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Cell Access Parameters
Cell Options Parameters
Cell Selection and Reselection Parameters Resource Allocation Parameters
Frequency Hopping Parameters
Power Control and Handover Parameters
GSM System SettableParameters
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RACH Control Parameters
Tx-Integer
- The maximum permissible limits of T3120 between RACH retransmissions.
Values : 3 - 12 /14/16/20/25/32/50 RACH Slots
Max Retransmissions
- No of times mobile can re-send a RACH to get AGCH.
Values set could be 1,2,4,7
Call Re-establishment Allowed
-- On Radio Link Failure can a Mobile do Call Re-establishment
0 : allowed // 1 : not allowed
Cell Access Parameters
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Access Control Class 000 - 015
- Informs which access class is barred access.
For each class ; 0 : not barred // 1 : access barred
Cell_Bar_Access
- Informs whether the cell is barred or not for access.
0 : not barred // 1 : barred
Emergency Calls
-- All MS allowed or only emergency class MS allowed to make emergency calls
0 : allowed to all MS's // 1 : allowed only to MS's of class 11- 15
RACH Control Parameters
Cell Access Parameters
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Neighbor Cells Description
- ARFCN numbers of neighboring cells on which the mobile should perform
measurements.
Cell Reselection - BCCH Allocation List ( BA List )
"0" : ARFCN not used
"1" : ARFCN used
EXT-
IND
BA-
IND
124
1
1
20
119
118
117
116
11
008
007
006
005
004
Cell Access Parameters
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PLMN Permitted
- Informs the Mobile which NCCs on the BCCH it should monitor.
- Coded in a bit map of 8 bits
" 0 " - not permitted
" 1 " - permitted
( NCC : xyy
x : operator
y : country )
Cell Access Parameters
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Cell Identity
-- Informs the Mobile the Cell global identity of the cell
-- Only used for engineering purpose
-- Coded in 2 octets. May be used in hex
-- If CGI less than 16 bits, than remaining bits coded to " 0 "
Digit
C
Digit
D
Digit
A
Digit
B
Cell Id : ABCD hex
Cell Access Parameters
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Location Area Identification
-- Informs the Location Area of the cell
-- Coded as : MCC + MNC + LAI
CCdigit2
1 1 1 1
NCdigit2
L(ti
Cell Access Parameters
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DTX Indicator
- Informs whether mobiles should use Discontinuous Transmission or not.
Values : " 0 " - MS's may use DTX
" 1 " - MS's shall use DTX
" 2 " - MS's shall not use DTX
Power Control Indicator ( PWRC )
- Indicates whether Downlink Power Control is used or not
Values : 0 : not used // 1 : used
RADIO-LINK-TIMEOUT
- Radio Link Time-out Counter Value.
Values : 4 - 64
Cell Options
Cell Options Parameters
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RXLEV-ACCESS-MIN
- This informs the mobile the minimum signal level which it should receive
to access system.
Values : 0 - 63
MX-TXPWR-MAX-CCH
- The maximum power at which the mobile can send a RACH.
Values : 0 - 31
Cell-Reselect Hysterisis
- The difference in db between new selected BCCH and the current BCCH for
cell reselection if Location Areas differ.
Values : 0 - 14 db
Cell Selection Parameters
Cell Selection and Reselection Parameters
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Optio nal Cell Reselectio n Parameters
C2 Cell Reselection Parameters
Cell_Reselect Offset :
-- Positive or negative offset value which the MS applies to the C2 value
Range : 0 - 126 dB // in steps of 2 dB
Temporary_Offset :
-- Negative offset value which the MS applies to the C2 value for a particular
duration..
Range : 0 - 60 dB in steps of 10 dB // value of 7 indicates infinity
Penalty_Time :-- The duration for which the above mentioned offset is applied
Range : 20s - 620s in steps of 20s// Value of 31 indicates that
cell_reslect_offset is negative.
Cell Selection and Reselection Parameters
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Cell_Bar_Qualify :
Used to assign normal or low priority to a cell for cell selection.. Used inconjunction with the cell_bar_qualify parameter
* 3rd and 4th conditions are same, because Phase 1 MS will not understand
the cell_bar_qualify parameter, so if access is "1" it will always consider thecell to be barred, where as a Ph 2 MS will look for the qualify also, and if set
to "1", then it will not consider the cell to be barred, but assign low priority and
will only select this cell if other normal priority suitable cells are not available.
