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Provide a peace of mind High-Capacity Optical Communications (Next-Generation Communication Network)

Interesting “Technology world”

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The Information and Communication Technology Contributing to the Construction of a Safe and Convenient Society

Capability of Communications to Compress Time and Space

The internet as social infrastructures.
The internet has become very familiar. Little discoveries and ideas, in our daily life, run around the internet. And there are people on the other side of the earth sharing the information in real time. Watching a movie on a train, completing in the free time and submit a document that has unfinished and so on; it is becoming a commonplace to do what one wants without bringing data.
If you can enjoy such a convenient and delightful internet, you can not quit to hold it, are you!
However, until we get into this stage, we have repeated a lot of technological discovery and break through in the world of the communication. In 1980s, computers were personalized from the general-purpose machine. From the middle of 1990s to 2000s, PC communication was generalized in accordance with the spread of the broad band and information communication amount was increased rapidly. In accordance with the improvement of mobile communication environment, mobile phones were spread. And based on the spread of smart phones merged with PC function, barriers were lowered infinitely and anyone can send and receive information at any time any where.
It is Information and Communication technology (ICT) that realizes the request of individuals without delay. In these 20 years, according to the progress of ICT in the mouse year (Note 1), more than a dog year (Note 2), internet became indispensable to be called a social infrastructure.

(note 1) mouse year: Words to liken mice that grow faster than dogs, in relation with the faster continuous change and innovation than a dog year.

(note 2) dog year: Words to liken a rapid change, in relation with dogs that grow in 7times faster than human being.

What Benefits are Provided by the Development of Information and Communication Technology?

The information and communication technology builds ties from people to material things and among material things, as well as among people. It is beyond the scope of personal use, and supports to realize a comfortable society and a safety region. For example,

  • Real time management of electric power usage. → energy saving and optimized electric power generation.
  • Real time processing of traffic information. → Traffic jam relieving.
  • Realization of the disaster signs detection, prevention from the disaster also guiding for early evacuation and minimizing damages.→Safe society.
  • Collection and analysis of big data→ Panic avoidance in times of disaster, activation of market by understanding the preference trend.
  • Remote control of situations in the home and lockups using mobile equipment. Hence, a safe and secured society.
  • Implementation of e-learning systems, where videos and communication technology are combined to enable free-time, free-selection learning. Hence, an education-oriented society.
  • Sharing of sophisticated medical treatments by means of coordinated hospitals connected online. Hence, realization of medical levels equalization.
  • Virtual home visit of a doctor based on a local network. Hence, elimination of the problem of shortages in doctors.
  • To have a chat with one's grandchildren who live far away using a digital television. Hence, an aged-people-friendly society.
  • Online shopping and buying and selling of secondhand goods. Hence, a convenient society saving time and money.

In the future, much more ideas will be realized.

Solutions to support the ever-increasing communication traffics.

In accordance with the expansion of the wireless communication networks based on the spread of mobile devices such as smart phones, and the spread of cloud computing, video distribution and social networks, communication traffic is continuously and rapidly increasing.

Communication amount, in Japan, increased by more than 30 % in comparison with the year before, also the world wide communication amount is estimated to be increased by 80 %. Cisco Systems predicts that the world wide mobile data traffic will be 11 times increased in 5 years, from 2013 to 2018.

Grasp of the total traffic in the internet in Japan. By Ministry on Internal Affairs and Communications
Grasp of the total traffic in the internet in Japan. 
By Ministry on Internal Affairs and Communications

Source: Grasp of the total traffic in the internet in Japan.
By Ministry on Internal Affairs and Communications, published in 2013 August.

To maintain such advanced information society, it is necessary to realize ultra-high-speed and large-capacity transmission of the entire network system, from trunk network (inter-city communication) to metro (within city communication), access network (user side end circuit) and to server or router. For this purpose, provision of the entire optimum solution, from the trunk line such as optical fiber cables and optical communication systems to optical devices and terminal equipments for communication, is desired.

Network Technology in the New Generation

It is said that the expanding traffic amount, electric power consumption, threat of security aspects against cyber attacks and vulnerability in disasters are the issues of the current networks. To overcome these issues, technology developments and standardization are promoted.

As countermeasures for the ever-increasing communication amount, following approaches are taken.

  1. ① To increase the number of light (the number of wavelength) transfer in one optical fiber.
  2. ② To increase the transmission capacity of one wavelength (improvement of the transmission speed).

The next figure shows the optical communication liken with the movement of vehicles.

The traffic is jammed by the increase of the traffic amount.

To increase traffic lanes. (① To increase the number of light (the number of wavelength) transfer in one optical fiber.)

Even the lane number reached to the limit. (The number of incoming light reached to the limit.)

To raise the speed of vehicles. (② transmission speed up)

High performance car (Racing car) is necessary.

Optical digital coherent transmission

By transferring 4 wavelength of light in one optical fiber, transmission information amount is increased to 4 times. By increasing signals transmitted in one unit to 4 times, information amount is increased to 4 times. In other words, by transmitting 4 wavelengths of light in one optical fiber, and increasing the signal density of each wavelength to 4 times, 16 times of information can be transferred in one optical fiber. This is focused as the technology to increase the transmission capacity of one wavelength; it is the optical digital coherent transmission technology.

The optical coherent transmission is the technology to transmit and receive signals by controlling phase and amplitude using the interference phenomenon of two light that maintains high-precision relationship between the phase and the amplitude. Currently, introduction of large-capacity transmission systems of 100 Gbps (Note 3) have been promoted in earnest all over the world.

Furthermore, developments and verification tests have been underway to realize the optical digital coherent transmission of ultra-high-speed 400Gbps. As a direction, high efficiency of the phase modulation method is the most promising; and such as 16 QAM (Note 4) multilevel modulation technology, Nyquist filter technology (Note 5) have been studied.

(note 3) 100Gbps is a transmission speed capable to transfer data stored in one DVD (4.7 Gb) in approximately 0.4 sec.

(note 4) 16QAM (quadrature amplitude modulation):
This is a kind of digital modulation technology. This technology is available to transmit 4 bit of information simultaneously, by making a symbol with 16 values combining the two straight going phases and modulation of 4 levels of amplitude. By subdividing the identification of the amplitude, further high-density technologies of 64 QAM (6 bit) and 256 QAM (8 bit) has been studied.

(note 5) Nyquist filter technology:
This is a technology to achieve a high density wavelength division multiplexing to increase the utilization efficiency of frequency. Conventionally, due to overlapping of tails of the adjacent pulses, it was difficult to identify during transmission, then there were no choice but to spread the interval of the adjacent pulses (signal). However, this technology makes possible the accurate information identification even the adjacent pulses are transferred with overlapped tails. Therefore, the technology makes possible to utilize the packed signal frequency.

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