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DESCRIPTION
Frequency Hopping In GSM Network
Citation preview
Frequency Hopping in
GSM Networks
Outline
Frequency Hopping in GSM Networks
Implementation Aspects
Frequency Assignment in FH Networks
Summary
Implementation Aspects
Frequency Hopping in GSM Networks
Frame N° 0Frame N° 1Frame N° 2Frame N° 3
Baseband FH
RF1
RF2
RF3
RF4
BB1
BB2
BB3
BB4
Logical Channel
1
2
3
4
Synthesizer FH
• Mobiles use Synthesizer Hopping only• BS implementation: power down, synthesizer re-
tuning and power up again within guard period 2 Synthesizers are implemented
RF1..n
RF1..n
RF1..n
BB1
BB2
BB3
BB4
RF1..n
Logical Channel
1
2
3
4
Implementation AspectsKey Differences Between
Baseband and Synthesizer FH
Baseband FH Synthesizer FH
Implementation Aspects Combining Equipment in
Baseband and Synthesizer FH
RF1
RF2
RF3
RF4
BB1
BB2
BB3
BB4
1
2
3
4
Filt
er
Com
bin
ing
TX Antenna
RF1..n
RF1..n
RF1..n
BB1
BB2
BB3
BB4
RF1..n
1
2
3
4H
ybrid
Co
mb
ing
TX Antenna
• Narrow Band• Low insertion loss (3-4 dB)
• Wide band• Higher insertion losses (~3 dB/stage)• On-air combining possible (DUCOM)
• Software Release: BR 3.7 or higher
• Cell Synchronization: up to 2/2/2 BS 6x/2x
up to 8/8/8 BS 24x
• No. of Hopping Frequencies:max. 16 per cell (BFH incl.
BCCH)max. 15 per cell (SFH w/o
BCCH)max. 64 per cell with BR 6.0
• BS11: SFH only (BR 4.0)
Implementation Aspects Hardware and Software for
Synthesized Frequency Hopping
• Baseband hopping Narrowband RFcombining sufficient
BCCH TRX except for TS0 may hop
• Synthesizer hopping Wideband RF combining required
One TRX per hopping frequency required!
• No. of RF = No. of TRX
• No. of RF > No. of TRX BCCH TRX must not hop
More hopping frequencies than TRXs feasible
Implementation Aspects Key Differences Between Baseband and
Synthesizer FH
Implementation AspectsHardware Requirements:
Repeater Wideband Repeaters:
• Usable for SFH and BFH
• Careful implementation (amplification of
signals
in the whole frequency band)
Channel selective Repeaters:
• Usable for BFH
• Number of frequencies is limited
• Usually not usable in tight reuse scenarios
Frequency Assignment in Hopping Networks
Frequency Hopping in GSM Networks
Frequency PlanningProcess Frequency
Assignment
Split of BandBCCH - TCH
DedicatedCommon
Multiple Reuse
Planning of BoundariesHopping – Non Hopping
Available Spectrumfor Hopping
Frequencyassignment with
fixed reuse schemes
Reuse 1x3 Reuse 1x1 other
Tools Interference Table Separation Settings
Tool optimizedfrequencyassignment
MAIO and HSNPlanning
Cyclic HoppingRandom Hopping
DatabaseGeneration
Planning of AnchorFrequencies in SFH
• Guideline for RF-planners
• Focus on SFH planning and hopping TCH - carriers
• BCCH - carrier assignment: planning with tool is always recommended
• Planning must be adjusted to each individual network
Frequency Planning Common Band - Dedicated Band -
Multiple Re-Use Patterns
5 hopping frequenciesPC on, DTX on
[%]
90%@FER2%
Dedicated Band 71.8%
Dedicated Band
15 BCCH carriers 28 TCH carriersCommon Band
59.7%
Common Bandtotal operator bandwidth 8.6 MHz = 43
carriers
43 carriers for both BCCH and TCH
MRP 54.3%
15 BCCH carriers12 TCH + 9 TCH + 7 TCH carriers
Multiple Re-use Patterns (MRP)
Achievable System Load
Fixed reuse scheme to all hopping cells
possible reuses:3/9, 2/6, 1/3, 1/1
Tool supported frequency assignment based on interference matrix considering FH gains
Frequency PlanningFrequency groups - Tool
supported planning
TCH 1 TCH 3
TCH 2
TCH 1 TCH 3
TCH 2
TCH 1 TCH 3
TCH 2
TCH 1 TCH 3
TCH 2
Frequency Planning Planning of BCCH
BCCH 3 BCCH 2
BCCH 1
BCCH 9 BCCH 8
BCCH 7
BCCH 6 BCCH 5
BCCH 4
BCCH 13 BCCH 11
BCCH 10
BCCHe.g. 4 x 12 Reuse
• Reliability
• Neighbor Measurements
• BSIC Decoding
• BCCH Frequency active at all timeslots in the downlink-> no interference averaging
Cluster 1/3
Channel
1, 4, 7, 10, ...
