bsspar1 s14 chapter 02_radio_resource_administration_v1.1
DESCRIPTION
BSS OptimizationTRANSCRIPT
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BSSPAR1: Chapter 2Radio Resource Administration
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Module Objectives
• Give an overview about the TDMA frame structure
• Describe the logical channels, their mapping to TDMA frames and their parameters
• Demonstrate, how the signalling capacity effect the mapping of the logical channels
• Describe the purpose of the Base Station Identity Code and the Training Sequence Code
• Explain the use of frequency reuse and the fundamentals of frequency hopping
• Discuss the parameter settings required for base band and RF frequency hopping
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TDMA frame= 8 timeslots( 0.577ms * 8 = 4.615 ms)
01
34
5
76
01
23
45
76
01
23
45
200 kHz
Physical channel e.g. allocated to onesubscriber with FR voiceand no frequency hopping
frequency
time
TDMA frame2
2 2 2
Basic TDMA Structure
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0 1 2 49 500 1 2 24 25
0 2047
0 1 2 48 49 500 1 24 25
0 7
2048 super frames = hyper frame
Super frame = 26 x (51 multi frame) or 51 x (26 multi frame)
26 multi frame = 120 ms 51 multi frame = 235 ms
TDMA frame = 4.615 ms
TDMA frame numbering
0 1 2 49 50
Multi, Super & Hyper Frames
(Traffic and associated signalling) (Signalling and Control channels)
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Base StationSubsystem
Logical Channelsfor transport of specific content
Physical Channelstransport medium
MS
mapping
Physical channel parametersARFCNTime slot numberFrequency hopping algorithm
GSM Channel Organization
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SCH
FCCH
PCH
BCCH
AGCH
RACH
SDCCH
SACCH
FACCH
Stand alone Dedicated Control Channel
Frequency Correction Channel
Synchronisation Channel
Broadcast Control Channel
Paging Channel
Slow Associated Control Channel
Fast Associated Control Channel
Paging Channel
Random Access Channel
Access Grant Channel
BCH
CCCH
DCCH
TCH
DL
DL
DL
UL
CommonChannels
DedicatedChannels
UL/DL
UL/DL
CBCH Cell Broadcast Channel
Logical Channels
FR/HR Full rate / Halft rate TCH
EFR Enhanced Full rate TCH
AMR FR/HR Adaptive multirate TCH (FR/HR)
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...
26 TDMA frames = 120 ms
1 26
t t tt t t t ft tt t t tt t t tt ft t t ttts i
Full Rate Traffic Channel Configuration (UL & DL)
Half Rate Traffic Channel Configuration (UL & DL)
26 TDMA frames = 120 ms
1 26
t
T T
t t
T
tf
t t
T T T T
t t
T
t
Tf
T
t
T
tt
T
s
S
t = full rate TCH, s = SACCH/T, i = idle TDMA frame
t = half rate TCH, s = SACCH/T (first user)T = half rate TCH, S = SACCH/T (second user) TDMA frame
Traffic Channel Mapping
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f s ff s f s
Downlink51 TDMA frames = 235 ms
-
Uplink
BCCH CCCH
f s f s
CCCH CCCHSDCCH 0
SDCCH 1SDCCH 2
SDCCH 3
SACCH0/2 SACCH
1/3
r r f r r rr r r r fr r r r r rr r r r fr r r r rr f r r
1 51
SACCH2/0 SACCH
3/1
SDCCH 0SDCCH 1SDCCH 3
SDCCH 2
f = FCCH, s = SCH, r = RACH TDMA frame- = dummy burst
51 TDMA frames = 235 ms
1 51
Signalling Channel Mapping(BCCH + SDCCH/4 + SACCH/C4)
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f s ff s f s
Downlink51 TDMA frames = 235 ms
-
Uplink
BCCH CCCH
f s f s
CCCH CCCH
r r f r r rr r r r fr r r r r rr r r r fr r r r rr f r r
1 51
CCCH CCCH CCCH CCCH CCCH CCCH
r rr r rr r r r r r r rr r r r r rr rr r r
f = FCCH, s = SCH, r = RACH TDMA frame- = dummy burst
51 TDMA frames = 235 ms
1 51
Signalling Channel Mapping(BCCH +CCCH/9)
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f
f
