Table of Contents
TABLE OF OF CONTENTS CONTENTS
3
SCOPE
4
HISTORY
4
REFE REFERE RENC NCED ED DOCUM DO CUMENT ENTS S
5
1 DOCUMENT OVERVIEW
5
2 TERMS USED USED IN IN FREQUENCY PLA PLANN NNIN ING G
6
3 PERFORMANCE INDICATORS OF A FREQUENCY PLAN 3.1 Before Frequency Plan Implementation 3.2 After Frequency Plan Implementation
8
8
4 FP PROCE PROCESS SS FOR FOR CLASSICAL NETWORK CONFI CON FIGU GURA RATI TION ON (ONE (O NE BAND. ONE LAYER N O SPECIAL SPECIAL CELL TYPES) 10 4.1 FP Targets 12 4.2 FP Strategy 12 4.2.1 Spectrum Spectrum Partitioning 12 4.2.2 Exception Exception Handling Handlin g of o f Sites Sites with Configurations 14 4.2.3 Decision on Frequen Frequency cy Hopping Implementati Implem entation on 15 4.2.4 and 15 4.2.5 and PC 16 4.2.6 Frequency Coordination at the Border 17 4.2.7 4.2.7 Frequency Frequency Coordination Coordi nation at Co-Existence of Several System Systems s 17 4.2.8 Allocation Alloca tion Strateg Strategy y 19 4.2.9 Frequen Frequency cy Planning Activation Mode 20 4.2.1 0 Definitio Def inition n of Hot Spot Areas 20 4.3 Inputs preparation 20 4.3.1 Retrieval of Netwo N etwork rk Design Parameters Parameters 20 4.3. 4.3.2 2 AFP Dry Run 21 4.3.3 OMC OM C Neighbors Relationships Relationships Clean-up 21 4.3.4 Experience Database 22 4.3.5 Prepare Comparison 4.4 Creat Cr eation ion of Frequency Plan 23 Setting of Parameters Parameters to Reflect FP Strategy 23 4.4.2 4.4.2 Run Run the AFP AFP 23 4.5 Frequency Plan Validation 23 4.6 Implementati Implem entation on of the new Frequency Frequency Plan Plan 24 4.7 Post Post Impl Im plem emen enta tatition on Task Tasks s 24 4.7.1 Intensive Analysis 24 4.7.2 Update Experience Database 25 5 FP PROCE PROCESS SS FOR DUAL DU AL LAYER NETWORK 5.1 FP Strategy 5.1.1 Spectrum 5.1.2 Decision on Frequency Hopping Implementation 5.2 Inputs preparation 5.2. 5. 2.1 1 Setting of Parameters to Reflec Reflectt FP Strategy
25 25 25 25 26 26
6 FP PROC PROCES ESS S FOR DUAL DUA L BAND BAND NETWORKS 6.1 FP Strategy 6.1.1 Spectrum Partitioning
26 26 26
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7 FP FP PROCE PROCESS SS FOR CONCE CON CENT NT RIC RI C CELLS CELLS 7.1 FP Strategy 7.1.1 Spectrum Partitioning
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8 FP PROCESS FOR HOPPING NETWORKS 8.1 FP Strategy 8. 1. Spectrum 8.1 .2 Decision on Frequen Frequency cy Ho ppin g Implementation 8.1 . 3 an d 8.1 8. 1.4 RF Load 8.1 .5 Frequency Frequency Coordinat ion a t the Border 8.1 . 6 Freque Frequency ncy Coordination at Co -Existence of Several Systems 8.2 Inputs Inputs preparation 8.2.1 Experience Experience Data base 8.3 Creation of Frequency Plan 8.3.1 Setting of Parameters to Reflect FP Strategy 8. 4 Post Tasks 8.4.1 Update Experience Experience Data base
27 28 28 28 30 30 30 31 31 31 31 31 31 31
Y FREQ FREQUE UENC NCY Y P U NN I NG TOOLBOX TOOLBOX 9.1 Short Description Description of A91 55 9.2 Short Description of 9.3 Short Description of SONAR 9.4 Short Description of RADAR 9.5 Tool related FP steps
32 32 33 33 34 34
10 PROP PROPOS OSAL ALS S OF DIFFER DIFFEREN ENT T FREQUE FREQUENCY NCY P U N N I N G CONFIGURATIONS
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11
REFERENCE NETWORKS
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12
ABBREVIATIONS
38
.
INDEX
39
SCOPE
Readership Profile Summary
The target group is GSM frequency planners The content of this guideline is to show the basic rules for frequency planning. recommendations for spectrum partitioning and important steps to be performed during a frequency frequency planni ng project. The main focus of this document is to capitalize all Alcatel experience from the real frequency frequency plan ning expert expertss on the field. Please send your comments. update wishes referring to this document to They They will be considered considered in a next editi on of the document.
Available
There are two main documents for Frequency Planners in
environment:
VAZZA Frequency Planning Guideline, 3DF 0 1 902 201 3 VAZZA A9155 V6 RNP Application Note: Frequency Planning, 3DF 01955 01 955 6082 BGZZA
HISTORY Ed .
