Dt notes part 2

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Dt notes part 2

  1. 1. ALL THE CHARACTARE ARE IN THIS TIPS ARE REFERED FROM THE RECOGNISEDNOTES UNDER THE GUIDENCE OF MY GODFATHER (VIKAS DESHMUKH). IF THERE IS ANY DOUBT REGARDING TO THIS PLEASE GO TO HELL (ITS VERY EASY TO UNDERSTAND YAAR! ). DEDICATED TO MR. VINAYAK GARAD 09423171882 (MY Physicists) ALL THE RIGHTS TO CHANGE ARE RESERVED TO (No need to give feed back at “khunesl @gmail.com”) HUNK IS SHANK (VICE VERSA) KHUNE S L CELL PLAN TECH. PVT. LTD. PUNE. (INDIAN MULTINATIONAL). HAND OVER HAND OVER IS THE PROCESS IN WHICH, THE SERVICE TO THE SUBSCRIBER IS TRANSFERRED FROM THE SERVING CELL TO THE ANOTHER CELL DURING ACTIVE MODE OF MS AND THE CALL WILL CONTINUE TILL MS DISCONNECT THE CALL. WHY HAND OVER? A] IN ORDER TO PROVIDE THE BETTER LINK QUALITY TO THE SUBSCRIBERS. B] MANAGE THE TRAFFIC DISTRIBUTION AMOUNG THE CELLS OF THE NETWORK. OR 1 TO MAINTAIN QUQLITY AND CONTINUETY OF CALLS. 2 CELL SIZE CONTROL IN ORDER TO MINIMIZE TOTAL INTERFERENCE IN THE NETWORK. HO IS THE EFFECT OF FREQUENCY HOPPING NOTE:GIVE THE SPECIFIC REASON FOR HANDOVER (H.O.)?REASONS:• RECIEVER(RX) SIGNAL QUALITY• RECEIVER SIGNAL LEVEL• INTERFERANCE• POWER BUDGET• CONGESTION
  2. 2. • RX QUAL.: IF THE RX LEVEL BAD AND RX QUAL.IS ALSO BAD THEN H.O. IS DUE TO RX QUAL.• RX.LEVEL: IF THE RX LEVEL IS BAD RX QUAL. IS GOOD THEN HO IS DUE TO RX.LEVEL.• INTERFERANCE: IF THE RECIEVER LEVEL IS GOOD AND THE RX QUAL. IS BAD THEN H.O. IS DUE TO INTERFERENCE.•(Receiver level is nothing but how much amount the signalstrength you get.)(Receiver quality is nothing but the voice quality which we getduring call.) (Interference is nothing but the disturbance or unwanted signal)LEVEL QUALITY H.OGOOD BAD INTERFERENCEBAD BAD RX QUAL.BAD GOOD RX LEVELWHAT ARE THE SHORT COMING IN HAND OVER?1 CALL DROP2 FAR AWAY CELL EFFECT3 PING PONG H.O.WHAT IS PING PONG HO? PING HO IN WHICH (UNNECSESARY) NETWORK TAKINGCONTINIOSLY H.O. LET US SUPPOSE 4 SITES. ARE SERVING IN ANY ONE AREATHEN THEIR WOULD BE SUCH TYPE OF POINT AT THEIR ALL 4SITES ARE GIVING THEIR OWN SIGNALS .SO WHEN U ENTER ONTHAT SPOT FIREST HO IS GIVEN TO 2’ND NO. SITE SIGNALS,AFTER IMMEDIATELY RECIVEING THE 2’ND NO.SITE 3,RD NOWILL TAKE HO ,AFTER 4’TH……AFTER 1’ST ……..2,ND SOON………SECOND REASON OF PING PONG IS PARTIAL CABLE SWAP. (SEEAT CABLE SWAP FOR DETAIL)
  3. 3. HOW IT CAN BE AVOID?SO ALWAYS GIVE THRESHOLD VALUE ACCORDING TOPLANNER OR FIX THE THRESHOLD VALUE.OrAdjust the mechanical and electrical tilt.(Choose one of the above solution because its depends on theclutter)If clutter is dense then choose tilt solution because if we adjustthreshold then our QUALITY would be decrease.WHAT IS THE BAD EFFECT OF PING PONG HO?NETWORK QUALITY IS BAD.WHAT IS INTELLIGENT HO?1 NEAURAL NETWORK2 FUZZY LOGICWHAT IS INTERNAL & EXTERNAL HO?INTERNAL HO:INTER BTS:CALLS TRANSFER BETWEEEN TWO CHANNELS (TIME SLOT) IN SAME CELL.INTRA BSC:CALLS TRANSFER BETWEEN BTS UNDER THE CONTROL OF SAME BSC.EXTERNAL HO:INTER BSC (BSC - BSC):1 CALL TRANSFER BETWEEN THE BTS UNDER THE CONTROL OFDIFF. BSC.INTER MSC (MSC - MSC):CALL TRANSFER BETWEEN CELLS UNDER THE CONTROL OFDIFF. MSC.WHAT IS INTRACELL HO?IT IS BASED ON THE UPLINK IDLE CHANNELINTERFRENCE MEARSURMENT CAN EFFICIENTLY AVOIDUPLINK INTERFERANCE WHEN THE NETWORK LOAD ISREASONABLE.
