PART _______2
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. 1 TO MAINTAIN QUQLITY AND CONTINUETY OF CALLS. 2 CELL SIZE CONTROL IN ORDER TO MINIMIZE TOTAL INTERFERENCE INTERFERENC E IN THE NETWORK. HO IS THE EFFECT OF FREQUENCY HOPPING GIVE THE SPECIFIC REASON FOR HANDOVER (H.O.)? REASONS: RECIEVER(RX) SIGNAL QUALITY RECEIVER SIGNAL LEVEL INTERFERANCE POWER BUDGET CONGESTION NOTE:
• • • • •
•
•
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 signal strength you get.) (Receiver quality is nothing but the voice quality which we get during call.) (Interference is nothing but the disturbance or unwanted signal) LEVEL GOOD
QUALITY BAD
H.O INTERFERENCE
BAD
BAD
RX QUAL.
BAD
GOOD
RX LEVEL
WHAT ARE THE SHORT COMING IN HAND OVER? 1. CALL DROP 2. FAR AWAY CELL EFFECT 3. PING PONG H.O WHAT IS PING PONG HO? PING HO IN WHICH (UNNECSESARY) NETWORK TAKING CONTINIOSLY H.O. LET US SUPPOSE 4 SITES. ARE SERVING IN ANY ONE AREA THEN THEIR WOULD BE SUCH TYPE OF POINT AT THEIR ALL 4 SITES ARE GIVING THEIR OWN SIGNALS .SO WHEN U ENTER ON THAT SPOT FIRST HO IS GIVEN TO TO 2’ND NO. SITE SIGNALS ,AFTER IMMEDIATELY RECIVEING THE 2’ND NO.SITE 3,RD NO WILL TAKE HO ,AFTER 4’TH……AFTER 1’ST ……..2,ND SO ON……… SECOND REASON OF PING PONG IS PARTIAL CABLE SWAP. (SEE AT CABLE SWAP FOR DETAIL) HOW IT CAN BE AVOID?
SO ALWAYS GIVE
THRESHOLD VALUE
ACCORDING TO
PLANNER OR FIX THE THRESHOLD VALUE. Or Adjust the mechanical and electrical tilt. (Choose one of the above solution because its depends on the clutter) If clutter is dense then choose tilt solution because if we adjust threshold 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 NETWORK 2 FUZZY LOGIC WHAT 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 OF DIFF. BSC. INTER MSC (MSC - MSC): CALL TRANSFER BETWEEN CELLS UNDER THE CONTROL OF DIFF. MSC. WHAT IS INTRACELL HO? I T IS IS B A S E D O N T H E U P L I N K I D L E C H A N N E L INTERFRENCE MEARSUR MENT CAN EFFICIENTLY AVOID U P L I N K IN T E R F E R A N C E W H E N T H E N E T W O R K L O A D I S REASONABLE.
WHEN TH E LOAD IS HIGH IN THE NETWORK , THE GAIN OF INTRACELL HO IS LOW. WHEN THE LOAD IS LOW THEN TH E GAIN IS GOOD.
IN CASE OF HANDOVER DEFINE BUT HANDOVER W OULD NOT TAKE PLACE? CHECK FOR: 1) CHECK NEIGHBO UR DEFINED OR NOT? FIRST SEE IN NET MONITER OR TEMS IF YES THEN F O L L O W 2 ’ N D S T E P IF N O T T H E N C A L L M S C A N D T E L L THEM TO DEFINE. 2)
IS F R E Q U E N C Y
BSIC
SAME (SEE IN MCOM)
3) CHECK IS THAT FREQ.ON WHICH HO W ILL TAKE DEFINED IN
MBCCH FREQUENCY
LIST OR NOT?
( C A LL M S C A N D A S K ) 4) CHECK
NCC PARA
(PARAMETER) IS SET OR NOT?
( C A LL M S C A N D A S K )
2)
IS F R E Q U E N C Y
BSIC
SAME (SEE IN MCOM):
A T B E L O W S E E 8 4 2 I S F R E Q . A N D ( 4 3 ) B S IC W H E R E 4 I S NCC 3 IS BCC.FREQ. AND BSIC IS SAME DOES NOT MEA TO CHECK 842 AND 43 IS SAME! IT MEANS THE SITE WITH SAME FRE Q.AND BSIC PAIR SHOULD NOT BE IN THE 15 KM OR 20 KM RADIUS .BECAUSE IF THIS HAPPENED, THEN TH ERE IS INTERFERENCE DUE TO FR EQ. HIT AND WE CAN’T FIND IT, DUE TO SAM E PAIR WE CANT FIND WHICH TWO FREQ. ARE HITTING . THE RADIUS IS ALSO DEPEND ON TERRION.
