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PlaceEngine(Positioning Technology Based on Wireless LAN signals)

For years people have relied on GPS equipment for generating positioning information. Unfortunately, GPS cannot be used indoors, and there is a significant time lag before positioning can begin. PlaceEngine technology offers a viable solution by taking advantage of the growing popularity of wireless LAN (Wi-Fi) systems. It determines a user's location by using signals emitted by numerous Wi-Fi access points. This approach can be used to estimate positions even in indoor or underground locations, where GPS is not an option.

The PlaceEngine Service

The PlaceEngine Service consists of the PlaceEngine server (where location estimation is performed), a terminal with a built-in Wi-Fi device, and the PlaceEngine client (which runs on the terminal to collect Wireless LAN signal information).
  • Figure 1: The PlaceEngine Service
    Figure 1: The PlaceEngine Service


As outlined below, the PlaceEngine service uses Wireless LAN signals from nearby Wi-Fi access points to estimate the user's position and display related information.

1. The first step is to install the PlaceEngine client software on a Wi-Fi terminal.
2. The PlaceEngine client software monitors signals from nearby Wi-Fi access points and acquires Wi-Fi data, including MAC addresses, SSIDs and field strengths.
3. The client software transmits the Wi-Fi information to the PlaceEngine server.
4. The PlaceEngine server estimates the user's position (including longitude, latitude and street addresses) by comparing this data with Wi-Fi information stored in its database. The results are sent back to the client software.
5. If no estimation results are returned from the PlaceEngine server, or if the results are incorrect, the user can register the current location to correct PlaceEngine's location estimation.
6. The PlaceEngine client software also works in conjunction with websites configured to support the PlaceEngine API. When visitors hit the "current location" button on these websites, various web-based positioning services can be provided, including maps displaying the user's current location, or downloads of local information, such as traffic data or locations of nearby restaurants.


Users can obtain positioning information through PlaceEngine even when not connected to the network (offline). The PlaceEngine client determines latitude and longitude by referring to a locally stored database (PlaceEngine local database), and the resulting information is transmitted to the application. This method has been implemented on portable computer entertainment systems, such as PlayStation Portable (PSP). Users can periodically download the latest PlaceEngine local database and store it on their devices.

Accurate within an Approximate Range of 5 to 100m

Factors influencing the positioning accuracy of the PlaceEngine system include the quality of the Wi-Fi information (including access point density) in the area where the client software is located, and the amount of Wi-Fi information stored in the server's database. While accuracy is therefore difficult to predict, the positioning information provided is estimated to be accurate within an approximate range of 5 to 100m.

Accuracy Enhanced through User Participation

By using PlaceEngine to estimate location or explicitly register locations, users can help improve PlaceEngine coverage and positioning accuracy. The system is self-maintaining, and its performance as a positioning technology will improve as usage increases.
  • Figure 2: PlaceEngine Coverage (Both coverage and accuracy improved through user participation).
    Figure 2: PlaceEngine Coverage (Both coverage and accuracy improved through user participation).


Another important feature of the PlaceEngine system is its ability to acquire extremely accurate positioning data, especially in urban areas, from Wi-Fi terminals, access points and other devices, which have proliferated rapidly in recent years. As a result, PlaceEngine is becoming an extremely effective positioning tool for urbanites in their daily activities. The positioning results plotted on the map in Figure 3 were obtained using PlaceEngine on a portable game console carried on a train traveling along Tokyo's Yamanote Line. Readouts were taken every 10 seconds.
  • Figure 3: Positions Recorded from a Yamanote Line Train
    Figure 3: Positions Recorded from a Yamanote Line Train



The Future of the Technology

In addition to triangulation based on wireless LAN signals, PlaceEngine can also be configured to search for any text tag corresponding to such signals through the introduction of pattern matching. This technology is currently used with the PlaceEngine service in not only providing the absolute position of the user, (longitude and latitude), but also their level (floor) within a building. Unlike GPS, which cannot determine altitude indoors, the PlaceEngine system can use this pattern matching technology to indicate on which floor of a building the user happens to be located. Future enhancements may lead to a more diverse range of information to include not only the floor information, but also the name of the buildings and points of interests, such as the name of the nearest train station, shopping district or complex.

* Sony Computer Science Laboratories initiated PlaceEngine research and development. Due to technological characteristics of the technology, including its network externality, Sony decided that PlaceEngine should be developed as openly as possible as an "ecosystem" in a network environment. This approach carried the potential to enhance the ultimate value of the technology more than closed development within a single company or product. Koozyt, Inc. was established under the ownership of So-net Entertainment Corporation to handle licensing and PlaceEngine technology-based solution proposals. Koozyt is currently developing PlaceEngine business through tie-ups with PlayStation Portable (PSP) game titles and major service sites.



Conferences, Papers and Patent Information

  • Jun Rekimoto, "Sensonomy, PlaceEngine, and LifeTag: Large-Scale Integration of Real World and Networks," Symposium on Database and Web information Systems (DBWeb2007), 2007.
  • Jun Rekimoto, "Toward Cybernetic-City: Sensonomy and Location Aware Computing," Geolocation and its Social Issues,"Seminar TECOG, Fondation Maison des Sciences de l'Homme, 2007.
  • Jun Rekimoto, Takashi Miyaki, and Takaaki Ishizawa, "LifeTag: WiFi-based Continuous Location Logging for Life Pattern Analysis," 3rd International Symposium on Location- and Context-Awareness (LOCA2007), pp.35-49, 2007. [ PDF ]
  • Jun Rekimoto and Takashi Miyaki, "WHEN becomes WHERE: Continuous Location Logging through WiFi Self-Logging, and Applications Thereof," Interaction 2007, 2007. (The following PDF is mostly in Japanese) [ PDF ]
  • Jun Rekimoto,"From Folksonomy to Sensonomy: Convergence of Real World Activities and Online Space," International Symposium on Applications and the Internet (SAINT2007) keynote.
  • Jun Rekimoto,"Positioning Data Mashups Using PlaceEngine," Workshop on Next-Generation Locationware Technology and Services, 2006 (in Japanese). [ PDF(slide) ]
  • Jun Rekimoto, Atsushi Shionozaki, Takahiko Sueyoshi and Takashi Miyaki, "PlaceEngine: WiFi Positioning Data Infrastructure Based on Accumulated Real World Knowledge," Internet Conference 2006,pp.95-104, 2006 (in Japanese).[ PDF ]

Awards

18th Nikkei BP Technology Award (2008), Information Technology Division

Related Information




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