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The first hours of every year in Japan give mobile network managers a huge headache as spikes force all networks to severely restrict traffic.
One of the major causes of this traffic surge is that many Japanese visit their favorite shrine straight after midnight. This often results in long traffic jams and in long queues at popular shrines. As they wait, they contact or rather try to contact friends.
Changing customs is another factor. 'These days young Japanese prefer to send happy New Year emails, often to many friends simultaneously, instead of traditional cards. And each year mobile phone companies ask their subscribers not to call or send emails during those first hours of the new year, but to no avail,' explained Michito Kimura, senior analyst at IDC Japan.
KDDI's au network, for example, could successfully handle only 20% of calls and emails between midnight and 1 am on January 1. Both voice and email traffic hit their biggest spike at this time. Even au's relatively little-used C-Mail SMS service was affected because restrictions limit all kinds of traffic to the same degree.
NTT DoCoMo introduced a voice and data network separation management system last August, having previously implemented a similar system on its Mova network. The system enables network managers to restrict traffic on the data or voice network independently. When it was rolled out, it only worked with the newest 18 handsets and, therefore, only a small number of its subscribers.
Despite this move, during the busy New Year period DoCoMo had to restrict calls on its FOMA network by 70% and data transmission to a lesser extent. The company, however, didn't have to control calls or email transmission on its Mova (PDC) network, said Kunio Ishikawa, senior executive VP and managing director of DoCoMo's network division.
Softbank Mobile, which has also partly implemented network separation management, said it had to restrict traffic but would not give details.
Events like firework displays where huge numbers of phone users gather in one place can also stretch parts of the networks. However, operators can prepare in advance by dispatching mobile base stations. 'There are no other time of the year when we normally have to restrict traffic,' said a KDDI spokesperson.
Whether or not network separation management will eventually solve the New Year's Day traffic surges remains to be seen. However, there is a more important reason for its implementation. The most feared mobile traffic surge problems in Japan are the voice traffic spikes right after a natural disaster, which aren't merely an inconvenience but can be a matter of life and death.
All operators now have Disaster Message Board services and encourage subscribers not to make calls to contact people at disaster sites but to write text messages on the screen, which automatically appear at the top of their Internet portal sites at such times. However, without network separation management, this service can be interrupted by traffic restrictions to deal with voice call congestion.
Another reason to implement network separation management is that the move to flat rates, higher HSDPA data transfer speeds and the growing popularity of music downloads now have the potential to cause big surges in network traffic and create congestion problems at specific times or locations.