WHAT IS BASIC? BASE STATION IDENTITY CODE IS THE CODE W HERE IN T H E F I R S T D I G IT I N D I C A T E S N C C A N D S E C O N D D I G I T INDICATES BCC. NCC: NETWORK COLOUR CODE BCC: BASE STATION COLOUR CODE THE NCC AND BCC HAVE VALUE RANGING FROM O TO 7 N C C : T H E N C C I S F I X E D F O R A N O P E R A T O R , S I G N I F Y IN G A T A N Y G I V E N P O I N T T H ER E C A N B E M A X I M U M O F 8 OPERATORS IN AN AREA. BCC:
B C C D E F IN IN E S T H E C L U S T E R N O . W H I C H M E A N S A
GROUP OF 8 CLUSTERS CARR Y UNIQE IDENTITY WHICH ARE USED FOR ANOTHER GROUP OF 8 AND SO ON. E X . I F B S IC I S 6 5 T H E N 6 I S N C C A N D 5 I S B C C I F B S I C IS 5 5 A N D F R E Q . I S 5 5 T H E N H O W O U L D N O T TAKE PLACE. WHAT IS CLUSTER? GROUP OF FREQ. CAN BE PLACED TOG ETHER INTO PATTERNS OF CELLS CALLED CLUSTER. CLUSTER IS A GROUP O F CELLS IN WHICH ALL AVAILABLE FREQ. HAVE BEEN USED ONCE AND ONLY ONCE.
THE PRINCIPAL FOR ALLOCATION OF THE BSIC IS THE SAME AS THE RF CARRIER BUT AT CLUSTER LEVEL RATHER THAN CELL LEVEL.
MBCCH FREQ: MBCCH NO. IS THE BCCH ALLOCATION (BCCH Allocation (BA) List is a
list of BCCH frequencies that every Idle mobile in a cell is supposed to monitor. The list can be of two types typ es - Idle BA List and Dedicated BA List. Idle is used by Idle mobiles while Dedicated BA List is used by Dedicated Mobiles. You always don’t need to make two BA lists, it depends on your planning process whether you will be using single BAL or 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 AND MEASURED IN IDLE .ACTIVE OR BOTH MODES.THIS NO. IS SENT TO MS IN THE SYSTEM INFORMATION MESSAGES ON THE BCCH CHANNEL IN IDLE MODE AND ON THE SACCH IN ACTIVE MODE.
UPTO 32 BCCH CARRIERS CAN B E DEFINED BY SPECIFAYING THEIR ARFCN.
DEEP CONCEPT OF HO: THE MEASUREMENT REPORT FROM THE IS SENT TO THE ON THE SACCH INDICATING THE SIGNAL STRENGTH AND QUALITY OF THE SERVING LINK AND THE
S I G .S T R E N G T H , F R E Q . A N D B S I C
FROM THE
SIX BTS WITH STRONGEST SIGNAL STRENGTHS. ONLY MEASURMENTS FROM THE NEIGHBOURING CELLS THAT FULLFILL THE REQUREMENT BY BCCH HAS A FREQ. AS INDICATED BY MBCCH NO. IT IS NECESSARY THAT THE MEASURED CELL IS DEFINED AS THE NEIGHBOUR OF THE SERVING CELL . UPTO 64 DIFF. CELLS CAN BE DEFINED AS N EIGHBOUR. HO PROCESS M AY BE TRIGGERED BY QU AL., FIELD STRENGTH OR DISTANCE VALUES FALL BELOLW / EXCEED THEIR THRESHOLD PERIODIC CHANGE S.
