Technical Enhancements to PHS


Enhancements to technical specifications respond to user requests for even greater PHS functionality

PHS public service traffic has increased since data transmission service was started in April 1997. Accordingly, there were more requests by PHS users to improve the services to be used anytime in any place as they could not access in some locations, such as inside buildings and suburban areas.
Responding to these requirements by the PHS users and operators, the Telecommunications Technology Council (TTC) made the report on the enhancement of PHS, “Recommended measure for implementation of technologies to facilitate enhancement in PHS.” Based on the report, Ministry of Posts and Telecommunications in Japan (MPT) has submitted this subject to the Radios Administration Council in order to proceed the necessary revision of related ministerial ordinances toward the implementation.
The following is an outline of the submission on the enhancement of PHS technical standards.

1. Transportable repeaters for indoor service areas:
Transportable repeaters, which can be installed inside buildings more economically and efficiently, have been newly adopted. Accordingly, technical requirements relating to these transportable repeaters with maximum 10mW output power are newly specified.


2. Expansion of service:
The service area covered by a public PHS cell station is expanded with the following measures:
- The maximum of the control channel antenna power is increased to 2W.
- When the cover area is expanded by an Adaptive Array Antenna, the maximum antenna gain is increased to 16dBi from the current 10dBi level.

3. Frequency sharing by indoor and public PHS:
The standards of frequency sharing by indoor and public PHS are reviewed for efficient application as a solution to congestion of public PHS services in the metropolitan area.
The frequency band of the indoor PHS (digital cordless) is shared with the one of the public PHS of maximum 10dBi antenna gain with maximum 20mW output power.
On the other hand, the lower 1.5MHz frequency band of public PHS is also shared with indoor PHS. 4. Enhancement of PHS phones:
In order to enhance the mobility and the speech quality of PHS phones for the public and indoor applications, the maximum antenna gain is increased to 10dBi for the public cell station (CS) and to 4dBi for the indoor CS and for both PS from the current 2.14dBi.
The report by the Telecommunications Technology Council includes the data transmission speed and additional services, which will be realized in due time.


1). Data transmission speed:
To cope with fast growing data transmission needs, the upper limit of data transmission has been raised to 128kbit/s (using 4 channels simultaneously) from the current 64kbit/s. Upper limit on transmission speed in walkie-talkie mode has also been raised from the current 32kbit/s to 64kbit/s.
2). Additional services:
Short message service standards are specified so that a PHS user can communicate with any users of any other PHS carrier. Enhancement of hand-over, seamless communication between public and the indoor systems and walkie-talkie mode function are also included in the report.
Related information is available on the PHS MoU Group and Japanese Ministry of Posts and Telecommunications web sites, which are linked.



Please also see the 3rd Annual PHS Symposium, Enhancement of PHS Service and Technology section of our website.

The Radios Administration Council is expected to make its report in due time and related ministerial ordinances will be issued around the end of 1998.