Summary and RecommendationsBased on what I've read, I think Softbank Mobile (SBM) will lack the network capacity to smoothly allow tethering on their FDD-LTE network until at least the end of the current fiscal year. SBM will repurpose one of it's four 3G channels to LTE. This could negatively impact existing 3G users and will only provide a single 10 MHz channel for FDD-LTE. The theoretical maximum downlink speed will accordingly be half that of NTT Docomo's XI and KDDI's 4G LTE networks.
Given SBM's well known network issues, the switch over to LTE could be a real disaster if not handled correctly. Miyakawa even said it'd be his job if it fails. As noted by Ishikawa, come 9/21, the media will be all over KDDI's and SBM's new LTE networks, and you know they're going to be testing in the most congested areas.
Concerns over network congestion aside, for me, the lack of tethering would be a deal breaker if I was in the market for an iPhone 5. After having used tethering for free with an NTT Docomo Xi SIM and various Nexus phones (all of them, actually) for the better part of a year, and with b-mobile prior to that, I simply cannot go back to life before tethering.
Therefore the KDDI iPhone 5 is recommended over the SBM iPhone 5.
Service start and build outSBM will begin it's 4G LTE service with the launch of the iPhone 5 on September 21. According to Miyakawa, SBM plans to have 91 to 92% of the population covered by March 2013, compared to KDDI's plans for 98%, though Miyakawa mischaracterized KDDI's coverage goal as the same as SBM's.
Speed and coverageSBM currently has deployed in urban areas 4 channels (20 MHz x2) for 2100 MHz 3G service. A fifth channel is used for the 900 MHz "platinum band" and will remain in use for 3G. SBM will take one of the 2100 MHz channels and dedicate it to LTE. Within the next fiscal year, Miyakawa would like to be able to dedicate a second channel to LTE.
Until that happens, SBM LTE 4G will be limited to a theoretical maximum of 37.5 Mbps, half of the NTT Docomo Xi and KDDI 4G LTE maximums. A second channel will be immediately secured for use in Saitama and Gunma prefectures, allowing 75 Mbps.
Removing one of these channels from 3G service will be particularly tricky inside the Yamanote Line, especially from Shinjuku to Shinagawa, around Ikebukuro, and between Akihabara and Ueno.
SBM is adding about 2000 base stations per month for each of it's 1) W-CDMA 3G (platinum band), 2) TD-LTE (acquired from wilcom), and 3) FDD-LTE networks. If they can keep up this pace for a year, by the next fiscal year they should be able to add an additional 10 MHz channel to platinum band, setting them up for low-frequency LTE coverage at a later date.
Comparisons to KDDI 4g LTEMiyakawa believes they have more experience with 2100 MHz and KDDI is going to have to catch up. As a result, KDDI is likely to have more gaps in urban coverage areas. He also points out that KDDI will be incapable of simultaneous voice and data, but again mischaracterized SBM's own capabilities, implying that they can do simultaneous voice and LTE.
No carriers are yet capable of VoLTE (voice over LTE), so data falls back to 3G when a phone call is initialed.
On the lack of tetheringAccording to Miyakawa, the business department is rushing to make it available, but until things calm down a bit, it will be difficult to implement. Currently 4% of users consume 50% of SBM's capacity, and this bias will only increase if they allow tethering. Rather, Miyakawa would like to focus on getting the large number of feature phone users converted over to smartphones but needs to be careful not to shock them with sky-high data prices.
Regarding whether it would be possible to allow tethering with the 7 GB data cap, Miyakawa indicates that it is likely but needs to be carefully considered. His most ideal scenario would be an additional tethering charge.
I'll note again that tethering is free from KDDI for the next two years and free with NTT Docomo.
The way I see it is the only way to institute a tethering charge is by working the premium angle of the iPhone experience. Androids do it for free with Docomo's LTE network. So they'll need to exploit an image of Apple quality - whether this image is correct is of no matter. It's clear that Apple users are more inclined to pay premium prices as evidenced by the number of ad-supported apps on the Google Play Store that are only available as paid apps in the Apple App Store.
The future of TD-LTEI always saw the AXGP network acquired from Wilcom as a stop-gap solution to the lack of FDD-LTE. In the end, the success of this could be argued given the likely large number of disappointed users because it was unclear why the iPad 4G LTE version didn't work with SBM's "4G LTE" network.
Anyway, as mentioned above, this network is alive and well and being expanded. According to Miyakawa, it easily provides 30 Mbps connections. While he'd love to see it supported by the iPhone, he's not surprised that they've not gotten an affirmative answer, since SBM is the only carrier in the world actively using TD-LTE.