A number of trends in wireless communications are becoming evident. First among these is the imminent deployment of Personal Communications Services (PCS) by licensed service providers. Auctions held in 1994-96 resulted in the assignment of licenses for both narrowband PCS-based services and broadband PCS-based services in the U.S.2.56 The objective of PCS is to offer so-called "next generation" digital cellular-like features, as well as offer competition for local loop services. Despite its hype, PCS is simply cellular at higher frequency.
The creation of a PCS industry has been driven by a combination of demand and technological evolution. Early cellular "mobiles" were large and bulky, requiring an automobile for transport. Early cellular systems were designed with this vehicular bias and were expected to serve no more than four or five million subscribers by the mid-1990's. As the size of mobile equipment has decreased to that of portable handsets, the costs of providing service has similarly decreased and cell phones have become almost a consumer staple. PCS is aimed at meeting this growing demand for anywhere anytime communications.
The narrowband PCS services will be offered via 10 nationwide licenses in the 930 MHz region. The inbound and outbound channel sizes vary between 12.5 and 50 kHz, depending on the particulars of the license. The target service offering for narrowband PCS is advanced messaging (e.g., acknowledged or two-way paging). A variety of technologies are under development to provide these services. Although the bandwidth for narrowband PCS prohibits general-purpose data networking applications, there is certainly the opportunity for specialized applications, such as telemetry, credit card verification, etc. These services and technologies are discussed in Chapter 9.
The broadband PCS services will initially be offered via 3 30-MHz licenses per market in the 1850-1990 MHz region (Table 2.6). Aimed at all types of voice and data communications, PCS services will compete with cellular and other existing wireless services. Existing technologies such as CDMA, TDMA and GSM (called PCS-1900 in this context) are targeted for broadband PCS; the additional spectrum created by PCS will also encourage enhancements of these standards to better support data services. New technologies are also likely to appear.
The current distinction between market segments is likely to disappear with the new technologies and services. A continuum of services-paging, two-way paging, short messaging, data at varying bandwidths-will likely replace the current paging and data segments. With existing cellular service providers and partnerships expanding their coverage area via the broadband PCS auction, the need for cooperation and interoperation between service providers is likely to become less important than it currently is in cellular.
Western Europe is expected to award up to 4 PCN licenses per country beginning in 1996, based on the DCS1800 standard, to compete with the GSM duopoly in these countries. However, the European Commission policy on PCN is vague, giving wide scope for national discretion in deciding who should obtain or bid to obtain PCN licenses. Also, licensing procedures vary between countries. The European Radiocommunications Committee (ERC) is likely to allocate 1710 to 1785 and 1805 to 1880 MHz bands for PCN use by January 1998.
Like AMPS, licenses for North American PCS are assigned on a per market basis. However, rather than considering only local markets, the FCC has also defined PCS markets which are regional in scope. These fifty-one regional markets are referred to as Major Trading Areas or MTAs. The A and B blocks of PCS licenses have been awarded on a per MTA basis.
The C- through F- blocks of PCS licenses will be awarded on the basis of the local markets, called Basic Trading Areas or BTAs. There are 491 BTAs defined in the U.S. Canada and Mexico are likely to follow suit in defining PCS licenses on the basis of MTAs and BTAs for commonality amongst North American mobile service providers.
The magnitude of the bets placed by the "winners," coupled with the fact that the "winners" have to underwrite the costs of relocating existing users of these frequencies (i.e., point-to-point microwave applications) to new frequencies, will exert great pressure on the service providers to get revenues flowing. The PCS service providers are free to use any air interface and system architecture, so long as transmit power levels, etc., are within specified ranges. The need for rapid service deployment will encourage the "winners" to use the existing digital cellular standards.
Probably the most controversial aspect of PCS is the continuation of the digital standards battle from the cellular industry; with the addition of GSM as a contender one could argue that the holy wars have escalated. With the possibility of one or more service providers offering nationwide service between their existing cellular licenses and the new PCS licenses, proprietary standards could also emerge. In some cases previously-supported standards and licenses from their cellular markets are being dropped by service providers in favor of the standards and licenses selected by PCS partnerships in which they are involved to avoid conflicts of religion (technical standards) and geography (licenses).2.57
In any case, as in digital cellular, the multiplicity of standards will limit the capability for "roaming" in another service provider's coverage area. As always, the old standby-AMPS in the 800 MHz bands-will be the common denominator. Most portables are likely to continue to support this analog standard to prevent subscribers from being limited to "islands" of mobile services.
At this time (mid-1996), the Joint Technical Committee (JTC) of the TIA and the T1/T45 engineering group have approved four technical airlink standards for PCS. They are CDMA, TDMA, GSM and a composite CDMA/TDMA/FDMA standard proposed by Omnipoint. All of the standards running in the 800-900 MHz bands have been modified in the appropriate ways to support "up-banded" operation. Each of the standards has its supporters and detractors.
The primary challenges for PCS service providers-once the standards decision has been made-are the relocation of current users of PCS frequencies to other frequencies and site acquisition. Relocating the current spectrum users-called "incumbents"-is projected to cost the PCS "winners" over $ 1 billion. Each market must be negotiated separately. According to the rules established by the FCC, the incumbents have provisions to return to the 1900 MHz frequencies if they are not satisfied with the new higher-frequency microwave operations. Up to ten thousand such microwave links must be relocated.
Site acquisition has always been a challenge for cellular service providers and will be for PCS service providers as well. Many of the best cell sites have already been taken by existing cellular service providers and zoning board approvals are getting harder to come by. The higher frequencies and lower power levels to be used for PCS dictate a greater number of cell sites than in conventional cellular systems. 2.58
The general idea of PCS is for base stations to be located on utility poles and billboards, etc., which will greatly reduce the costs of acquiring real estate. However, this will be mitigated by the additional infrastructure equipment required. Meanwhile the existing cellular carriers aren't exactly standing still; both in terms of additional deployment and customer penetration they have been extremely active.
The emphasis of PCS services is on small, low power mobile devices. The user is assumed to be a pedestrian, rather than an occupant of a vehicle-the design point for early cellular services. PCS cell sizes are small-less than one kilometer in diameter for small low power mobile devices. Three-dimensional coverage considerations apply, as opposed to the conventional cellular "flatland."
However, with the threat of increased competition from PCS, existing cellular service providers are increasingly offering services that are indistinguishable from PCS except for the frequencies in use. The decreasing prices paid by subscribers will force lower margins and a continuation of the mergers between service providers. It has been estimated that in the end there will be at most three nationwide service providers for combined cellular and PCS services.