TheabovecontentisreviewedandannouncedbytheNationalScienceandTechnikaTermReviewCommittee
Úvod
PersonalhandheldphoneSystem(PHS——-personalhandyphonesystem)technologyoriginatedinJapan,andithasbeendevelopedinJapanasasecond-generationmobilecommunicationtechnology.OurcountrymakesfulluseoftherichresourcesofthefixedtelephonenetworkandorganicallycombinesthelocaltelephoneexchangeandtransmissiontechnologytoformPHS,commonlyknownas"LittleSmart".ThePHSnetworkhasafastnetworkconstructionspeed,asmallinvestment,andiseconomicalandconvenient.
Technika
PHStechnologyisactuallyadigitalmobilecommunicationtechnology,whichbelongstothesecondgenerationofcommunicationtechnology.ThecoverageofPHSbasestationsislimited,andthedistancebetweencommunicationbasestationsandterminalsisrelativelyshort.Therefore,thecommunicationpowerusedissmaller,andmorebasestationsarerequiredtocoveralargerarea.ThismakesPHSmoresuitableforuseinurbanareas,buttheeffectisnotgoodwhenusedinthefieldandotherplaces.Inthegenerationofmobilephonecommunicationspeed,PHSbelongstotherangeof2G.Itsdesignalsocausesaslightdelayduringthecall.(Becauseofitssmallcoverageareaandsmall"cellular"area)
PHSusesTDMA/TDDasitsradiocommunicationinterface,and32KADPCMasitsvoicetransmissioncode.ModernPHSphonescanalsosupportsomeotherISP'svalue-addedservices,suchasInternetnarrowbandcommunications,textmessages,e-mail,andevenimagemessaging.
PHSthistechnologyisalsosuitableforsmall-scaleradiocommunications.
Použití
Theinitialreleasewasin1989attheNTTlaboratoryinJapan,asaformoftechnologycompetingwithGSMandPDC.Intheearlydays,itwasdevelopedbyJapanbasedonitsownnationalconditions(thecharacteristicsofhighpopulationdensityinmostplacesandlowpopulationmobility).In1995,itwasinitiallyoperatedbythreetelecomoperatorsinJapan:NTT-Personal,DDI-PocketandASTEL.However,shortlyaftertheservicewaslaunched,duetoinsufficientcoverageandroamingcapabilities,thetechnologywascalled:"PoorMan’sCellular"InJapan,itisheavilyrestricted.Themarketshareisalsograduallydecreasing.SomecountriesthatoriginallyusedPHStechnologyhavealsobeguntouseGSM,suchasChile.However,thePHStechnologyisalsopopularinsomecountriesandregionswithlowerfeesandfeweradditionalservices,suchasChina,Taiwan,Vietnam,Bangladesh,Nigeria,Mali,TanzaniaandHonduras.
AfterthePHSservicewasterminatedat24:00onDecember31,2014,somePHSusersinBeijinghaverepeatedlycomplainedtoandnegotiatedwithBeijingUnicom.Butintheend,thetwopartiesfailedtoreachanagreementoncompensationissuesaftertheterminationoftheservice.ChinaUnicomBeijingBranch(hereinafterreferredtoasBeijingUnicom)terminatedthesuspectedmonopolyandinfringementofPHSbusinessisthefirstanti-monopolylawsuitinthewithdrawalofPHS.
PHSmarket
InMainlandChina,ChinaTelecomandChinaUnicom’sPHSservicesusePHStechnologyinmostplaces.InTaiwan,VolkswagenTelecom'slow-powermobilephonesalsousePHStechnology.
BusinessScope
Inadditiontobasicvoiceservicesandsupplementaryservices,thePHSnetworkalsoprovidesthefollowingvalue-addedservices:
1.SMSservices:PHSSMSservicesandmobileTheshortmessageserviceofthephoneissimilar,anditcansendandreceivetextmessagesoflimitedlengthfromPHSterminals.
2.Dataaccessservice:PHSsystemhasgoodhigh-speedwirelessdatacarryingcapacity,itssingleservicechannelcancarry32KBPSofunrestricteddata,anditcansupport64KBPSofwirelessdataservicebybundlingtwoservicechannels.TheterminalpartcanbeaPHSmobilephonefordirectdataservices(thecomputerisconnectedtothemobilephonethroughaspecialcableforthePHSmobilephone),orotherformsofdataterminals,suchasanetworkcardsuitableforcomputers.
3.Colorringbacktoneservice:referstotheringbacktoneofspecialsoundeffects(music,song,storyplot,characterdialogue)setbythecalleduserforothercallinguserswhotransferthecalltothemobilephone.
4. Slepý přístup k podnikání.
5.TerminálInternetbusiness.
6.Umístění podnikání.
7.Předplacené podnikání.
Výhody a nevýhody
1.Výhody
·Ochrana životního prostředí
ThePHShaslowpowerconsumption,verysmallelectromagneticwaveradiation,andradiationtothehumanbodyTheharmissmall,anditisstilllovedbysomespecialgroups,suchastheelderly,pregnantwomen,andmedicalstaff.Longstandbypowersaving:PHSconsumeslesspowerandhasalongstandbytime.Chargeitonce,thestandbytimecanreach10days,savingthetroubleoffrequentcharging.
· Výhradní šířka pásma
ThecallqualityofPHScanbecomparabletofixed-linephoneswithinthenetworkcoveragearea;unlikemobilewirelessInternetmulti-personsharing,PHScanenjoy64/128Kbpsbandwidth.
· Grabusery
PHSisaproductofaspecialperiod.ItwasalsothehelplessmoveofChinaTelecomandChinaNetcomwhentheydidnothavemobilelicenses,buttheyalsoseizedalargenumberofoperatorsbefore3G.user.
2. Nevýhody
· Méně funkcí
ThePHShasfewerauxiliaryfunctions.EarlyshortmessagescanonlybesentbetweenthePHSs,browsetheInternetandusemobilephones.Manyfashionablenewfeatures,suchasgames,areonlybeingperfectedinthelaterstages.
·Špatné pokrytí
Thenetworkcoverageispoor,generallylimitedtotheurbanarea,withpoorsignal;therearefewbasestations,andthecallisnotsmoothinsomepartsofthecity,anditisimpossibletocallintheeventofapoweroutage.
·Slabý výkon
Whenthevehiclespeedexceeds40kilometers,thecallisintermittent.AlthoughJapanisconstantlyimprovingitstechnology,itisbasicallynolongerdevelopinginthecountry.
· Cannotroam
PHScannotroamacrossthecountrylikeamobilephone,soitcanonlybeusedasa"fixed-linesupplementandextension",andthereisalwaysagapbetweenthefunctionandthemobilephone.