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👩‍🎓 | Saitama Prefectural Junior High School allows you to bring your smartphone conditionally


Photo Handling of mobile phones by school type

Saitama Prefectural Junior High School allows you to bring your smartphone conditionally

 
If you write the contents roughly
For each prefectural school, regarding the handling of mobile phones in the school, based on the actual situation of each school, the guidance policy of each school is set according to the basic guidance policy, and it is made known to children and parents, and children and students Is requested to take appropriate measures.
 

On January 2021, 1, the Saitama Prefectural Board of Education told prefectural schools "Basics regarding the handling of mobile phones in schools ..." → Continue reading

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Wikipedia related words

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Mobile phone

Mobile phone(cell phone,British: mobile phone) IsWireless communicationMade it possible to carryTelephoneIs[1]. Also,TelephoneIn the form of carryingMobile communicationsystem,Telecommunication services.TerminalThe携 帯OrMobile phoneMay be abbreviated.SmartphoneIs a type of mobile phone.

Mobile phonewireless deviceBecause it is a kind ofRadio ActIs regulated by.A mark indicating that mobile phones that are generally distributed in Japan comply with the technical standards stipulated by the Radio Law (Technique mark) Is engraved.

Definition

As a category of "mobile phone" in the narrow sense of the world,iDENSuch asSecond generation mobile phoneUses the following standardsDigital MCA radioSuch asMobile communicationMobile devices,Wireless licenseUnlicensed Personal Communications Services (UPCS) AndPHS,DECTSo calledLow power radio stationThere are mobile terminals, etc.

History

Concept time

The idea of ​​the mobile phone existed from the time when the phone was invented. It was a dream that people could communicate wirelessly using radio waves and that humans could talk to each other by voice.Morse codeThe wireless telegraph that uses is a base technology for mobile phones, but it was not considered at this time that it would explosively spread even if it was put into practical use.

In addition, although concrete research to develop a mobile phone has been conducted for a long time,noiseProblems andbatteryIt was difficult to realize because the telephone becomes very large due to many problems such as (XNUMX) and communication speed.

Car transceiver from transceiver

The predecessor of mobile phones isSecond World WarinsideU.S. ForcesUsed byMotorolaMade oftransceiver"Walkie Talkie"(SCR-536).

In 1946 after the war,AT&TIs a wireless telephone line service(English edition)Started. This is a walkie talkieWireless phone, While using a dedicated wireless line, by using a public telephone line, wireless communication has been extended to the general service. In this way, mobile communication services have become available in addition to fixed communications in the private sector. However, at that time, a telephone that could be carried by a person on a daily basis was not technically put into practical use, and what could be installed as an in-vehicle telephone was the limit of miniaturization. Following the United States, similar services have started one after another in European countries. This wireless telephone line service will later be compared with the newer mobile telephone line service (1G-5G),0GCame to be called (Retro Nim).

Fully automated wireless telephone line service in Sweden(English edition)The service was started in 1956. Although these services were difficult to reach the general public in terms of practicality, they were launched in Finland in 1971.(English edition)The 0G serviceMobile communication networkIt became the first successful example that was widely used by users, because it could be used throughout the country for seamless coverage of radio waves.

1960s-1970s: Efforts toward terminal miniaturization

Before that, it could be installed in cars, motorcycles, and other vehicles, but it was impractical for people to carry.1960 eraThen, it became possible to make it small enough to hold a conversation with both hands, but it was heavy enough to get tired even for a short time.1970 eraIn that case, I reduced the size to a size that I could hold with one hand if I worked hard.

1970å¹´ToOsakaHeld atJapan World ExpositionThen,Wireless phoneThe cordless phone, which I will call later in the year, was exhibited.[2].. This is a device that allows radio waves to travel only a few meters and allows terminals to talk with each other in the venue, and is strictly different from a telephone that uses a public telephone line.[3].