Proposal 01
1
Creation
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7 FP FP PROCE PROCESS SS FOR CONCE CON CENT NT RIC RI C CELLS CELLS 7.1 FP Strategy 7.1.1 Spectrum Partitioning
27 27 27
8 FP PROCESS FOR HOPPING NETWORKS 8.1 FP Strategy 8. 1. Spectrum 8.1 .2 Decision on Frequen Frequency cy Ho ppin g Implementation 8.1 . 3 an d 8.1 8. 1.4 RF Load 8.1 .5 Frequency Frequency Coordinat ion a t the Border 8.1 . 6 Freque Frequency ncy Coordination at Co -Existence of Several Systems 8.2 Inputs Inputs preparation 8.2.1 Experience Experience Data base 8.3 Creation of Frequency Plan 8.3.1 Setting of Parameters to Reflect FP Strategy 8. 4 Post Tasks 8.4.1 Update Experience Experience Data base
27 28 28 28 30 30 30 31 31 31 31 31 31 31
Y FREQ FREQUE UENC NCY Y P U NN I NG TOOLBOX TOOLBOX 9.1 Short Description Description of A91 55 9.2 Short Description of 9.3 Short Description of SONAR 9.4 Short Description of RADAR 9.5 Tool related FP steps
32 32 33 33 34 34
10 PROP PROPOS OSAL ALS S OF DIFFER DIFFEREN ENT T FREQUE FREQUENCY NCY P U N N I N G CONFIGURATIONS
35
11
REFERENCE NETWORKS
38
12
ABBREVIATIONS
38
.
INDEX
39
SCOPE
Readership Profile Summary
The target group is GSM frequency planners The content of this guideline is to show the basic rules for frequency planning. recommendations for spectrum partitioning and important steps to be performed during a frequency frequency planni ng project. The main focus of this document is to capitalize all Alcatel experience from the real frequency frequency plan ning expert expertss on the field. Please send your comments. update wishes referring to this document to They They will be considered considered in a next editi on of the document.
Available
There are two main documents for Frequency Planners in
environment:
VAZZA Frequency Planning Guideline, 3DF 0 1 902 201 3 VAZZA A9155 V6 RNP Application Note: Frequency Planning, 3DF 01955 01 955 6082 BGZZA
HISTORY Ed .
Proposal 01
1
Creation
CONFIDENTIAL
Edition 01
RELE RELEA ASED SED
3DF 01 9 0 2 20 1 3 VAZZA VAZZA
Ed. 01 Released
Document released
REFERENCED DOCUMENTS Slow Slow Frequency Frequency Hopping Hoppin g Document Document 3DF 3DF 0099 5 000 0 UDZZA UDZZA Radio Measurement Statistics (RMS) i n Releas Release e Alcatel Alcatel Document Document 3DC 21 14 4 0 027 TQZZA TQZZA Alcatel Frequency Hoppin g Solutions Solutions Alcatel Document Synthesized Frequency Hopping in Romania Alcatel Document 3DF 00997 0007 UAZZA Antenna System System Solutions for Site Sharing Alcatel Document 3DC 21019 2101 9 00 5 TQZZA TQZZA RNP Extension Training on Dual Band Alcatel Training Engineering Rules for Radio Networks Alcatel Document 3DF 00995 0000 UAZZA RNP Extension Training Micro Cells Alcatel Training RNP Extension Training: Concentric Multi Band Cells Cells Alcatel Training Concentric Cells: Easy Implementation in Live Networks Alcatel Document 3DF 00958 PGZZA Spectrum Spectrum Planning in GSM Networks Alcatel Document 3DC 21 150 0 279 TQZZ TQZZA A RNP Extension Extension Training: Trainin g: Frequency Hop pin g Alcatel Training Radio Frequency Hopping: Implementation Implement ation Strategy Strate gy Alcatel Document 3DF 00976 TQZZA SFH SFH Field Trial Report: Report: VOD V ODACO ACO M South Africa Alcatel Document 3DF 00997 001 UAZZA Frequency Planning for Cape Town Alcatel Document 3DF 00997 0008 UAZZA Specifications on and 80 Integration into A9155 A9155 V6 Alcatel Document 3DF 01 95 5 604 4 DSZZ DSZZA A A9155 - A956 File Interface Interface Specifications Specifications Alcatel Document 3DF 0098 3 10 20 DSZZ DSZZA A A9155 V6 RNP Application Note: Frequency Planning Alcatel Document 3DF 01955 6082 BGZZA A91 55 PRC Generator Mo dule V2.30 User User Gu ide id e Process Description Alcatel Document Document 3DF 0195 5 0 08 0 PCZZ PCZZA A Radio Network Planning Process Alcatel Document 3DF 01902 01 902 300 0 DEZZ DEZZA A PRC Generator Module User User Manua l Proc Proces ess s Description Descriptio n for A91 Document 3DF 01955 01955 00 80 PCZZ PCZZA A Inter Syst System em Compatibility: Challenges an d Solutions Alcatel Document 3DF 019 02 301 2 VAZZ VAZZA A ERC Recomme Reco mmend ndati ation on T/R 2 0 - 08 E - Frequency Frequency Planning a nd Frequency Frequency Coordination for the GSM http://www.ero.dk
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1 DOCUMENT OVERVIEW
There is is always need for capacity improvement improvement of the GSM network. The main impact on network capacity i s given by the frequency frequency planning, particula rly by the number of TRX per cell and a nd frequency fr equency reuse reuse in the network. netwo rk. Therefore Therefor e there i s a need of a proper frequency planning. The main task of this document is to give rules and strategies for
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frequency planning in a GSM project. This document is presenting also an overview of frequency planning tools used within There are two documents related to frequency plannin g process, in Alcatel: this document and A91 55 V6 RNP Application Note: Frequency Planning 2 TERMS USED IN FREQUENCY P LA NN IN G This chapter is intended to make a clear view on the ge neral concepts and acronyms used i n frequency plan ning process
Average Reuse Cluster Size (ARCS) As the frequency spectrum is limited, frequencies have to be reused to provi de enough capacity. ARCS is defined as:
of available GSM channels used
ARCS =
Average amount of
per cell
The more often a frequency is reused within a certain amount of cells, the smaller is frequency reuse. The ARCS has to be as small as possible to increase traffic capacity and as high as possible to avoid network interference. For frequency planning the ARCS gives an i dea about the traffic capacity as well as network interference. By appl ying frequency hopp ing the ARCS can be reduced while the network quality is not changed significantly. Below there is a table which presents the typical values for ARCS. ARCS typical values
