Au "4G LTE" communication obstacle 700 yen refund & iPhone trade-in review under consideration, further investment totaling 30 billion yen for facility expansion

A PDF file on causes and countermeasures was released on KDDI, which caused a communication failure of 4G LTE compatible models for a total of three times, once at the end of April and twice at the end of May. According to the report, a bug in the LTE base station controller (MME) caused a communication failure in April, and file input to correct it caused a communication failure in May.

Causes and countermeasures of a series of LTE communication failures | 2013 | KDDI CORPORATION
http://www.kddi.com/corporate/news_release/2013/0610a/index.html


Cause and measures of a series of LTE communication failures (2.8 MB) (PDF)
(PDF file)http://www.kddi.com/corporate/news_release/2013/0610a/pdf/sanko.pdf


Data communication · voice communication failure occurred 3 times, 27th April, 29th May, 30th May. The occurrence time is 6 hours 17 minutes on April 27, 18 hours 43 minutes on May 29, and 9 hours 58 minutes on May 30. The influence is maximum in some parts of Tokyo, Kanagawa and Yamanashi prefectures It reached 640,000 cases.


Outline of disability


Here is an illustration of how connection management at the LTE base station is. Communication from the terminal flows through two base stations MME 01 and MME 02 via the base station.


On April 27th, due to the reset bug, MME01 became unusable (disconnected from one side), inducing a recovery process bug, the remaining MME 02 also collapsed and both systems were broken.


On May 29th, I was introducing a correction file to MME 01 to cope with this bug, hardware failure occurred, and the system was disconnected due to switching back. Then, MME02 takes over the processing of MME01, but some congestion occurs here, a recovery processing bug occurs again, and both systems are disconnected.


On 29th May, not only data communication but also voice communication failed. This is because a congestion occurs due to a large amount of connection notification to the subscriber information management system (HSS) due to the 4 M LME compatible terminal moving from the LTE network to the 3 G network, and the connection to some HSS There is a terminal which is not normally performed, and which makes it difficult or impossible to send / receive voice.


I tried to populate MME 01 with a correction file on May 30 and 29 as well, but since a specific process was overloaded during the preparation, it was disconnected from one side. Congestion occurred in the handover process to MME 02, a recovery processing bug was induced, and both MMEs were disconnected.


There are critical issues such as "dealing with reset bugs related to fragmentation processing" and "coping with recovery processing bugs", but it is said that it is in a situation where it can be operated stably right now.


We have decided to restore, review the monitoring system, and implement capital investment in response to the communication failure on 27th April, but the MME extension schedule ahead of schedule due to twice communication trouble at the end of May , And capital investment totaled 30 billion yen.


The schedule is like this. According to KDDI, the number of installed MME is currently 19, but it is planned to increase to 50 at the end of August and 58 at the end of September.


Those who are affected by this communication failure will be charged 700 yen on the invoice. The target people will be contacted by e-mail such as "Important Notice" by the end of June.


In addition, this document also explains the mechanism of LTE once again. The difference in bandwidth used by Android LTE terminal, 2.1 GHz band LTE terminal (iPhone 5 etc.), 3G terminal is like this.


And also mention about real population coverage rate. Android's LTE terminal covers 97% with 75 Mbps maximum service. Even for LTE terminals using the 2.1 GHz band such as iPhone 5, it covers 71% at the end of May at 37.5 Mbps and 20% at 75 Mbps service even at LTE terminals.


Tanaka, president of KDDI considered trade-in in the form of compensating purchase price when buyer of iPhone 5 replaces to another terminal, in response to the problem of excessively displaying real population cover rate of iPhone 5 It is said that.

Trade in iPhone 5 trade-in au, cover rate over-displayed - 47 NEWS (Yona no news)
http://www.47news.jp/CN/201306/CN2013061001001594.html