1973å¹´April 4rd, Motorola engineerMartin cooperDemonstrated the prototype of the world's first handheld mobile phone that can be connected to an actual wireless telephone line to make a call. At this time, he was in charge of mobile phone development rival Bell Systemen: Joel S. EngelI called to[4].. The phone is cordless, weighs 1.1 kg, measures 23 x 13 x 4.5 cm, and could talk for 30 minutes on a single charge, but it took 10 hours to recharge.[5].

Late 1970s-early 1980s: Practical era (car phone)

1979年IsJapanIn1rd generation mobile communication systemThe service that adopted (1G) was put into practical use for the first time in the world.This was a new technology with improved speed and coverage over the 0G mentioned above.However, this used an in-vehicle phone like 0GCar phoneAs a service, mobile phones for people to carry have not yet been realized.1981年ToバーレーンとScandinavianServices have also started in the region.

Incidentally,アメリカ合衆国Then.1978年ToAT&TとMotorolaHowever, the permission for the practical application was issued, but it was not realized. The lagging country was Motorola'sRonald ReaganPresidentThe direct appeal to was also successful, and it was put into practical use in 1981.

It started as a business around 1980, and someDeveloped countryThe sale and service of mobile phones as in-vehicle phones (car phones) has started. Back thenFixed-line phoneBoth the introduction price and communication cost are several tens of times compared to the machine, and the communication area was limited to the urban area, so only a limited number of users introduced it.

Around the mid-1980s: era of practical use (portable type)

Not in-vehicleportableAs a type, it was released by Motorola in 1983.Motorola DynaTACIs the world's first handheld mobile phone.

in Japan,1985å¹´NTTShoulder phoneHas been released. It is carried around the shoulder and weighs 3 kg.[6]was. The so-called mobile phone was released by NTT in 1987 and has a volume of 500cc and a weight of 900 grams.[7][8]was.

1990s: Digitalization/multifunctionalization

1990 eraThe spread of terminals has becomeLiquid crystal displayStarted to be installed. Also, starting in Finland in 1991, in Japan from the mid-1990s2rd generation mobile communication system(2G) service has begun and the communication method isanalogからデ ジ タ ルIt moved to. As a communication standard,GSMAnd the AmericanCDMAwas there. by this,着 信 音You can set your favorite musicRingtone melodyAndPagerSolidarized withMessage serviceIs now available.

In 1999i-modeStarted in Japan,インターネットYou can connect to the network, improve communication speed,JavaIt was usedゲームIt became possible to use such as.

Since 2001: 3G era (fusion with the Internet)

2000 eraWhen you enter3rd generation mobile phone(3G) will appear.2001年First in the world, 3G (W-CDMA) commercial service started in Japan.VideophoneHas become possible,computerIt became possible to perform high-speed data communication by connecting with. Also,Last one mileBecause the problem of is easy to solveDeveloping countryHowever, it began to spread explosively, and according to the announcement by the British research company “Informa Telecoms & Media” on November 2007, 11 (UK time), the penetration rate reached 29% worldwide.[9].. thingAfricaIn Japan, the fixed infrastructure was stagnant while the penetration rate of mobile phones andPotential marketIs expected to be huge, and the rapid growth of the market is attracting attention[10]But on the other handelectricityIn areas where infrastructure development has not caught up, it is essential to use mobile phones.电源AsAutomobile OfbatteryKarayaHuman power generationA business like a "charger" is also emerging.

In the history of its development, mobile phones were initially focused on miniaturization and weight reduction.However, by this time, a somewhat easy shape was realized,カメラOr browsing the internet,Mobile wallet, Waterproof, solar charging, XNUMXSeg and other additional features were factors that differentiated the product (for details, seeMobile phone # terminal in JapanSee also).

As competition in the mobile phone industry intensified, manufacturers were competing with each other in developing terminal designs and functions, which would be a great attraction to users.However, hold it in your handNumeric keypadDifferentiating it is not easy under the common conditions of maintaining the function of making a phone call.Touch panel,Gyro sensorIt was inherited by smartphones after using modern cutting-edge technology such as the adoption of.

