Personal Communications Services (PCS) is a set of wireless communication services personalized to the individual. Subscribers can tailor their service package to include only the services they want, which may include stock quotes, sports scores, headline news, voice mail, e-mail and fax notification, and caller ID. The service offers full roaming capability, allowing anywhere-to-anywhere communication.
Unlike many existing cellular networks, PCS is a completely digital service. The digital nature of PCS allows antennas, receivers, and transmitters to be smaller. It also allows for the simultaneous transmission/reception of data and voice with no performance penalty. Eventually, PCS will overtake analog cellular technology as the preferred method of wireless communication. Several technologies are being used to implement PCS.
In Europe, the underlying digital technology for Personal Communication Networks (PCNs) is Global System for Mobile (GSM) Telecommunications, where it has been assigned the 1800-MHz frequency band. GSM has been adapted for operation at 1900 MHz for PCS in the United States (i.e., PCS 1900). Other versions of GSM are employed to provide PCS services in other countries, such as the Personal Handyphone System (PHS) in Japan.
Many service providers in the United States have standardized their PCS networks on Code Division Multiple Access (CDMA) or Time Division Multiple Access (TDMA) digital technology.
The PCS Network
A typical PCS network operates around a system of microcells— smaller versions of a cellular network’s cell sites— each equipped with a base station transceiver. The microcell transceivers require less power to operate but cover a more limited range. The base stations used in the microcells can even be placed indoors, allowing seamless coverage as the subscriber walks into and out of buildings.
Similar to packet radio networks today, terminal devices stay connected to the network even when not in use, allowing the network to locate an individual within the network via the nearest microcell and routing calls and messages directly to the subscriber’s location. For a “follow me” service, which incorporates more than one device, a subscriber may be required to turn on a pager, for example, to receive messages on that device.
If the subscriber receives a phone call while the pager is on, the network may store the call, take a message, or send the call to a personal voice-mail system and simultaneously page the subscriber. In this way, PCS allows the concept of universal messaging to be fully realized. Currently, cellular switching systems operate separately from the Public Switched Telephone Network (PSTN).
When cellular subscribers call a landline phone (and vice versa), the two systems are interconnected to complete the communications circuit. Many PCS services are supported on the same switches that handle calls over the wire-line network, with the only distinction between a wireless and wire-line call being the medium at each end of the circuit.
In some places, wireless PCS and cable television (CATV) are already integrated in a unified CDMA-based architecture called “PCS over cable.” The use of CATV allows PCS to reach more potential subscribers with a lower startup costs for service providers.
Broadband and Narrowband
There are two technically distinct types of PCS: narrowband and broadband, each of which operates on a specific part of the radio spectrum and has unique characteristics. Narrowband PCS is intended for two-way paging and other types of communications that handle small bursts of data. These services have been assigned to the 900-MHz frequency range, specifically, 901 to 912, 930 to 931, and 940 to 941 MHz.
Broadband PCS is intended for more sophisticated data services. These types of services have been assigned a frequency range of 1850 to 1990 MHz. Narrowband PCS and broadband PCS license ownerships have been determined by public auctions conducted by the Federal Communications Commission (FCC). PCS service areas are divided into 51 regional service areas, which are subdivided into a total of 492 metropolitan areas.
There is competition in each service area by at least two service providers. There are 10 national service providers plus 6 regional providers in each of 5 multistate regions called “major trading areas.” An unlicensed portion of the PCS spectrum has been allocated from 1890 to 1930 MHz. This service is designed to allow unlicensed operation of short-distance—typically indoor or campus-oriented environments—voice and data services provided by wireless LANs and wireless Public Branch Exchanges (PBXs).
One of the largest PCS networks is operated by Sprint PCS. At year end 2001, the company’s CDMA-based wireless network served close to 13 million customers, making it the fourth largest wireless carrier. In addition to offering voice services from 300 major metropolitan markets, including more than 4000 cities and communities in the United States, the company leads the wireless industry in the number of wireless Web users on its Internet-ready phones and devices.
In addition, users may shop online at Amazon.com from their Internet-ready Sprint PCS phones. The service supports two-way transactional electronic commerce services to provide users with easy and convenient shopping on the Internet. Users also easily access the Sprint PCS Wireless Web to check e-mail, news, stock portfolios, or flight schedules.
The service offers the ability to customize and receive important news, receive e-mail and information updates from Yahoo, as well as dial into a corporate intranet or the Internet using a Sprint PCS phone in place of a modem connected to a laptop, PDA, or other handheld computing device.
Migration to 3G
PCS service providers are in the process of migrating their wireless networks to the global third generation (3G) framework. In the case of PCS based on CDMA, this entails a multiphase rollout of new technology that will increase the network’s capacity for both voice and data.
The first phase of deployment will be to migrate to a Code Division Multiple Access 2000 (CDMA 2000) network, which will double the PCS network’s capacity for voice communications, increase data transmission speeds from 14.4 to 144 kbps, and lower handset battery consumption.
In early 2003, PCS service providers will move to the second stage of their transition to 3G and offer data speeds of up to 384 kbps. By late 2003, data transmission speeds will reach up to 2.4 Mbps, and in early 2004, transmission speeds for voice and data are expected to hit between 3 and 5 Mbps.
The popularity of PCS is bringing about a variety of new mobile and portable devices such as small, lightweight telephone handsets that work at home, in the office, or on the street; advanced “smart” paging devices; and wireless electronic mail and other Internet-based services. PCS services are available in all regions of the United States.
Most of the smaller PCS networks are now interconnected to the nationwide PCS networks, providing users with extensive roaming coverage without having to switch to analog cellular on a dual-mode handset. At this writing, momentum toward 3G networks has stalled. Questions about how much demand there is for 3G services and delays in 3G network implementations are causing many PCS service providers to rethink their transition timetable.