Andrew Seybold: The Rush to 4G

Over the next year, we will be hearing more about the network operators' move to 4G all over the world. I see the shift to 4G as inevitable, but does it need to happen as soon as LTE, for example, is finalized and the first equipment is built? We are hearing wonderful things about LTE, but the data rates and capacity increases being bandied about are theoretical and based on using 20 MHz of spectrum.

One reason the WiMAX community can claim data speed and capacity gains over today's EV-DO Rev A and UMTS/HSPA is due to the amount of bandwidth it uses. EV-DO Rev A occupies only 1.25 MHz of spectrum per carrier and UMTS/HSPA occupies 5 MHz per carrier. The WiMAX community is basing its claims on bandwidths of 8 MHz or more. If you normalize these three technologies in 10 MHz of spectrum, you find they offer about the same data rates and capacity.

Not many network operators have 20 MHz of contiguous spectrum to use for LTE, but LTE can run in any amount of spectrum from 1.25 MHz up to 20 MHz so it will fit almost anywhere. The caveat is that when LTE is used in less than 20 MHz of spectrum, data speeds and capacity are lower than the published specifications and, in most cases, are about the same as the next revisions of UMTS/HSPA+ and EV-DO Rev B (second release). Thus, I wonder why there is a rush to LTE instead of continuing with the enhancements to HSPA and EV-DO. If you put LTE in the A and B Blocks of the just-auctioned 700-MHZ spectrum, you are using 6 MHz by 6 MHz, which is a long way from 20 MHz of spectrum. When you look at what else can be done with this spectrum, you find that you can deploy four or five carriers of EV-DO or one carrier of UMTS/HSPA or LTE (depending on guard bands).

If you look at the data speeds and capacity of all three of these technologies in 10 MHz of spectrum, you will find that LTE has only a slight advantage (10 percent or less). Verizon, with its C Block holdings of 11 MHz by 11 MHz of spectrum, fairs better with LTE but not as much as is being claimed by LTE promoters. As with any new technology, it will take time to get the bugs out and it will be more expensive to deploy.

A lot of the rush to move to LTE is because of the "threat" of WiMAX and WiMAX proponents' claims about high-data speeds and lots of capacity. We are about to learn the truth about WiMAX as the Sprint portion of the new Clearwire network is turned on and independent tests are conducted. For an idea of what is in store for us, go to the WiMAX Forum website (http://www.wimaxforum.org/technology/ [1]) where you can read the following statement: "Mobile network deployments are expected to provide up to 15 Mbps of capacity within a typical cell radius deployment of up to three kilometers." If you compare both of the 3G standards deployed today, you will see that there is virtually no difference in total data capacity available per cell sector or cell site.

Perhaps the commercial wireless community is rushing headlong into 4G when it should be continuing to deploy the next revisions of 3G and watching LTE. But most network infrastructure companies would not be happy with this since many of the revisions for the 3G networks are software upgrades and not nearly as expensive as the upgrade to LTE.

The race is on. NTT DoCoMo has fully committed to being the first LTE network operator and others are raising their hands. But like any new technology, it will take years to fully build out on a nationwide basis. The best we will see over the next three to four years is LTE deployed where there is a high demand for data services, and I don't believe we will see anything like a nationwide network in the United States until 2014 or 2015.

Network operators are trying to attract more customers to their broadband data networks and are still rolling out coverage in some areas. If I were a network operator, I would stay with 3G and implement the new revisions as they become available. I would let LTE technology and pricing mature before I made up my mind to deploy it, especially in less than the 20 MHz of spectrum on which today's specifications, including data speed and capacity, are being calculated.

Don't get me wrong, I believe in LTE and next-generation technology. But I also believe in making money and that the best way for networks to do that is to let demand drive them to LTE, not competition from WiMAX or wanting to be the first kid on the block with LTE.

Andrew Seybold is an authority on technology and trends shaping the world of wireless mobility. A respected analyst, consultant, commentator, author and active participant in industry trade organizations, his views have influenced strategies and shaped initiatives for telecom, mobile computing and wireless industry leaders worldwide. www.andrewseybold.com [2]