Wednesday, February 29, 2012

Softbank Mobile wins low-frequency (900 MHz) allocation

Here's what you can do when you get rid of analog TV broadcasts. Repurpose bandwidth. In Japan 900 MHz became available after TV went all digital. The original plan, as I was aware, was to auction it to the highest bidder. That would have been a disaster for SBM. Either they'd have to really shell out the yen or continue to be the only one of the Big Three without a low-frequency allocation. Low frequencies are attenuated less and penetrate deeper underground and in mountainous areas.

However, it turns out that the MIC gave it away based on need. After evaluating the state of network congestion of each of Japan's four carriers, who all applied for it, SBM was awarded the band. This will help with their LTE plans. [Update: SGM deployed 900 MHz for 3G.] Emobile would have also liked to have had it, as they not only have no low frequency band, but also have an exotic frequency not used by other carriers. It will be interesting to see how this effects Emobile's LTE plans. It doesn't even overlap with AWS used by US T-Mobile.

Below is how the higher-frequency bands are distributed between Japanese carriers. It becomes obvious why US T-Mobile handsets work with Docomo.
The overlap is just an idealized IMAGE. The curves are just a gaussian fit to a uniformly distributed histogram of random numbers between the ranges of each band's up and downlink. I have no idea how power is actually distributed within the spectrum.

Sources: IT Media and Sven.


  1. Christian RodriguezMarch 16, 2012 at 10:38 AM

    Based on this, do you still strongly stand by KDDI instead of Softbank if you were buying an iPhone in Japan?

    (I'm a new foreigner in Sapporo looking to buy an iPhone. Androids gave me too many problems back in the states.)

  2. Right this moment? Yes. Especially if you are in more rural areas. In the future, it could be different. However, for the current iPhone to benefit from this, SBM will have to use this band for 3G. I'd expect they use it for FD-LTE.