  4. 4. WHEN THE LOAD IS HIGH IN THE NETWORK, THE GAINOF INTRACELL HO IS LOW.WHEN THE LOAD IS LOW THEN THE GAIN IS GOOD.IN CASE OF HANDOVER DEFINE BUT HANDOVER WOULDNOT TAKE PLACE?CHECK FOR:1) CHECK NEIGHBOUR DEFINED OR NOT?FIRST SEE IN NET MONITER OR TEMS IF YES THENFOLLOW 2’ND STEP IF NOT THEN CALL MSC AND TELLTHEM TO DEFINE.2) IS FREQUENCY AND BSIC SAME (SEE IN MCOM)3) CHECK IS THAT FREQ.ON WHICH HO WILL TAKEDEFINED IN MBCCH FREQUENCY LIST OR NOT?(CALL MSC AND ASK)4) CHECK NCC PARA (PARAMETER) IS SET OR NOT?(CALL MSC AND ASK)2) IS FREQUENCY AND BSIC SAME (SEE IN MCOM):AT BELOW SEE 842 IS FREQ. AND (43) BSIC WHERE 4 ISNCC 3 IS BCC.FREQ. AND BSIC IS SAME DOES NOT MEANTO CHECK 842 AND 43 IS SAME!IT MEANS THE SITE WITH SAME FREQ.AND BSIC PAIRSHOULD NOT BE IN THE 15 KM OR 20 KM RADIUS.BECAUSE IF THIS HAPPENED, THEN THERE ISINTERFERENCE DUE TO FREQ. HIT AND WE CAN’T FINDIT, DUE TO SAME PAIR WE CANT FIND WHICH TWO FREQ.ARE HITTING .THE RADIUS IS ALSO DEPEND ON TERRION.
  5. 5. WHAT IS BASIC?BASE STATION IDENTITY CODE IS THE CODE WHERE INTHE FIRST DIGIT INDICATES NCC AND SECOND DIGITINDICATES BCC.NCC: NETWORK COLOUR CODEBCC: BASE STATION COLOUR CODETHE NCC AND BCC HAVE VALUE RANGING FROM O TO 7NCC: THE NCC IS FIXED FOR AN OPERATOR, SIGNIFYINGAT ANY GIVEN POINT THERE CAN BE MAXIMUM OF 8OPERATORS IN AN AREA.BCC: BCC DEFINES THE CLUSTER NO.WHICH MEANS AGROUP OF 8 CLUSTERS CARRY UNIQE IDENTITY WHICHARE USED FOR ANOTHER GROUP OF 8 AND SO ON.EX. IF BSIC IS 65 THEN 6 IS NCC AND 5 IS BCCIF BSIC IS 55 AND FREQ.IS 55 THEN HO WOULD NOTTAKE PLACE.WHAT IS CLUSTER? GROUP OF FREQ. CAN BE PLACED TOGETHER INTOPATTERNS OF CELLS CALLED CLUSTER.CLUSTER IS A GROUP OF CELLS IN WHICH ALLAVAILABLE FREQ. HAVE BEEN USED ONCE AND ONLYONCE.
  6. 6. THE PRINCIPAL FOR ALLOCATION OF THE BSIC IS THESAME AS THE RF CARRIER BUT AT CLUSTER LEVELRATHER THAN CELL LEVEL.MBCCH FREQ:MBCCH NO. IS THE BCCH ALLOCATION (BCCH Allocation (BA) List is alist of BCCH frequencies that every Idle mobile in a cell is supposed tomonitor. The list can be of two types - Idle BA List and Dedicated BAList. Idle is used by Idle mobiles while Dedicated BA List is used byDedicated Mobiles. You always don’t need to make two BA lists, itdepends on your planning process whether you will be using single BALor BAL rotation or Dual BAL. We can use one BAL for all the mobiles(idle & dedicated).) i.e. IT INDICATES TO THE MS THE FREQ.MUST BE MONITERED ANDMEASURED IN IDLE .ACTIVE OR BOTH MODES.THIS NO. IS SENT TO MSIN THE SYSTEM INFORMATION MESSAGES ON THE BCCH CHANNEL INIDLE MODE AND ON THE SACCH IN ACTIVE MODE.UPTO 32 BCCH CARRIERS CAN BE DEFINED BYSPECIFAYING THEIR ARFCN.DEEP CONCEPT OF HO:THE MEASUREMENT REPORT FROM THE MS IS SENT TO THEBSC ON THE SACCH INDICATING THE SIGNAL STRENGTH ANDQUALITY OF THE SERVING LINK AND THESIG.STRENGTH, FREQ.AND BSIC FROM THESIX BTS WITH STRONGEST SIGNAL STRENGTHS.ONLY MEASURMENTS FROM THE NEIGHBOURING CELLS THATFULLFILL THE REQUREMENT BY BCCH HAS A FREQ. ASINDICATED BY MBCCH NO. IT IS NECESSARY THAT THE MEASURED CELL IS DEFINED ASTHE NEIGHBOUR OF THE SERVING CELL .UPTO 64 DIFF. CELLS CAN BE DEFINED AS NEIGHBOUR. HO PROCESS MAY BE TRIGGERED BY QUAL., FIELDSTRENGTH OR DISTANCE VALUES FALL BELOLW /EXCEED THEIR THRESHOLD PERIODIC CHANGES.HO ALGORITHUM:
  7. 7. The locating algorithm: Works out the basis forhandover decisions .It is implemented in the basestation controller. It is the algorithm for cell selectionfor active mobile stations (i.e. ongoing connection) afterimmediate assignment.INPUT:THE I/P TO THE ALGORITHUM IS SIGNAL STRENGTH ANDQUALITY MEASUREMENT FROM THE MS AND FROM THEBASE STATION CURRENTLY SERVING THE CONNECTION.OUTPUT:THE OUTPUT IS THE LIST OF CELLS THAT THEALGORITHUM JUDGES TO BE POSSIBLE CANDIDATESFOR HANDOVER .THE CELLS IN THE LIST IS RANKEDAND STORED IN DESCENDING ORDER OF PREFERENCEFOR HANDOVEAR.THE ALGORITHUM WORKS CONTINUESLY, COMPLETINGA CALCULATION CYCLE IN GENERAL EVERY 480 ms.MOST FREQUENTLY THE ALGORITHUM WILLRECOMMEND NOT TO PERFORM A HANDOVER. HANDOVER CRITERIA ARE BASED ONTHREE TYPES OF MEASUREMENT1] FIELD STRENGTH (SIGNAL STRENGTH AND OR PATH THELOSS) OF THE CONNECTION AND OFBROADCAST CONTROL CHANNEL CARRIERSFOR NEIGHBOURS.2] SIGNAL QUALITY OF THE CONNECTION (BIT ERRRORRATE ESTEMATION MAPPED ON ALGORITHUM SCALE)3] TIMING ADVENCE USED BY THE MS. WHAT IS TIMING ADVANCE?IT IS A SOLUTION SPECIALY DESIGNED TO COUNTERACTTHE PROBLM OF TIME ALLIGNMENT .ITS WORKED BY
  8. 8. INSTRUCTING THE MIS ALIGNED MS TO TRANSMIT ITSBURST EARLIER OR LATER THAN IT NORMALLY WOULD.IN GSM TA INFORMATION RELATES TO BIT TIMES.THUS ,AN MS MAY BE INSTRUCTED TO COMMENCE ITSTRANSMISSION A CERTAIN NO OF BIT TIMES EARLIEROR LATER ,RELATED TO PREVIOUS POSITION TO REACHITS TIMESLOT AT THE BTS IN RIGHT TIME.WHAT IS THE DIFF. BETWEEN CELL RESELECTION ANDHANDOVER?HAND OVER HAPPENED IN DEDICATED MODE ANDCELL RESELECTION IN IDLE MODE.FREQUENCY HOPPINGCall is transmitted through several frequencies in ordertoAverage the interference,Minimizing the impact of fading. ORIt is defined as sequential changeof carrier frequency on the radiolink between the mobile and basestation.Advantage of frequency hopping: Frequency diversityInterference averaging
  9. 9. How in frequency hopping there is enhancement ofnetwork ?1 FH implement will enable more aggressive frequency reusepattern that leads to better spectrum efficiency.2 It can add more transceivers in the existing site, whilemaintains the network quality .3 freq. hopping compressing the available spectrum to makeroom for extra freq.Frequency reuses?FREQUENCY REUSE IMPLIES THAT IN A GIVEN COVERAGE AREA THERE ARESEVERAL CELLS THAT USES THE SAME SET OF FREQ.THESE CELLS ARE CALLED COCHANNEL CELLS .AND THE INTERFERENCEBETWEEN SIGNALS FROM THESE CELLS ARE CALLED CO CHANNELINTEREFERENCE.Define all the parameter in frequency hopping? Following are the parameter in FHMOBILE ALLOCATION (MA)MOBILE ALLOCATION INDEX (MAI)MOBILE ALLOCATION INDEX OFFSET (MAIO)HOPPING SEQUENCE NO. (HSN)MOBILE ALLOATION:IT IS THE SET OF FREQ. The mobile allowed to hope over.maximum of 63 freq. can be defined in MA list.MOBILE ALLOCATION INDEX (MAI):It is the no. ranging from zero to the no. of freq. in the MAlist subtracted by one.It is the output of hopping sequence algorithms.HOPPING SEQUENCE NO. (HSN):It determines the hopping order used in the cell .it is possibleto assign 64 diff.setting .when HSN = 0 provides cyclichopping (pattern).HSN = 1 TO 63provides various pseudo random hopping.