Table
Frequency usage
Aggressive
Typical
Conservative
BCCH
12
18
20
TCH non hopping
10
12
12
7
9
12
TCH BBH
Fractional Reuse Cluster Size Applying r adio frequency hopping, the fraction reuse techniques can be used. The principl e of fra ctional reuse is, to use more frequencies in a cell than are equipped: FARCS is defined as:
FARCS
Number of available GSM channels used =
The later introduced reuse
of frequencies per cell
and 1x3 hopping schemes are defined by
Frequency hopping Frequency hopping consists in changing the frequency used by a channel at regular intervals. In GSM there are defined two hopping types: Base Band Ho ppin g (BBH) and Radio Frequency Hoppi ng (RFH).Mor e details can be foun d i n BBH
Each transceiver i s transmitting on one fixed frequency. Hopping is performed by switching the mobiles f rom burst to burst to different ca rrier units of BTS. (Number of hopping frequency Number of =
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RFH
TRXs do no get a fixed frequency assignments, they may change their frequency from to according to a predefined hopping sequence. (Number of hopping frequency = Number of TRXs)
Reuse 1x3 Reuse 1x3 is defined for RFH. During frequency hopping sequence allocation the TCH frequency band i s split in three groups. Each cell in the network is using one of these three groups.
Reuse The same as reuse 1x3, this reuse is defined for RFH. In this case the frequency band is not split, and each cell i s using the frequency from the complete frequency band.
only one
RFLoad RF Load represents a relation between number of
TRX per cell and the "on-air number of frequencies assigned to the cell. Definition of Max RFLoad i s presented below. RFLoad =
#
"
Cell Cell
Maximum RFLoad is only achieved, if all TRXs within the cell are fully loaded. Table 2 Max RFLoad Proposed Values
Reuse scheme xl
Service targets Maximum theoretical synchronized hopping)
limit
Maximum acceptable
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Service targets
Reuse scheme 1
Maximum theoretical synchronized hopping )
limit
for
Maximum acceptable
50% 30%...35%
The maxi mum acceptable values are taken into account d urin g RFH plan ning. Besides Max RFLoad, i n documentation can be foun d also the term Real RFLoad. The Real RFLoad can be calculating according to fo llowing formula:
real RFLoad
=
#Active timeslots Cell (#Frequencies Cell)
8
Only active timeslots contribute to RFLoad. timeslots do not create interference and are not contributing to the RFLoad. The real RFLoad is only an indicator of network quality a nd it cannot be used in RFH planning.
PERFORMANCE INDIC ATO RS O F A FREQUENCY PLA N The definition of the frequency plan performance indicators is a key issue. It makes frequency plans comparable with each other before and after implementation.
3.1 Before Frequency Plan Implementation The frequency pla n must be checked and validated b efore its implementation. Since the frequency plan is not yet implemented other measurable parameters than must be used. "
"
A clear definition of frequency plan performance, using predictable parameters, is .necessary to perform a comparison between frequency plans before and after the new frequency plan implementatio n. To overcome this issue, here are defined different parameters, which can be taken into account to describe the performance of a frequency plan.
I
Interference indicators The quality of a frequency plan in a certain area can be estimated by the number of points with a C/I value higher than a certain threshold. Two indicators can be defined related to interference: percentage of area with a C/I higher than a threshold or number of points with a C/I higher than a threshold. The methods to estimate interference are: C/I weighted over area. of interference indicator.
points have the same weight in final value
C/I weighted over traffic: The points from different traffic zones have different weight factor i n the final result.
I I
The interference indicators may be calculated for different planning area: Rural areas or areas with less importanc e (low traffic) Hot-spots area o r areas specified by customer (problem atic areas or high traffic) This splitting is done to avoid validation of frequency plans with an overall interference better than before, but with interference worse in hot-spots areas. By focusing more on more importance areas the quality in less important areas i s sacrificed. All indicators presented in this chapter can be calculated by A91 55.
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In order to get an overview, for the value o f interference indicators in each FP project, please send the fin al value of the indicator: percentage of higher than a dB to:
[email protected].
Constraints violation Number of constraints violation. This indicator represents the number of and experience matrix constraints violation. The very critical violations (co -cell) have a higher weighted factor that less critical ones (neighbor violations) in the final value of this indicator.
Best 'visual' frequency plan Using frequency visualization method the spreading o f frequencies over the planning area can be easily observed. The frequency plan is better if the frequency distribution is homogenous. good "visual" frequency plan is an indicator that the frequency plan might be good, but is not mandatory to be so.
Optimum distribution of frequencies Another indicator that can be used is the frequency distribution. The frequency pla n is using the resources in a best way, if al l frequencies are used with an equal distribution (all frequencies are used in a same amount). But an optimum frequency distribution does not imply all the time a good frequency plan. To have a good indication that the new frequency plan is better than the previous one, all performance indicators mentioned here are mandatory.