2, 5, 8, 11, ...
3, 6, 9, 12, ...
With a deliberately MAIO - assignment and identical HSN assignment to sectors you can avoid adjacent-channel interference between the sectors within one site
Frequency Planning Examples for frequency
groups (I)
Co-channel interference is avoided by the frequency groups MAIO TRX1 TRX2 TRX3 ...
Sector 1 0 2 4 ...
Sector 2 1 3 5 ...
Sector 3 0 2 4 ...
Min # RF 6 12 18
TCH C TCH B
TCH A
TCH C TCH B
TCH A
TCH C TCH B
TCH A
TCH C TCH B
TCH A
TCH C TCH B
TCH A
TCH C TCH B
TCH ATCH A
TCH B
TCH C
Frequency Planning Examples for frequency
groups (II)• Each sector within a site
uses a different Frequency Group
• No co-channel collisions between sectors of a site
• Synchronisation between the sectors and MAIO management avoid adjacent channel collisions
• Homogeneous network:no co-channel collisions between serving cell and all nearest neighbour cells
TCH uses each frequency onlypart of the time (e.g. 50%)
50% fractional load
TCH 1 TCH 3
TCH 2
TCH 1 TCH 3
TCH 2
TCH 3
TCH 2
TCH 1 TCH 3
TCH 2
TCH 1
Cluster 1/1
• All sectors same frequency group
• Identical HSN to sectors of one site
• MAIO assignment to avoid co- and adjacent channel interference
Frequency PlanningExamples for frequency
groups (III)
MAIO TRX1 TRX2 TRX3 TRX4 ...
Sector 1 0 6 12 18 ...
Sector 2 2 8 14 20 ...
Sector 3 4 10 16 22 ...
Min # RF 6 12 18 24
Frequency PlanningExamples for frequency
groups (IV)
• Each sector within a site uses the same frequency group
• Synchronisation between the sectors and MAIO management required to avoid co-channel collisions
• Homogeneous network:Co-channel collisions between serving cell and nearest neighbor
TCH TCH
TCH
TCH TCH
TCH
TCH TCH
TCH
TCH TCH
TCH
Frequency PlanningHopping Sequence Generation
(I)MAI = (FN + MAIO) modulo N if HSN = 0 (cyclic hopping)
GSM 05.02.
MAI ... Mobile Allocation Index (integer 1...N-1)
FN ... TDMA Frame Number (0... 26*51*2048-1 = 2 715 647)
MAIO ... Mobile Allocation Index Offset (0 ... N -1)
N ... Number of allocated frequencies For example: (MAIO=0)
MA = 1,4,7,10,13,16,19,21,24,27,30,33,36,39,41
set of ARFCN numbers to be used in the hopping
sequence N=15
1. burst FN = 0: MAI = (0 + 0) mod 15 = 0 ARFCN = 12. burst FN = 1: MAI = (1 + 0) mod 15 = 1 ARFCN = 4
14. burst FN = 14: MAI = (14 + 0) mod 15 = 14 ARFCN = 4115. burst FN = 15: MAI = (15 + 0) mod 15 = 0 ARFCN = 1 16. burst FN = 16: MAI = (16 + 0) mod 15 = 1 ARFCN = 4etc...
