The Hard Truth about LTE Mobile Broadband Deployments

Posted by: Joan Marsh on September 13, 2012 at 9:00 am

On Friday, RCA (now CCA) representatives renewed their call for an inappropriate and ineffective technology mandate in the lower 700 MHz band.  I have previously written extensively about the real interference challenges that led to a separate Band Class for the 700 MHz lower B and C blocks, but I write again to address their newest assertions.

In a News Release, the interoperability alliance said: “Every user of the over 325 million mobile users in the United States relies upon wireless services to communicate, conduct commerce, and to keep us safe — but before they can communicate with one another, their devices must work across multiple networks.  The interoperability of mobile devices from network to network is critical to fulfill the promise of next-generation 4G/LTE wireless services . . . .”

As with most of RCA’s advocacy on this issue, that statement is glibly misleading and glosses over the complexity of current LTE deployments.

First, the over 300 million commercial mobile users in the United States already can communicate with one another.  Wireless carriers have long interconnected with each other and to suggest otherwise is ridiculous.

But beyond that, RCA wholly ignores a fundamental aspect of LTE network deployments in the 21st century — LTE is currently being deployed both domestically and globally on a multiplicity of different spectrum bands and the deployments are and will remain fragmented across bands.  Every carrier, regardless of size, will have to rely on multi-band chipset solutions to provide full LTE coverage and RCA’s members are no exception.

To understand how RCA is attempting to deliberately mislead policymakers with respect to this issue, one needs to understand some basic facts about band classes.

There are currently over 25 different LTE FDD band classes on which LTE technologies can be supported.  Deployments in AWS-1 (see T-Mobile and MetroPCS) require a Band 4 chipset.   LTE in PCS requires a Band 2 chip set, unless the deployment is in the PCS G Block (see Sprint), in which case a Band 25 chip set will be required.

Deployments in the cellular bands (see CSpire), require a Band 5 chip set, while deployments in the future AWS-4 bands (which Dish claims to be planning if granted appropriate flexibility) will require a Band 23 chip set.  LTE in BRS (Clearwire) requires a Band 41 chipset, and deployments in 700 MHz require a Band 12 (US Cellular), a Band 13 (Verizon) or a Band 17 (AT&T) chipset, depending on the spectrum blocks supported.

If you are deploying in multiple bands, as most carriers will be required to do, you’ll need to support multiple band classes domestically, and a few more internationally if you want to support LTE roaming around the globe.

In short, RCA’s suggestion that a narrow ill-advised technology mandate for the lower 700 MHz band will somehow solve LTE interoperability is fanciful.

Equally ridiculous is the observation by New American Foundation that “convergence to a single technology — LTE for 4G communications — gives consumers seamless coverage across carriers.”  Not true.  RCA members, for example, will not be able to rely on Sprint’s LTE deployment in the PCS G block unless a Band 25 chip set is built into their LTE devices.  Similarly, RCA members will not be able to rely on T-Mobile’s AWS-1 LTE deployment absent use of a Band 4 chipset.

A Band 12/17 combination is but one option for 700 MHz A Block licensees and it would be unprecedented, inappropriate and ineffective for the FCC to mandate that option while ignoring all the other LTE band class combinations that could provide A block licensees with broad LTE support.

A device that supports LTE Band 12, 25 and 4, on the other hand, would provide RCA members with seamless coverage across the LTE deployments of Sprint, T-Mobile and the A-Block carriers.  Perhaps that is the solution that RCA should be pursuing.

Comments (2)

If AT&T allowed for B12 devices to work on its B17 network, then the following band configuration would work for cross U.S. compatibility (except VZW and TD-LTE): 12, 25 (includes 2), 26 (includes 5), and 4.

That’s four frequency bands to support the grand majority of carriers in the United States.

Conan Kudo (ニール・ゴンパ) September 13, 2012 at 9:16 am

Joan, when is AT&T going to wake up to the fact that interoperability across the whole 700MHz. band will happen with or with out AT&T’s blessings . Yes we are talking about the 700 MHz. spectrum band CH 39 – CH 69 not the PCS spectrum band which already has interoperability and the same go’s for AWS spectrum band. Joan, please read the C- Spire law suite first before you start asking the small wireless A block license companies to look to Sprint or T-Mobile for interoperability This stonewalling by AT&T on interoperability is in bad faith . Your silly comments are like the sparks that catches dry grass, leaves, and bark on fire. AT&T just keeps adding wood to the fire . Before AT&T turns around a whole bunch of small game changing wireless companies are going to be born in some garage for one reason to crush AT&T and it’s ego . Before you can say boo every kid in the country will be making mobile VoLTE phone calls with unlimited access for $22. per month bypassing your over price network all together. Like a new start up called YaknChat wireless.

vincent d. mcbride September 17, 2012 at 8:09 pm

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