HO ALGORITHUM:
The locating algorithm : W o r k s
out the basis for
h a n d o v e r d e c i s i o n s . I t is i m p l e m e n t e d i n t h e b a s e station controller. It is the algorithm for cell selection for active mo bile stations (i.e. ongoing connection) after immediate assignment. INPUT: T H E I /P T O T H E A L G O R I T H U M I S S I G N A L S T R E N G T H A N D Q U A L IT Y M E A S U R E M E N T F R O M T H E M S A N D F R O M T H E BASE STATION CURRENTLY SERVING THE CONNECTION. OUTPUT: THE OUTPUT IS THE LIST OF CELLS THAT THE ALGORITHUM JUDG ES TO BE POSSIBLE CANDIDATES F O R H A N D O V E R . T H E C E L L S I N T H E L I S T IS R A N K E D A N D S T O R E D I N D E S C E N D IN G O R D E R O F P R E F E R E N C E FOR HAND OVER. THE ALGORITHUM WORKS CONTINUESLY, COMPLETING A CALCULATION CYCLE IN GENERAL EVER Y 480 ms. MOST FREQUENTLY THE ALGORITHUM W IL RECOMMEND NOT TO PERFORM A HANDOVER. H A N D O V E R C R I T E R IA A R E B A S E D O N THREE TYPES OF MEASUREMENT 1 ] F IE IE L D S T R E N G T H ( S I G N A L S T R E N G T H A N D O R P A T H LOSS) OF THE CONNECTION AND OF
B R O A D C A ST C O N T R O L C H A N N E L
CARRIERS
FOR NEIGHBOURS. 2 ] S IG IG N A L Q U A L I T Y O F T H E C O N N E C T I O N ( B I T E R R R O R R A T E E S T E M A T I O N M A P P E D O N A L G O R I TH U M S C A L E ) 3] TIMING ADVENCE USED
BY THE
W H A T I S T I M IN G A D V A N C E ? I T IS IS A S O L U T I O N S P E C I A L Y D E S I G N E D T O C O U N T E R A C THE PROBLM
OF TIME ALLIGNMENT
. IIT TS WORKE D BY
I N S T R U C T I N G T H E M I S A L I G N E D M S T O T R A N S M I T IT S B U R S T E A R L IE R O R L A T E R T H A N I T N O R M A L L Y W O U L D . IN GSM TA INFORMAT ION RELATES TO BIT TIMES . TH U S , A N M S M A Y B E I N S TR U C T E D T O C O M M E N C E I T S T R A N S M I S S I O N A C E R T A I N N O O F B IT IT OR LATER ,RELATED I T S T IM E S L O T A T T H
T I M E S E A R L IE R
TO PREVIOUS POSITION TO REACH
BTS IN
RIGHT TIME.
WHAT IS THE DIFF. BETWEEN CELL RESELECTION AND HANDOVER? H A N D O V E R H A P P E N E D I N D E D IC A T E D M O D E A N D CELL RESELECTION IN IDLE MODE.
FREQUENCY HOPPING Call is transmitted through several frequencies in order
M i n i m i z in g t h e i m p a c t o f fa d i n g . Average the interference I t i s d e f in e d a s s e q u e n t i a l c h a n g e o f c a r r ie r f r e q u e n c y o n t h e r a d i o l in k b e t w e e n t h e m o b i le a n d b a s e station. Advantage of frequency hopping: Frequency diversity Interference averaging
How in frequency hopping there is enhancement of network?
1
H i m p l e m e n t will enable more aggressive aggressive frequency
reuse pattern that leads to better spectrum efficiency. 2 It can add more transceivers in the existing site, while maintains the network quality. 3 freq. hopping compressing the available spectrum to make room for extra freq.
Frequency reuses? FREQUENCY REUSE IMPLIES THAT IN A GIVEN COVERAGE AREA THERE ARE SEVERAL CELLS THAT USES THE SAME SET OF FREQ. THESE CELLS ARE CALLED COCHANNEL CELLS .AND THE INTERFERENCE BETWEEN SIGNALS FROM THESE CELLS ARE CALLED CO CHANNEL INTEREFERENCE.
D e f i n e a l l t h e p a r a m e t e r i n f re q u e n c y h o p p i n g ? Following are the parameter in FH MOBILE ALLOCATION (MA) MOBILE ALLOCATION INDEX (MAI) MOBILE ALLOCATION INDEX OFFSET (MAIO) H O P P I N G S E Q U E N C E N O . (H (H S N ) 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 list subtracted by one.
