Tang YouXi: Discuss from Japan's emergency communication system that deals with the burst calamity
Doctoral supervisor, professor of electronic University of science and technology Tang YouXi
New York from U.S.A. " 9.11" The incident, the bomb terrorist attack of British London that get, and then enormous earthquake calamity reaching Wen Sichuan of China, in front of burst of large-scale natural calamity and accident, the public communication network receives the maximal challenge. The technology of the public communication network has determined, in the accident like violent earthquake in Wen Sichuan, if can't arrange for traffic to flow into rationally and flow control, not only users will think the telephone can not be typed at crucial moment, can't throw into outside the province, even influence and meet an urgent need the communication of important departments such as commanding, providing disaster relief, radio,etc. to need.
Bitterness' neighbor Japan of the earthquake calamity, has already basically set up the developed, system of the communication network of complete taking precautions against natural calamities at present too deeply, if the central authorities take precautions against natural calamities in the radio network, take precautions against natural calamities and interconnects the communication network etc., will further improve public communication network and communication network of meeting an urgent need to China in the future and draw lessons from meanings.
In sudden large-scale disasters such as the earthquake taking place in all parts of the world, terrorist attack,etc., apparatuses such as base station, aerial, optical cable,etc. even computer lab are damaged directly, sporadic enormous telephone traffic has exceeded the design limiting value of the commutation equipment, it is the major cause causing the network to be obstructive.
In addition, the public communication network designed for the social life of the constant state, its resource that can converse is far smaller than user's quantity and user's scale. Search the toll circuit data announced through Internet to the operator to see, Sichuan UNICOM has about 5 million users, offer 25,000 pieces of circuit provincial governor's ways, China Mobile is about 20 million users, offer 500,000 pieces of circuit provincial governor's ways. In the mobile subscriber of Sichuan total nearly 25 million, there are long-distance calls of simultaneously using. After the large-scale disaster of dashing for ward hairdoes takes place, nearly the simultaneously using telephones of several ten million users of the whole network, the users who can get through the long distance only account for 2.1% at most. In front of the burst disaster, often the heart has insufficient surplus energy in the public communication network, assaulted and can't meet the need that magnanimity users called out in the face of the traffic of magnanimity.
Another important reason of the disconnected network of the intersection of this earthquake-stricken area and large-area is, use wire transmission such as the optical cable in a large amount in the course of transmitting. When this kind of geologic hazard the earthquake takes place, wired transmission means such as optical cable are very easy to be damaged. Second fiber optic trunk cable is always 6039 -km-long in China Mobile Sichuan Province, cuts off 3866.5 kilometers, accounts for 64%; One in two long-distance optical cables from Xi'an to Chengdu of CHINAUNICOM is cut off.
Bring up the rear in the optical cable, the engineering time is long, easy to be damaged again again in the aftershock. The the intersection of Wen and Sichuan first rob into coherent Maerkang, get Li County get the intersection of Wen and the intersection of Sichuan and fiber optic communication cable in the violent earthquake, shaken and broken in the strong aftershock of magnitude 5.9 on the Richter scale of burst of Li County on the the afternoon of May 16 again. Adopt traditional wire transmission to guarantee the project communication network of network link, often an optic fibre is cut off, all communication interrupt.
Satellite communications has played a positive role in this violent earthquake in Wen's Sichuan, but satellite communications money Figo, the call rate of the Chinese satellite telephone is about 2 yuan every minute, maritime affairs satellite telephone is up to 20 yuan every minute; It is of great impact that the satellite telephone receives the weather, the signal is unstable, the delay time of conversation is longer. Moreover user that satellite mobile communication hold less, use limited and a lot of on a large scale, unable popularization of scale.
How the public communication network tackles the large-scale calamity of burst, it is a world-class difficult problem
The more developed the society is, the more serious to communication especially reliance of mobile communication. When the large-scale natural calamity takes place, the demand for the communication network of the bulky user's quantity presents explosive growth, and the definite realistic message capacity is far from meeting this demand. How to solve this problem, even in very developed in industry countries of communication such as U.S.A., Britain,etc., also still a difficult problem.
On July 7, 2005, the terrorist attack of exploding of bomb of experience of London, though the mobile phone revealed the full dose of signal, but can't phone normally. Among them, the operator BT of fixed net (British Telecom) Telephone traffic to be compared with the same period of last year interval of time two double; And move telephone traffic of Company, Vodafone of operator, explode and increase by 250%, message business doubled; Cable&Wireless Company stands the impact of nearly 10 times of telephone traffic at ordinary times, reaches 300,000 conversations every 15 minutes; Telephone traffic jumps and rises to from conventional 7 million conversations 11 million times on the same day to move the operator O2 Company, in several hours that increased 4 million conversations all concentrate after the accident happen mainly. At this moment, it is unprecedented that the traffic that the network suffers is assaulted.
In the violent earthquake in this Wen Sichuan, the public communication network of the disaster area has met the unprecedented challenge too, the networks of several big operators ask for emergency help completely after the calamity.
China Mobile have 4457 move base station, withdraw from the service because of deenergization, the intersection of optic fibre and the intersection of person who break down and reason; Shake the last a large number of users and set aside and phone with mobile telephone at one time, telephone traffic is ten times higher than at ordinary times, China has three switchboards that happen to move Sichuan Company congestedly; Optic fibres leading to epicenter regional Wen Sichuan, Li County, Mao County, Beichuan, Pingwu are all cut off, Wen Sichuan, Li County, Mao County, Beichuan, Pingwu become the communication detached island.
It is influenced that the mobile communication network of CHINAUNICOM has been received too severely: Backbone surround the intersection of network and northwest ring, nine schort break down, Wen the intersection of Sichuan and G, C two network all break down; Aba area G, about 200 base stations C two networks is paralysed; The communication of Gansu Gannan area 4 counties is cut off; The pronunciation of the main urban area of Chengdu is 7 times at ordinary times; The message is twice at ordinary times, the message is slow in communication; Shaanxi near 500th base station, area of Sichuan, break down, 8327 base station suffer from disaster, because base station retreat user that clothes influence reach 1,500,000 multi-households.
When large-scale calamity takes place, how to guarantee public users can transmit the valid communication information, noncongestion, capacity of the balancing network and demand for the telephone traffic of the communication information of guaranteeing to meet an urgent need, it is China and even question that the global operator demands urgently to think deeply.
Improve and meet an urgent need the construction of the communication network
At the time of this kind of burst disaster of dealing with violent earthquake in Wen Sichuan, in time, the valid guarantee communication is the task of top priority. Here, we can use the case of explosion of subway of London and some experience and lessons which Japan obtain in the earthquake for reference, it is started with that network of taking precautions against natural calamities,etc. is all-round from building and improving the public communication network and meeting an urgent need, improve the traffic carrying capacity of period of the special calamity.