3.2 After Frequency Plan I mplementati on The frequency plan quality can be measured by different indicators with the help of a before-after comparison. The main important indicators are presented below: CSSR
-
- Call Setup Success Rate
CDR - Call Drop Rate
HO rate Causes (Qualit y HO, Better Cell HO, Level HO)
-
SDCCH Assign Fail Rate Indicators (since
o
o
Frame Erasure Rate Qual
I
FP PROCESS FOR CLASSICAL NETWORK CONFIGURATION (ONE BAND, ONE LAYER N O SPECIAL CELL TYPES) The RNP process is subdivided into different phases
Bark
Figure 1 RNP Process Frequency planning occurs during the phases of implementation and optimization. Because it's impossible to wait with the opening of the network until the last BTS is integrated, the network is launched step by step (Turn on Cycle by Turn on Cycle) during the implementation phase. At each TOC, the RNE has to decide which sites go on air and new frequency plan has to be created. New frequency plans have to be done for each extension of the network and the frequency distribution may be tuned during the optimization phase, to improve the The frequency plan has to be checked regularly because due to manual modifications the frequency plan comes out of shape from a global point of view. In regular periods (for instance every 4 weeks) a performance analysis should be performed, by downloading the frequency plan from the OMC and checking its performance. If performance falls under a certain threshold an overall re -tuning should be triggered. The frequency plann ing process is explained in Figure 2.
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Figure 2 Frequency Planning Process This chapter presents the classical frequency planning process with one
band and no special cell types in the network. All details, related to configurati on will be explained in the next chapters.
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The first step of the FP process is to define the FP inputs and targets: target area of the new frequency plan has to be defined, as well as the list of all involved cells from this area. frequency spectrum. The FP targets must cont ain the available frequencies. If there are usage constraints related to the frequency spectrum they must be provided. Day when the new frequency plan has to be ready for implementati on. The new plan must take into consideration the network configuration planned for this day. In order to prepare the frequency plan validation the chosen performance indicators have to be calculated for the old frequency plan. The target of the frequency pla n is to improve these indicators. Of course the customer will care more about end user but if, for example, the mediu m C/I value is improved, also the end user of will be increased after frequency plan implementation. Frequency plan optimization has to be done to keep a certain in the network, while increasing the traffic capacity by network densification. The expected results fro m the FP should be clearly stated from the beginning, and the whole strategy should be driven by these goals.
4.2
FP
Strategy In
this chapter the strategy to perform the frequency plan will be explained. Frequency planning targets define the strategy chosen. The strategy is defined by performing the spectrum partitioning, by setting the way to treat different areas with different site configuration, by frequency hopping implementation decision, by different parameters setting, by frequency plan ning at planning border or for co-existence of several systems and by allocation strategy.
4.2.1 Spectrum Partitioning This step is performed in order to optimize the frequency resources used by frequency planning process. The resources must be used in a n optimal way in order to achieve a maximum capacity with the minimum number of frequencies for each layer. Spectrum usage strategy depends on several aspects: available bandwidth customer specifications network environment and design For areas with very different default BTS configuration different subdivisions of frequency band can be used. At the beginning of the frequency plan construction, the frequency band is split into different parts: Macro layer BCCH -
1
Micro layer
TCH
Guard Bands /Joker Frequencies
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Macro layer
Micro layer separation
At the beginning o f the design, it has to be known if a complete micro layer has to be installed (often to anticipate a cell densification of the network). In this case, a dedicated frequency band must be a llocated exclusively to BCCH and TCH of these micro cells (7 carriers are usually sufficient for planning micro BCCH layer). The detailed explanation of micro layer separation will be explained later in a micro layer dedicated chapter. BCCH
TCH separation
The BCCH i s the most important carrier as it transmits the network information towards the mobile. The network cannot be used by a mobile, which cannot identify the BCCH carrier and decode this information. In these conditions, the BCCH band must be separated from TCH band (as presented in Figure 3), and the BCCH must be planed separately with a less dense frequency reuse scheme.
TCH
BCCH Frequency Band Figure 3 Frequency Bond Split
This separation is not mandatory, but is recommended for interference reductions BCCH and TCH. A91 55 can determine the number o f frequencies we need to pl an the BCCH layer with the method described next. In order to define the required number of BCCH channels in the network, and to keep a certain level of interference a first dry run of the Automatic Frequency Planning (AFP) is required. The process begins with allocating a defined number of frequencies to the BCCH layer and launching the frequency plan calculat ion fo r these BCCH only. If the number of allocated frequencies is insufficient, the next calculation will be performed with more frequencies. If the solution is f ound quickly, the opposite way is to decrease the number of frequencies to optimize the frequency reuse. Because frequency plannin g allocation process is quite t ime consuming, the calculation should begin with a well -adapted number of frequencies for the BCCH to limit the number of re-calculation. Usually the number of BCCH frequencies is arou nd 18. However, the topology and the morphology of the terrain influence this parameter. Guard Band and Joker Frequencies
The guard band is the number of frequencies which are not used for frequency allocation, to prevent interference between operators o r different types of frequency usage (SFH, concentric cells, micro cells, BCCH). Guard band between operators: mandatory Guard band between different types of frequency usage is not mandatory, but i s sometimes needed for interference reduction. between BCCH and TCH in RFH mod e) If the frequency band is large enough, some frequencies (generally less than 4 frequencies) can be kept as joker frequencies to solve quickly isolated problems of interference or to allow implementation of new cells without changing the complete plan. The number of frequencies is given by the number of frequencies not necessarily needed for BCCH or TCH allocation to achieve the required FP quality. The guar d band con also be used as joker frequency.
