One PHS cell station (CS) covers a radius of 100 to 500 meters, much smaller than cellular base station. This characteristic is the leading factor behind the accuracy of the PHS location information service, which is already being offered by the three PHS carriers.
PHS operation centers constantly monitor whether PHS terminals are inside or outside the service areas; however, these centers don’t detect which cell stations terminals are in.
The PHS location information service, using dedicated control signals, finds the particular CS area that a terminal is in, and provides the service user with the CS’s location in terms of latitude and longitude. Since its launch, the PHS location information service has been widely used for maintenance, security, distribution and many other purposes.

This article shows how Tokyo Xerox Co., Ltd.’s maintenance division, with 178 maintenance personnel, uses the service.
Tokyo Xerox is a unit of the Fuji Xerox Co., Ltd., which is involved in the sale and maintenance of office equipment such as photocopiers, printers and computers.
Besides routine maintenance, the service center dispatches engineers when customers call to ask for repairs. Because the company deals with office equipment, it is very important to respond to customers quickly, and efficiently dispatch maintenance staff.
The 178 maintenance personnel all carry PHS terminals that are linked to the location information service of NTT Central Personal Communications Network Inc. (NTT-P)..
An automated system at NTT-P’s location information center keeps track of PHS terminals and detects their location. Tracking is updated at 5, 10, 15, 30, or 60-minute intervals, depending on client requirements. Tokyo Xerox uses 10-minute interval tracking: a choice that balances the cost of the service and the accuracy of location detection required by the company.

Location Detection Service

Location data of PHS terminals is saved at 10-minute intervals at NTT Personal Location data in the form of latitude and longitude are sent to Tokyo Xerox maintenance center Maintenance personnel are paged when close-by customers ask for repairs

The location information center pages all these photocopier company’s 178 PHS terminals every 10 minutes. When the terminals respond to the paging, each terminal transmits the ID number of its closest CS back to the center. These ID numbers are converted at the center into location data in the form of latitude and longitude, and saved.
Tokyo Xerox’s maintenance service center is connected with the location information center via an ISDN network. The latest location data are transferred to the company every 10 minutes. It uses the data to indicate the most recent locations of maintenance personnel on an on-screen map.
When responding to a customer’s demand for repairs, operators at the maintenance service center look for the maintenance staff nearest the customer, and have them call on the customer.
The PHS location information service has made it easy for its operators to select staff in the vicinity, and has also reduced the time required to dispatch them, increasing customer satisfaction as well as the maintenance efficiency of the personnel.
When maintenance personnel are on site, their PHS terminals are sometimes out of service area and don’t respond to paging. In this case, operators make assumptions as to the whereabouts of the staff, based on the most recent location data from their terminals.
Prior to its introduction, there were worries that maintenance workers might be unhappy with this system, saying, for example, “It is uncomfortable being monitored all day long.” However, the system is operating smoothly and there have been no reports of similar reactions.
Both management and maintenance workers are said to be very satisfied with the PHS location information service. Workers can now receive more technical training, thanks to the improved efficiency in the field that has come from using PHS location detection service.