One of the more interesting filings in the FCC's ongoing 3.5 GHz proceeding is a letter submitted by China Mobile, the world's largest wireless operator, which pushes the TD-LTE agenda.
The letter to FCC Chairman Tom Wheeler is also signed by Chinese vendors Datang and Huawei. It reminds the FCC that the TD-LTE ecosystem is maturing rapidly worldwide. "By adopting TDD mode, U.S. operators will be able to cooperate with operators in other countries and regions to develop the global TDD market on 3.5 GHz band. We believe it will leverage the economics of scale and benefit all the partners of 3.5 GHz ecosystem," the filing said.
"3.5 GHz is being increasingly recognized as the most probable global harmonized TDD band and will play a key role in meeting the explosive mobile data demands," the letter said. It added that TDD on 3.4-3.6 GHz "could combine with 3.6-3.8 GHz to provide a 400 MHz band for future mobile broadband, and form a giant uniform market for [the] U.S."
The FCC has proposed to create a Citizens Broadband Radio Service (CBRS) in the 3.5 GHz band, using a complicated three-tiered access and spectrum-sharing model that would be comprised of federal and non-federal incumbents, priority access licensees (PALs) and general authorized access (GAA) users. The CBRS is being eyed by some for use with small cell technologies.
As China Mobile, Datang and Huawei indicate, there is a potential global harmonization problem in that the FCC is defining the CBRS 3.5 GHz band as 3550-3650 MHz, with possibly 50 MHz more being added to take it to an upper limit of 3700 MHz, while 3GPP has defined Bands 42 (3400-3600 MHz) and 43 (3600-3800 MHz) specifically for TDD use. 3GPP also defined Band 22 for FDD, with 3410-3490 MHz uplink/3510-3590 MHz downlink.
China Mobile, Datang and Huawei said they "hope to cooperate with U.S. operators to promote the global TDD market of 3.5 GHz band." This is an interesting statement as no major U.S. carriers have committed to operating TD-LTE at 3.5 GHz.
However, Sprint (NYSE: S) is rolling out TD-LTE in its Band 41, 2.5 GHz spectrum and is allied with China Mobile in the Global TD-LTE Initiative (GTI). In February 2011, Clearwire--which was subsequently acquired by Sprint--joined China Mobile, Bharti Airtel, Softbank Mobile, Vodafone, E-Plus, and Aero2 to officially launch GTI, which now has 82 operator members.
BTIG analyst Walter Piecyk points out that former Clearwire CTO John Saw--who now has a key technology role at Sprint--is on GTI's steering committee and "was the point man for the China Mobile relationship."
So, do these relationships point to Sprint seeking to expand its TD-LTE deployment to the 3.5 GHz band, following the lead of operators in China, Japan and South Korea that are eyeing 3.5 GHz TDD deployments and the more than 21 operators in other countries that are deploying TD-LTE on 3.5GHz or have publicly announced commercial contracts?
Apparently not, according to Piecyk.
"The spectrum cap imposed by the FCC, which does not weight Sprint's high mix of high-band spectrum, makes it unlikely that Sprint could expand into this band anyway. If anything, the adoption of 50-100 MHz of additional TD-LTE spectrum in the hands of a competitor could reduce Sprint's potential differentiation in the market which might be a greater risk than the benefit of broader scale for this technology," he wrote.
Meanwhile, Huawei's inclusion as a signer on the FCC letter is intriguing given its poor track record in Washington, D.C. Clearwire had been using Huawei as its primary TD-LTE network vendor, but Sprint--bowing to national security concerns--agreed to rip out Huawei gear in exchange for winning regulatory approval to acquire Clearwire. Sprint also eliminated Huawei from consideration as a vendor for its Network Vision project due to those same concerns.
Yet a larger TD-LTE ecosystem, bolstered by support in the United States, would likely add to Huawei's global fortunes even if the vendor did not gain entry into the U.S. infrastructure market. And given its TD-LTE prowess, Huawei might see FCC support for TD-LTE at 3.5 GHz as opening a door for the company to get back in the good graces of U.S. lawmakers and network operators.
That would probably be too late to provide any good news for Sprint, however. Piecyk contends "the exclusion of Huawei in Sprint's network has led to higher costs and delays in building out the TD-LTE 8T8R network" and "hampers Sprint's ability to be competitive."
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