It is the output of hopping sequence algorithms. HOPPING SEQUENC E NO. (HSN): I t d e t e r m i n e s t h e h o p p i n g o r d e r u s e d i n t h e c e l l . it it i s p o s s i b l e to assign
d i f f .s .s e t t i n g . w h e n H S N
=
provides cyclic
hopping (pattern). H S N = 1 T O 6 3 p r o v id id e s v a r i o u s p s e u d o r a n d o m h o p p i n g .
t h e r e a r e 6 4 d i f f . p a t t e rn s o f F H One of them is a simple cyclic or sequential pattern. The remaining 63 are known as pseudo random p atterns which an operator can choose from the MA list.
WHERE WE USE CYCLIC AND RANDOM PATTERN? C Y C L I C : IT I S U S E D I N T H E A R E A W H E R E T H E I T E R F E R E N C E IS NOT A PROBLEM. R A N D O M : IT IT I S U S E D IN T H E A R E A W H E R E I N T E R F E R E N C E I S A PROBLEM.(HIGH TRAFFIC AREA).
MOBILE ALLOCATION INDEX O FFSET (MAIO): Determines inside the FH sequence w hich freq. the mobile starts do transmit on. The value of MAIO ranges betw een zeros to N-1. W h e r e N i s t h e n o . o f f r e q . d e fi n e d i n t h e M A l i s t .
Presently MA IO is set on per carrier basis.
What are the types of
a n d ? W h a t i s d if if . b e t w e e n t h e m ?
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:
N o . o f h o p p i n g f r e q . c a n b e in in t h e r a n g e o f 1 t o 6 3 .
-
here here the ARFCN ARFCN wud wud be more more than than the the no. no. Of TRX/ TRX/TRU TRU in in bts.al bts.also so 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
SFH is synthesizer freq hopping and AMR is adaptive multirate. These two terms are in all different from each other. One defines the way of using fewer frequencies more efficiently and other defines the way of controlling the quality of call in FULL RATE as well as HALF Rate so as to increase capacity indirectly with controlled quality.
W h a t i s t h e e f f e c t o f fr e q . h o p p i n g ? 1 Hand over 2 Call set up 3 F r a m e e r a s e r r a te ( F E R ) These are the eff. of FH. What is FER? I T I S TH TH E R A T IO O F
D I S C A R D E D S PE A C C H F R A M E S C O M P A R E D T O
ALL 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: % O F F E R = ( N O .E R A S E D B L O C K S ÷ T O T . N O . OF BLOCKS) × 10O Deep concept: MAIO:
It is a parameter that will allow the operator to specify a list of up to 32 MAIO values in order in which they are to be allocated to a channel group. This parameter set to
default which
removes the manual MAIO list in favor for the default MAIO list. The no. of MAIO values in list stretches from zero up to one less than 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 group depend on the no. of TRX in the channel group.
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 the even values in ascending order. After the even values all the odd values are arranged an ascending 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 TO A MOBILE EVERY TIME .IT IS ASSIGNIED TO
HOPPING
PHYSICAL CHANNEL. THE MA LIST IS A SUBSET OF
CA LIST.
#WHAT IS CA LIST?
THE MA LIST IS AUTOMATICALLY GENERATED IF THE BASEBAND HOPPING IS USED. IF THE NETWORK UTILISES THE RF HOPPING THE MA LIST HAVE TO BE GENERATED FOR EACH CELL BY THE PLANNER. The MA list is able to point the 64 of freq. defined in the CA list .However the BCCH BCCH freq. is also included In the CA list , so
the practically practically max.no. Of freq. freq. in the MA list is 63.
The freq. in the MA list is required to be in increased order
because of the type of signaling used to transfer t ransfer the MA list.
HOPPING sequence algo? Input: The hopping seq. algo. Takes HSN & FN (freq.no.) as an input. Output: Mobile allocation index (MAI) is the O/P. MAIO: WHERE THERE ARE MORE THAN ONE TRX IN THE BTS USING THE SAME LIST THE MOBILE ALLOCATION INDEX OFFSET IS USED TO ENSURE THAT EACH TRX 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 FROM THE MA LIST.
MAIO AND HSN ARE TRANSMITTED TRANSMITTED TO A MOBILE STATION TOGETHER WITH MAIO LIST. HSN DEFINES WHICH HOPPING SEQUENCE TO BE USED. MAIO DECIDES STARTING POINT OF HOPPING.