  10. 10. In GSM there are 64 diff.patterns of FH.One of them is a simple cyclic or sequential pattern.The remaining 63 are known as pseudo random patternswhich an operator can choose from the MA list.WHERE WE USE CYCLIC AND RANDOM PATTERN?CYCLIC: IT IS USED IN THE AREA WHERE THE ITERFERENCEIS NOT A PROBLEM.RANDOM: IT IS USED IN THE AREA WHERE INTERFERENCE ISA PROBLEM.(HIGH TRAFFIC AREA).MOBILE ALLOCATION INDEX OFFSET (MAIO):Determines inside the FH sequence which freq. the mobilestarts do transmit on.The value of MAIO ranges between zeros to N-1.Where N is the no.of freq.defined in the MA list.Presently MAIO is set on per carrier basis.What are the types of FH and? What is dif.between them?Two types of freq. hopping.Base band FH (BBH)Synthesized FH (SFH)Diff.:BBH: IN BBH no. of hopping freq. same as no.of TRX. (TRU)SFH: No. of hopping freq. can be in the range of 1 to 63. - here the ARFCN wud be more than the no. Of TRX/TRU in bts.also we have better hopping gain here.& also we need not to go for new frequency scheme when we add new trxs to the site as this is to be do done in Base band hopping. Definition of SFH AND AMR: SFH & AMR IS different terms
  11. 11. SFH is synthesizer freq hopping and AMR is adaptive multirate. Thesetwo terms are in all different from each other. One defines the way ofusing fewer frequencies more efficiently and other defines the way ofcontrolling the quality of call in FULL RATE as well as HALF Rate so as to increase capacity indirectly with controlled quality.What is the effect of freq. hopping? 1 Hand over2 Call set up3 Frame eraser rate (FER)These are the eff. of FH. What is FER?IT IS THE RATIO OF DISCARDED SPEACCH FRAMES COMPARED TOALL THE RECEIVED SPEECH FRAMES.It is the right measure of voice quality.It is performed on speech and signaling frame.FFR 0 to 4 % good 4 to 15 % slightly degrade Greater than 15 %FORMULA:% OF FER = (NO.ERASED BLOCKS÷TOT.NO.OF BLOCKS) × 10ODeep concept:MAIO:It is a parameter that will allow the operator to specify a list ofup to 32 MAIO values in order in which they are to be allocated toa channel group. This parameter set to default whichremoves the manual MAIO list in favor for the default MAIO list.The no. of MAIO values in list stretches from zero up to one lessthan no. of freq. in the HFS.Ex. 9(0 to 8) freq. their than maio list will be 0 to 7.The actual MAIO values to be used for a channel groupdepend on the no. of TRX in the channel group.
  12. 12. Default list:In order of the MAIO values in the default list is arranged in a“first even then odd.” MAIO values manner.This means that the beginning of the list will consist of all theeven values in ascending order.After the even values all the odd values are arranged anascending order.Ex.For hopping group with 9 freq. the default list will be 0, 2, 4, 6, 1,3, 5 and 7.MA: MA LIST IS A LIST OF HOPPING FREQ. TRANSMITTEED TOA MOBILE EVERY TIME .IT IS ASSIGNIED TO HOPPINGPHYSICAL CHANNEL.THE MA LIST IS A SUBSET OF CA LIST.#WHAT IS CA LIST?THE MA LIST IS AUTOMATICALLY GENERATEDIF THE BASEBAND HOPPING IS USED.IF THE NETWORK UTILISES THE RF HOPPINGTHE MA LIST HAVE TO BE GENERATED FOREACH CELL BY THE PLANNER.The MA list is able to point the 64 of freq. defined in the CAlist .However the BCCH freq. is also included In the CA list ,sothe practically max.no. Of freq. in the MA list is 63.
  13. 13. The freq. in the MA list is required to be in increased orderbecause of the type of signaling used to transferthe MA list.HOPPING sequence algo?Input: The hopping seq. algo. Takes HSN &FN (freq.no.) as an input.Output: Mobile allocation index (MAI) is theO/P.MAIO:WHERE THERE ARE MORE THAN ONE TRX IN THE BTS USING THE SAME LISTTHE MOBILE ALLOCATION INDEX OFFSET IS USED TO ENSURE THAT EACHTRX USES ALWAYS AN UNIQUE FREQ.EACH HOPPING TRX IS ALLOCATED A DIFF. MAIO.MAIO IS ADDED TO MAI WHEN THE FREQ. TO BE USED DETERMINED FROMTHE MA LIST.MAIO AND HSN ARE TRANSMITTED TOA MOBILE STATION TOGETHER WITHMAIO LIST.HSN DEFINES WHICH HOPPING SEQUENCE TO BE USED.MAIO DECIDES STARTING POINT OF HOPPING.WHAT IS SLOW FREQ.HOPPING AND WHAT IS FASTFREQ.HOPPING?THE PRINCIPAL OF FREQUENCY HOPPING USEDWITHIN GSM IS THAT:“SUCESSIVE TDMA BURST OF CONNECTION ISTRANSMITTED VIA. DIFF. FREQ.”