Feature phones can be roughly divided into three types: "straight type", "folding type", and "sliding type".Although not mainstream, there were also "flip type", "3-axis hinge type" and "rotary type".

Straight type
Basic form of mobile phone. The control panel and display screen are in the shape of a bar. Since the display screen is exposed outside as it is, it is easily scratched. In addition, the display screen is becoming larger and larger, and it is difficult to make it compact. With the widespread use of folding and sliding types, the number of straight type models has rapidly decreased.
Foldable
The display screen becomes larger as the mobile phone becomes more multifunctional, and the flat type tends to be larger in the straight type, and from the viewpoint of protecting the operation unit and the display screen when not in use, a hinge is provided in the middle of the main body. It is designed so that it can be folded in half. It tended to be thicker than the straight type, but later technological innovation introduced a very thin product even in two folds.
The foldable type can protect the screen and operation part, but the cable that exchanges information between the two at the hinge and the fulcrum of folding is subject to stress, so it is easy to break, and there is a possibility of breaking if bent too much beyond the movable range of folding. Also, if it is closed, you cannot check the caller at a glance when you receive a call or mail, you cannot start the operation quickly because the opening/closing operation is required, and opening/closing is annoying if you use it frequently for a short time. There are drawbacks.
In order to improve these drawbacks, models with a sub-display on the back and models with a mechanism that opens the liquid crystal by spring force when you press the button on the side without opening the liquid crystal with both hands have appeared. ..
Sliding
Opening and closing system that slides horizontally horizontally by rails. The main body is divided into two layers, an upper layer liquid crystal part and a lower layer operation part, and the operation keys inside the operation part are exposed by sliding the liquid crystal part. Unlike the foldable type, the display is exposed on the surface, and many of the basic functions can be used without sliding.
It has the advantages that the display part can be designed larger than the straight type and foldable type, it can be made compact, and it can be easily opened and closed with one hand unlike the foldable type. On the other hand, like the straight type, the display is easily scratched, and the buttons on the lower layer are often smaller due to the space of the slide mechanism. In addition, a button may be pressed when sliding, causing an unintended operation.
On some models, the cross key/menu key, etc. are mounted on the liquid crystal part, and the numeric keypad is installed separately on the operating part.
The former has the advantage that it can be used as a key with the same size as a foldable type, which allows basic operations even when it is closed. On the other hand, it tends to cause unintended movements when sliding. The latter has the advantage that the cross-shaped key/menu key and the numeric keypad can be made thinner, and the fingers can easily move back and forth between the cross-shaped key and the numeric keypad. On the other hand, since the area of ​​the operating portion is small by the amount of the slide mechanism, the keys are small and there is a drawback that accurate key operation is required.
Although it is a very small number, it is horizontally long and the short side slides up and down, making it more suitable for entering characters than the numeric keypad.QWERTY arrayThere is also a model equipped with a button, which targets heavy users such as Internet browsing and email.
Flip type
As a derivative type of the straight type, there is also a type called "flip type" in which only the operation key part is covered with a folding cover and the cover is opened when used, but such products are few after the spread of the folding type.
2-axis hinge type
As a foldable derivative type, the "2-axis hinge type" is a type that has two rotating shafts and can rotate not only vertically but also horizontally. The ability to rotate the screen sideways is aimed at achieving comfort when watching 2Seg or video and operability like a digital camera when shooting with the camera. You can select the vertical, horizontal, and opening method suitable for the usage scene.
Rotary
Slide in the horizontal plane as in the slide system. Instead of a vertical slide like the slide type, the "rotary type" rotates horizontally around the axis above the numeric keypad.SO505i(Docomo, SONY) andA5305k(Au, Kyocera) and so on. It was called “180° style (one-eight style)” by SONY and “revolver style” by Kyocera.
Slide + rotation type
As a more minor shape than the rotary type, there was also a system that combines vertical linear slide and horizontal rotation. docomo F-09AHas been adopted by.

