Increasing number of users possessing only mobile phone and smartphone with no landline phone has made the importance of GPS/GNSS function more important than before especially for search and rescue in an emergency situation. For outdoor locations, such positioning function of GPS/GNSS is mandatory for all users in Japan, without exception also mandatory in the world wide regulation. However, positioning functions does not work at indoor locations where GPS/GNSS signal are not reachable. Thus there has been a new technology to maximize sensitivity of receiver to secure positioning function even where GPS/GNSS signal level is very low, with major limitations on accuracy and its stability due to multi path signal reflected by walls. Since such technology could not be applied to further in depth of indoor space, a seamless positioning environment was not made possible. Recent technologies including Wi-Fi and Bluetooth becoming more common now have the other technical limitations that its positioning information is not accurate enough for social infrastructure for search and rescue in an emergency situation especially in buildings with multiple floors.
As one of solutions for the indoor positioning with floor information, a research has been conducted on several technologies including RF Tag/Bluetooth to provide more accuracy (especially for altitude). And one of the solutions is the IMES (Indoor Messaging System) that is developed based on conventional GPS positioning technologies. This IMES has been highlighted in a large number of technological communities both in Japan and globally. This new indoor positioning technology utilizing the GPS/GNSS functions available in every mobile phones and smartphones is co-developed and co-patented by JAXA and GNSS Technolgies, Inc. Now from the new products line up of various mobile devices available from 2014 Autumn, this IMES function has been made available and its line up will be further expanded in the future.
IMES Advantages are:
1. Made available with GPS/GNSS function of telecommunication chips from major chip vendor embedded in the mobile phones and smartphones
2. Unlike GPS/GNSS positioning, no need for timing synchronization
3. Absolute position with high accuracy without relative positioning measurement
4. Display 3D positiion, floor number, room number, and other related information
5. Positioning at indoor spaces located in-depth
6. No accuracy deterioration greater than distances among transmitters
7. Functional with all positioning services including GPS, Galileo, GLONASS and QZSS
The US Government has allocated 10 PRN codes between 173 and 182 in L1C/A for IMES. Based on this, JAXA has published the QZSS system user interface speccfication (IS-QZSS). For urther information, please visit QZ-Vision website at http://qz-vision.jaxa.jp/USE/en/index.
The IMES (Indoor MEssaging System) is an unique technologies incubated in the development process of “Michibiki”, the first QZSS. The IMES utilizes the same signal with GPS from the US and provide longitude, latitude, and altitude information from its transmitter. GNSS Technologies, Inc. have developed the worlds’s first commercial IMES Chip and participated in number of social experiments programs. Our research and development on indoor psuedolite technologies was dated back in 1996. After our first development of single channel psuedolite signal generator in 2001, we have further brushed up its technological strengths through the development of timing synchronization equipment in 2002, and finally developed the first prototype of IMES transmitter in 2007. Then we have further improved its functionality via four generations of transmitter developments. And later we have started the IMES LSI chip development and succeeded to make it more compact (12 x 12 mm) for smaller transmitter products. At the same time, we have promoted the IMES as social infrastructure together with JAXA and endeavored to expand the number of compatible receivers.
Those those years, the number of GPS/GNSS embedded devices has been expanded rapidly. Unlike a decade before, when GPS/GNSS functions were mainly used for car navigation systems and mobile phones, its applications were broadened not only to Smart Phones and Tablet PCs but to various products including Digital Cameras, Watches, Wearable Devices, GPS Tracker, Wearable GPS Tracker, Driver Recorder, and Transceiver/Handy Terminals.
With increasing number of GPS/GNSS embedded products, the number of IMES compatible mobile devices has been expanding as the number of supported receiver chips has been increasing. Now with the wide range of Smart Phones supporting the IMES, the services leveraging IMES for consumer segment has been moving on toward the stage of diffusion process. Since the number of Tablet PCs supporting the IMES has been also increasing, the further diffusion in the business segment is anticipated in the future.
Now, let us take a look at the comparison between two Smart Phones, one supporting the IMES and the other not supporting it. Smart Phone supporting the IMES is on the right and the other one is one the left. Both display the position accuracy with blue circle. As shown in the screen capture, the one supporting the IMES has better position accuracy. Imagine the emergency situation where the search and rescue is required. The position accuracy is very important as a life line.
However, since the indoor positioning is very important for the other commercial applications, the developments of other technologies has been pushed forward. Now there are various technologies including not only IMES but also Wi-Fi, Bluetooth and other technologies. We know that some people said “Wi-Fi is sufficient and IMES is not needed” as Wi-Fi is supplemental to GPS/GNSS positioning. There are also other supplemental technologies using microphone, RFID, Optical Sensor and other sensors with relative positioning.
Even PDR（Pedestrian Dead Reckoning）technologies utilizing gyro sensors embedded in Smart Phones can determine position and moving directions by attitude and movements can further provide more accurate supplemental positioning information for GPS/GNSS without the IMES. However those technologies can only determine relative positions. It has limitation of security issues. The reason why GPS/GNSS function is embedded in mobile phones as mandatory specification is to provide the same level of security on positioning information for emergency call including a situation where a crime is committed. Thus the IMES level of security with absolute positioning should be required as a social infrastructure.
The relative positioning is only a supplemental process after absolute position is determined with outdoor GPS/GNSS. PDR accuracy can be deteriorated when moving in escalators, elevators and staircases. This becomes a major limitation without other indoor positioning services with absolute positioning. A leading chip company like Broadcom positions the IMES as an ace in the hole of positioning solutions after studying the big picture of positioning technology trends. Now all Broadcom’s communication chips and GPS/GNSS chips has the IMES compatibility as standard. In addition to the time stamp technologies used for authentication of electronic documents, a newly developed concept of location stamp has come uder spot light for further enhancement of the document security avoiding spoofying and falsification more strictly. Not only with the single use of the IMES, but also with the combination of the other technologies including Wi-Fi, Bluetooth and PDR, now the IMES can be the ace in the hole of indoor positioning technologies expected to be more important to solve the limitation issues of security and deployment cost at the same time as the social infrastructure in the future.