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From projects it i s seen that very often the customer checks the frequency plan before implementation and give special hints for final fine-tuning. Therefore, it is very useful to have some frequencies available for this purpose.
Spectrum Partitioning Example The frequency spectrum, depending on the network configuration, is split using different algorithms. Therefore, in this case (one layer, one band network), the frequency spectrum is split in two sub-bands: one for BCCH channels and one for TCH channels. An spectrum partitioning example for a classical network is presented below:
Figure 4 Spectrum Partitioning for Classical Network
. , ,
Therefore, for diff erent frequency usage are defined different Average Reuse Cluster Size (ARCS) Table 3 for ARCS Frequency usage BCCH macro layer
18
BCCH micro layer
7
TCH non
12
TCH RFH
3
In a real network there might be different areas with different configuration such as very dense areas and rural areas. For an optimized frequency plan, the spectrum can be partitioned in different ways for different areas. ARCS depends on the number of available frequencies, number of installed TRX on each cell an d the topography. For a hilly terrain, for example, a lower ARCS can be used, as presented in
Figure 5
Below
for Different Areas
The spectrum partitioning is dependent on the chosen frequency planning strategy. Next chapters contains the particularities of dual layer (chapter 5 ) , dual band (chapter 6), concentric cells (chapter 7) or hopping (chapter 8) networks. 4.2.2Exception
Handling of Sites with
Configurations
For sites with configuration, such as sites with an increased number of TRX, the frequency planning process has to be treated in a particular way. The solution is to provide fixed frequencies from BCCH band and using for example concentric cells, for interference reduction. By assigning specific frequencies manually, the frequency planning tool has to find less frequencies automatically, while keeping all constraints fulfilled.
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4.2.3 Decision on Frequency Hopping Implementation During strategy definition the decision for implementation or not of frequency hopping should be taken. The decision for frequency hopping implementation is taken either for improvement or due to capacity saturation. Base Band Hopping (BBH) solution is performed in order to increase the network From the frequency planning process point of view the implementation of BBH has no impact. Radio Frequency Hopping (RFH) is implemented i f it is impossible to perform extension or site densification due to lack of a free frequency. The FP for hopping networks will be presented Chapter 7. 4.2.4 TRX PREF MARK and GPRS PREF MARK
-
-
-
-
is used to distribute circuit switch (CS) traffic on the less interfered frequencies. Its value is in the range: lowest priority 7 highest priority.
For BCCH band interference reduction, the RCS of BCCH frequencies i s higher. Therefore, since the frequencies from the BCCH band are less interfered, the traffic can be distributed on these frequencies. To perform this, i s used to set the highest priority for BCCH frequency. This is performed also in order to reduce the real RF Load (see chapter 8.1.4). TRX-PREF-MARK can be used to give different priorities to different TCH frequencies. Different priorities can be set for each frequency from each cell, but to perform this for entire network is a very time consuming process. To speed up this process, a solution is to: divide the TCH band in two sub bands set a higher priority for frequencies from the less interfered sub-band. In case of non-GPRS networks the proposed values of TRX-PREF-MARK are for BCCH frequency 7, for clean TCH frequencies 5 and for interfered frequencies GPRS-PREF-MARK is the preference mark assigned to a TRX to favor PS radio resource allocations on a TRX, for GPRS networks. This parameter i s introduced in release B7 no GPRS support 3: highest GPRS priority). From release B8 its functionality is taken by TRX-PREF-MARK. From frequency planning point of view this parameter i s used to distribute packet switch (PS) frequencies on the less interfered frequencies. Example of tuning GPRS-PREF-MARK networks:
and
for non hopping
Set al l TRX foreseen with only CS service to: (Range 1-7) GPRS-PREF-MARK Set all TRX favoring for
=
service
TRX-PREF-MARK
=
GPRS PREF-MARK interference)
-
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TRX4
TRX6
4
1
3
1
2
1
1
2
3
1
2
1
1
2
0
3
2
1
1
0
3
Figure 6 Example of tuning
0
China)
and
Example of tuning presented in chapter 8.1.3.
and
for hopping networks is
and are not used by frequency allocation algorithm, but can be used after frequency plan implementation for interference reduction. 4.2.5 DTX and PC Discontinuous transmission (DTX) consists in interrupting the transmission when there is nothing to transmit, during silence time. DTX i s performed both in UL and DL directions. The main target of DTX is to reduce the RF Load (see chapter 8.1.4) in the network and enhance spectrum utilization. By RF Load reduction the interference in the network is decreased while speech quality is improved. The table below presents the results of drive tests performed in Jakarta before and after DTX activation. Table 4 DTX ActivationComparison
Without DL
Range
-DTX
With
DL-DTX
With
3
5 Statistical Indicators
I
.
.
STD
,
Variance
Another feature used for interference reduction i s power control (PC) activation. Therefore, the network overall interference can be reduced also by applying PC and DTX, leading to a lower effort in frequency planning optimization. The activation of DTX and PC does not influence the frequency planning strategy, but is used for interference reduction after frequency plan implementation.