WHAT IS SLOW FREQ.HOPPING AND WHAT IS FAST FREQ.HOPPING? THE PRINCIPAL OF FREQUENCY HOPPING USED WITHIN GSM IS THAT: “SUCESSIVE TDMA BURST OF CONNECTION IS TRANSMITTED VIA. DIFF. FREQ.”
THAT FREQ. BELONGING TO A RESPECTIVE CELL ACCORDING TO NETWORK PLANNING. THIS METHOD IS CALLED SLOW FREQ. HOPPING. SINCE TRANSMISSIOMN FREQ. REMAIN CONSTENT DURING ONE BURST. IN CONTRAST FAST FRFEQ. HOPPING WHERE THE TRANSMISSION FREQ. CHANGES WITHIN THE ONE BURST.
DETAILS OF FRAME ERASER RATIO:
IT IS THE RATIO OF DISCARDED SPEACH FRAMES COMPARED TO ALL THE RECEIVED SPEECH FRAMES. A SPEECH FRAME IS GENERALLY DISCARDED IF AFTER THE DECODING AND ERROR CONNECTION PROCESS ANY OF THE CATEGORY A BIT IS FOUND TO BE CHANGED BASED ON THE THREE PARITY BITS FOLLOWING THEM IN A SPEECH FRAME. FER IS MEASURE OF HOW SUCESSFUL THE SPEECH FRAME WAS RECIVED AFTER THE ERROR CORRECTION PROCESS AND IT IS THUS A BETTER INDICATION OF THE SUBJECTIVE SPEECH QUALITY COMPARED TO THE LINK QUALITY IN TERMS OF BER .THE RECIEVER QUALITY DOES NOT INDICATE HOW THE BIT ERRORS WERE DISTRIBUTED IN A SPEECH FRAME.
“THE BIT ERROR DISTRIBUTION AFFECTS THE 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 TOTAL NO.OF BITS RECEIVED.
RESIDUAL BIT ERROR RATE:
IT IS PERFORMED ON DEMODULATED SPEECH FRAMES THAT ARE NOT MARKING CORRECT. WHAT HAPPENS WHEN SPEECH FRAMES DISCARDED IN FER? ANS: SYSTEM WILLS INTERPOLUTE.
SPEECH QUQLITY INDEX DEPENDS ON FER AND BER. 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 AND NEGATIVE) 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 CABLE SWAP OR FREQUENCY HIT. CABLE SWAP : TWO WIRES CAME FROM THE GSM AND JOIN AT THE TRX IN BTS ROOM. WHILE CONNCTING THESE WIRE THEIR COULD BE MISMATCH OR SWAPPING.BECAUSE FROM THESE TWO WIRES ONE WIRE IS OF TRANSMETER SECTION (+ SIGN ON THAT CABLE ) AND ANOTHER SIGN IS OF RECIEVER ( - SIGN IS ON THAT CABLE).SO THERE SHOULD BE CHANCES THAT + WIRE WOULD BE ATTACHED TO - AND VICE VERSA. TWO SOLVE THE PROBLEM OF CABLE SWAP WE WANT TO SEE WHETHER THESE 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 HIT TOWARDS 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.
IN FIRST CABLE SWAP TWO WIRES ARE FROM ANY ONE SECTOR IS CONNECTED IN ANOTHER SECTOR TRX/TRU .BUT IN PARTIAL CABLE SWAP ONLY ONE WIRE WOULD BE SWAP MEANS ONE WIRE FROM ANY ONE SECTOR AND 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 ANTENA 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-channel 2>sdcch time slot faulty 3>poor TRX DL quality 4>hardware fault like antenna or duplexer malfunction 5>may be feeder cable and connectors are faulty. 6>site taking calls from a very far distance. 7>Bad 7>Bad Radio link quality (any sort of interference, if highly) Bad Radio link quality (any sort of interference, if highly destructive) 8>Could be a problem problem at NSS end and 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 di rected retry, then in that case what happens? SD waits for a timer value and then also if it doesn't find a TCH it can't hold SD, so drops………………..
WHAT IS VSWR? VOLTAGE WAVE STAND RATIO: IT IS THE RATIO OF FORWARD POWER 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.
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.
ABOVE TEMS 6.1 S/W IS COMPITABLE WITH INSTRUMENTS(MOBILE) T610.
