PHS location information service has been increasingly put to a variety of purposes. Services can be classified into two types -- one using PHS location data of third parties, and the other using one's own. Expansion has been seen in both types of service. Typical examples of each type of service are introduced below.

Case 1 Service using third party PHS location data from J. G. Telenet Corp.

J. G. Telenet Corp., headquartered in Tokyo, provides PHS location information service using the networks of DDI Pocket Telephone, Inc. (DDI-P) and NTT DoCoMo, Inc. The service is targeted at the elderly and children. In fiscal 1998, PHS location information service was chosen as a model project for the next-generation Geographic Information System (GIS) by the Ministry of International Trade and Industry (MITI). Encouraged by this, J. G. Telenet and Toshiba Corp. jointly conducted field trials of a PHS-based search and tracking system. After confirming the feasibility of the service, the two companies launched the service commercially. Another technology used for location detection is satellite-based GPS (Global Positioning System), known for its adoption in car navigation systems. Unlike GPS, PHS can narrow down the location of a target PHS terminal to an area approximately the size of a PHS cell with no need of major changes to PHS networks thanks to its unique microcell zone method. To achieve higher accuracy in location detection, the method using data from multiple PHS Cell Stations (CS), such as the CS ID numbers and the strength of the radiowaves they emit, has also been adopted (see Fig. 1).

Fig. 1 PHS Cell Method

J. G. Telenet's service works like this. People (third parties) to be tracked are handed special PHS terminals for data transmission/reception only (see Photos 1 and 2).

Photo 1 "P-doco?" from NTT DoCoMo

Photo 2 "PHS Terminal for Location Detection System" from Toshiba

Once the customer staff at the call center receive a search request from the family of a missing person, they ask for the location of the terminal carried by the person to the location information center. The location information center automatically retrieves the terminal's location data from PHS networks, and forwards them in realtime to the call center staff (see Fig. 2).

Fig. 2 Outline of location information service system

Staff at the call center then narrow down the location of the target person, cross-referencing the strength of the radiowaves generated by densely-installed multiple PHS antennas and the location data from PHS CSs. The accuracy of location detection can deteriorate across rivers, in low-lying areas and other poor reception areas with various geographical impediments, but J. G. Telenet says it has developed a method to improve accuracy in such areas. In September last year, an elderly man walked out of a department store in Tokyo while his family were not paying attention. The man, in his 80s, has a tendency to wander off like this. When they realized what had happened, his family began a desperate search for him in the surrounding area, but could not find him. Having signed up for the J. G. Telenet service, the family called the company and requested a search for him. Staff at the call center, which is operational around-the-clock, paged the small PHS terminal carried by the man to find his exact location (see Photo 3).

Photo 3 Call center

The first response was from Omiya City, Saitama Prefecture, which is to the north of Tokyo Metropolis. The man was next tracked to Kumagaya City, followed by Takasaki City in Gunma Prefecture (see Fig. 3).

Fig. 3 The elderly man's move

This indicated that he was moving at very high speed. Staff at the call center came to the conclusion that the man must be on the Joetsu Shinkansen "bullet train" shuttling at very high speed between Tokyo and Niigata City, some 330 km away. Taken aback by this, one family member said, "It can't be true. He's getting senile, it's impossible for him to take the Shinkansen alone." The call center staff called the Niigata Police Department, and soon afterward, the elderly man was found safe at Tsubame-Sanjo station in Niigata. "If the family had searched for the man mainly in the vicinity of the department store, they would probably have taken a week to find him. We generally get the first search done in a few minutes if conditions are favorable, and need only a few hours on average to locate missing persons," said a J. G. Telenet spokesperson. "We are very concerned about security, and take great precautions to prevent unauthorized people accessing customers' personal information that could be used for spying or other malicious acts." (see Fig. 4)

Fig. 4 Procedure of placing a search request

J. G. Telenet provides the service targeting elderly people at 4,500 yen (about 45 U.S. dollars) a month. The sign-up fee of 25,000 yen is also charged. The Japanese Ministry of Health and Welfare intends to support such PHS- or GPS-based location detection services as part of its policy for helping families taking care of their elderly members at home. A considerable number of local governments are expected to adopt and implement these services.

Case 2 The Kyushu Matsushita Electric Co., Ltd. service that utilizes the PHS location data of the user

Kyushu Matsushita Electric Co., Ltd. launched a location information notification service on April 1 this year that allows users to voluntarily indicate their own whereabouts to others. The service uses DDI-P's PHS network and the KX-GT30 Series portable navigation system (see Photo 4) from Kyushu Matsushita.

Photo 4 Panasonic portable navigation system

As the first step, service users retrieve location data from nearby PHS CSs using PHS terminals with the service function, such as H" terminal from DDI-P. This data is then transmitted to the intended recipients (who must also be subscribers to the system) by calling (see Fig. 5).

Fig. 5

The recipient then forwards the data to navigation support center, where it is translated into longitude and latitude bearings. On receipt of this data from the center, the recipient's system displays the approximate location of the caller on a map in the car navigation system (see Figs. 6 and 7).

Fig. 6

Fig. 7

This service is very useful when users have rendezvous or have to pick up people at unfamiliar places. Users can also get to their destination efficiently by setting the route on their car navigation system. This service costs 30 yen (about 0.3 U.S. dollar) for each retrieval of information.