Indoor Orientation tracking method using ubiTrack * * This work was supported by DSE of SEC in Korea Woojin Jung and Woontack Woo GIST U-VR Lab. Gwangju 500-712, S.Korea +82-(0)62-970-2226 {wjung, wwoo}@gist.ac.kr ABSTRACT In this paper, we propose the indoor orientation tracking method using ubiTrack. In ubiquitous computing environment, the information of the location is one of the important contexts which are used to the context-aware service. But most of the indoor location tracking method causes the problem of the infringement on people’s privacy. Necessity of orientation tracking is proposed in order to provide the more intelligent services with the location tracking. To know orientation of a user or device, we attach two infrared receiver modules to the ubiTrack receiver. Two IR receiver modules attached to the ubiTrack receiver track the location, the direction and size as well as the orientation from the location information of a user and device. As the ubiTrack receiver attached on the device informs the location information of a device to the environment every some terms, the proposed method can provide the user with the location and orientation in the condition that user’s privacy problem is guaranteed. Experimental results show that the method recognizes orientation of a device in home environment with the errors below 15 degrees. The proposed method can be applied to many LBS gearing the context-aware services in ubiquitous computing environment. Keywords: ubiquitous computing, context tracking, location, orientation, LBS 1. INTRODUCTION In the ubiquitous computing environments, the environments recognize the users’ context by themselves, and provide personalized services anywhere and any time. To realize these intelligent environments, many research organizations have studied the context awareness and developed various applications exploiting context [1-3]. Even though they deal with different context according to their services, they have the common factor that the location information has been utilized. In this sense, the location information has considered as the important information to realize ubiquitous computing environments. Recently, the studies on the orientation-aware as well as location-aware have grown increasingly. Currently, various location tracking systems have been developed in order to track users indoor. Cricket compass [4] developed by MIT uses a RF and ultrasound signal,and added the some ultrasound receiver modules to the traditional Cricket. Thus, it can track the location and orientation of a user and device. But when tracking the location of a user and several devices at the same time, a server which manages the location information of devices is needed. It is a disadvantage that the ubiquitous computing aims the decentralized environments. Active Badge [5] developed by AT&T uses a RF and ultrasound such as Cricket but it has a privacy problem because it consists of an active sensor and several passive beacons. UbiTrack [6] which is infrared-based indoor location tracking system has advantages of simple operation and consideration of privacy problem. However, it is a difficult to recognize the specific contexts of a user and device because it cannot track the orientation of a user and device. In this paper, we propose the orientation tracking method using ubiTrack. We connect two IR receiver modules using not only one but different ID each other to ubiTrack receiver. Two IR receiver modules can be attached to any place where the user wants because they are connected to each other with the long wire. And mobile device attached on a device broadcasts its information. Proposed method has three advantages. First, ubiTrack receiver can recognize the orientation of a user and device by using two IR receiver modules which have each different ID. Second, we minimize inconvenience that a user always has to hold the mobile device through