From the 3rd generation onward, PC-like display of the Internet browser and mail,One SegIn addition to the 16: 9 screen ratio so that you can view such things on a large screen, the function to switch to the horizontal screen display when tilted sideways has become widespread.

Since 2007: smartphone era

From 2007Mobile information terminal(PDA) has evolved further, and the only difference from the personal computer is the difference in processing capacity.SmartphoneIs widespread. Prior to 1999, several extended products that combined the functions of mobile terminals with PDAs with certain processing functions were sporadically released, and some existed.[11]Was released in 2007iPhoneAs a result, attention has been focused on smartphones (in Japan,2008å¹´On saleiPhone 3GHowever, initially the demand remained mainly for enthusiasts and some business people. With some manufacturers that had their own OS ahead of the iPhone and acquired users who were interested in some advanced devices,GoogleandOpen Handset AllianceDeveloped byAndroidVarious manufacturers with OS asMicrosoftTo developWindows MobileAnd the OS that followed Windows was installedWindows Phone(Manufacturing is a mobile phone manufacturer)2010å¹´From each carrier, when Android-equipped smartphones were released one after another, general users were interested in smartphones, and explosive spread began.

However, some users have higher communication costs, are difficult to understand, and have a feeling of refusal to smartphones such as poor battery life, and they are still conventional as of 2015 in Japan.feature phoneThere is a demand for However, because the feature phone has a heavy burden on the manufacturer because the terminal is designed exclusively, it seems that the inside is an eclectic type that uses the same as that of the smartphone while following the feature phone (Garaho) Has also appeared[12].

In the 2010s, it became even faster with the development of 3G4rd generation mobile phone(4G) Service has begun.WiMAXThe method is AmericanLTEThe scheme was first available in Scandinavia.

From 2018 to 2019,5rd generation mobile phone(5G) Service operation has started locally.

Mobile phone

TerminalIn general society and everyday life, the main body is simply携 帯Often referred to as "(keitai)", the word "mobile" is used as a general term for mobile phone terminals and is completely established.On the other hand, it is also a mobile terminalPager,PHS,PDAWas often distinguished from "mobile".

Also known as "Mobile phone""MobileIt is often written as ".NTT DoCoMoOr "Denden FamilyIn the technical document produced byMobileIt is often written as (palpitations).In the smartphone erasmartphoneThe opportunity to be called has also increased.

Components

As a common part from the beginning to the smartphone,antenna,speaker,MicrophoneAnd control theseElectronic circuitAnd there is a power supply.

On many terminals since the 2000sdisplayIs equipped withliquid crystal,Inorganic EL,Organic EL,Light emitting diodeVarious materials are used. The antennas were mostly exposed in the early model products, but the number of models with built-in antennas increased in the middle of the 2000s, and most of the current antennas are built-in type (One SegCompatible models have a TV antenna).In the feature phone era, each company's original design was characteristic, and the number of unique functions tended to increase one after another.In the early days of the smartphone era, many were strongly influenced by the iPhone, but with technological innovation, various styles are reappearing.

电源

The power supply is initiallyPrimary batteryWas used,Secondary batteryBy the development ofNicad batteryandNickel/hydrogen storage batteryBut since the 2000sLithium ion batteryIs the mainstream. The mobile phone bodyChargerIt also serves as a secondary battery charging circuit.Therefore, by connecting an external power supply, charging is possible without removing the battery from the main body.Depending on the model, a dedicated charging simple stand is attached.

As an external power supplyAC adapterbyDC power supply, USB power supply,QiEtc. are used.With direct power supply, household power supply is used as the power source, 3.7-5VIt is supplied with the voltage reduced to the extent.

Arithmetic/storage device

With the digitization of terminals, computerization has advanced using a baseband LSI that controls communication processing.Flash memoryThe non-volatile memory device has an auxiliary storage area. This made it possible to add variations to the ringtone.

