Recent revisions to RCR STD-28 version 3 have made possible 64 kbit/s data transmission using PHS terminals. This transmission method uses two wireless channels at a speed of 32 kbit/s each. The revisions enable high-speed wireless access from PHS terminals to ISDN networks, and this feature is expected to expand the wired data transmission environment into wireless.

This 64 kbit/s data transmission service enables unrestricted digital information between ISDN networks and PHS networks as well as between PHS terminals.
Figure 1 shows system configuration of 64 kbit/s PHS data transmission service.

One 32 kbit/s transmission channel (TCH 1) is allocated to a cell station (CS) and then another 32 kbit/s channel (TCH 2) is allocated after the addition is requested using TCH 1. Channel switching within one CS is done by TCH 1 and TCH 2 independently. Neither TCH, with the switching procedures, affects the other. On the contrary, channel switching across two CSs is simultaneous across TCH 1 and TCH 2. Signals for requests or indications to switch TCH are handled by message in accordance with Radio Frequency Transmission Management (RT) on Layer 3. TCH 2 on Layer 3 offers only RT function.

Figure 2 shows the protocol layer configuration in the communications phase.
Some new technical standards will be also added to the PHS Internet Access Forum Standard (PIAFS) to nearly double the current effective transmission speed of 29.2 kbit/s to 58.4 kbit/s.
Products using the new standards are eagerly awaited.