PERSONAL COMMUNICATIONS NETWORKS: AN INTRODUCTION By Dr. Ernest Simo 5.0 PCS: PROMISE OR CHALLENGE The Conceptual PCN features and characteristics discussed above are far from being commercial realities. However, various Embryonic technologies are emerging in Europe, Canada, Japan and the United States. They include Cordless Telephone systems, Digital Cellular systems, Digital SMR and Paging systems, Wireless In-Building networks and Low Earth Orbiting satellite systems. On Technical grounds, PCS is a promise. Leading edge technologies in the areas of Voice, Data and Video Compression, Digital Signal Processing, Bandwidth-efficient modulation and Access techniques, have advanced beyond the Research and Development stages. Along with intelligent signaling systems, processors and databases, they form a sound array of enabling technologies that could support cost-effective Personal Communications services by year 2000. On Regulatory issues, the outlook is not as bright however. Despite the World Administrative Radio Conference 1992's attempt to converge on Global strategies, there is a fragmentation, or indeed, a lack of consensus worldwide. Within the PCS Industry, various nations and corporations seem to diverge on issues such as PCS standards, defmitions, licensing procedures, Frequency bands of operation and appropriate technologies. In the United States, some particularly outstanding issues include: * The TDMA versus CDMA debate: Trials and theoretical arguments are being used by various proponents to demonstrate the relative advantages of their particular system. * A secondary debate is also emerging between the proponents of Narrow band CDMA technology [less than 10MHz of spread bandwidth], and the advocates of broad band CDMA alternatives. * The Fight for the 1850-1990 MHz band remains intensive between existing microwave users and PCS proponents. This is despite WARC 92 and FCC's recommendations that the two parties use the band on a co-primary basis. Another issue, not currently well understood is the potential risk for Health Hazards. The acceptance of wireless Communications in the office will be significantly conditioned by the user perception of health hazards related with electromagnetic radiations. Some Industry experts think that due to this concern to electromagnetic radiation, fiber-delivered services may well get an upper arm in the workplace of the future. So, the PCN Industry needs to clearly understand the short and long term effects of electromagnetic radiation on users, in all the frequency bands of interest. CODE: AN INTRODUCTION By Dr. Ernest Simo © 1999 DR. ERNEST SIMO - SPACE2000