i = idle TDMA frame
f
51 TDMA frames = 235 ms
iii
iii
SDCCH 0SDCCH 1
SDCCH 2SDCCH 3
SDCCH 4SDCCH 5
SDCCH 6SDCCH 7
SDCCH 1SDCCH 2
SDCCH 3SDCCH 4
SDCCH 5
SDCCH 6SDCCH 7
SDCCH 0
Downlink
Uplink
SACCH0/4 SACCH
1/5
SACCH2/6 SACCH
3/7
SACCH6/2 SACCH
7/3
SACCH4/0SACCH
5/1
51 TDMA frames = 235 ms
1 51
1 51
Signalling Channel Mapping(SDCCH/8 +SACCH/C4)
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Channel configuration defined by parameter channelType
TCHF (0) = full rate traffic channelTCHH (1) = half rate traffic channelTCHD (2) = dual rate traffic channelSDCCH (3) = standalone (SDCCH/8)MBCCH (4) = broadcast control channelMBCCHC (5) = BCCH + SDCCH/4MBCCB (7) = BCCH + SDCCH/3 with CBCHSDCCB (8) = SDCCH/7 with CBCHNOTUSED (9) = timeslot has no radio definition or Abis allocationERACH (10) = random access channel of extended areaEGTCH (14) = EGPRS packed data traffic channel for extended areaLRTCH (15) = long reach traffic channel
Channel MappingParameter Setting
Note: • Some values not allowed in certain tsl (e.g. TSL0 can’t have value 8)• PBCCH is not supported in S13 and onwards
MO Class TR/RTSLParameter channelxType (CHx) where x = 0…7
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When static SDCCHs overbooked Free TCHs used for SDCCH traffic
Rules for dynamic SDCCH allocation:
• SDCCH is configured to TRX with least number of SDCCHs or no SDCCHs yet at all• SDCCH is configured to TRX with least number of occupied channels• If between different types of TCHs must be selected, the preference order is: HR, FR, DR TCH• DFCA: SDCCH and Dynamic SDCCH not supported on DFCA TRXs (only on regular TRX)
Exceptions:
• Configuration of any dynamic SDCCH resource in the BTS not possible• Only one TCH of the BTS is available
Dynamic SDCCH allocation + FACCH call set up enabled simultaneously dynamic SDCCH allocation has higher priority
Dynamic SDCCH Allocation
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S13 Feature (Licence Based)
• Up to 24 SDCCH channels for a BCCH TRX, • Up to 32 SDCCH channels for a non-BCCH TRX• Only supported by Ultrasite & Flexi BTS
Dynamic SDCCH must be activated in the BSC before Increased Dynamic SDCCH Capacity can be activated.
TRXSIG of 64kbps is required for the feature
Increased Dynamic SDCCH AllocationBSS21113
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Alternative to dynamic SDCCH allocation (for call setup case)
• Assignment of TCH to MS from CCCH instead of SDCCH• Call set up on FACCH instead on SDCCH
Parameters (SEG Level)
newEstabCausesSupport (NECI) Y/N Enables feature is general
Parameters (BSC level)
ordinaryCallOnFacch (EOF) Y/N Enables ordinary call set up on FACCHemerCallOnFacch (EEF) Y/N Enables emergency call set up on FACCHreestablishOnFacch (ERF) Y/N Enables call reestablishment on FACCHpagingAnsOnFacch (EPF) Y/N Enables answer to paging call setup on FACCH
FACCH Call Set Up
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Mobile terminating call -> MSC performs paging
MS identifies paging message with the IMSI/TMSIMS listens to own paging group only
SEG-BTS parameters
MSC parameters
Repaging Interval (INT) 0.5s…10s Time between consecutive pagingattempts
Repaging Attempts (AT) 0…5 Number of paging repetitions
Buffering
BTS stores up to 8 paging messages of the MSC in page group bufferBTS sends paging messages to MS according noOfMultiframesBetweenPaging
Paging Channel (PCH) Parameters
MO Class
Abbreviated Name
Range And Step
Description Default value
BSC - MML Name
BTS noOfMFramesBetweenPaging
2...9, step 1
Defines the number of multiframes between two transmissions of the same paging message to the MSs of the same paging group.