On a mobile phoneMobile browserMoving images, music,マ ル チ メ デ ィ アWhen it came to handling data, it became independent of the baseband LSI.CPUCame to be installed. The need for auxiliary storage increased further, and the capacity of the built-in auxiliary storage was insufficient. Therefore, in the 2000s,memory card OfslotIt is also possible to record to an external memory. In the beginningSD card,Memory stickWas used, but because the volume occupied by the terminal was large,miniSD card,microSD card,Memory Stick DuoMemory cards specialized for mobile phones such as these have been developed.As technology evolved to enable large-capacity communications, the means of storing in cloud storage also appeared.

Features

With normal call functionSMSThere are various products, from classic models with only a single function to high-performance smartphones comparable to personal computers.The price of the terminal is proportional to the function due to the separation of the line contract and the terminal,contentSince high-performance terminals are not required unless services are required, inexpensive and basic-function terminals are also very popular.In Japan, even high-performance (expensive) modelsIncentiveSince the business model of distributing at low cost was adopted by (sales incentive), high-performance feature phone models became widespread.Also South KoreaMobile phones are also known for their high-performance models.

Mobile phone with cameraAppeared,カメラBy the image analysis function using the functionQR code,JAN codeCan be read. In particular, QR codes have become popular because they can store a large amount of character data (reference:Mobile device).

OS

Dedicated OS

Often used in the 2000soperating system(OS),Symbian OS(Symbian),REX OS/BREW/ (Qualcomm),ITRON/T-Engine(TRON Project) Other than that,OS-9,Nucleus RTOS, China MobileSoft, MIZI, SavaJe.LinuxThere is also an OS (,) based on the kernel.

OS-9, Nucleus RTOS, iTRON etc.RTOSFrom Symbian OS, Linux, etc.General-purpose OS for mobile phonesAdoption of 3G is due to the arrival of XNUMXG and its developmentcostIs rising. Since the functions of terminals are becoming more sophisticated and the scale of software is becoming huge, RTOS that assumes embedded applications that operate with limited hardware has many cost disadvantages such as development environment and middleware procurement. Is coming. There is also a hybrid OS implementation that "RTOS takes charge of communication control, and general-purpose OS is responsible for operation of user interface and application", but it is difficult to operate two OSs in cooperation, and it is a general-purpose OS that improves real-time performance. It tends to be integrated into the OS.

NTT Docomo is a platform that shares the OS and middleware above it with terminal makers.MOAP,Operator packWas developed. The OS part uses Symbian OS or Linux. Until then, each terminal maker has developed its own mobile phone interface, middleware, etc. However, the common platform can reduce development costs and improve development speed.

Similarly, KDDI uses Qualcomm's REX OS, BREW, and Brew MP as their bases.KCP(2005 summer model-until spring 2015 model),KCP +(2007 winter model-until 2011 summer model),KCP3.x(2010 summer model-2014 winter model) has developed a common platform.

OS for smartphone

SmartphoneOS foriOS,Android,BlackBerry,Windows Mobileand so on.

In particularGoogleWith androidア ッ プ ルIOS accounts for 98% of the market share (as of 2019, according to IDC research).

software

While a mobile phone has a limited memory space, it is a high-performance electronic device equipped with many functions, and therefore has dedicated software.Windows,MacOSThere are cases where a subset of PC OS such as is installed, but since the PC application did not work as it is,chromebookThere is also a move to aim for compatibility with personal computers.

Manufacturer

Mobile phone production (XNUMX units)
Country1998å¹´2000å¹´2005å¹´Ratio (%)
People's Republic of China1,0264,10026,68735.0
South Korea1,9405,75019,86026.0
Japan3,4085,5354,7036.2
Taiwan53504,5606.0
Malaysia1904802,2362.9
Singapore1605,5001,6002.1
World total17,637.542,31576,286100.0

Worldwide smartphone and mobile phone sales in the first quarter of 2018 were 1 million. Of these, smartphone sales were just under 4 million, accounting for 5,500% of mobile phone sales.GartnerResearch).

The following companies supply terminals internationally. The country name is the location of the head office,2018å¹´Are sorted by the number of devices sold byGartnerResearch). The top 10 companies have a share of about 87%.

