Why 4G won't fix your mobile woes

Sprint and others are already hyping '4G' mobile services, but make no mistake, the next generation of mobile will perpetuate 3G's primary flaws

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AT&T has made a lot of noise that its iPhone users are already straining its 3G network in the United States, and carriers elsewhere in the world have said the same thing. That's just one device used by 3 percent of its customers -- imagine what happens when smartphones, 3G-enabled laptops, and wireless e-readers such as the Amazom.com Kindle and the rumored Apple media slate are commonplace.

Even as carriers bolster their local cell stations' capability to relieve local congestion, the FCC has warned that there is not enough spectrum to go around -- despite the fact that just two years ago a big block of analog-TV spectrum was auctioned off to carriers for use in "3G-plus" LTE and WiMax networks. WiMax is available in about a dozen cities now, while the first-generation LTE network should start coming online in 2011 -- but don't confuse these 3G LTE and 802.16d/e WiMax deployments with the 4G LTE Advanced and 802.16m WiMax networks expected in the next decade or so.

Exponential mobile device growth is one culprit in this presumed shortage of spectrum. The other is the quiltwork of wireless spectrum allocated to carriers. Each country has set aside spectrum for various purposes, but the spectrum used in one country for, say, 3G may be different than the spectrum used in another. Because of this, four spectrum bands comprise the GSM cellular technology used by most carriers. Even within a country, carriers may use different bandwidths for the same technology, based on what became available when they put in their bid.

Thus, in the United States, AT&T uses a different spectrum than T-Mobile does for its GSM-based voice and data services. Each carrier also uses different spectrum for 3G, even though both run the same network technology (UMTS). Many GSM-capable phones work with all four GSM 2G bands by having tunable radios -- but they are rarely designed to work with all the UMTS 3G bands -- and that's why Google's Nexus One, designed for T-Mobile, can't do 3G on AT&T's network.

Throw in multiple bandwidths for the CDMA 2G/3G technology used by Sprint and Verizon Wireless, and you quickly get so many technology and frequency variations that the phones can't easily be designed to support them all. Adding the circuitry and multiple radio tuners to support every possibility quickly causes space, power usage, and heat issues -- and higher costs.

Avoiding these issues is a big reason why smartphones are tied to specific carriers. But the fractured networks that result are subject to oversaturation, as carriers cannot divert excess traffic to one another to better balance the load. AT&T says that most iPhone users' complaints about poor 3G coverage center around New York and San Francisco, where the local networks are saturated -- but AT&T can't divert users to T-Mobile's network, though both are based on the same technology. (AT&T and T-Mobile do divert voice traffic to each other when the 2G network is overloaded.)

T-Mobile's late entry into 3G services via Android smartphones this past year also raises concerns, Redman notes, since T-Mobile doesn't have a lot of spectrum available, a consequence of sitting out several spectrum auctions in the past decade due to economic woes at its parent company Deutsche Telekom. Worse, T-Mobile doesn't have any spectrum that could be used with the expected LTE devices; Verizon and AT&T locked up most of that spectrum in 2008.

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