4 MFR
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Mobile sends channel requests to BTS separated by random time intervals in case of no answer!
Parameters
Random time interval between consecutive retransmissions
t = S + random [0,.. numberOfSlotsSpreadTrans – 1] RACH slots
S depends on numberOfSlotsSpreadTranssignalling channel mapping (CCCH + SDCCH combined or not in one multi frame)
numberOfSlotsSpreadTrans = 10
signalling channel mapping = not combined S = 58
Therefore t = 58..to..67 RACH slots
time channel requests
RACH Parameters
MO Class
Abbreviated Name
Range And Step Description Default value
BSC - MML Name
BTS maxNumberRetransmission
1,2,4,7 Maximum number of retransmissions on the RACH that the MS can perform.
4 RET
BTS nbrOfSlotsSpreadTrans
MML Range: 3..12, 14, 16, 20, 25, 32, 50
The number of TDMA frames over which retransmission is spread on the RACH (random access channel)
10 SLO
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Network gives the MS dedicated resources
Downlink CCCH blocks
• PCH can be used for AGCH messages• AGCH cannot be used for PCH messages
Reservation of CCCH blocks for AGCH
noOfBlocksForAccessGrant (AG) 0..7 possible number, if CCCH and SDCCH are not combined1..7 possible number, if CBCH is used in non combined configuration0..2 possible number, if CCCH and SDCCH are combined
Preference of AGCH messages on PCH
noOfBlocksForAccessGrant 0 PCH can be used only, if no paging messages have to be send
= 0 AGCH messages have higher priority than PCH ones
Number of paging groups
N = (number of CCCH blocks – noOfBlocksForAccessGrant) * noOfMultiframesBetweenPaging
AGCH Parameters
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Chs 1% 2% 3% 5% Chs 1% 2% 3% 5%
1 0 .01 0 .02 0 .03 0 .05 21 12 .80 14 .00 14 .90 16 .20
2 0 .15 0 .22 0 .28 0 .38 22 13 .70 14 .90 15 .80 17 .10
3 0 .46 0 .60 0 .72 0 .90 23 14 .50 15 .80 16 .70 18 .10
4 0 .87 1 .09 1 .26 1 .52 24 15 .30 16 .60 17 .60 19 .00
5 1 .36 1 .66 1 .88 2 .22 25 16 .10 17 .50 18 .50 20 .00
6 1 .91 2 .28 2 .54 2 .96 26 17 .00 18 .40 19 .40 20 .90
7 2 .50 2 .94 3 .25 3 .75 27 17 .80 19 .30 20 .30 21 .90
8 3 .13 3 .63 3 .99 4 .54 28 18 .60 20 .20 21 .20 22 .90
9 3 .78 4 .34 4 .75 5 .37 29 19 .50 21 .00 22 .10 23 .80
10 4 .46 5 .08 5 .53 6 .22 30 20 .30 21 .90 23 .10 24 .80
11 5 .16 5 .84 6 .33 7 .08 31 21 .20 22 .80 24 .00 25 .80
12 5 .88 6 .61 7 .14 7 .95 32 22 .00 23 .70 24 .90 26 .70
13 6 .61 7 .40 7 .97 8 .83 33 22 .90 24 .60 25 .80 27 .70
14 7 .35 8 .20 8 .80 9 .73 34 23 .80 25 .50 26 .80 28 .70
15 8 .11 9 .01 9 .65 10 .60 35 24 .60 26 .40 27 .70 29 .70
16 8 .88 9 .83 10 .50 11 .50 36 25 .50 27 .30 28 .60 30 .70
17 9 .65 10 .70 11 .40 12 .50 37 26 .40 28 .30 29 .60 31 .60
18 10 .40 11 .50 12 .20 13 .40 38 27 .30 29 .20 30 .50 32 .60
19 11 .20 12 .30 13 .10 14 .30 39 28 .10 30 .10 31 .50 33 .60
20 12 .00 13 .20 14 .00 15 .20 40 29 .00 31 .00 32 .40 34 .60
Erlang B TableFor reference in upcoming calculations
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Combined CCCH / SDCCH configuration
noOfBlocksForAccessGrant = 1 2 CCCH blocks for PCH
3 MSs paged per paging message 3 pages per block2 blocks per multi frame 3 * 2 = 6 pages per multiframe
Number of pages per hour 3600 s / 0.235 s * 6 = 91915
Avg of 2 pages required per MS 91915 / 2 = 45957 MSs per hour