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These new frequencies components are either harmonics of the input frequencies or a combination of them (mixing). If we consider the input signal is made up of two signals with frequencies f l and f2, the output signal will contain frequency components at: =
with
+
=
order of
the intermodulation product
The frequency planner have to avoid the intermodulation products falling inside a used receive band.
of
Because, high-order interrnodulation products have lower levels than those with a loworder, only the very low-order products will be critical for the quality of the network and have to be taken in considerations (generally we only consider 2nd and 3rd order). The frequency planning will take place in this case to avoid these low-order interrnodulation products of falling inside a used receive band. Two different types of interference generated by intermodulation have to be considered in a GSM network:
intraband intermodulation derived from inside frequencies of the network. By avoiding a certain channel separation, intraband intermodulation products are reduced. For GSM 900 the avoided channel separation is 11 channels for IM3 and 75 channels for IM5 and for GSM 1800 i s channels for co-located systems intermodulation that is generated mixing terms TACS-GSM). The intermodulation from different networks for co located systems must be treated different since these information is not used by FP tools. Several measures are possible to prevent this type of A careful frequency planning is one of them. Table 5 remind the spectrum of main used networks and Table 6 recommendations for frequency planning depending on the co-located systems: Table 5 Radio Band
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Table 6 Recommendations depending on the to located systems -
Co - located Systems
Recommendation
1 800
Avoid
order intermodulation products
No problem at all
- Avoid
order intermodulation products
GSM1 OR
-
Use UMTS frequencies above 1955 MHz
OR
-
Other TACS-GSM)
frequency band smaller than 40 MHz
Use
Avoid low-intermodulation products only if other techniques [7] can't be used to prevent them antenna decoupling, filters
Systems
Example:
- GSM - GSM
1900: avoid
order intermodulation
:
avoid
order intermodulation
:
avoid
order intermodulation
avoid
order intermodulation
avoid
order intermodulation
- GSM
GSM - GSM
:
The frequency planning strategy should be in that way that the IM must be avoided. Therefore, each operator must avoid using frequencies combinations that can create products in other operator frequency band. 4.2.8 BSlC Allocation Strategy The BSlC code is set to distinguish between BTS using the same BCCH frequency. The aim of BSlC planning is to use different combination on cells having the same BCCH frequency. BSlC is composed from Network Color Code (NCC) and Base Station Color Code (BCC): BSlC NCC + Therefore, the number of available is between 8 (for one NCC) and 6 4 (for 8 =
The method for BSlC pla nnin g is: Gro up a ll cells which are using the same BCCH frequency Provide to each cell from group different BSlC code. If there are not enough BSlC codes (more than 64 cells are using the same BCCH frequency: For first and second order neighbou rs provide different BSlC codes for the others cells, provide same BSlC code to cells which are located as far as possible from each other. The feature of BSlC allocation of A91 55
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In order to avoid conflicts an intensive planning is required. (8)are Therefore, this step should not be underestimated in cases where not a ll available. 4.2.9 Frequency Planning Activation Mode Frequency plans can be activated in different ways: message mod e or Massive Logical Update (MLU) mode (see chapter 4.6). To avoid any schedule problems, the decision of frequency plann ing activation mode should be clearly taken at the beginning. 0
The modality of frequency planning activation has no impact on frequency allocation process. 4.2.10 Definition of Hot Spot Areas This step is made to give a higher priority for hot spots areas or for customer specified areas. By defini ng these areas and setting different AFP Weight, the A91 55 AFP module uses a higher priority for these areas. The disadvantage is that the areas with lower traffic are sacrificed for areas with high traffic. The AFP Weight factor can be set manually for some specific areas (known areas with high traffic or areas defined by customer). Also to provide different AFP Weight for different traffic zones, A91 55 can use a t raffic ma p.
4.3 Inputs preparation The preparation of network frequency plan involves a period of intensive work, requiring the careful scheduling of a number of service affecting tasks. The keys of a good frequency plan are reliable input data and carefully settings of the AFP parameters. This chapter is presenting the needed parameters and how they are influencin g the frequency allocati on process. 4.3.1 Retrieval of Netwo rk Design Parameters For a pr oper frequency planning, network design in the too l must be consistent with the network design of the real network. For this both the physical and the logical parameters has to be imported in the planning tool. Unfortunately not both parameter types are foun d in the OMC-R
-
-
Physical parameters for all sites from planning area should be retrieved from audit reports, installation reports or optimization report. The information needed are the sites coordinates, antenna azimuth, antenna type, antenna height a nd antenna tilt. Logical parameters extracted, from all OMC -R of the sites belonging to the planning area, by interface in csv files. PRC Generator is the tool used to interface between A9155 and OMC-R. This tool converts the files from OMC -R (csv) into A9155 readable format The csv files from OMC -R are: contains logical parameters for each cell of the OMC -R contains all the neighbor relations for this OMC-R contains the OMC- R external cells contains
the
logical
parameters
related
to
handovers contains the parameters related to BSC
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,
contains the topographical information of the sites contains logical parameters for contains
the
information
regarding the hopping contains logical parameters for power control contains a hierarchy of all
files.