  14. 14. THAT FREQ. BELONGING TO A RESPECTIVE CELLACCORDING TO NETWORK PLANNING. THIS METHODIS CALLED SLOW FREQ. HOPPING.SINCE TRANSMISSIOMN FREQ. REMAIN CONSTENTDURING ONE BURST.IN CONTRAST FAST FRFEQ. HOPPING WHERE THETRANSMISSION FREQ. CHANGES WITHIN THE ONEBURST.DETAILS OF FRAME ERASER RATIO:IT IS THE RATIO OF DISCARDED SPEACH FRAMES COMPARED TO ALL THERECEIVED SPEECH FRAMES.A SPEECH FRAME IS GENERALLY DISCARDED IF AFTER THE DECODING ANDERROR CONNECTION PROCESS ANY OF THE CATEGORY A BIT IS FOUND TOBE CHANGED BASED ON THE THREE PARITY BITS FOLLOWING THEM IN ASPEECH FRAME.FER IS MEASURE OF HOW SUCESSFUL THE SPEECH FRAME WAS RECIVEDAFTER THE ERROR CORRECTION PROCESS AND IT IS THUS A BETTERINDICATION OF THE SUBJECTIVE SPEECH QUALITY COMPARED TO THE LINKQUALITY IN TERMS OF BER .THE RECIEVER QUALITY DOES NOT INDICATEHOW THE BIT ERRORS WERE DISTRIBUTED IN A SPEECH FRAME.“THE BIT ERROR DISTRIBUTION AFFECTSTHE ABILITY OF THE CHANNEL DECODING TO CORRECT THE ERRORS”. A BLOCK IS ERASED WHEN PARITY CHECK FAILED.BIT ERROR RATE:IT IS THE RATIO OF THE NO. OF ERRORNEOUS BIT RECIEVIED TO THE TOTALNO.OF BITS RECEIVED.RESIDUAL BIT ERROR RATE:
  15. 15. IT IS PERFORMED ON DEMODULATED SPEECH FRAMES THATARE NOT MARKING CORRECT.WHAT HAPPENS WHEN SPEECH FRAMES DISCARDED IN FER?ANS: SYSTEM WILLS INTERPOLUTE.SPEECH QUQLITY INDEX DEPENDS ON FER ANDBER.SPECCH QUALITY IS DEPENDING ON BER. TROUBLSHOOTING WHAT IS CABLE SWAP AND PARTIAL CABLE SWAP? THERE ARE TWO TYPES OF CABLE SWAP/SECTOR SWAP. FIRST CABLE SWAP/SECTOR SWAP AND ANOTHER IS PARTIAL SWAWP.CABLE SWAP IS NOTHING BUT WHEN TWO WIRES WHICH IS COMING FROM GSM AND CONNECTED IN TRX/TRU IN BTS WIL CONNECT WRONGLY. MEANS FIRST SECTOR TWO CABLE (POSITIVE ANDNEGATIVE) CONNNECTED IN SECOND SECTOR TRU/TRX OR SECOND SECTOR TWO CABLE CONNNECTED IN THIRD OR THIRD SECTOR IN FIRST . WHAT IS THE SOLUTION OF TCH OR CALL DROP?BOTH PROBLEMS WOULD BE OCCURRED DUE TO THE POSSIBILITY OF CABLESWAP OR FREQUENCY HIT. CABLE SWAP : TWO WIRES CAME FROM THE GSM AND JOIN AT THE TRX INBTS ROOM. WHILE CONNCTING THESE WIRE THEIR COULD BE MISMATCH ORSWAPPING.BECAUSE FROM THESE TWO WIRES ONE WIRE IS OFTRANSMETER SECTION (+ SIGN ON THAT CABLE ) AND ANOTHER SIGN IS OFRECIEVER ( - SIGN IS ON THAT CABLE).SO THERE SHOULD BE CHANCESTHAT + WIRE WOULD BE ATTACHED TO - AND VICE VERSA.TWO SOLVE THE PROBLEM OF CABLE SWAP WE WANT TO SEE WHETHERTHESE CONNECTION IS EXACT OR NOT.DUE TO CABLE SWAP THERE WOULD BE CHANCES OF CALL DROP.SECOND CASE:FREQUENCY HIT: THIS MEANS ADJUCENT FREQUENCY WOULD BE HITTOWARDS AREA.SOLUTION OF THIS CASE GIVES DOWN TILT TO OUR GSM. WHAT IS PARTIAL CABLE SWAP? THERE ARE TWO TYPES OF CABLE SWAP ONE IS ABOVE AND SECOND IS PARTIAL CABLE SWAP.
