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The Wireless Directory

   

A View from America

Taken from the foreword to the book by

Donald Cox

Stanford University

California

USA

Cordless telephony in North America has evolved along a quite different path than in Europe or Asia. US cordless telephones have evolved as handset/base unit sets essentially independent of network functionality, except for the base units providing a wireline interface that is indistinguishable from that of a wireline telephone. Early sets operated at 1.6 / 49 MHz, then evolved to 46 / 49 MHz and more recently to the 902-928 MHz Industrial-Scientific-Medical (ISM) band. The speech quality of early US cordless telephones was poor - people bought sets by the millions, but also discarded them by the millions because of the poor quality. When manufacturers finally started producing cordless telephones with speech quality comparable with wireline telephones, the market exploded. There are today, perhaps, 100 million cordless phones in use in the US.

Again unlike elsewhere, in the US there has been a wireless research and development activity completely separate from either the cordless or the cellular industries. Originally sponsored by the local exchange (telephone) companies at Bellcore, this activity was aimed at providing widespread, cordless telephone-like, highly mobile services through wireless access to large scale intelligent fixed infrastructure networks, eg local exchange networks or, perhaps, the combination of cable TV and intelligence in interexchange (long distance) networks. It was pursued under various identities such as wireless local loops (WLL), universal digital portable communications (UDPC), and, more recently, Wireless Access Communication System (WACS). Hughes Network Systems (HNS) and Motorola developed WACS prototypes, which, along with Bellcore prototypes, have been used in many successful technology trials.

With the new opportunities for PCS service, derivatives of WACS, eg Personal Access Communications System (PACS), have emerged as serious contenders for both high- and low-tier, cellular- and cordless-like, PCS. PACS-UB was thus created to provide a compatible unlicensed companion technology to PACS; it is akin to other digital cordless technologies, but was derived by an entirely different route. Thus, US evolution to a high capability digital cordless technology, although not starting from cordless telephone optimized standards like CT2, DECT or PHS, has resulted in technical solutions such as PACS and PACS-UB which offer potential for dual mode, cordless/cellular, service, and the capability to support wireless loop access. The evidence of the recent spectrum auctions demonstrates the major level of commercial interest in such opportunities.

Given this background, this book is to be welcomed, providing a timely overview of the field, comprehensive coverage of the engineering principles of low-power cordless telecommunications and descriptions of digital cordless technologies. It would appear that in the US, simple cordless telephones and complex cellular will continue to evolve independently for some time; however, digital cordless technologies have significant potential to supplant existing cordless telephones, cellular telephones and wireline telephones. "Cordless Telecommunications Worldwide" provides a perspective of the low-complexity low-power side of wireless communications that is quite different from that of high-complexity high-power cellular communications. Thus, the book is a valuable resource for the reader to explore how different regions of the world are developing, applying and commercialising such technology.




 
 
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