Technical standards for the PHS air interface are stipulated under RCR STD-28 by the Association of Radio Industries and Businesses (ARIB). Taking PHS trends into consideration, the following three standards have been added to RCR STD-28.

1. Standards for 64 kbit/s data transmission

Public PHS 32 kbit/s data transmission service began in Japan in April 1997. Since then, the number of PHS subscribers as well as the number of calls using the data transmission service have been steadily rising, with data transmission accounting for approximately 10 % of all PHS communications call duration.
Technical standards for 64 kbit/s data transmission have been created to meet demand for higher-speed data transmission services. These standards will increase usage of PHS data transmission service, which is already known for its excellent reliability and high-speed.

2. Standards for private PHS functions

Standards for private PHS functions have been long-awaited. In response to this, technical standards have been set for the following functions available within a cell station: holding, call transfer, call waiting, conference call (up to three parties), system holding (See Note.), indication of the main or extension line, and remote control from personal stations (PS) including activation of the answering machine.
The standards also designated timer setting conditions as well as telephone ID numbers for direct communications between PHS PS. If PHS PS are manufactured in conformity with the standards, direct communications is possible between extensions from different vendors.
(Note) “System holding”is a method designed to use radio frequencies efficiently. When a PS is on hold, the radio communications channel to the PS is closed and when the PS releases the holding, it takes a new radio channel.

3. Standards for expanded PHS frequency bands

The 3-MHz frequency bandwidth has been added to public PHS services, as reported in the February 1998 issue of PHS MoU News (No. 14). Technical standards have been established for this additional allocation of frequencies to PHS.
The revised “RCR STD-28 v-3, rev-1”is scheduled for release in June 1998.