Editor’s Note: Understanding the billing side of next-generation wireless services such as 2.5G and 3G is very important to the process of rolling out new networks. But knowing the technical underpinnings of the various wireless networks is an absolute necessity. This month’s Billing Q&A column addresses these next-generation technologies and sorts through the terminology.
Q—It seems that every newspaper and magazine these days is covering the new wireless technologies that are going to provide more services and higher speeds. But the jumble of acronyms and terms can be confusing. Can you sort out the technologies and explain the difference among them?
A—Given that many of these services are still under development, I can only describe the objectives that have been set for most of them. There are a number of additional factors beyond the technologies themselves that will influence their success or failure. In general, the various technologies to which you are referring are intended to provide wireless data services in addition to traditional voice.
While all early cellular offerings were analog, most carriers in Europe and Asia quickly embraced a single digital standard called Global System for Mobile Communications, or GSM, as soon as it became commercially feasible.
Only a handful of North and South American carriers have introduced GSM to date. The remainder of the major operators selected TDMA, CDMA or iDEN as their digital technology. For this discussion you can consider GSM, TDMA and CDMA as 2G (second-generation) technologies, which are primarily designed for voice and short message services and very limited additional data capabilities.
Today, many wireless carriers are in the process of upgrading their 2G systems to more advanced networks that can carry broadband data. Globally the industry has agreed to eventual interoperability of the various technologies, but that objective is still some years away. The choices that carriers have made in the past will also affect how they eventually migrate to 3G. And that has led to an interim generation of technologies generally referred to as 2.5G—faster data transmission than the original 2G digital, but slower than 3G.
Here is a summary of the most commonly recognized wireless transmission technologies:
CDMA (Code Division Multiple Access). This is in use today with data transmission rates of up to 14.4 Kbps.
GSM (Global System for Mobile Communications). Also in use today, GSM users enjoy data transmission of 28 Kbps.
TDMA (Time Division Multiple Access). Also current, but less popular digital technology than CDMA. TDMA may transmit data at up to 64 Kbps.
1xRT. This is a preliminary phase of CDMA2000 currently being introduced that offers data rates of up to 144 Kbps. This approach will be an overlay on existing CDMA voice networks so no additional spectrum will be needed to use this technology.
GPRS (General Packet Radio Service). GPRS is being introduced in a number of areas where GSM is used. It is an overlay technology so additional GSM spectrum is not required. Carriers expect data speeds of up to 117 Kbps.
CDMA2000. Designed as the next generation of CDMA networks, CDMA2000 will require additional spectrum, but according to published descriptions, it may transmit data at speeds of up to 2 Mbps.
EDGE (Enhanced Data rate for Global Evolution). EDGE is less well known than GPRS but is supposed to enable data speeds of up to 384 Kbps. It too can be deployed using existing GSM spectrum.
UMTS (Universal Mobile Telecommunications System). The 3G term for W-CDMA (Wideband Code Division Multiple Access). Like other 3G technologies, it could support data speeds up to 2 Mbps, but it will also require extra spectrum.
So, where is all this additional spectrum going to come from? Well, that depends on where you are in the world. In Europe, most countries already have had or are planning auctions similar to those held in the United States for both 2G and 3G digital bands. The cost of spectrum in some European countries has resulted in virtual bankruptcy of some carriers. In a Catch-22 situation, they have the spectrum, but no money left to build out the systems.
Some spectrum has been allocated for auction by the FCC for next-generation services in the United States, but with another set of Catch-22s: Various entities are using that spectrum now and are not inclined to give it up easily. Here are some examples.
Television broadcasters are using frequencies 746–764 MHz and 776–794 MHz for TV channels 60 through 69. The FCC has rescheduled the auction for Sept. 12, 2001. However, digital TV, which uses different frequencies, has not been the success it was expected to be, so broadcasters have not vacated channels 60–69, nor are they required to do so by law.
Various federal agencies, including the Forest Service, the Coast Guard and the Pentagon are using the 1710–1885 MHz frequencies. This was supposed to have been auctioned by Sept. 30, 2002. However, military officials have stated that they cannot (or do not wish to) share frequencies with commercial users for a variety of reasons, including national security.
Nextwave Telecommunications was the original winner of the 1895–1910 MHz and 1975–1990 MHz bands. Unfortunately, the company spent all its money on the auction and went bankrupt a few years ago. Even while they were claiming they had the funds to pay for the frequencies, the FCC re-auctioned their holdings to a number of large carriers. Nextwave appealed in federal court, which reversed the FCC and gave the frequencies back to Nextwave in June this year.
Nextwave has signed contracts with Lucent to build out its national network. Some observers believe it may eventually sell out to the carriers who won the re-auction (and who are still waiting to get their deposit money back from the FCC). Either way, unless the FCC prevails in a possible appeal to the Supreme Court, Nextwave will win big.
School districts and Sprint, WorldCom and some telephone companies are currently using the 2500–2690 MHz frequencies. The FCC had wanted to set aside these bands for 3G, but strong lobbying and the huge costs of reassigning schools to other frequencies caused the FCC to back off, at least for now. No auction dates have been scheduled.
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