to investigate analytically three performance metrics including average access delay, average throughput and average number of users in the system.Furthermore, the proposed analytical characterization in the multi-channel environment is shown to be useful in quantifying the performance of contention-based Physical Random Access Channel (PRACH) procedure in 3GPP LTE. As a conclusion, the perfect convergence between analysis and simulation-level results confirms the rigorousness of the proposed model to be used for optimizing Random Access (RA) procedure or to be employed as a baseline in other relevant MTC over LTE research works.