The cof files, which are imported in A9155 are: logical information for a ll cells contains neighbor relations for all cells contains the frequency hopping sequences contains the allocated frequencies of all cells contains the hopping mode and contains the logical parameters for GPRS Using PRC Generator the subsets of logical network parameters are imported in A91 55. A detailed explanation on PRC Generator usage is presented in The most important aspect of this step be reliable.
is
that the A9155 inputs, like design data, must
Before starting the frequency allocation process, it is very important to have in A9155 V6 the network configuration for the day Y (when the frequency plan is implemented). Any changes in this configuration imply the restart of frequency allocation Therefore, the customer must be informed that any changes in network configuration delays the implementation of the new frequency plan. 4.3.2 AFP Dry Run After the network design is imported in A91 55, the dry run of AFP should be performed. This is done in order to:
-
-
-
4.3.3
Test the frequency planning tool and predict the possible problems that might appear during frequency allocation Find the optimum RCS for BCCH. The starting point should be 18 frequencies for BCCH. Then in an iterative way, based on interference, it is found the number of BCCH needed for a proper frequency plan (by the RCS). Optional the time estimation can be performed. Therefore, after finding the RCS of BCCH and using the remaining frequencies for TCH, the time of frequency allocation can be find.
OMC Neighbors Relationships Clean-up One problem in most running networks is that there are too many neighbors declared in the OMC-R. One reason i s for example when the network is growing, neighboring relations are increasing and no old relation is removed. This to an increased number of unnecessary neighbors. On the other hand taking into consideration all neighbors will lead to a bad frequency plan, because too many constraints. Before running the the unnecessary neighbors must be deleted. Generally the number of neighbors should be as small as possible to make the HO process faster and more reliable and as big as necessary to avoid having interference from strong cells not declared as neighbor. The neighbor relationships reduction is a between the need of decreasing the call drop indicators and the available spectrum and seporations.
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The solution is to visual check the neighbor relations on the map in neighbors can be deleted manually.
-
An optional solution i s to use traffic flow measurement counters to check the unnecessary neighbors. H O attempts between cell couples are by this counter. and SONAR are using and the HO relationships are sorted according to the number of HO attempts between cell couples. First cell couples with a lower amount of HO attempts will be checked and decide to keep or delete the neighbor relation.
The
4.3.4 Experience Database The experience database is an important AFP parameter. This step has to be treated carefully, by creating certain constraints for each problematic cell-couples. Field feedback can be used to get an accurate frequency plan. This kind of information can be inserted manually in 955 in so called "experience matrix "
By using experience database, AFP takes into account besides standard constraints, like co-cell, co-site and neighbors constraints, as well as the constraints imposed by frequency planner, based on experience (network behavior). The experience matrix is based on a good knowledge of critical cells and known problem in the network. During projects this kind of information are usually summarized by old reports, like anomaly reports, or based on team experience during network operation. To add the interference information in the matrix the possibilities are: -
4.3.5 Prepare
List all areas with bad quality due to interference. Select cell couples with high interference and than set a proper channel separation in the experience matrix.
-
Another possibility i s to make drive tests and find the areas with high interference. Afterwards for cell couple with interference, a proper channel separation will be set in experience matrix.
-
Using A9155 worst interferer" feature finds the interferer sites in the network. This information can be used as it is in the experience matrix or it can be used as input for drive test team to verify the predicted interference. "
Comparison The comparison is performed in order to quantify the gain of indicators of the new frequency plan. To see clearly the impact of the new frequency plan, should be measured before and after the frequency plan implementation. During this phase are defined the procedures, the tests to be performed and the relevant statistics in terms of for this comparison. The overall tests.
indicators can be retrieved from OMC-R or measured during
OMC-R. The indicators checked are Call Setup Success Rate (CSSR) and Call Drop Rate (CDR). In order to see clearly the impact, it has to be taken into account that not all the parameters are referring to the area where the new frequency plan was implemented. The advantage is the possibility to check the overall network quality. Drive tests. To see the improvements of new frequency plan the drive tests are performed, on the same routes before and after implementation, in area where the new frequency plan is changed. The same indicators as presented below are measured. The areas with low quality due to coverage must be listed and excluded fro m area where indicators comparison is performed. This i s done because no improvement can be expected by introduction of the new frequency plan in these areas. 1
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At the end of this step, the frequency planner has a cle ar view on the frequency plan acceptance procedure, the compared indicators and drive tests routes.
4.4 Creation of Frequency Plan This chapter presents briefly how to set up frequency planning strategy.
AFP parameters to follow the chosen
Since this information is tool related all detailed information related to A9155 i s detailed explained i n 4.4.1 Setting of Parameters to Reflect FP Strategy A91 55 parameters must be set, in or der to fol low the strategy defined.
Spectrum Partitioning. For in case of classical network configuration a cell type with one frequency band for BCCH and one f or TCH must be defined. The way to perf orm this is explained in Frequency Constraints. If there are some frequency usage constraints defined they must be set during this phase. For example if some frequencies must be used in specific areas, these frequencies can be set as fixed an d are not touched by AFF! In the same way if some frequencies must be avoided in some specific they must be set as forbidden, and therefore, not alloca ted by AFP These parameters setting can are done o n cell basis.
Experience Matrix. The experience database in A9155 relies in exceptional cell pair constraints. It contains cell pairs having a specific channel separation, based on field experience
Interference Matrix. Another input for frequency allocation process is the interference matrix. This matrix can be generated by A9155 and is based on predictions. It contains the interference probability between cell pairs. Detailed information about, creation, import and export of A9155 interference matrix can be found i n GSM Frequency Constraints. During this phase, the specific GSM constraints must be set. As explained in co-cell, co-site and neighbor constraints are defined and used by
The default values proposed fo r these constraints are:
co-site constraint a separation of 2 channels co-cell constraint a separation of
:
2 channels, from BTS G3 3 channels, for G2 BTS or less neighbors constraint the separation is 1 channel
Hot spots or high traffic areas. All cells fro m these areas will have a higher AFP Weight for frequency allocation process (as explain ed i n 4.2.10). 4.4.2 Run the AFP Frequency planning allocation process is an iterative process. After all input data i s available inside the tool, the frequency allocation process is started. All the required parameters to set up the frequency plan ning a re presented in 4.5 Frequency Plan Va lidati on
The validation o f frequency plan consists in taking the decision to implement or not the new frequency plan. Using the indicators presented in chapter 0, the new frequency pla n is compared with the previous one.