Frequency PlanningHopping Sequence Generation
(II)MAI = (S + MAIO) modulo N if HSN 0 (random hopping)
with:
S = M’ if M’ < N
S = (M’ + T’) modulo N else
M’ = M modulo [2^Integer(log2(N)+1)]
T’ = T3 modulo [2^Integer(log2(N)+1)]
M = T2 + RNTABLE((HSN xor T1R)+T3)
T1R, T2, T3 ... Different Time ParameterRNTABLE ... Table of 114 Integer numbers
Frequency PlanningExample for MAIO -
Management (I) Frequency group 1x1 reuse / Random Hopping (1, 2, 10, 7, . . . )
10
7
Time (TDMA - frame)
Time (TDMA - frame)
1
35
911
13
1517
2
46
8
TRX0
TRX1
TRX2
TRX3
BCCH
MAIO = 2
MAIO = 8
MAIO = 14
TRX0
TRX1
TRX2
BCCH
MAIO = 4
MAIO = 10
MAIO = 16 TRX3
TRX0
TRX1
TRX2
TRX3
BCCH
MAIO = 0
MAIO = 6
MAIO = 12
1012
14
1618
1 2 3 4 5 6 1817161514131211987 10
1214
16
182
4
68
7
9
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
Time (TDMA - frame)
Frequency PlanningExample for MAIO -
Management (II) Frequency group 1x1 reuse / Random Hopping (1, 2, 10, 7, . . . )
1 2 3 4 5 6 1817161514131211987 10
Avoid Co - channel collision:
min # RF = number of hopping TRX (example 9 frequencies)
Avoid Adjacent - channel collision:
only odd or even RF numbers on air at same time
Minimum total number of frequencies for hopping system with MAIO - Management = 2* number of hopping TRX of site
(18 frequencies in example)
TRX0
TRX1
TRX2
TRX3
BCCH
MAIO = 2
MAIO = 8
MAIO = 14
TRX0
TRX1
TRX2
BCCH
MAIO = 4
MAIO = 10
MAIO = 16 TRX3
TRX0
TRX1
TRX2
TRX3
BCCH
MAIO = 0
MAIO = 6
MAIO = 12
Frequency PlanningExamples for frequency groups
and MAIO - Assignment
TRX0
TRX1
TRX2
TRX0
TRX1
TRX2
TRX0
TRX1
TRX2
TRX0
TRX1
TRX2
TRX0
TRX1
TRX2
TRX0
TRX1
TRX2
TRX0
TRX1
TRX2
HSN = 1
HSN = 2
HSN = 3
TRX0
TRX1
TRX2
TRX3
f B
f B
f B
f B
f B
f B
f B
f C
f C
f C
f C
f C
f C
f C TRX3
TRX0
TRX1
TRX2
TRX3
BCCH
BCCHBCCH
BCCH
BCCHBCCH
BCCH BCCH
BCCH
MAIO = 0
MAIO = 1MAIO = 0
MAIO = 0
MAIO = 1MAIO = 0
MAIO = 0 MAIO = 1
MAIO = 0
MAIO = 2
MAIO = 3MAIO = 2
MAIO = 2
MAIO = 3MAIO = 2
MAIO = 2 MAIO = 3
MAIO = 2
f A
f A
f A
f A
f A
f A
f A
MAIO = 5MAIO = 4
MAIO = 4
Frequency group: A: 1 4 7 10 13 16B: 2 5 8 11 14 17C: 3 6 9 12 15 18
Frequency Planning ToolsThe Automatic Frequency
Planning Process
Input datafrom radio networkplanning tool
•Automatized Planning Routines•Variety of Planning Algorithms
•Setting of planning constraints•Common / Dedicated Band Planning
•Global / Local Parameter Settings
Frequency Assignment
Live Network
Data
Minimisation of
interference
•Consideration of FH, PC, DTX
Evaluation of the assignments•C/I and FER plots•C/I and FER analysis on per carrier basis
Evaluation of the assignments•C/I and FER plots•C/I and FER analysis on per carrier basis
Frequency Planning ToolsThe SIEMENS Advanced
Automatic Frequency Planning Tool
Efficient algorithms for different optimization targets: Minimizing global interference
Minimizing worst interfering cell relations
...
