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PCS Networks

PCS networks will be fully digital in nature, with the various providers most likely making use of TDMA or CDMA access and coding technology [12-7]. For example, Sprint, Bell Atlantic, and US West have embraced CDMA; AT&T, BellSouth and Southwestern Bell are committed to TDMA, citing the immaturity of CDMA [12-32], [12-33] and [12-34]. GSM (TDMA-based), or DCS 1900 (a GSM derivative) will likely be the PCS technology of choice in most countries, although analog networks will be supported during the transition to digital. Pacific Bell, by the way, also chose DCS 1900, thereby adding to the confusion because of the issue of incompatibility [12-35].The networks will be based on microcell configurations, supporting large number of stationary or slow-moving users. Signaling System 7 is an intrinsic element of PCS. In addition to improved call setup times, SS7 is the technology that will deliver enhanced features such as selective call forwarding, call blocking, call trace, and Calling Line ID (CLID).

While the spectrum allocation will vary by country or region, the designated U.S. frequencies include Narrowband, Broadband, and Unlicensed PCS spectrum. Actually, much of the PCS spectrum was already spoken for by high-band microwave systems. Clearing that spectrum is the responsibility of the PCS licensees, at an estimated cost of at least $70 million [12-3]. For the first time in U.S. history, the PCS spectrum was auctioned (and re-auctioned in some cases, after default on downpayments) by geographic area. The 1995 auctions of two frequency blocks brought in $7.7 billion, and the 1996 auctions are expected to account for another $6 billion or so [12-36].

Unfortunately, the competing PCS providers are not expected to provide interconnectivity, except through the PSTN, much as is the case with cellular providers. Additionally, different technologies will be deployed in support of PCS, from region-to-region. This translates into a lack of portability, or roaming capability; in other words, the PCS terminal used in San Francisco may not be able to access a PCS network in Dallas.

Narrowband PCS

Narrowband PCS has been allocated spectrum in the ranges of 900 to 901 MHz, 930 to 931 MHz, and 940 to 941 MHz. That spectrum will be used to extend the capabilities of pagers to include acknowledgement paging, two-way messaging and digital voice.

Broadband PCS

Broadband PCS is allocated 120 MHz in the 1850 to 1990 MHz range. This spectrum will deliver next-generation wireless communications including WLL, voice and data services, and cellular-like services for pedestrian traffic in high-density areas. [12-31]

Unlicensed PCS

Unlicensed PCS spectrum will serve Wireless LANs, wireless PBXs, and PCS voice and data services within a building or campus environment. Unlicensed PCS spectrum has been set aside in two ranges. Bandwidth of 20 MHz in the 1.900 GHz to 1.920 GHz range will be used by asynchronous devices such as PDAs. Additionally, 20 MHz, split into two 10 GHz bands, is set aside in the 1.890 GHz to 1.900 GHz range and the 1.920 GHz and 1.930 GHz range. This spectrum is set aside for isochronous voice communications [12-3].

PCS Equipment

PCS equipment will take a variety of forms, including PDAs, PCS telephones, and enhanced pagers. Many devices will be dualmode—for example, a PCS/Cellular telephone. Such a telephone might incorporate a built-in pager. As PCS is based on microcell architecture, the devices will be low-power and, therefore, lightweight and low cost. Even though the batteries will be much smaller than those found in contemporary wireless devices, developing battery technology is expected to yield much longer battery life. Most PCS devices will be cordless telephones, which will work exactly like a contemporary cordless telephone when the user is at home or at the office. They also will offer mobility, so that the user can make and take calls on the move. The size and weight are expected to be such that they truly will be pocket-size.

PCS Services and Applications

PCS promises to offer a wide range of services and applications at a wireless level. The most common application will be that of voice communications on a basis similar to cordless telephony. Through the use of an inexpensive, low-power handset, the user will be able to both originate and receive calls within the provider’s area of coverage, as long as he is within the limited range of the antennae. Additionally, the user can be mobile, although not at a high rate of speed. PCS is designed to support stationary or slow-moving pedestrian traffic, whereas cellular telephony is provided in support of high-speed vehicular traffic, as well.

Enhanced paging will be supported, ultimately through multifunction terminal equipment. Such pagers will support short message service, ultimately transmitted from a personal computer through the network and received on a small display built into the PCS terminal. The next step in this applications evolution is the ability to receive email through wireless access to the Internet or a corporate email server. Taking the scenario one more step, wireless database access will be supported, as will a limited level of wireless computing. Although with limitation, Personal Digital Assistants (PDAs) presently provide such capabilities through wireless access to packet radio networks. In all likelihood, PDA connectivity will be a function of PCS networks, which will provide better coverage than do the current proprietary packet radio network providers [12-37] and [12-38].

Ultimately, PCS is expected to provide multimedia communications, even incorporating slow-scan video at perhaps 7 to 10 frames per second. It also will support facsimile and Group III speeds or higher. Radio-determined vehicle locations will be provided, and smart terminals will provide maps and instructions to the destination, with constant adjustments based on dynamic traffic conditions.


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