Excerpt of PHS Seminar by DDI-P at the General Meeting
The 8th PHS MoU Group General Meeting on December 20, 1999 in Bangkok, Thailand featured seminars on PHS. Among the seminar presenters was Mr. Yoshiki Chika of DDI Pocket Telephone, Inc. The following is an excerpt of his presentation, entitled “Public PHS Service in Japan.” The presentation material is also available on the PHS MoU Group website at: http://www.phsmou.org.
Public PHS service was first launched in Japan in July 1995. At the beginning, PHS service provided voice communications only within limited service areas, and the mobility of PHS was not very good (see Fig. 1). Nonetheless, other strong features of PHS, such as voice quality superior to that of cellular phone and low call charges, in addition to availability of a wide variety of compact PHS terminals, appealed greatly to users, drawing an increasing number of subscribers.
In April 1997, launch of 32-kbit/s PHS data communications service ? the fastest speed achieved by any of mobile communications services at that time ? marked PHS’s evolution into the second generation. Coinciding with this accomplishment was the launch by PHS carriers of text messaging services known as Short Message Service (see Fig. 2).
These remarkable advances in PHS service exerted a tremendous impact on the mobile communications market, prompting the rival cellular sector to lower their call charges, manufacture more compact cellular terminals and attain a higher data communications speed. As a result, PHS carriers were put at the disadvantage as they could not differentiate the strengths of PHS clearly from those of the cellular phone.
With the aim of breaking down this stagnancy, great efforts were made from 1998 to 1999 in solving PHS’s supposed weaknesses: low mobility and limited service coverage, as well as in reinforcing its strengths: excellent voice quality and high-speed data communications capability. These efforts have resulted in the realization of the seamless handover system (see Fig. 3), Macro Cell CS (see Fig. 4), wireless entrance system (see Fig. 5), Portable Repeater and 64-kbit/s data communications service. Apart from these infrastructure-related develop ments, new types of PHS terminal endorsed with a brand-new concept have been marketed. All these approaches have succeeded in satisfying user needs (see Fig. 6).
Web browsing and e-mail communications through use of PHS terminals have been on the rise, with the popularity of the Internet ever on the increase. This trend is expected to continue into the future. Thus, strenuous efforts are under way to launch 128-kbit/s data communications service and packet data communications service by the end of 2000 (see Fig. 7). Following these services, PHS AO/DI (Always on Dynamic ISDN) will also be launched, which enables flexible handling of varied volumes of data flow as well as of different types of data (see Fig. 8).
Wireless communications technologies that are crucial to PHS’s further advance in the 21st century include Dynamic Channel Assign (DCA), frame synchronization and adaptive array antenna. When these technologies are used for further enhancement of the conventional PHS facilities, very high-speed PHS data communications and more efficient use of frequencies will become possible.
PHS is anticipated to achieve a speed higher than 128 kbit/s in data communications by the year 2001. This means that much before the launch of the Third-generation Mobile Communications System ? IMT-2000, PHS will be able to provide about the same quality of service as IMT-2000, inexpensively.
PHS surely has the potential of evolving into the fourth generation some time around the year 2005 or 2010 (see Fig. 9).