Mobile phone market share
ManufacturerShare (%)
Samsung electronics30.07
ア ッ プ ル22.34
Huawei7.37
Xiaomi7.26
Unknown4.81
OPPO4.14
LG3.12
Motorola2.78
Mobicel2.69
Lenovo2.00
Other13.42

Service

Due to the development of base stations, stable calls and communications can be used even when moving outdoors at high speed in a wide service area.XNUMXrd generation mobile phoneIs fastPacket communicationIt features high frequency utilization efficiency. It should be noted thatWireless accessHowever, depending on the type of usage, it may be expensive to charge, and this phenomenon is commonly used.Pake deathCalled. In addition, the percentage of the total traffic (data volume) of telephone calls and communications by a single telephone terminal tends to be high. In addition, multi-functionalization as a digital tool is also involved.

Call

The mobile phone voice transmission method initially adopted the analog method, and was switched to the digital method halfway. The analog communication at the time the service was initially started,CipherSince it was transmitted as it was without being converted, it had the drawbacks that it was easy to pick up noise and that it was possible to easily intercept it. Therefore, digitization that enables strong encryption was performed.

In some countries at that time,Fixed-line phoneThe network is analog to digital (ISDN) Was progressing, but the digital system of the fixed telephone networkPulse code modulation(PCM), the mobile phone network has higher compressionCodec(MainlyAMRFormat) is used. In the case of mutual connection calls between both telephone networks, codec conversion is required in the network gateway switch, although it is simple between analog systems, but in digital system (including the time when analog and digital coexist).

In addition, since the voice codec system differs depending on the mobile phone carrier and service type, it is also necessary to convert the voice codec between carriers and systems. For this reason, depending on the combination of codecs, the quality of voice may deteriorate due to conversion loss. Basically, there is no loss due to conversion in calls between mobile phones of the same carrier and the same method, so the original call quality can be exhibited.

communication

Initially, mobile phones had only a call function,Voice callThe whole terminal is digitized by the digitization ofPacket communicationHas made it possible to connect to digital networks. Even among digital networks, connection to the world widespread Internet has been made early on, and it has become possible to access the Internet network with mobile phones.clientIt is becoming.

This targeted mobile phonesWeb pageFrom the mobile operatorOfficial WebsiteWas established as a privately owned or targeted mobile phone on the InternetSelfish siteThe site called will be opened. Furthermore, due to the high-speed communication of mobile phones, the communication function is used to manage money on mobile phones.Mobile banking,Online tradeNot only is it possible to doMovieIt became possible to browse the content.

Traditionally, mobile phones are simpleHTMLI was able to display only the web page byブ ラ ウ ザA terminal equipped with was also realized, and it became possible to browse content created for PCs.

Communication standard

The mobile phone communication standards (methods) in each region are roughly as follows.

Region1G2G3G3.9G4G5G
JapanTACS,HiCAPPDC,cdmaOneCDMA2000,W-CDMALTE,Mobile WiMAX,AXGPLTE-Advanced,WiMAX 2.1, AXGP(CA)NR (5G NR)
South KoreacdmaOneCDMA2000, W-CDMA
North AmericaAMPSGSM (850/1900MHz), cdmaOne,D-AMPS,CDMA2000, W-CDMA
OtherTACSGSM (900/1800MHz), cdmaOne, D-AMPS, iDENCDMA2000, W-CDMA

First generation mobile phone(1G) is an analog method. MotorolaTACS,NTT OfHiCAPand so on.

Second generation mobile phone(2G below), the GSM method has become the mainstream worldwide. GSM has not been adopted in Japan, South Korea and North Korea. in Japan PDCThe original method called “Personal Digital Cellular” was the mainstream, so while original terminals and services were popularized, the entry of overseas terminal manufacturers and internationalroamingService does not progressIsolationI was in a good state. In Korea, in the United StatesQualcomm(Qualcomm)cdmaOne(IS-95) system is adopted,Samsung electronics,LG ElectronicsEtc. became the basis for an international leap. North AmericaEUUnlike, the government did not force mobile operators to choose technology, but left it to their choice. As a result, the current situation is that GSM and cdmaOne are almost in competition.

