omf007001 frequency planning issue1.4
TRANSCRIPT
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Content of Frequency planning
Frequency resource of GSM system
Requirement for interference and carrier-to-
interference ratio
Signal quality grade coding
Concept of frequency reuse
4*3 frequency reuse
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GSM 900 :
GSM 1800 : 1710 1785 1805 1880Duplex distance : 95 MHz
890 915 935 960
Duplex distance : 45 MHz
Frequency Resource of GSM System
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All useful signals carrier All useless signals interference =
GSM standard: C / I >= 9 dBIn practical projects: C / I >= 12dB
Useful signal Noise from environment
Other signals
Requirement for Interference and Carrier-to-Interference Ratio
C/I =
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Requirement for Interference and Carrier-To-Interference Ratio
All useful signals carrier All useless signals interference =
GSM standard: C / I >= 9 dBIn practical projects: C / I >= 12dB
Useful signal Noise from environment
Other signals
C/I =
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Effect of Interference
Decrease of signal quality
Bit error
Recoverable: channel coding, error correction
Irrecoverable: phase distortion
System interference model
Unbalanced: uplink interference downlink interference
Asymmetrical: the interference is different at the MS and BTS ends
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RXQUAL Mean BER BER rangeclass (%) from... to0 0.14 < 0.2%1 0.28 0.2 ... 0.4 %2 0.57 0.4 ... 0.8 %3 1.13 0.8 ... 1.6 %4 2.26 1.6 ... 3.2 %5 4.53 3.2 ... 6.4 %6 9.05 6.4 ... 12.8 %7 18.1 > 12.8 %
Fairly good
Intolerable
Good
Acceptable
Signal Quality
Receiving quality (RXQUAL parameter)
Level of receiving quality (0 ... 7)
Bit error rate before decoding and error correction
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{fi,fj..fk}
{fi,fj..fk} {fi,fj..fk} {fi,fj..fk} .. ..
Macro-cell system
d Micro-cell system
Concept of Frequency Reuse
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The Reason of Frequency Reuse
Frequency resource is limited. If there is 8MHz frequency
resource, 8 MHz = 40 channels * 8 timeslots = 320
==> max. 320 users can access the network at the same
time.
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Looser reuse
Higher frequency reuseefficiency, but interference
is serious. More technique
Is needed.
Tighter reuse
0 10 20
Little interference, but frequency
reuse efficiency is low.
Reuse Density
Reuse density is the number of cells in a basic reuse cluster.
4*3 12
n*m n*m
n: BTS number in a basic reuse cluster
m: Frequency group number in a BTS
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[fn]
[fn]
D
[fn]
R
Reuse of a frequency causes the co-channel interference
Problem of Frequency Reuse
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Interference (C/I) Estimation
6
1 q
I
C /q= /(
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R
D
This old-fashioned frequency distributionmode is not recommended
Frequency Reuse Patterns
Purpose: to minimize the interference in the whole network with
the final frequency allocation plan
Theoretically
Regular hexagon cell
Regular network distribution
Cell cluster
Multiplexing distance
D = R *sqrt(3*K)
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A1C1
B1D1
A2
A3B2
B3
C2
C3D2
D3
A1C1
B1D1
A2
A3B2
B3
C2
C3D2
D3
A1C1
B1
D1A2
A3B2
B3
C2
C3D2
D3 A1C1
B1D1
A2
A3B2
B3
C2
C3D2
D3
A1C1
B1D1
A2
A3B2
B3
C2
C3
D2D3
A1C1
B1D1
A2
A3B2
B3
C2
C3D2
D3
4*3 Frequency Reuse
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A1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D3
34 34 35 36 37 38 39
40 41 42 43 44 45 46 47 48 49 50 51
52 53 54 55 56 57 58 59 60 61 62 63
64 65 66 67 68 69 70 71 72 73 74 75
76 77 78 79 80 81 82 83 84 85 86 87
88 89 90 91 92 93 94 95
Illustration of Frequency Allocation of 4*3Frequency Reuse
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Outline
Frequency planning
Tight frequency reuse
Frequency hopping
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Tight Frequency Reuse Technology
Multi-layer reuse pattern
Underlaid and overlaid cell
1*3
1*1
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Multi-layer Reuse Pattern
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BCCH: n1
TCH1: n2
TCH2: n3
TCHm-1: n m
n1 n2 n3 n4 ...... n m
And n1+n2+...+n m =n
Multi-layer Reuse Pattern
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Multi-layer Reuse Pattern Frequency Allocation
Suppose that the available frequency carrier is 10MHZ,
channel number is 46 94, the Multi-layer reuse pattern
should be:
RC type AllocatedfrequenciesNumber ofavailable
frequencies
BCCH 46~57 12
TCH1 58~66 9
TCH2 67~74 8TCH3 75~82 8
TCH4 83~88 6
TCH5 89~94 6
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BCCH TCH1 TCH2 TCH3 TCH4
{f1,f3,f5...f23}
{f1,f2,f3,f4,f5...f40}
{f2,f4..f22,f24...f40}
Multi-layer Reuse Pattern Frequency Allocation
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Capacity increase when reuse density is multiplied:Supposing there are 300 cellsBandwidth: 8 MHz (40 frequency)
Normal 4*3 reuse: reuse density=12 ==> network capacity = 40/12 * 300 = 1000TRX
Multiple reuse:BCCH layer: re-use =14, (14 frq.)Normal TCH layer: re-use =10, (20 frq.)