WHAT IS TEMS? TEST EQIPEMENT MOBILE SYSTEM IS A TESTING TOOL USED TO READ AND CONTROL THE INFORMATION SENT OVER AIR INTERFACES BETWEEN BASE
RADIO COVERAGE MEASUREMENS.IN ADDITION TO FIELD STATION AND THE MOBILE STATION .IT CAN BE USED FOR
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 CHANNEL 2]SERVING NEIGHBOUR 3]RADIO PARAMETER 4]C/I 5] 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.
-10 TO -70 - 71 TO -80
3]RADIO PARAMETER : FULL SUB A] RX LEVEL RANGE -10 TO -120 BEST GOOD
-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 RATIO IT IS DEFINED AS THE RATIO BETWEEN THE LEVEL OF THE RECIVED DESIRED SIGNAL TO THE LEVEL OF RECIVED UNDESIRED SIGNAL. C/I IS DEPENDENT ON THE INSTANTANEOUS POSITION OF THE MOBILE STATION AND IS AFFECTED BY TERREIN DETAILS AND VARIOUS SHAPES,TYPES AND NO.OF LOCAL SCATTERS. OTHER FACTORS SUCH AS ANTENNA TYPE DIRECTIONALITY AND HEIGHT ,SITE ELEVATIONS ,POSITIONS AND THE NO. OF LOCAL SOURCE OF INTERFERENCE ALSO EFFEECT THE DISTRIBUTION OF THE C/I RATIO IN A SYSTEM .
C/A: CARRIER TO ADJUCENT RATIO IT IS DEFINED AS THE RELATION IN DB IN SIGNAL STRENGTH BETWEEN THE SERVING AND AN ADJUCENT FREQ.
COCHANNEL INTERFERENCE: FREQUENCY REUSE IMPLIES THAT IN A GIVEN COVERAGE AREA THERE ARE SEVERAL CELLS THAT USES THE SAME SET OF FREQ. THESE CELLS ARE CALLED COCHANNEL CELLS .AND THE INTERFERENCE BETWEEN SIGNALS FROM THESE CELLS ARE CALLED CO CHANNEL INTEREFERENCE. SOLUTION:TO REDUCE CO CHANNEL INTERFERENCE CO CHANNEL CELLS MUST BE PHYSICALLY SEPERATED BY A MINIMUM DISTANCE IN ORDER TO PROVIDE SUFFIECIENT ISOLATION.
WHAT IS BASIC? B A S E S T A T I O N I D E N T IT Y C O D E I S T H E C O D E W H E R E I N T H E F I R S T D I G IT IT I N D I C A T E S N C C A N D S E C O N D D I G I T I N D IC A T E S B C C NCC :NETWORK COLOUR CODE BCC: BASE STATION COLOUR CODE THE NCC AND BCC HAVE VALUE RANGING FROM AN O TO 7 N C C : T H E N C C I S F I X E D F O R A N O P E R A T O R , S IG IG N I F Y I N G A T A N Y G I V E N PO I N T TH E R E C A N B E M A X IM U M O F 8 O P E R A T O R S
IN AN
AREA. BCC :
B C C D E F I N E S T H E C L U S T E R N O .W .W H I C H M E A N S A G R O U P O F 8
CLUSTER
C A R R Y U N I Q E ID ID E N T I T Y W H I C H A R E U S E D F O R A N O T H E R
GROUP OF 8
A N D SO O N .
EX. IF BSIC IS 65 THEN 6 IS NCC AND 5 IS BCC I F B S IC I S 5 5 A N D F R E Q . I S 5 5 T H E N H O W O U L D N O T T A K E P L A C E . WHAT IS
CLUSTER?
GROPU OF
FREQ. CAN BE
PLACED TOGETHER INTO
PATTERNS
OF CELLS CALLED CLUSTER. CLUSTER IS A GROUP OF CELLS IN WHICH A LL AVAILABLE FREQ. HAVE BEEN USED ONCE AND ONLY ONCE. T H E P R IN C I P A L F O R A L L O C A TI O N
O F T H E B S IC IC I S T H E S A M E A S
THE RF CARRIER BUT AT CLUSTER LEVEL RATHER THAN CELL LEVEL.
Transmission problem: Path loss:
Path loss occurs when the received signal becomes weaker and
weaker due to increasing distance between MS and BTS ,even if there are no obstacles between the transmitting and receiving antenna . The path loss problem seldom leads to a dropped call because before the problem becomes extreme a new transmission path is established via another BTS .