XNUMXrd generation mobile phone(3G) is a standard for third-generation mobile phones, based on the reflection that 2G adopts its own system and different frequencies in each country and region, and the same system could not be used all over the world.IMT-2000In its decision, an index was set up to make mobile phones globally available. However, in the process of standard development,W-CDMAとCDMA2000Became a form of parallel adoption, and the GSM campW-CDMATo the cdmaOne campCDMA2000It was decided to move to (North and South AmericaAsiaPart of the region).ChugokuThe government has its ownTD-SCDMAIs about to be introduced. Also of 3G technologyPatentRegarding the generation,licenseQualcomm and the phone vendor (sales company), saying that the price is too high,ChipsetSeveral vendors are currently in dispute.

in JapanNTT DoCoMo,Softbank mobileHas adopted W-CDMA, and international roaming and entry into overseas manufacturers are being promoted.KDDI(au) Has adopted the CDMA2 system for 2000G cdmaOne system. However, Japanese cdmaOne andCDMA2000It is,UHFWith tv broadcast waveinterferenceUp and down to avoidfrequencyHas been reversed from other countries. For this reasonGlobal passportInternational roaming is not possible except for CDMA terminals.

Most developed nations and most cdmaOne camps have already introduced 3G, but the GSM camp hasn't made the transition to costly W-CDMA because users tend to prefer cheaper GSM handsets. Inexpensive GSM terminals are more popular than expensive W-CDMA terminals. Even for expensive GSM terminals such as smartphones, there are terminals that do not support 2000G such as W-CDMA and CDMA3, which consume a lot of power to reduce the battery weight. Also in GSMEDGE,EDGE EvolutionIt can be used for high-speed data communication comparable to 3G.

Therefore, as of 2008, there are no GSM operators that have set a deadline for GSM service suspension.

In developing countries, the introduction of 2000G networks by using CDMA400 technology in the 3MHz band was implemented from the beginning in order to complement the lack of fixed telephone networks and expand the area by incorporating data communication networks at low prices. There is.

In 2006, GSM accounted for less than 7% of global mobile phone sales, CDMA (cdmaOne + CDMA2000) accounted for more than 2%, and W-CDMA accounted for less than 1%.

3.9rd generation mobile communication systemThen, all four companies in JapanLTEAdopt the method.

Charge form

It is internationally common that the charge is calculated based on the call time for voice calls and the communication time or amount of data for data communications.pre-paid(Prepayment), do not own the networkVirtual mobile operatorThere is also a service by (MVNO).

In the case of prepaid, there is no basic charge, but the expiration date is determined by the number of days that have passed since the last deposit, so it is necessary to deposit regularly even if the usage frequency is low. EU generally has a high prepaid ratio.

In the United States and other countries, voice calls are generally fixed until a certain time. Also, many contracts are free for calls after 9 pm and on weekends. On the other hand, generally, not only the calling party but also the receiving party incurs a call charge.

business model

Technically,SIM cardIt is possible to change the telecommunications carrier by exchanging. For this reason, it is the mainstream for handset manufacturers to first develop a global model and customize it for small-scale specific businesses only when necessary.

Overseas, there are two types of products, the "standard version", which has only the industry-standard functions provided by the manufacturer, even with one model, and the one that adds carrier-specific services. The former does not have a SIM lock, so it can be used anywhere in the world if the communication method is the same. The latter is sold with a SIM lock under the incentive system. The circumstances around here are the same as in Japan, but the amount of incentives in Japan is by far the largest.

The huge market-scale mobile phones have gained enormous shipments due to price competition through mass sales on a global scale.