  16. 16. IN FIRST CABLE SWAP TWO WIRES ARE FROM ANY ONE SECTOR IS CONNECTED IN ANOTHER SECTOR TRX/TRU .BUT IN PARTIAL CABLE SWAPONLY ONE WIRE WOULD BE SWAP MEANS ONE WIRE FROM ANY ONE SECTORAND ANOTHER WIRE FROM ANY OTHER SECTOR IS CONNECTED AT ONE TRX/ TRU. WHAT IS THE SOLUTION FOR PROBLEM OF UPLINK? SEE AROUND YOUR SITE ANY CDMA SITE IS PRESENT IF YES THEN USE CDMA FILTER.IF NOT THEN SEE IS THEIR SECTOR EXPANTION PRESENT THEN CHECK FOR THE ORIENTATION OF BOTH EXPANSION ANTEENA AND MAIN ANTENA IS DIFF. OR SAME. WHAT IS THE SOLUTION FOR DOWNLINK PROBLEM? THE SOLUTION FOR THE DOWNLINK IS SAME FOR THE TCH /CALL DROP. WHAT IS TH E SOLUTION FOR SD DROP? IF SD DROP INCREASED THEN ASSIGN ONE MORE TIME SLOT BY USING PLANNER.WHAT IS THE REASON FOR SDCCH DROP?1>high interference of freq., like co-channel2>sdcch time slot faulty3>poor TRX DL quality4>hardware fault like antenna or duplexer malfunction5>may be feeder cable and connectors are faulty.6>site taking calls from a very far distance.7>Bad Radio link quality (any sort of interference, if highly) Bad Radiolink quality (any sort of interference, if highly destructive)8>Could be a problem at NSS endand may be some other reasons....SD drop happens after SD is assigned, and if TCH is not free but SD is assigned and there is no directed retry, then in that case what happens? SD waits for a timer value and then also if it doesnt find a TCH it cant hold SD, so drops……………….. WHAT IS VSWR? VOLTAGE WAVE STAND RATIO:IT IS THE RATIO OF FORWARD POWAR TO THE REFLECTED POWER.[(1-ROW)/ (1+ROW)]IT THE PROBLEM OF LOOSE CONNECTOR OR DUST OR SHARE BENDING OR RAIN WATER . DUE TO THIS PROBLEM THERE IS LESS COVERAGE IN THAT AREA. WHENEVER THIS PROBLEM OCCURRED THERE IS ALARM FOR THIS IS IN MSC.
  17. 17. THERE ARE LOTS OF TYPE OF ALARMS ANOTHER IS IF BTS DOOR IS OPEN THEN THERE IS ALSO ALARM WILL OCCURD IN MSC.TO SOLVE THE PROBLEM OF VSWR PROBLEM WE CONNECT TIGHTLY (LOOSE CONNECTOR) ALL CONNECTOR/CABLE WHICH ARE LOOSE.
  18. 18. ABOVE TEMS 6.1 S/W IS COMPITABLE WITH INSTRUMENTS(MOBILE) T610.
  19. 19. WHAT IS TEMS?TEST EQIPEMENT MOBILE SYSTEM IS A TESTING TOOL USED TO READ ANDCONTROL THE INFORMATION SENT OVER AIR INTERFACES BETWEEN BASE RADIO STATION AND THE MOBILE STATION .IT CAN BE USED FOR COVERAGE MEASUREMENS.IN ADDITION TO FIELD MEASUREMENT AND POST PROCESSING. ALL KIT CONSIST OF MOBILE STATION WITH SPECIAL SOFTWARE, A PORTABLE PC AND OPTIONALLY A GLOBAL POSITONING SYSTEM RECIEVER.THE PC IS USED FOR PRESENTATION ,CONTROL AND MEASUREMENT STORAGE . MS IS USED IN ACTIVE OR IDLE MODE. WHICH WINDOW WE NEED TO CHECK IN DRIVE TEST?1] CURRENT CHANNEL2]SERVING NEIGHBOUR3]RADIO PARAMETER4]C/I5] C/A TELL US ABOUT DETAILS? 1] CURRENT CHANNEL: CELL NAME CGI (MCC NCC LAC (BSC) CI) BAND 900/1800/1900 CHANNEL TYPE CHANNEL MODE SPEECH CODEC CIPHERING ALGORITHUM SUB CHANNEL NO. HOPPING CHANNEL MAIO HSN 2]SEERVING NEIGHBOUR: FULL SUB HERE THE DEFINED NEIGHBOUR WILL APPEAR. 3]RADIO PARAMETER : FULL SUB A] RX LEVEL RANGE -10 TO -120 -10 TO -70 BEST - 71 TO -80 GOOD
  20. 20. -91 TO -120 BAD PURPOSE NEW SITE AT THIS AREA. B] RX QUALITY (ITS DEPEND ON INTERFERENCE ) RANGE 0 TO 7 0 TO 3 GOOD 4 TO 5 AVG. 6 TO 7 BAD C] FER ACTUAL D] BER ACTUAL E] SQI 21 TO 30 OK ABOUT SQI :IF BSIC AND FREQ ARE SAME THEN SQI GOES NEGATIVE. 4]C/I (WORST /BEST) RANGE 5 TO 25 15 AVG. 10 TO 15 5 TO 10 BAD MS POWER CONTROL LEVEL DTX TA 1 TA = 500m (RECEIVING LEVEL)RL TIME OUT COUNTER (MIN) RL TIME OUT COUNTER (MAX) MS BEHEVIOR MODIFIED 5] C/A ANOTHER NETWORK PROBLEM:C/I:CARRIER TO INTERFERENCE RATIOIT IS DEFINED AS THE RATIO BETWEEN THE LEVEL OF THE RECIVEDDESIRED SIGNAL TO THE LEVEL OF RECIVED UNDESIRED SIGNAL.C/I IS DEPENDENT ON THE INSTANTANEOUS POSITION OF THE MOBILESTATION AND IS AFFECTED BY TERREIN DETAILS AND VARIOUSSHAPES,TYPES AND NO.OF LOCAL SCATTERS.OTHER FACTORS SUCH AS ANTENNA TYPE DIRECTIONALITY AND HEIGHT,SITE ELEVATIONS ,POSITIONS AND THE NO. OF LOCAL SOURCE OFINTERFERENCE ALSO EFFEECT THE DISTRIBUTION OF THE C/I RATIO IN ASYSTEM .C/A: CARRIER TO ADJUCENT RATIOIT IS DEFINED AS THE RELATION IN DB IN SIGNAL STRENGTH BETWEEN THESERVING AND AN ADJUCENT FREQ.