BTS 3 MS
Paging_Request
BTS 3 MS
Paging_Request
Paging CapacityExample
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Cell with 325 subscribers1 call per subscriber once in a hour1 location update (LU) per subscriber once in 2 hours
Duration of call assignment = 4 s 4 s / 3600 s = 1.11 mErl on SDCCH per subscriber325 subscribers 325 * 1.11 mErl = 0.3607 Erl on SDCCH
Reservation time for LU = 5s 5 s / 7200 s = 0.69 mErl on SDCCH per subscriber325 subscribers 0.2242 Erl on SDCCH
Total SDCCH traffic 0.3607 Erl + 0.2242 Erl = 0.5849 ErlBlocking probability = 1% 4 SDCCHs required SDCCH combined with
CCCH can be used (MBCCHC)
SDCCH Signalling CapacityExample with call Establishment & Location Update
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Same cell with 325 subscribers
Additional SMS traffic of 1 mErl per subscriber
325 subscribers 325 * 1 mErl = 0.325 Erl on SDCCH
Total SDCCH traffic 0.5849 + 0.325 Erl = 0.9099 Erl
Blocking probability = 1% 5 SDCCHs required not combined with CCCH (MBCCH)
SDCCH Signalling CapacityExample including SMS
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Base Station Identity Code BSIC = Network Colour Code NCC + Base Station Colour Code BCC
bsIdentityCode Setting of BSIC
NCC 0..7, distinguishes between PLMNsBCC 0..7, distinguishes between clusters
BSIC + frequency channel unique identity of adjacent cell
f1f2
f3
f1
f1
bcc = 1
bcc = 2
bcc = 3
Base Station Identity Code
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Training Sequence Code (TSC) 0…7
Defined on TRX level Used to determine signal distortion and bit error rate
trainingsequence
encrypted bitsencrypted bits3 31
stealing flag stealing flag
57 bits 57 bits26 bits
1
tail bits tail bits
Burst on TCH
data± difference =difference
expected bursttraining sequence ??
received burst
correlation
data* data*training sequence*
data*
Training Sequence Code
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200 kHz
890 915 935 960
1 2 3 4 124123 1 2 3 4 124123
duplex distance
Absolute radio frequency carrier number ARFCN
uplink direction downlink direction
Example: GSM 900
Defining Frequency carrier number
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Frequency to be used by TRX (must be unique within a BTS)
initialFrequency (FREQ) 1…1023 Setting of ARFCNs
GSM 800: 128 .. 251 GSM 900: 1..124 and 975..1023, 0 GSM 1800: 512..885 GSM 1900: 512..810
f1f2
f3f4
f5f6
f7
f1f2
f3f4
f5f6
f7
f1f2
f3f4
f5f6
f7
Frequency Reuse
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Defining BA list
bCCHAllocationList ID 1…2000 Indicates ARFCN values given by BCCHallocation list
frequencyBandinUse 800, 900, 1800, 1900, Multi
Frequency list of ARFCN in the BAL
Idle mode MS listens on BCCH
idleStateBCCHAllocation (IDLE) 0,1…2000 0 = MS gets frequency information fromadjacent cells defined for the BTS1..2000 = MS gets frequency information fromthe defined BCCH allocation list
Dedicated mode MS listens on SACCH
measurementBCCHAllocation (ACT) ADJ = MS gets frequency information fromadjacent cells defined for the BTSIDLE = active MS uses same BCCH freq list as
idle MS
Frequency Information for MS
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Frequency
Time
F1
F2
F3