Features for advanced network planning strategies Frequency hopping
Power Control
Discontinuous transmission
Graphical evaluation of frequency assignments based on C/I
FER
Very good results in European research program COST 259 benchmarks in quality of result at short execution times (typically seconds to minutes)
High performance proved in live networks with different customers
Frequency Planning Tools Consideration of Radio Link
Control Options Automatic consideration of hopping gains and
interference reduction due to PC and DTX on cell basis
during
• interference matrix calculation
• optimum assignment of frequencies by using highly
efficient optimisation algorithms
Graphical evaluation of the assignment results based
on FER
Frequency Planning Tools
Required C/I in FH-GSM (TU3),
Cyclic Hopping
FH Gains as determined via Real Network Simulations
Shift: 6.5 dB 13.5 dBGain: up to 7 dB
NH2 Ch3 Ch4 Ch5 Ch8 Ch
50%
Frequency AssignmentFrequency Reuse & C/I values
(Non Hopping) Required no. of frequencies Cluster size / Reuse distance: q = SQRT(3*N) C/I rule of thump: C/I abs 1,5 * N2
N Anzahl f q C/I [dB]2 6 2,45 7,783 9 3,00 11,304 12 3,46 13,805 15 3,87 15,746 18 4,24 17,327 21 4,58 18,668 24 4,90 19,829 27 5,20 20,8510 30 5,48 21,7612 36 6,00 23,3415 45 6,71 25,2818 54 7,35 26,8720 60 7,75 27,78
Frequency Planning Tools Analyses of FER
Graphical FER analysis of an SFH network
1x3 reuse, 0,3 fractional load 1x3 reuse, 0,6 fractional load
< 1%
< 2 %
< 3 %
3 %
FER in %
< 1%
< 2 %
< 3 %
3 %
FER in %
Frequency AssignmentExample for Tool-supported
Planned Reuse (I)
3
33
4
443
22
3
43
3
33
4
22
4
44
4
443
33
2
44
2
44Network Example:
• 11 Sites
• 33 Cells• 6 cells 2 TRX• 12 cells 3 TRX• 15 cells 4 TRX• 33 TRX BCCH• 75 TRX TCH
No. of TRX
Frequency AssignmentExample for Tool-supported
Planned Reuse (II)Given Spectrum: 42 channels
12 frequencies for BCCH - TRX
30 frequencies for TCH - TRX (hopping)
Reuse of: 4 30/4 = 7.5 frequencies per cell in average
5 30/5 = 6 frequencies per cell in average
6 30/6 = 5 frequencies per cell in average
7 30/7 = 4.2 frequencies per cell in average
Network Example:• 11 Sites• 33 Cells• 6 cells 2 TRX• 12 cells 3 TRX• 15 cells 4 TRX
Frequency AssignmentExample for Tool-supported
Planned Reuse (III)
Planning Rule: (example)
1 Hopping TRX 3 frequencies2 Hopping TRX 4 frequencies3 Hopping TRX 6 frequencies
No. of assigned
frequencies for FH
Frequency Reuse Factor:
156 / 33 = 4.7 frequ. / cell in average
30 frequ. / 4.7 frequ. per cell = 6.3
4 / 6
4 / 66 / 4
3 / 4
3 / 44 / 3
2 / 3
4 / 66 / 4
No. of TRX
Network Example:• 11 Sites• 33 Cells• 6 cells 2 TRX• 12 cells 3 TRX• 15 cells 4 TRX
Frequency AssignmentExample for Tool-supported
Planned Reuse (IV)Separations for hopping TCH:• Intra cell separation: 3
• Intra site separation: 1
• Neighbour separation: 1
Interference Matrix for hopping TCH:• co-channel: C/I curve 7 dB (50% probability)• adjacent channel: C/I curve -6 dB (50% probability)
MAIO and HSN:• HSN = 0 for all cells (cyclic hopping)• MAIO = 0 for TRX1 (TRX0 = BCCH)
• MAIO = 1 for TRX2• MAIO = 2 for TRX3 etc.
Frequency AssignmentExample for Tool-supported
Planned Reuse (IV)
etc....
Example for a site list:Site Id Sector TRX BCCH f1 f2 f3 f4 f5 f6 MAIO HSN
0001 1 0 2 - -1 1 19 36 41 0 02 0 4 - -2 1 13 18 21 25 30 42 0 02 2 13 18 21 25 30 42 1 02 3 13 18 21 25 30 42 2 03 0 9 - -3 1 15 23 27 32 0 03 2 15 23 27 32 1 0
0002 1 0 12 - -1 1 22 26 34 40 0 01 2 22 26 34 40 1 02 0 8 - -2 1 16 19 28 0 0
Frequency PlanningStrategies Cyclic Hopping -
Random HoppingCyclic hopping sequence {... f4, f0, f1, f2, f3, f4, f0, f1, f2, f3 ...}, MAIO 0Cyclic hopping sequence {... f1, f2, f3, f4, f0, f1, f2, f3, f4, f5 ...}, MAIO 2
F
r e
q
u
e n
c
y
TDMA frame
f0
f1
f2
f3
f4
Principle of Cyclic Hopping
• Optimum frequency Diversity• Sufficient Interference diversity by avoiding frequency groups• No Interference diversity using frequency groups
Random hopping sequence {... f1, f4, f2, f0, f0, f3, f0, f1, f2, f4, ...}, MAIO 0Random hopping sequence {... f3, f1, f4, f2, f2, f1, f2, f3, f4, f1, ...}, MAIO 2
F
r e
q
u
e n
c
y
TDMA frame
f0
f1
f2
f3
f4
Principle of Random Hopping
• Optimum interference diversity
• Less frequency diversity
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