Yuki Yonezawa

The wireless localisation matching problem and a maximum likelihood based solution

We propose a new approach towards wireless localisation related to scenarios where the device positions are known a priori, however the device IDs are not, and therefore need to be matched using RF methods. We propose a maximum-likelihood based matching algorithm called MLMatch for resolving this problem based on measured RSSI values. Since the search space of node-to-positions permutations grows factorially with the number of target devices, an Integer Linear Programming formulation is therefore utilised to reduce computation time. In addition, we analyse the stability of the algorithm with respect to different fading models and other wireless propagation parameters such as pathloss. Finally, we report on experiments performed indoors and outdoors using up to 33 wireless devices in order to validate our results.

Development of autonomous power electronics products with communication middleware

In this paper, we introduce a communication middleware and its implementation on two kinds of inverters. This middleware provides services of an automatic and dynamic network configuration (plug-and-play) and operation mode/master switching for distributed cooperative control of electric facilities. Energy end-nodes such as photovoltaic (PV) or batteries are clustered by the middleware to form a larger power conversion system. We made two types of prototypes and compared them. The first implementation was based on an embedded processor of a commercial inverter and the other was based on an ARM/Linux control board that will be attached on the aforementioned inverter. Though both worked well, Linux and its powerful, free software offered certain advantages in terms of design and operation. Loosely coupled design was applied to an abstraction layer of an open-source framework ZeroMQ, and a standardized message format JSON with its library JSON-C were employed for the middleware. They contribute flexibility for various applications in the smart grid. A demonstration with five prototype inverters showed that our concept and implementation work well.

The Wireless Localization Matching Problem

We propose new approaches toward wireless localization of devices belonging to the Internet of Things (IoT), specifically related to scenarios where the device positions are known a priori, however, the device IDs are not. These positions and device IDs therefore need to be matched using radio frequency positioning methods, which are more time and cost efficient as compared to manual installation. Immediate examples of real world applications include but are not limited to smart lighting and heating. We propose maximum-likelihood matching algorithms called MLMatch and MLMatch3D for resolving this problem based on measured received signal strength indicator values. Since the search space of node-to-position permutations grows factorially with the number of target devices, we propose several searching methods including mixed integer programming, linear programming relaxation to reduce computation time. The MLMatch3D algorithm further addresses the problem whereby nodes are located at multiple rooms and/or floors of a building. This algorithm first utilizes a graph partitioning method to determine in which room a node is located, followed by MLMatch for finding room specific positions corresponding to each node. In addition, this paper analyzes the stability of these algorithms with respect to different wireless fading models as well as compares the performance of these algorithms in various environments via numerical simulations. Finally, we report on experiments performed indoors and outdoors using up to 33 wireless devices in order to demonstrate the problem and validate our results.