Friday, March 04, 2005

1G, 2G, 3G, 4G

Wireless phone standards have a life of their own. You can tell, because they're spoken of reverently in terms of generations. There's great-granddad who's pioneering story pre-dates cellular, grandma and grandpa analog cellular, mom and dad digital cellular, 3G wireless just starting to make a place for itself in the world, and the new baby on the way, 4G.

Most families have a rich history of great accomplishments, famous ancestors, skeletons in the closets and wacky in-laws. The wireless scrapbook is just as dynamic. There is success, infighting and lots of hope for the future. Here's a brief snapshot of the colorful world of wireless.

First of all, this family is the wireless telephone family. It is just starting to compete with the wireless Internet family that includes WiFi and the other 802 wireless IEEE standards. But it is a completely different set of standards. The only place the two are likely to merge is in a marriage of phones that support both the cellular and WiFi standards.

Wireless telephone started with what you might call 0G if you can remember back that far. The great ancestor is the mobile telephone service that became available just after World War II. In those pre-cell days, you had a mobile operator to set up the calls and there were only a handful of channels available.

The big boom in mobile phone service really began with the introduction of analog cellular service called AMPS (Analog Mobile Phone Service) starting in 1981. This generation is 1G, the first for using cell technology that let users place their own calls and continue their conversations seamlessly as they moved from cell to cell. AMPS uses what is called FDM or frequency division multiplexing. Each phone call uses separate radio frequencies or channels. You probably had a 1G phone, but never called it that.

The next generation, quick on the heels of the first, is digital cellular. One standard uses a digital version of AMPS called D-AMPS using TDMA (Time division Multiple Access). A competing system also emerged using CDMA or Code Division Multiple Access. As you might suspect, the two are incompatible but you can have a phone that works with both. Europe embraced yet a third standard called GSM which is based on TDMA. Digital transmissions allow for more phone conversations in the same amount of spectrum. They also lay the groundwork for services beyond simple voice telephone calls. Data services such as Internet access, text messaging, sharing pictures and video are inherently digital.

This is where the whole "G" thing got started. The original analog and digital cellular services were invented to cut the wire on landline phone service and give you regular telephone service you could take with you. As such, the bandwidth they offer for adding data services is pretty meager, in the low Kbps region. Now that a cell phone is not merely a cell phone, but also a PDA, a messaging system, a camera, an Internet browser, an email reader and soon to be a television set, true broadband data speeds are needed. That new generation of cell phone service has been dubbed 3G for 3rd generation.

3G has proven to be a tough generation to launch. The demand for greater bandwidth right now has spawned intermediate generations called 2.5G and even 2.75G. One such standard is GPRS (General Packet Radio Services) which is an extension of the GSM digital cellular service popular in Europe. It offers download speeds up to 144 Kbps.

3G phones and services are just starting to come into their own. One service you'll find is called EVDO which stands for EVolution Data Only. EVDO has download speeds up to 2.4 Mbps, which is faster than T1, DSL or Cable broadband service. There is also an evolution that includes voice called EVDV which is in the works.

While 3G is going to enable telephones to also become Internet computers, video phones and television receivers, its maturity phase will find it competing with wireless VoIP telephone services on WiFi, WiMAX, WiTV and the new wireless mobile standard 802.20, which doesn't seem to have a catchy name yet. The slug-fest between analog wireline phone service and wired VoIP seems likely to be continued on the wireless front.

There is also an emerging cellular standard you should be aware of called 4G. The fourth generation being championed in Japan will boost the data rates to 20 Mbps. These speeds enable high quality video transmission and rapid download of large music files. The first 4G phones may appear as soon as 2006. That means we better starting thinking about what to do with 5G if this generation thing is going to continue.

You may also enjoy reading some telephone history.

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