Aggressive TCH layer:re-use = 6, (6 frq.) ==> Network capacity = (1 +2 +1)* 300 =1200 TRX
cap N BW re use
i
i
.
Advantages of Multi-layer Reuse Pattern
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Capacity increases when reuse density is multiplied:Supposing there are 300 cellsBandwidth: 8 MHz (40 frequency)
Normal 4*3 reuse: reuse density=12 ==> network capacity = 40/12 * 300 = 1000TRX
Multiple reuse:BCCH layer: re-use =14, (14 frq.)Normal TCH layer: re-use =10, (20 frq.)
Aggressive TCH layer:re-use = 6, (6 frq.) ==> Network capacity = (1 +2 +1)* 300 =1200 TRX
cap N BW re use
i
i
.
Advantages of Multi-layer Reuse Pattern
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The inner circle covers a smaller area, and thefrequency can be reused more tightly.
Underlaid/Overlaid Frequency Allocation
Overlaid-cell Underlaid-cell
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Super fn
Regular fm Regular fm
Regular fm
Super fn
BCCH 15f Regular 24f Super 12f
BCCH Reuse density: 15
R TCH TRX reuse density: 12
S TCH TRX reuse density: 6
Overlaid/Underlaid Frequency Configuration
Super fn
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TRX1 TRX2 ... TRX7
TRX8 TRX9... TRX14 TRX15 TRX16...TRX21
TRX1 TRX2 ... TRX7
TRX8 TRX9... TRX14 TRX15 TRX16...TRX21
The red items are BCCH RCs
Illustration of 1*3 TCH Frequency Allocation
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Frequency Planning Principle
There should be no co-channel frequency carriers in one BTS.The frequency separation between BCCH and TCH in the same cell
should be not less than 400K.
When frequency hopping is not used, the separation of TCH in the
same cell should be not less than 400K.In non-1*3 reuse mode, co-channel should be avoided between the
immediately neighbor BTS.
Neighbor BTS should not have co-channels facing each other directly.
Normally, with 1*3 reuse, the number of the hopping frequencies
should be not less than twice of the number of frequency hopping
TRX in the same cell.
Pay close attention to co-channel reuse, avoiding the situation that
the same BCCH has the same BSIC in adjacent area.
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An example network in a specific place, BTS are densely located.
The topography is plain. The maximum BTS configuration is S3/3/2.Initial planning:
Example of Frequency Planning
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Final frequency planning:
Example of Frequency Planning
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Example of 1*3 Frequency Reuse
Suppose 900 band: 96 124
BTS configuration: S3/3/3
BCCH layer: 96 109 reuse pattern: 4*3
TCH layer: 110 124 reuse pattern: 1*3
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Group 1 (MA1): 110 111 112 113 114 Cell1
Group 2 (MA2): 115 116 117 118 119 Cell2
Group 3 (MA3): 120 121 122 123 124 Cell3
TCH Consecutive Allocation Scheme
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TCH Interval Allocation Scheme
Group 1 (MA1): 110 113 116 119 122 Cell1
Group 2 (MA2): 111 114 117 120 123 Cell2
Group 3 (MA3): 112 115 118 121 124 Cell3
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Comparison Between Example of FrequencyPlanning and 1*3
The frequency planning for the 1x3 mode is simple and it iseasy to plan the frequency for new added BTS.
1x3 mode requires a rather regular BTS location distribution.
For the cells with fixed number of TRX, when the traffic is
heavy, the 1x3 provides higher service quality than that of
Multi-layer reuse pattern.
TRX can be easily added to the 1x3 network, but TRX number
of hopping should not exceed the product of the allocatedhopping frequency number and the max RF load ratio.
BCCH of Multi-layer reuse pattern can take part in the
frequency hopping, while BCCH in 1x3 mode can not.
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Content of Frequency Hopping
Class of hopping
Advantages of hoppingParameter of hopping
Collocation of hopping data
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Class of Hopping
Hopping can be implemented in two waysBase-band hoppingRF hopping
Class according to the min hopping time
unitTimeslot hoppingFrame hopping
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Base Band Hopping Principle
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RF Hopping Principle
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Class of Hopping
Frame hopping
Frequency changes every TDMA frame. The different channel
of one TRX uses the same MAIO.
