I am at Wireless Japan 2011 in Tokyo right now. On the first day, CEOs of all wireless carriers are speaking at Keynote, and found that DoCoMo’s Mr. Takashi Yamada’s talk about their disaster readiness plans quite interesting.
As I have been reporting in this blog, DoCoMo has been quickly recovering their damaged service and as of now, service is recovered at most of the affected areas. One of the remedies that they took was to build small number of backup large zone base stations on high ground, instead of rebuilding each individual small zone base stations. In Fukushima Daiichi Nuclear Plant area, they built a special long-range base station at the outer edge of the 30km radius area, facing towards the Nuke Plant for the people working on the recovery effort.
In addition to the direct recovery effort, DoCoMo is introducing 20-billion yen scale disaster readiness plans across the nation. Some are regular things such as increasing the satellite phone inventory, and my favorites are those two.
1) Large zone backup
DoCoMo is building the backup base stations on top of the DoCoMo/NTT switching offices, where robust power back up is available. It gets lit up to cover 7km radius when a disaster strikes and regular base stations are down in the area. They are building average of 2 of these backup stations per prefecture (5 for Tokyo and 4 for Osaka).
2) Voice transfer system
Right after the earthquake this time, they had to limit circuit switch voice traffic by 80%, but data could get by with only 30% limit. However, some people still have difficulties in using e-mails, so they are planning a backup voice file system to be implemented this fiscal year. When a caller makes a call but hits the limitation, the circuit automatically diverted to the voice mail system, and the voice message gets turned into a voice file and gets delivered to the destination phone number in digital voice.