Cell Selection and Reselection Parameters
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Power Offset
Used only by DCS 1800 Class 3 MSs to add a power offset to the value of the
Access Power used for its random attempts. It is also used by the MS in its
calculation of C1 and C2 parameters.Range : 0 - 6 dB // in steps of 2 dB
Cell Selection and ReselectionParameters
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Attach - Detach allowed- Informs whether mobile should perform IMSI Attach/Detach or not.
0 : not allowed // 1 : allowed
Control Channel Description
CCCH - CONF
- Defines the Multiframe structure of CCCH blocks.
- Informs how many CCCH's and SDCCH's are available
Value BS_CC_CHANS BS_CCCH_SDCCH_COMB
000 1 No
001 1 Yes
010 2 No
100 3 No110 4 No
BS_CC_CHANS : No of PCHNS ( timeslots ) supporting CCCH
BS_CCCH_SDCCH_COMB : Whether SDCCH is combine with CCCH ( TN 0)
or is on a separate timeslot
Resource Allocation Parameters
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T3212 timeout value
- Informs the mobile the timeout value for Periodic Location Update.
Values 0 - 255 decihours.
( "0" indicates no periodic update will be used )
Control Channel Description
BS-PA-MFRMS
-- No of multiframes for transmission of paging messages to same paging group
Values : 0 - 9
BS - AG - BLKS - RES
- Informs the Mobile the number of blocks reserved for AGCH.
Values : 0 - 2 for combined
0 - 7 for non combined
Resource Allocation Parameters
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Channel type and TDMA offset- Informs the Mobile , the channel type and subchannel for CBCH
Values : 0 0 1 T T -- CBCH ( SDCCH/ 4 )
0 1 T T T -- CBCH ( SDCCH/ 8 )
T indicates the subchannel
Training Sequence Code
- It is the Base Station Color Code. BCC of BSIC
Values : 0 - 7
Timeslot Number ( TN )
-- Indicates the timeslot number for CBCH
Values : 0 - 7
( CBCH ) Channel Description
Hopping Channel ( H )
-- informs whether CBCH channel is hopping or single
Values : 0 - Single RF Channel
1 - RF hopping channel
CBCH Parameters
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Cell Allocation Number- Informs the band number of the frequency channels used.
0 0 -- Band 0 ( current GSM band )
Cell Allocation ARFCN Number
- The ARFCN channels used in the cell for the purpose of hopping- ARFCN numbers are coded in bitmap of 124 bits
Cell Channel Description
"0" : ARFCN not used
"1" : ARFCN used
"Max 64 channels can be coded"
1241
12011911811711611
008007006005004
Frequency Hopping Parameters
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Mobile Allocation Index Offset ( MAIO )-- Informs the mobile where to start the hopping sequence
Values : 0 - 63
Hopping Sequence Number ( HSN )
-- Informs the mobile in what order the ARFCN's should be used for hopping
Values : 0 - 63
( HSN = 0 indicates cyclic hopping,
HSN = 1 - 63 , Frequency hopping algorithm is used )
Frequency Hopping Parameters
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Mobile Allocation Table
-- Informs the mobile the which RF channels set in the cell allocation areused in the mobile hopping sequence
Cell Allocation
Values : 0 = ARCN not used for hopping
1 = ARFCN used for hopping
Mobile Allocation
124123122121120119118117116115114113
016
1
015
1
014
1
013
0
012
1
011
1
010
0
009
1
008
1
007
1
006
0
005
1
004
0
003
1
002
0
001
1
010120011100900081007001
Frequency Hopping Parameters
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Derives the sequence of ARFCN's on which the mobile will hop
Algorithm
MAIO Frame No HSN
Mobile Allocation Table
ARFCN Number corresponding to Frame number
Frequency Hopping Algorithm
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Neighbor Cells Description
- ARFCN numbers of neighboring cells on which the mobile should perform
measurements in the active mode.
