China delays 4G LTE by 3 years, how is this going to impact Sprint and Clearwire?


There are two flavors of 4G LTE: FDD (frequency division duplex) and TDD (time division duplex). Without getting too technical, let’s just say that the former makes a lot more sense for operators who are already running a GSM network, whereas the latter isn’t expected to gain any widespread adoption outside China. Now Sprint entered the 4G race a year or two before everyone else by launching a WiMAX network, thinking that the industry would rally around that particular standard. The support never came, and Sprint was forced to announce that they’d have to switch to LTE to remain competitive. The thing is though, when Sprint built their WiMAX network they did it by creating a separate company called Clearwire. Why? So other companies could invest in said network. Clearwire is going to transition to 4G LTE using the TDD flavor, the one that’s China only for now. They can’t do FDD because they don’t have the right kind of spectrum. Sprint on the other hand is going to launch their own FDD 4G LTE network by reusing some of their PCS spectrum, which today is being used to run their CDMA network.

All of these complicated abbreviations aside, something important just happened on the other side of the world. The Chinese government announced that they’re not going to issue any 4G LTE licenses for another two to three years. This is significant because China is a huge market that infrastructure vendors and handset makers want to play in; translation: no one will give a shit about TDD 4G LTE for the next three years, which puts Clearwire in the exact same situation they were in back when they were using WiMAX.

It’s not all doom and gloom however. Qualcomm’s Snapdragon S4, which will be at the heart of a majority of Android smarpthones coming out over the next 12 to 24 months, supports both FDD LTE and TDD LTE, though we don’t know how much extra a device that complicated would cost.

  • Anonymous

    FDD = Frequency Division Duplexing

  • J_n

    You should really double check your technical statements. “Without getting too technical” (I thought this was a tech blog), FDD is actually frequency-division duplexing, not full division duplexing, meaning uplink and downlink are done on separate frequencies.

    Both GSM and WCDMA use frequency-division duplexing, while China’s network is using TD-CDMA and TD-SCDMA, so obviously it makes more sense for China to use TDD version of LTE.

    • Thanks for correcting my abbreviation mistake!

    • boettger1

      China uses all of GSM, UMTS-FDD (WCDMA), UMTS-TDD-LCR (TD-SCDMA), CDMA, and EVDO. The only one of these over which it “obviously it makes sense” to deploy TD-LTE is China Mobile’s TD-SCDMA system.

  • What difference does it make to Clearwire  that handset makers don’t support TDD-LTE? Clearwire is just a mobile internet ISP.  They don’t even offer phone service.  They just need a few types of cheap usb-dongles and MiFis to offer their customers

    • Because Clearwire’s WiMAX network is what Sprint uses to offer their users “4G” access.

    • quintus murray

      soon they will be very obsolete due to superphones

  • Ranger

    TDD and FDD have nothing to do with “the kind of spectrum”.

    There are 2 directions of traffic flow to a subscriber’s device, download/upload (dl/ul). 

    FDD uses one set of frequencies to dl on and one set of frequencies to ul on. To make this simple, if we have 10MHz of spectrum to use, you would use 5MHz of the spectrum for dl and the other 5MHz of the spectrum to ul on. The advantage to this is that traffic will flow in one direction in each chunk of spectrum and the timing will always be consistent.  This is good for voip applications. (wireless companies) The disadvantage is the maximum capacity of data that can be dowloaded in that portion of spectrum. It is only 5MHz in each direction.

    TDD uses the whole 10MHz of spectrum to either dl or ul and it uses an algorithm to split the time that the subscriber(s) can talk to the base station. You could potentially use the whole 10MHz chunk of spectrum to get a faster dl to your device. You can typically set the amount of time and modulation level for ul/dl traffic. ie: 80% dl and 20% ul which makes perfect sense since most people that are on the internet are pulling data into their subscriber device whether it is on a wired or wireless connection.

    Of course there are a lot more details than described above but you can see why you would choose one over the other.

    • Thing is though, governments sell spectrum either in one contiguous block or in as a pair of blocks. The latter configuration makes up the bulk of the spectrum sold around the world. So yes, there is a “kind of spectrum”.

    • boettger1

      Ranger, you say TDD and FDD have nothing to do with “kind of spectrum” and then launch into an explanation of how TDD and FDD work. You have missed the point. Regulators tend to allocated blocks of spectrum according to the kind of duplex (FDD, TDD, or even simplex) that will be employed. For example, there are completely distinct allocations for UMTS-FDD and UMTS-TDD. So the “kind of spectrum” a carrier owns absolutely DOES impact their technology choice.

  • quintus murray

    sprint was GENIOUS TO DROP clearwire or should I say CLEARFAILURE!!!!!!!!

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