Software Defined Radio for NB-IoT

The next generation of mobile radio systems is expected to providing wireless connectivity for a wide range of new applications and services involving not only people but also machines and objects. Within few years, billions of low-cost and low-complexity devices and sensors will be connected to the Internet, forming a converged ecosystem called Internet of Things (IoT). As a result, in 2016, 3GPP standardizes NB-IoT, the new narrowband radio technology developed for the IoT market. Massive connectivity, reduced UE complexity, coverage extension and deployment flexibility are the targets for this new radio interface, which also ensures harmonious coexistence with current GSM, GPRS and LTE systems. In parallel, the rise of open-source software combined with Software Defined Radio (SDR) solutions has completely changed radio systems engineering in the late years. This thesis focuses on developing the NB-IoT’s protocol stack on the EURECOM’s open-source software platform OpenAirInterface (OAI). First part of this work aims to implement NB-IoT’s Radio Resource Control functionalities on OAI. After an introduction to the platform architecture, a new RRC layer code structure and related interfaces are defined, along with a new approach for Signalling Radio Bearers management. A deep analysis on System Information scheduling is conducted and a subframe-based transmission scheme is then proposed. The last part of this thesis addresses the implementation of a multi-vendor platform interface based on Small Cell Forum’s Functional Application Platform Interface (FAPI) standard. A configurable and dynamically loadable Interface Module (IF-Module) is designed between OAI’s MAC and PHY layers. Primitives and related code structures are presented as well as corresponding Data and Configuration’s procedures. Finally, the convergence of both NB-IoT and FAPI requirements lead to re-design PHY layer mechanisms for which a downlink transmission scheme is proposed.