Active Mode - Type 5 Neighbor List
"0" : ARFCN not used
"1" : ARFCN used
EXT-
IND
BA-
IND
1241
12011911811711611
008007006005004
Handover Parameters
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Measurement Results Averaging period ( Hreqave)
Measurement Results Averaging Type
Power Control Algorithm parameters
Handover Decision Algorithm Parameters
Handover Target Cell Algorithm Parameters
Handover Margin
Power Control and HandoverParameters
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--- MS sends Downlink measurement report to BTS every 480ms.
--- BTS sends the report from MS and its own uplink measurement every 480ms to
the BSC.
The BSC Averages the Measurement received after a set period ( Hreqave )
--- The averaging could be following types :
Unweighted Average
Weighted Average
Modified Median
Hreqave : Averaging Period for Rxlev,Rxqual & Timing Advance
( In terms of SACCH Frames ( 480ms ). Range : ( 1, 31 )
Measurement Averaging
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Based on Measurements BSC will decide for Power Control or Handover
Uplink Power Control Increase Algorithm for Rxlev
RXLEV_UL : Rxlev reported by BTS on UplinkL_RXLEV_UL_P :Rxlev threshold on Uplink for power increase ( - 103 to - 73 dbm )
N1 : Number of Rxlev Measurement Averages to initiate process ( Range = 1 , 31 )
P1 : Proportion of Averages for comparison ( Range = 1, 31 )
" If , P1 out of N1 are lower than L_RXLEV_UL_P , then Increase Power"
RXLEV_UL : Rxlev reported by BTS on Uplink
U_RXLEV_UL_P: Rxlev threshold on Uplink for power decrease
N2 : Number of RXlev Measurement Averages to initiate process ( Range = 1 , 31 )
P2 : Proportion of Averages for comparison ( Range = 1, 31 )
"If , P2 out of N2 are greater than U_RXLEV_UL_P , then Decrease Power"
Uplink Power Control Decrease Algorithm for Rxlev
Other Parameters : Pow_Incr_Step_Size= Range 2, 4 or 6 db
Pow_Red_Step_Size= Range 2, or 4 db
P_Con_Interval= Min Interval betn changes in Power level ( 0, 30s )
For Downlink Power Control on Rxlev the Parameters remain the same
Power Control Algorithm Parameters
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For Downlink Power Control on Rxqual the Parameters remain the same
Uplink Power Control Increase Algorithm for Rxqual
RXQUAL_UL : Rxqual reported by BTS on Uplink
L_RXQUAL_UL_P :Rxqual threshold on Uplink for power increase
N3 : Number of Rxqual Measurement Averages to initiate process( Range = 1 , 31 )
P3 : Proportion of Averages for comparison ( Range = 1, 31 )
"If , P3 out of N3 are greater than L_RXQUAL_UL_P , then Increase Power"
RXQUAL_UL : Rxqual reported by BTS on Uplink
U_RXQUAL_UL_P: Rxqual threshold on Uplink for power decrease
N4 : Number of Rxqual Measurement Averages to initiate process ( Range = 1 , 31 )
P4 : Proportion of Averages for comparison ( Range = 1, 31 )
"If , P4 out of N4 are lower than U_RXLEV_UL_P , then Decrease Power"
Uplink Power Control Decrease Algorithm for Rxqual
Other Parameters : Pow_Incr_Step_Size= Range 2, 4 or 6 db
Pow_Red_Step_Size= Range 2, or 4 db
P_Con_Interval= Min Interval betn changes in Power level ( 0, 30s )
Power Control Algorithm Parameters
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Thresholds :
If set too low, Uplink Interference to other users will be reduced
Less transition time from Power Control to Handover
(may result into drops on edges)
Talk time for Mobile Phones will increase if coverage is moderate
If set high, Uplink interference to other users will increase
Probability of call drops will reduce since handovers will increase
Talk time for Mobile Phones will reduce if coverage is moderate
N and P parameters
If set low, ( lowest value 480ms) Power control will be fast, poor quality mobiles will be misbehave
If set high,(highest value 14.88 sec) Power control will be slow, may result into proxy handovers