Timeslot hopping
Frequency changes every timeslot. The different channel of one
TRX uses the different MAIO.
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Advantages of Hopping
Get an agreeable radio environment.
Provide a similar communication quality for every user.
Tighter reuse patterns are possible to be used for larger
capacity.
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Smoothen the rapid fading (Rayleigh fading)
Frequency Diversity of Hopping
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Description Hopping Parameters
At the Um interface, the ARFCN on a specific burst is an
element in MA set. MAI is used for indication, referring to a
specific element in the MA set.
When 0< MAI
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Description Hopping Parameters
At the air interface, the RC number on a specific burst is an
element in MA set. MAI is used for indication, referring to a
specific element in the MA set.
When 0< MAI
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Hopping Parameters
MA (Mobile Allocation Set): the set of available RF bands
when hopping, containing at most 16 frequency carriers. The
frequency being used must be those of the corresponding cell
number in Cell Allocation Table , and no frequency of
BCCH channel should be in the set.
Location: in Carrier Configuration Table .
HSN (Hopping Serial Number): used to define the actual rule
for hopping. 0 stands for sequence hopping and other valuesfor pseudo random sequence hopping.
Location: in Frequency Hopping Table .
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Note: means absolutely same; means absolutely different;
# means uncertain.
Hopping Data Configuration Rules
TSC CA MA HSN MAIO
The same RCin the cell
Different RCin the cell
Co-channelcell #
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Description of Cell Allocation Table
Field name Meaning Value range Suggestion
Module ID Module ID is the number of the modulecontaining the cell
0~255
Cell ID Cell ID is the index value of the cell 0~65535
Cell name It is just a prompt 30 bit
ARFCN 0~63 It is used to configure the ab solute RC numberin the cell using frequency bands; each cell canbe configured with at most 64 frequency bands.The number of frequency bands to be used inpractice is usually determined in networkplanning.When there are less than 64 frequency bands,the invalid field need no configuration. Forexample, if only 6 bands are used, effective
bands 0~5 should be configured and thesubsequent effective bands 6~63 should not beconfigured.
M900:
1~124;M1800:
512~885
Configureas
necessar y
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Field Name Meaning Value range Suggestion
Module ID Module ID is the number of the modulecontaining the cell 0~255Cell ID Cell ID is the index value of the cell 0~65535
HW-IUOproperty
Indicating whether TRX should be configuredas OverLaid or UnderLaid subcell.
equipmentgroup ID
The number of the equipment group at thesite. One site supports at most 3 equipmentgroups; It is usually configured as 0 at
present.
0~2 0
ARFCN
Configure the frequency that the RC unitoccupies. Configure one frequency when thereis no hopping. If hopping is necessary,configure 3~64 bands. These effective RCsmust be the subset of the effective RCs in thecell distribution table.
The subsetof the
effective RCin Cell
AllocationTable
Static TRXPower classl
Static transmitting power level of the RC. 0corresponds to the static power 46dBm, i.e.40W. The static power is lowered by 2dB withthe level goes up by 1.
0~13 Subject toactual
conditionand the
equipmentcapacity
Description of RC Configuration Table
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Fieldname
Meaning Value range Suggestion
FH indexnumber
The index number of all sorts of hoppingstatus, providing index value for RadioChannel Configuration Table . The numbersare in a sequence starting from 0.
0~255
HSN
HSN, indicating the sequence rule of thehopping. Usually, there is only one HSN in
the same cell and the HSN in the co-channel
cell must be different. The above-mentionedrules must be observed.
0~63
TSC
Decide the parameters of the self-adaptiveequalization filter in the receiving processing
filter. It is the same as the correspondingbase color code (BCC).
0~7
FH ARFCN
Number of frequency in the hopping serial. According to hopping algorithm, at least 3
frequencies are required for hopping gain. Ifthis field is left blank, it is invalid.
Correspondingparticipant hopping
frequency in CellConfiguration DataTable
Configure as
necessary
Description of Hopping Data Table
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Domain name Meaning Value range Suggestion
TRX ID The number of TRX unit in an BS 0~24
Channel ID Number of physical timeslot in TRX 0~7
Ch type Logic channel type of timeslots, includingTCH Full Rate, TCH Half Rate 01, TCHHalf Rate 0, SDCCH8 , Master BCCH,Composite BCCH, BCH, BCCH + CBCH,
SDCCH + CBCH, etc.
9 channelgroupings
FH indexnumber
It is used to index to corresponding record inHopping Data Table .
0~255
MAIO MAIO, used to decide initial frequency offsetof the hopping.
Less thanthe numberof hoppingfrequency
Sub-ch ID One timeslot is divided into 2 sub- channel 0,1at half rate. It is all 0 at full rate. 0~1
circ uit number Number of trunk circuit at Abis interfaceoccupied by the corresponding physicaltimeslot.
0~65535
Description of Radio Channel Configuration Table
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