Unfiltered

Clearwire isn’t the only U.S. WiMax operator holding forth the possibility of switching 4G technologies. Clearwire’s primary investor and biggest 4G wholesale partner Sprint is investigating a long-term evolution rollout. At the LTE Summit in Amsterdam, Kevin Packingham, SVP of product and technology development for Sprint, said the operator was doing a technology evaluation of its current network and would be weighing the possibility of its own LTE network.

He further clarified in an interview with Light Reading Mobile that he didn’t mean that Sprint would piggyback on whatever LTE network Clearwire may deploy in the future, but rather Sprint is weighing migrating part of its own CDMA networks to 4G technology. And it’s issued requests for proposals to its vendors asking them how it could pull such an upgrade off. According to LR, Packingham wasn’t dismissing WiMax: “We don’t see WiMax and LTE as being mutually exclusive,” he said.

Connected Planet’s take,
Kevin Fitchard:

What a kick in the pants this would be for WiMax. Sprint has been WiMax’s biggest champion from the beginning. It lent credibility to the technology in its early days, and so far it’s been the only major traditional wireless operator to fully commit to WiMax as its 4G strategy. If Sprint were to make the switch, WiMax wouldn’t go away in the U.S. — unless Clearwire also switches — but it would certainly be a huge blow to what credibility WiMax has as a competing technology to LTE.

Of course, Sprint could just be messing with us the same way I suspect Clearwire is messing with is us. Given LTE’s momentum, it’s impossible for any wireless operator to dismiss. Just like Clearwire, Sprint might just be telling the industry what it wants to hear: In case WiMax doesn’t work out no reason to worry, we can insert LTE into our strategy with little difficulty. It’s also important to note that Sprint is famous — or infamous — for testing out whatever technologies are available. When it made its original WiMax decision, it was also running Flarion Technologies’ mobile broadband and IPWireless’ time division-CDMA through the motions. If there is a operator that truly does evaluate all technologies available to it, it’s Sprint. The ironic thing is that Sprint had considered LTE during that same 4G trail run, finding it lacking. What a difference a few years makes.

So assuming Sprint does embrace LTE, how would it go about it? Light Reading indicated that Sprint’s RFP is for its CDMA networks at 1900 MHz and 800 MHz, though the majority of Sprint’s CDMA networks are in the PCS band. So instead of identifying new spectrum for a 4G network it would look to upgrade or overlay LTE in its existing 2G and 3G bands. That means it would have to clear out at 10 MHz to 20 MHz in all of its markets to launch a proper 4G network.

Sprint has always bragged about its strong spectrum position, but I’m sure it’s not leaving that much bandwidth to fallow. So in order to build LTE, it would have to rely on, of all things, Clearwire’s WiMax network. As Clearwire expands its footprint to all of the major markets and Sprint moves the bulk of its broadband data traffic on to WiMax, it can start shutting down EV-DO carriers. As CDMA 1X technologies improve their voice capacity or as it moves customers to VoIP services, Sprint could start shutting down 1X channels as well. Remember, CDMA carriers are only 1.25 MHz wide, so it will have to take several offline before it can aggregate the spectrum for a much broader LTE carrier. It would essentially play network leapfrog, moving customers off of EV-DO to WiMax and then off of WiMax to LTE. All the while it would have to maintain a balance, though, to ensure that the EV-DO network had enough capacity to provide fall-back coverage outside of the WiMax and LTE footprints. I’m sure the last thing Sprint would want to do is support tri-mode devices, so it would be unlikely for it to use WiMax as a fall-back while the LTE network was rolling out.

Sprint would be on different frequencies than AT&T and Verizon Wireless — at least initially. But its plans might match closely with T-Mobile, which has fielded a similar spectrum re-farming proposal though a more voice-centric one. As customers move to its 3G network at the AWS band, it would take voice pressure off of the GSM network at 1900 MHz, spectrum T-Mobile could then start using for LTE. AT&T and VZWs’ LTE network will probably wind up at PCS and cellular eventually. They only have a limited amount of 700 MHz and AWS spectrum and will have to look into repurposing their 2G and 3G frequencies for 4G.

Sprint might also have some upgrade options in its current 3G footprint. One of its prime suppliers, Alcatel-Lucent, has long touted its software-defined radio technology as being future-proof, and Sprint maybe able to upgrade its newer equipment directly to LTE through software. It’s a question of whether the baseband processing capabilities in those base stations are powerful enough for LTE. But because the radios are at the same frequencies, they should be good to go.

If Sprint had to go about building a new LTE network entirely, though, my question is why it isn’t looking squarely at the Nextel iDEN network. Sure it supports a good deal of its current growth through Boost Prepaid and it has that handy push-to-talk feature, but Sprint’s going to have to sunset that network at some point. LTE might present the perfect opportunity.

That’s our take on this. Let us know what you think in the comments section below:

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