Effect of Settings
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RXLEV_XX : Rxlev reported by BTS [ XX = UL or DL ]
L_RXLEV_XX_H :Rxlev threshold for Handover ( - 103 to - 73 dbm ) [ XX = UL or DL ]N5 : Number of Rxlev Measurement Averages to initiate process ( Range = 1 , 31 )
P5 : Proportion of Averages for comparison ( Range = 1, 31 )
On Rxlev
" If , P5 out of N5 are lower than L_RXLEV_XX_P , then Handover is required "
On Rxqual
RXQUAL_XX : Rxqual reported by BTS [ XX = UL or DL ]L_RXQUAL_XX_H :Rxqual threshold on Uplink for power increase
N6 : Number of Rxqual Measurement Averages to initiate process( Range = 1 , 31 )
P6 : Proportion of Averages for comparison ( Range = 1, 31 )
" If , P6 out of N6 are greater than L_RXQUAL_XX_P , then Handover is required "
On Timing AdvanceMS_RANGE_MAX : Maximum permissible limits
N8 : Number of Rxlev Measurement Averages to initiate process ( Range = 1 , 31 )
P8 : Proportion of Averages for comparison ( Range = 1, 31 )
"If , P8 out of N8 are greater than MS_RANGE_MAX , then Handover is required"
Handover Comparison Algorithm Parameters
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1. RXLEV_NCELL ( n ) > RXLEV_MIN ( n ) + Max ( 0, Pa )where : Pa = [ MS_TXPWR_MAX (n) - P ) ]
2. [ Min ( MS_TXPWR_MAX, P ) - RXLEV_DL - PWR_C_D ]
- [ Min ( MS_TXPWR_MAX (n), P ) - RXLEV_NCELL (n) ]
- HO_MARGIN (n) > 0
BSC will evaluate Equation 2 for each Neighbor cell ,
only if the cell satisfied Equation 1.
BSC shall compile list of preferred neighbor cells depending on Equation 2
The cell with maximum value of Eqn. 2 will be be first target cell and so on
where,
PWR_C_D : Max_DL_RFPOWER - Actual_DL_RFPOWER ( due to BS Pwr Cntl )
P : Maximum TXPWR capability of the Mobile
HO_MARGIN (n) : Hytserisis value to avoid repetitive handover ( 0 to 24 db )
Target Cell is always decided on the basis of Rxlev
*
* This parameter not reqd if DL Power control is not used
Handover Decision Algorithm Parameters
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Criteria
Uplink Interference Downlink Interference
O & M
Resource Management
Uplink Interference Handover
Parameters for Decision
RXQUAL_UL & RXQUAL_DL
L_RXQUAL_UL_H & L_RXQUAL_DL_H( Rxqual Threshold for Handover )
RXLEV_UL & RXLEV_DL
RXLEV_UL_IH & RXLEV_DL_IH
( Rxlev thresholds for Interference Handover)
(Range : - 80dbm to -40dbm )
N7 = No of Rxlev Averaged Measurements
P7 = Proportion for Comparison
RXQUAL_UL > L_RXQUAL_UL_H
&
RXLEV_UL > RXLEV_UL_IH
Downlink Interference Handover
RXQUAL_DL > L_RXQUAL_DL_H
&
RXLEV_DL > RXLEV_DL_IH
Decision
IF ....
..... then,Intracell Handover
..... then,Intracell Handover
IF.....
P7 out of N7 for
P7 out of N7 for
Intra - Cell Handover Parameters
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PBGT(n) =[ Min ( MS_TXPWR_MAX, P ) - RXLEV_DL - PWR_C_D ]
- [ Min ( MS_TXPWR_MAX (n), P ) - RXLEV_NCELL (n) ]
If PBGT ( n ) > 0 & PBGT ( n ) > HO_MARGIN ( n )
......... then, Handover on the basis of Power Budget is initiated
Power Budget ( PBGT )
If PBGT is enabled , then every 480 ms the BSC shall evaluate the following
equation for each of the 16 possible neighbor cells.
Power Budget HandoverParameters
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Calculate the minimum and the maximum time
with reference to the parameter settings , a
handover command will come to the Mobile?
Quiz ??
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Min value of Hrequave = 1
So Handover algorithm will start every 480ms
Min value of N = 1
So Handover algorithm will also end every 480ms
Minimum time for Handover Command = 480ms + Processing time
Max value of Hrequave = 31
So Handover algorithm will start every 14.88sec
Max value of N = 31
So Handover algorithm will end after another 14.88 sec
Maximum time for Handover Command = 29.76sec + Processing time
Solution