Call is transmitted through several frequencies to• average the interference (interference diversity)• minimise the impact of fading (frequency diversity)
Frequency hopping techniques
hoppingMode (HOP) BB,RF,NBB = base band hopping (1)RF = RF hopping (2)N = no frequency hopping at all (0)
Principle of Frequency Hopping
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Baseband Hopping
TRX 1
TRX 2
TRX 3
0 1 72 Timeslot
TRX 4
BCCH
f 1
f 2
f 3
f 4
HSN1 (BB hopping group 1 and RF hopping)Timeslot 0 hops over TRXs 2-4 onlyBCCH does not hop
HSN2 (BB hopping group 2)Timeslots 1-7 hop over all TRXs
TRXs do not hopPhysical channels moved from one TRX to another
Hopping sequencehoppingSequenceNumber (HSN) 0..63
0 = cyclic hopping1..63 = pseudorandom hopping
Base Band Hopping
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RF HoppingStandard technique
TRX 1
TRX 2
TRX 3
0 1 72 Timeslot
TRX 4
BCCH f1 – no hopping
f2,f3..fn – hopping accordingmobile allocation list One hopping sequencenumber only
All TRXs hop except TRX1 (provides BCCH)Up to 63 frequencies available defined by mobile allocation list -> better hopping gain
mobileAllocationList Setting of ARFCN values usedMobileAllocation (MAL) 0,1...2000 0 = BTS detached from any list
1..2000 = indicates list which shall be used
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Standard technique
9 hopping hopping frequencies MAI = 0..8But 3 frequencies available for every TRX only
Freeform hopping
For every sector samemobile allocation listhopping sequence numberframe number (frame synchronization)
For every sector differentstarting points for hopping sequencepossible by mobile allocation index offset
maioOffset (MO) 0..62
setting of MAIO
9 hopping hopping frequencies MAI = 0..89 frequencies available for every TRX
RF HoppingFreeform Hopping
MAIO Offset MAI
TRX-1 (BCCH) -
TRX-2 0
TRX-3 1
TRX-4 2
TRX-5 (BCCH) -
TRX-6 3
TRX-7 4
TRX-8 5
TRX-9 (BCCH) -
TRX-10 6
TRX-11 7
TRX-12 8
Sector-3 6
Sector-1 0
Sector-2 3
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Freeform hopping
• Not adequate for MA list with consecutive ARFCN values• Avoids co-channel interference but not adjacent channel interference
Flexible MAIO management
MAIO increases with constant step size from one TRX to the next one
maioStep (MS) 1..62
maioOffset = 0, 6, 12 for sector 1, 2, 3maioStep = 218 frequencies required (2 * number of hopping TRXs)
RF HoppingFlexible MAIO Management
MAIO Offset
MAIO Step MAI
TRX-1 (BCCH) -
TRX-2 0
TRX-3 2
TRX-4 4
TRX-5 (BCCH) -
TRX-6 6
TRX-7 8
TRX-8 10
TRX-9 (BCCH) -
TRX-10 12
TRX-11 14
TRX-12 16
Sector-3 2
0
6
12
Sector-1 2
Sector-2 2
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BCCH
Band allocation:
MA listConsecutive ARFCN
Only BCCH frequency planning requiredOnly BCCH frequency planning required
Flexible MAIO managementMAIO Offset + MAIO Step
BCCH
Band allocation:
MA listNon-adjacent ARFCN
Freeform hoppingMAIO Offset
MA list and BCCH frequency planning requiredMA list and BCCH frequency planning required
RF Hopping (Tight Frequency Reuse)
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Changing Frequency Plan
BSIC / TSCFrequenciesFrequency hopping settingIntelligent underlay overlay TRX settings
• Plan downloaded to BSC/BTSs via MML or GUI• File-based plan provisioning• Immediate Plan activation method