Equipment malfunction

Getting wet

Mobile phones that do not have a waterproof function will break down even if exposed to a slight amount of water, so users will complain that "this is the case for defective products to break down."National Life CenterHave been sent to. At the National Center for Living, users are cautioned not to let the non-waterproof model get wet with water, and people who use it get wet should buy a waterproof model. It is requested that the mobile phone company be well-informed to consumers and that they do not give a unilateral burden to consumers when making improvements and repairs so that they will not break down due to daily slight water wetting.[13].

Abnormal overheating

There are also cases where the lithium-ion battery built into the device may explode due to abnormal overheating, resulting in injury or fire.[14].

Impact on health

WHOBe part of (World Health Organization)IARC(International Cancer Research Institute) May 2011, 5IARC Carcinogenic Risk List), "Use of mobile phone" was added to the category of Group5B, which is the third from the top among the five stages (Group3B is a group suspected of being carcinogenic to humans).[15][16].

In addition,Heart pacemakerThe effects of malfunctions caused by electromagnetic waves emitted from mobile phones and smartphones on users are warned.

Other uses

Research is underway to utilize the multi-functionality of mobile phones for applications other than communication. Application as a portable diagnostic device is promoted in areas where satisfactory medical care cannot be received[17][18][19][20].

Mobile phones in countries/regions

footnote

[How to use footnotes]
  1. ^ Japanese Language Dictionary, World Encyclopedia Reference, ASCII jp Digital Glossary, Digital Daijisen, Encyclopedia Mypedia, Dictionary that understands IT terms, World Encyclopedia XNUMXnd Edition, Daijibayashi XNUMXrd Edition, Britannica International Encyclopedia Small Item Encyclopedia, Complete Book of Japanese Encyclopedia (Nipponica), Selected Edition. “What is a mobile phone?”(Japanese). Koto bank. 2020/10/6Browse.
  2. ^ NTT History Museum Wireless Phone
  3. ^ Kakehodai, a mobile phone 40 years ago
  4. ^ A chat with the man behind mobiles
  5. ^ "Martin Cooper-The Inventor of the Cell Phone". 2012/3/23Browse.
  6. ^ http://history-s.nttdocomo.co.jp/list_shoulder.html
  7. ^ http://history-s.nttdocomo.co.jp/list_mobile.html
  8. ^ "Showa 55 Photographer Life" (2017, Diapress) p108
  9. ^ Asia-Pacific Mobile Phone Market Will Over 2008 Million in 4-IDC Survey("Nikkei BP'ITpro (Retrieved November 2007, 11)
  10. ^ Africa (1) Rapidly growing African mobile phone market(WirelessWire News(Retrieved November 2017, 10)
  11. ^ "Evolution of Smartphones" GalleryWIRED2010.11.2
  12. ^ [Yuichi Kogure's mobile watch] The 75th keyword is “region”!? Whereabouts of “Garaho” newly announced by DOCOMO and auRBB TODAY May 2015, 5
  13. ^ National Life Center Mobile phone malfunction due to water getting wet
  14. ^ Abnormal overheating of lithium-ion battery, research to elucidate mechanism by X-ray AFP, April 2015, 4.
  15. ^ IARC CLASSIFIES RADIOFREQUENCYELECTROMAGNETIC FIELDS ASPOSSIBLY CARCINOGENIC TO HUMANS WHO
  16. ^ Cell phones are as carcinogenic as coffee Journal of Carcinogenesis Gopala Kovvali
  17. ^ Zhu, Hongying, et al. "Optofluidic fluorescent imaging cytometry on a cell phone."Analytical chemistry 83.17 (2011): 6641-6647.
  18. ^ Mobile phone-based biosensing: An emerging "diagnostic and communication" technology.
  19. ^ Wei, Qingshan, et al. "Imaging and sizing of single DNA molecules on a mobile phone."ACS nano 8.12 (2014): 12725-12733.
  20. ^ Roda, Aldo, et al. "Integrating biochemiluminescence detection on smartphones: mobile chemistry platform for point-of-need analysis." Analytical chemistry 86.15 (2014): 7299-7304.

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