Shadowing: Shadowing occurs when there are physical obstacles including hills and building between the BTS and MS .The obstacles create a shadowing effect which can decreases the received signal strength . when the MS moves the signal strength fluctuates depending on the obstacles between the MS and BTS .
FADING DIPS: A signal influenced by fading varies in signal strength . Drops in strength are called fading dips. Multipath fading : It occurs when there is more than one transmission path to the MS or BTS .This may be due to building or mountains either close to or far far from the rec dBi, dBd,dBm dB itself is a measure of power on logarithmic scale.....when we talk abt dBi (one more thing i want add here is dBd ), these indicate gain of a 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. IN INTE TERF RFER EREN ENCE CE 2. LO LOW W SIGN SIGNAL AL STR STREN ENGT GTH H 3. MI MISS SSIN ING G NEIG NEIGHB HBOU OUR R OFTEN, THESE PROBLEMS CAN BE SPOOTEED BY LOOKING AT THE RXQUAL LEVELS AND /OR DROPPED CALLS.HOWEVER DUE TO LITTLE OR NO TRAFFIC IN THE SYSTEM, IT IS NOT POSSIBLE TO SPOT ALL THE PROBLEMS THAT MIGHT OCCUR WHEN THERE IS MORE TRAFFIC IN THE SYSTEM.FOR EX.
INTERFERENCE FROM THE NON BCCH CARRIERS DOES NOT AFFECT THE QUALITY .THEREFORE IT IS IMPORTANT THAT THE LOG FILES ARE CAREFULLY ANYLYSED EVEN THOUGH THERE ARE NO SIGNS OF
POOR
QUAL. 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 DOE DOES S NOT NOT ON BEST BEST SERVE SERVER R 2. INTE INTERF RFER EREN ENCE CE 3. LOW LOW SIGN SIGNAL AL STR STREN ENGT GTH H 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 BEST SERVER, 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 (IF USED) SHOULD BE REVIEWED TO FIND THE REASON FOR THE MS NOT BEING ON THE STRONGEST CANDIDATE. THERE IS SITUATION WE CAN IMPROVE THE COVERAGE, BY INCREASING THE OUTPUT POWER AND/OR MAKING ANTENNA ADJUSTMENTS. OUTPUT POWER: BY INCREASING THE OUTPUT POWER,THE DOWNLINK SIGNAL STRENGTH INCREASE .HOWEREVER ,IF THE O/P POWER IS TOO HIGH (APPROXIMATELY -43 DBM OR MORE),A HIGHER O/P POWER WILL NOT GREATLY AFFECT THE OVERALL PERFORMANCE DUE TO THE LACK OF POWER BALANCE BETWEEN UPLINK AND DOWNLINK . BUT AN INCREASE IN O/P POWER MAY LEAD TO HIGHER INTERFERENCE IN COCHANNEL AND ADJUCENT CHANNEL CELLS. THE CELL BORDERS ARE ALSO AFFECTED. ANTENNA ADJUSTMENTS: A HIGHER ANTENNA POSITION GENERALLY INCREASE THE CELLS COVERAGE AREA .SOMETIMES THE RE – DIRECTION OF AN ANTENNA MAY HELP THE SITUATION. IF THE ANTENNA IS DOWNTILTED ,A DECREASES OF THE TILT GENERALLY INCREASE THE COVERAGE AREA.
JUST LIKE THE CHANGING THE O/P POWER ,AN ANTENNA ADJUSTMENTS AFFECTS THE ENTIRE CELL PLAN REGARD TO CELL BOARDERS AND INTERFERENCE. INTERFERENCE PROBLEM MAJOR IINTERFERNSE PROBLEMS REQUIRE A CHANGE OF FREQ. ON ONE OR MORE CELLS. FOR A CELLS SEVERE PROBLEM ,ANATENNA DOWNTILTS CAN HELP SITUATITIONS . MINOR INTERFERENCE PROBLEM CAN SOMETIMES BE ELIMINATED OR REDUSED BY PARAMETER CHANGES .MOVIING CELL BOARDER AND /OR CHANGING THE HANDOVER (EX. SMALLER HANDOVER HYSTERIS AND SHORTER FITER LENGTHS ) CAN TAKE CARE OF LOCAL INTERFERENCE PROBLEMS. 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.