  21. 21. COCHANNEL INTERFERENCE:FREQUENCY REUSE IMPLIES THAT IN A GIVEN COVERAGE AREA THERE ARESEVERAL CELLS THAT USES THE SAME SET OF FREQ.THESE CELLS ARE CALLED COCHANNEL CELLS .AND THE INTERFERENCEBETWEEN SIGNALS FROM THESE CELLS ARE CALLED CO CHANNELINTEREFERENCE.SOLUTION:TO REDUCE CO CHANNEL INTERFERENCE CO CHANNEL CELLSMUST BE PHYSICALLY SEPERATED BY A MINIMUM DISTANCE IN ORDER TOPROVIDE SUFFIECIENT ISOLATION.WHAT IS BASIC?BASE STATION IDENTITY CODE IS THE CODE WHERE IN THE FIRSTDIGIT INDICATES NCC AND SECOND DIGIT INDICATES BCC .NCC :NETWORK COLOUR CODEBCC: BASE STATION COLOUR CODETHE NCC AND BCC HAVE VALUE RANGING FROM AN O TO 7NCC: THE NCC IS FIXED FOR AN OPERATOR ,SIGNIFYING AT ANYGIVEN POINT THERE CAN BE MAXIMUM OF 8 OPERATORS IN ANAREA.BCC : BCC DEFINES THE CLUSTER NO.WHICH MEANS A GROUP OF 8CLUSTER CARRY UNIQE IDENTITY WHICH ARE USED FOR ANOTHERGROUP OF 8 AND SO ON.EX. IF BSIC IS 65 THEN 6 IS NCC AND 5 IS BCCIF BSIC IS 55 AND FREQ.IS 55 THEN HO WOULD NOT TAKE PLACE.WHAT IS CLUSTER? GROPU OF FREQ. CAN BE PLACED TOGETHER INTO PATTERNSOF CELLS CALLED CLUSTER.CLUSTER IS A GROUP OF CELLS IN WHICH ALL AVAILABLE FREQ.HAVE BEEN USED ONCE AND ONLY ONCE. THE PRINCIPAL FOR ALLOCATION OF THE BSIC IS THE SAME ASTHE RF CARRIER BUT AT CLUSTER LEVEL RATHER THAN CELLLEVEL.Transmission problem:Path loss: Path loss occurs when the received signal becomes weaker andweaker due to increasing distance between MS and BTS ,even if there are noobstacles between the transmitting and receiving antenna .The path loss problem seldom leads to a dropped call because before theproblem becomes extreme a new transmission path is established via anotherBTS .
  22. 22. Shadowing: Shadowing occurs when there are physical obstaclesincluding hills and building between the BTS and MS .The obstacles create ashadowing effect which can decreases the received signal strength . when the MS moves the signal strength fluctuates depending on theobstacles between the MS and BTS .FADING DIPS: A signal influenced by fading varies insignal strength .Drops in strength are called fading dips. Multipath fading : It occurs when there is more thanone transmission path to the MS or BTS .This may bedue to building or mountains either close to or far fromthe rec dBi, dBd,dBm dB itself is a measure of power on logarithmic scale.....when we talkabt dBi (one more thing i want add here is dBd ), these indicate gain ofa given antenna with respect to isotropic and Lambda/2 dipole antenna respectively....isotropic antenna is a non existent ideal antenna and Lambda/2 as it indicates is half-wavelength antenna., here iso.. is an omni directional antenna while Lambda...is a directional antenna ..When we measure gain wrt iso..Antenna,.gain is more bcoz it radiates lesser in distance ..bt its less with Lambda/2 antenna ... bcoz its radiation is directional hence more. Here is the relation... dBi (gain of the given antenna wrt Isotropic antenna)=dBd(Gain wrt Lambda/2 antenna +2.15 dB).READ THIS AFTER LEARN THE DT FOR 10 DAYS!ANALYASING THE LOG FILES?AFTER HAVING THE ENTIRE NETWOR OR A GIVEN PART OF THE NETWORK,THE LOG FILES SHOULD BRE ANAYLIESD .WHEN ANALYISING THE LOG FILES,THE MAIN THINGS TO LOOK FOR : 1. INTERFERENCE 2. LOW SIGNAL STRENGTH 3. MISSING NEIGHBOUROFTEN, THESE PROBLEMS CAN BE SPOOTEED BY LOOKING AT THE RXQUALLEVELS AND /OR DROPPED CALLS.HOWEVER DUE TO LITTLE OR NO TRAFFICIN THE SYSTEM, IT IS NOT POSSIBLE TO SPOT ALL THE PROBLEMS THATMIGHT OCCUR WHEN THERE IS MORE TRAFFIC IN THE SYSTEM.FOR EX.
