Supporting Energy-Efficient Node Mobility using Characteristics of Radio Waves in IoT

다국어 초록 (Multilingual Abstract)

Internet of Things (IoT) refers to the technology of connecting to the Internet with built-in sensors and communication function in a resource constrained devices (things). IoT technologies for connecting things are wirelessly being developed as the connections among things. The IoT technologies provide various services in a number of fields. In order to improve the mobility of IoT in a variety of services, it is necessary to find methods to make mobile devices energy-efficient.
IoT network solutions have the advantages of freedom of mobility and ease of installation, but most of IoT network solutions operating at low bandwidth use external batteries as a power source. In addition, node mobility should be handled as an important issue. This is the reason why the IoT network solutions are used for application services requiring node mobility. Therefore, energy-efficient algorithms for stable and reliable data transmission are needed in IoT.
In this dissertation, we propose novel algorithms to support energy-efficient node mobility in 802.15.4-based RPL and LPWA-based LoRa, which are representative wireless technologies that need consideration of battery resources. The first algorithm proposed in RPL supports the mobility of nodes by dynamically adjusting the transmission interval of the message requesting the route based on the moving speed and direction of the mobile node and the cost between neighboring nodes. The second algorithm proposed in LoRa dynamically adjusts transmission power by LoRa end-devices according to the distance between LoRa end-device and LoRa gateway.
In the first simulation for performance evaluation of the proposed algorithm in RPL, it was observed that the proposed algorithm requires fewer messages per unit time for selecting a new parent node following the movement of a mobile node. Since fewer messages are used to select a parent node, the energy consumption is also less than that of previous algorithms. In the second simulation for performance evaluation of the proposed algorithm in LoRa, it was shown that energy-efficient data communication is possible at the data rate supported by the LoRa SPs (Spreading Factors), even though the transmission power is dynamically allocated by the LoRa end-device.

목차 (Table of Contents)

• CHAPTER 1
• Introduction
• 1.1. Dissertation roadmap
• 1.2. Background and statement of the problem
• 1.3. Dissertation contribution
• 1.4. Dissertation organization
• CHAPTER 2
• Timely transmission of solicitation messages for energy-efficient node mobility
• 2.1. Introduction
• 2.2. Motivation and related works
• 2.3. Proposed algorithm for energy-efficient node mobility in RPL
• 2.3.1. Procedure of the proposed algorithm
• 2.3.2. A time interval calculated according to the moving speed and distance of a mobile node
• 2.3.3. Scenarios based on mobile node movement
• CHAPTER 3
• Supporting energy-efficient node mobility by adjusting transmit power in LoRa
• 3.1. Introduction
• 3.2. LoRa overview
• 3.2.1. LoRa physical layer
• 3.2.2. LoRa ADR
• 3.3. Motivation and wireless transmission link design method
• 3.4. Modeling for adjusting the transmit power of end-devices in LoRa
• 3.4.1. Link budget
• 3.4.2. Path loss model
• CHAPTER 4
• Performance evaluation
• 4.1. Environment for simulating timely transmission of solicitation messages for energy-efficient node mobility
• 4.1.1. Parameters and network topology for simulation
• 4.1.2. Energy model for simulation
• 4.2. Simulation for adjusting the transmit power of end-devices in LoRa
• 4.2.1. Parameters for simulation
• CHAPTER 5
• Performance analysis
• 5.1. Performance analysis of timely transmission of solicitation messages for energy-efficient node mobility
• 5.1.1. Cumulative transfer count
• 5.1.2. Packet loss rate
• 5.1.3. Energy consumption of the mobile node
• 5.2. Performance analysis of adjusting the transmit power of end-devices in LoRa
• 5.2.1. Path loss of LoRa
• 5.2.2. Calculation of transmit power according to sensitivity of receiver
• CHAPTER 6
• Conclusions and further studies
• References