Analog Cellular to Shut Down

Posted by Sam Churchill on

Older OnStar systems that operate over AT&T’s original analog cell phone network will be going off-air on January 1, 2008. OnStar has about 500,000 users who will no longer have access to their automotive emergency communication services. As many as one million cell phone users and about 400,000 wireless home security systems will also be cut off. Many people are unaware this shutdown is coming, reports the Associated Press.

In 2006, OnStar said it had let customers know of the shutdown with a posting on its Web site, and this year, the company states that it had notified all affected customers. General Motors, which owns OnStar, is now modifying its cars. But some cars made as late as 2005 weren’t designed to use today’s digital network for OnStar, nor can they be upgraded. For other cars, made in the intervening years, GM provides digital upgrades for $15, says the AP.

An analog data system, called Cellular Digital Packet Data (CDPD) uses unused bandwidth normally used by analog (AMPS) mobile phones to transfer data. CDPD was a favorite of law enforcement for data connectivity in vehicles, due to its long range and ruggedness, but GSM and CDMA data alternatives eventually overtook it.

OnStar links customers to a communication center that offers a variety of services. The basic service ($199/year) includes: unlocking power doors; unauthorized vehicle entry and movement warning; notification of air bag deployment; medical response and accident assistance (by means of a built-in phone); and remote engine diagnosis to avoid breakdowns. The Directions & Connections package ($299/year) includes a concierge service for hotel and entertainment reservations; checking flight schedules; and locating local attractions or ATMs.

OnStar now integrates digital cellular phone and data with on-board GPS for real-time location data.

In 2002, the FCC allowed cellular operators to shut down their analog cell phone service (and CDPD with it). It takes effect on February 18, 2008. Here’s how to know if you will be affected:

  • Cell phones. If your phone is less than five years old, or has features like texting, Internet access or a built-in camera, it’s not analog. Carriers say less than 1 percent of all U.S. cell phones are analog. AT&T, Verizon Wireless and Alltel still offer (some) analog service and their subscribers have told that digital upgrades are necessary for some time. Sprint Nextel and T-Mobile USA have no analog networks.
  • Car communication systems. Generally, cars from the 2003 model year and older with OnStar from General Motors Corp., TeleAid from Mercedes-Benz or Lexus Link are affected, and most won’t be upgradable. Upgrade kits are available for most OnStar systems from model years 2004 and 2005. Class action lawsuits, consolidated in federal court in Detroit, are seeking compensation for the lowered value of the more than 500,000 affected cars with OnStar plus about 200,000 with other systems.
  • Home alarms. Affected are burglar and fire alarms that use the analog network as a sole or backup link between the home and an alarm center. Generally, only homes with no wired phone service have used analog wireless service. Homes that have them will lose wireless backup alarms, which kick in if someone cuts the phone line. Alarm systems using digital wireless links became available in 2006.

Cellular operators, using digital technology, can pack many more subscribers into the 800 MHz band.

Analog cellular service began almost 25 years ago, in 1983, with the analog Advanced Mobile Phone System (AMPS) system which operated in the 800 MHz band in the United States.

A first-generation digital technology known as D-AMPS or TDMA (for Time Division Multiple Access) replaced it. D-AMPS (Digital-AMPS) increased capacity over three times by dividing each 30 kHz channel pair into three time slots (hence time division), then digitally compressed the voice traffic for three times the call capacity in a single cell.

AT&T has been phasing out TDMA since 2001. It is now replaced with GSM, the international cellular standard. GSM (Global System for Mobile communications) packs eight full-rate or sixteen half-rate speech channels per radio frequency channel. The uplink frequency band is 890–915 MHz, and the downlink frequency band is 935–960 MHz. This 25 MHz bandwidth is subdivided into 124 carrier frequency channels, each spaced 200 kHz apart.

Some 82% of all mobile subscribers on Earth now use GSM mobile phones, with over 2 billion people utilizing the GSM standard. General Packet Radio Service (GPRS) is GSM’s Mobile Data Service while EV-DO is used by CDMA carriers like Sprint and Verizon.

“3G”, using W-CDMA for voice and HSDPA for data, is now available through many GSM carriers. The next step after “3G” is LTE or Mobile WiMAX. A working definition of “4G” includes mobile 100 Mbps.

The 800 MHz Cellular band (from 839 MHz to 880 MHz) is divided into 2 frequency blocks (A and B). There are 306 Metropolitan Service Areas and 428 rural service areas. Each trading area consists of one or more counties. After much buying and selling, AT&T and Verizon Wireless own most of the 800 MHz frequencies in the United States.

It also explains while they are interested in 700 MHz — they have infrastructure in place. Blogrunner follows the 700MHz auction.

Posted by Sam Churchill on Thursday, December 27th, 2007 at 12:28 pm .

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