  23. 23. INTERFERENCE FROM THE NON BCCH CARRIERS DOES NOT AFFECT THEQUALITY .THEREFORE IT IS IMPORTANT THAT THE LOG FILES ARECAREFULLY ANYLYSED EVEN THOUGH THERE ARE NO SIGNS OF POORQUAL.POOR QUAL:THERE ARE THREE MAJOR REASONS FOR POOR QUALITY.INTERFERENCR PROBLEM, LOW SIG. STRENGTH OR A MISSING NEIGHBOUR.THE REASON FOR THE POOR QUAL.CAN BE: 1. MS DOES NOT ON BEST SERVER 2. INTERFERENCE 3. LOW SIGNAL STRENGTH MAKE THE NECERRY CHANGES /ADJUSTMENTS DEPEPNDING ON THE REASON FOR THE POOR QUAL. MISSING NEIGHBOUR RELATIONS: MISSING NEIGHBOUR RELATIONS DISABLES A HANDOVER AND MIGHT LEAD TO POOR QUALITY AND EVENTUALLY A DROPPED CALL. INCLUDING ALL THE BCCH FREQ. IN THE MEASURING LIST DURING THE INTIAL TUNING, MAKES MISSING REALATIONSHIP EASIER TO DETECT. NEIGHBOUR THAT ARE NOT INCLUDED IN THE NEIGHBOUR LIST ARE NOT NOT EVALUATED BY LOCATING.IF HANDOVER IS NOT PERFORMED TO WHAT SEEMS TO BE THE BESTSERVER, THERE IS A POSSIBILITY OF A MISSING NEIGHBOUR RELATION.IF THAT IS NOT THE CASE AND TH EQUAL.IS POOR, HAND OVER HYSTERISIS,OFFSET, L- CRITERION PARAMETERS (IF USED) AND HCS – PARAMETER (IFUSED) SHOULD BE REVIEWED TO FIND THE REASON FOR THE MS NOT BEINGON THE STRONGEST CANDIDATE.THERE IS SITUATION WE CAN IMPROVE THE COVERAGE, BY INCREASINGTHE OUTPUT POWER AND/OR MAKING ANTENNA ADJUSTMENTS.OUTPUT POWER:BY INCREASING THE OUTPUT POWER,THE DOWNLINK SIGNAL STRENGTHINCREASE .HOWEREVER ,IF THE O/P POWER IS TOO HIGH (APPROXIMATELY-43 DBM OR MORE),A HIGHER O/P POWER WILL NOT GREATLY AFFECT THEOVERALL PERFORMANCE DUE TO THE LACK OF POWER BALANCE BETWEENUPLINK AND DOWNLINK .BUT AN INCREASE IN O/P POWER MAY LEAD TO HIGHER INTERFERENCE INCOCHANNEL AND ADJUCENT CHANNEL CELLS.THE CELL BORDERS ARE ALSO AFFECTED.ANTENNA ADJUSTMENTS: A HIGHER ANTENNA POSITION GENERALLYINCREASE THE CELLS COVERAGE AREA .SOMETIMES THE RE – DIRECTION OFAN ANTENNA MAY HELP THE SITUATION. IF THE ANTENNA ISDOWNTILTED ,A DECREASES OF THE TILT GENERALLY INCREASE THECOVERAGE AREA.
  24. 24. JUST LIKE THE CHANGING THE O/P POWER ,AN ANTENNA ADJUSTMENTSAFFECTS THE ENTIRE CELL PLAN REGARD TO CELL BOARDERS ANDINTERFERENCE.INTERFERENCE PROBLEMMAJOR IINTERFERNSE PROBLEMS REQUIRE A CHANGE OF FREQ. ON ONE ORMORE CELLS.FOR A CELLS SEVERE PROBLEM ,ANATENNA DOWNTILTS CAN HELPSITUATITIONS .MINOR INTERFERENCE PROBLEM CAN SOMETIMES BE ELIMINATED ORREDUSED BY PARAMETER CHANGES .MOVIING CELL BOARDER AND /ORCHANGING THE HANDOVER (EX. SMALLER HANDOVER HYSTERIS ANDSHORTER FITER LENGTHS ) CAN TAKE CARE OF LOCAL INTERFERENCEPROBLEMS. ANTENNA ADJUSTMENTS: ANTENNA ADJUSTMENTS SUCH AS ANTENNA TILT AND HEIGHT AFFECTS THE SIGNAL STRENGTH AND THEREBY THE CELLS BOARDERS AND INTERFERENCE LEVELS . BY DOENTILTING THE ANTENNAS ,A CALMER BEHAVIOR IS GENERALLY ACHIEVED IN THE NETWORK .THE SIGANL STRENGTH BECOMES MORE CONCENTRATED TO THE AREA CLOSE TO THE SITE .DOWNTILTING AN ANTENNA CAN REDUCE IN INTERFERENCE IN CO- CHANNEL OR ADJUSTENT CHANNEL CELLS AS WELL AS IN THECELL ITSELF. THE MAJOR DRAWBACK OF HAVING TOO MUCH DOWNTILT IS THE RISK OF A LOSS IN OVERALL COVERAGE.

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