MOBILE PHONEPART 2 Continuing frompart 1
Dear friends, I am thankful to the response of Sri TNC Rangarajan,former High court Judge about the posting of Part 1 with added information thatBSNL plans to convert all landlines to fiber optics and the link about theinformation. I am continuing with part2. Gopalakrishnan 24-12-2022. 10 Initialuse of mobile phone While mobile phones were introduced, the cost of mobile phone was prohibitive even to middleclass. The callcharges were based on minutes of usage, incomingcalls were charged. When the subscriber used mobile out of thedistrict, roaming charges were added. Topping was done with charging card. Card purchased in a state had to beused with in the state. Later mobiletopping changed to shops dealing with mobile recharge. Mobile charging shopswere busy with topping up. If any mistake was therein giving the number the amount paid was lost. The same continues now also. Subscribers noted the incoming call number and madecall from Land phones. Mostly very important mobile calls were only attendedbecause of charging for incoming calls. 11. Mobilecompany adding money to subscriber account. All mobile companies provided with Rs 10-00 when topping amount got exhausted till nextcharging was made for making/ answeringemergency calls. It was deducted on next recharge on the available balance. This procedure is more now. 12 All mobilephones in a home under one account Now most companies implement all phones under one account as postpaid billconnection. I have my Airtel mobile, my son’s Airtel mobile, my Airtel dataconnection comes in one account as postpaid bill. This is in addition to my BSNL mobile connection, Landline and internet connection. Theadvantage of airtel data connect is itfunctions on battery and usable when power failure is there. 13. Present daycharging Now charging is done for days, certain amount of data,any number of calls free with in India. I recollect the trunk calls werecharged Rs 16-00 for 3miinutes. Fromland phone certain number of free calls are allowed. No separate charges forSTD calls. ISD calls are charged more either from mobile or Land phones. Forvalidity separate charging is done. 14. Mobilephones working. When the Mobile phone is used for the first time, itsends a number called International Mobile Subscriber Identity – IMSI presentin the SIM card to the network, which looks it up in a database to ensure the card is registered.If the IMSI is recognized, the network creates another number called aTemporary Mobile Subscriber Identity (TMSI), which is encrypted and sent backto the phone. In all subsequent calls, the phone identifies itself bybroadcasting the TMSI. 15 What happenswhen we make a call? When we switch on the mobile phone, it tries for anSID on the Control channel. The Controlchannel is a special frequency that the phone and basestation use to talk to one another. If the Mobile phone findsdifficulty to get link with the control channel, it displays a “no service”message. My note- Thissituation occurs when tower fails or base stationhas problems. A hand held mobile is connected to base station through towers.There may be tower/towers near his phone to substation. If the Mobile phone gets the SID, it compares the SIDwith the SID programmed in the phone. If both SID match, the phone identifiesthat the cell it is communicating is the part of its home system. The phone alsotransmits a registration request along with the SID and the MTSO keeps track of your phone’s location ina database. MTSO knows in which cell you are when it wants to ring the phone. The MTSO then gets the signal, it tries to find thephone. The MTSO looks in its database to find the cell in which the phone is present.The MTSO then picks a frequency pair to take the call. The MTSO communicates with the Mobile phone over thecontrol channel to tell it what frequencies to use. Once the Mobile phone andthe tower switch on those frequencies, the call is connected. When theMobile phone move toward the edge of the cell, the cell’s base station willnote that the signal strength is diminishing. At the same time, the base station in the cell inwhich the phone is moving will be able to see the phone’s signal strengthincreasing. The two base stations coordinate themselves throughthe MTSO. At some point, the Mobile phone gets a signal on a control channeland directs it to change frequencies. This will switch the phone to the newcell. 16 Summary In mobile working system an area is divided in to circles. The mobile phone will bein a circle. Through a control frequencythe mobile is connected to a base station via tower. The dialing is donethrough this. The subscriber talks through another set of frequencies. The technical details will be told in simplestlanguage possible. Earlier each communication company had there owntowers. Now towers are shared. On this account we can see many dishes/receiversin a single tower nowadays. I will continue innext posting -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/thatha_patty/685305961.2799967.1671887596193%40mail.yahoo.com.