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The validation is done in order to ovoid the implementation of a worse frequency plan. The validation of the frequency plan is done both automatically, in the tool (different analysis), manually (by RNO team, due to a detailed knowledge of the network). There are several means of evaluating and improve the frequency plan. As explained in chapter the comparison of previous and new frequency plan is made through the next performance indicators:
-
Interference calculation
-
Constraints violation
-
Visual analysis of frequencies pla n
-
Frequency distribution.
More detailed explanation of A91 55 usage can be found i n 4.6
lmplementation of the new Frequency Plan lmplementation of the frequency plan is done via OMC -R through the PRC. It can be performe d both manually f or one to several cases and using external tools.
Manually Implementation. The manually frequency plan implementation is used for small networks or to change only some cells. When only microscopic changes ore performed, the PRC can be created manually: by copying parts of the SC to a PRC or enter the changes fr om a excel list into the PRC. Then the PRC can be activated in OMC-R via message mode a nd is mor e effective. Using External Tools. To implement the frequency plan fo r a complete network or for large number of cells (over several is recommended to use MLU activation mode. In this case of gl obal changes, the use of a external tool chain fo r csv fil e creation is strongly recommended. A91 55 RNP offers wi th its A91 55 PRC Generator Module the possibility to interface with planning data to the open interface of the OMC-R
-
More detailed information about PRC Generator usage can be found in
4.7 Post lmplementation Tasks After frequency pla n implementation, usually there is need fo r optimization. In this phase the problematic frequencies are changed manually : using joker frequencies (more easy) re-using frequencies fr om another cells. The network possible problems are found from OMC -R and from drive tests. If RNO is available, its usage is recommended, since it provides a better visualization of OMC-R counters and indicators. 4.7.1 Intensive
Analysis In orde r to check the frequency pla n after implementation, intensive be pe rformed. All problems discovered must be solved immediately.
analysis must
Drive tests have to be performed in the entire area of the new frequency plan. In this way the areas are foun d an d solved very fast. A9155 has the visualization option feature. Using this feature the possible problems are found very quickly. The optimization solutions are: Using joker frequencies. Problems discovered can be solved very easy and quiclky if joker frequencies have been reserved fro m the beginning.
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Using feature. If joker frequencies are not available, f indi ng clean frequencies could be useful i n ord er to replace interfered ones. Traditionally, these measurements are o btai ned through measurement campaigns realized on the field. However, using release and features and these measurements are avai lable directly from the network for any period of time. "
"
Manual optimization. This solution consists in changing manually the frequency plan, while trying to fulfill imposed constraints. The possible methods to improve the frequency plan for different types of network configur ation are presented in the next chapters. 4.7.2 Update Experience Database All changes performed in the frequency plan must be reflected by the experience database. Keeping an up-to-date experience data, leads t o a better automatically created frequency plans in the future. During the frequency plan optimization all the problematic areas or interfered cell couples are discovered. If there are performed any changes in the frequency plan, the new channel separation must be written into experience matrix also.
5 FP PROCESS FOR DUAL LAYER NETWORK In this chapter only the particularities of micro cell frequency planning related to classical frequency planning are presented.
5.1
FP
Strategy
5.1.1 Spectrum Partitioning Dual layer issue from spectrum partitioning point of view can be seen in two modes: continuous micro layer implemented or sporadic use of micro cells, for traffic hot spots coverage. -
Sporadic implementation of micro cells. If the mi cro cells do not create a continuous layer, there is no special case for spectrum partitioni ng. The frequencies for macro layer are used in the micro layer. The partitioning strategy is the same as presented in Chapter 4.2.1.
-
Continuous implementation. In this case the frequency spectrum must be partitioned to provide a dedicated frequency band for micro cells. It was seen that a good BCCH planning for micro cell is achieved with a RCS of 7. Since for micro cells it is recommended to use synthesized frequency hopping, due to quality improvement, there is no dedicated bandwidt h for micro cells TCH. To assign the macro cellu lar TCH frequencies to micro cells TCH, wi thout keeping a dedicated band for micro cells, is used the algo rith m AIMS Integrated Microcellular Solution) is used only if the macro layer is hopping with a reuse of 1x3 (RFH).
A special treatment i s made for indoor cells located in very high buildings. The interference in ind oor cells at high floors is higher. To overcome this proble m a dedicated band has to be kept in before. Usually 3 frequencies are enough for a good indo or frequency plan . If joker frequencies are reserved fro m the beginning, they can be used also for these indoor cells. 5.1.2 Decision on Frequency Hopping Implementation
It is recommended to use frequency hopping for micro cell frequency planning since micro cells gain more f rom frequency diversity, than macro cells.
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BBH. The BBH can be deployed in case of micro cells network wide implementation (where there is a dedicated bandwidth for micro cells). Since BBH does not change the frequency plan, there are n o changes fro m classical frequency plannin g. BBH implementa tion for micro cell will increase the network only when the number of hopping frequencies is equal o r greater than 3. RFH. The advantage of RFH is that allow micro cells to use frequencies from macro cells, except the ones in the umb rella cell (AIMS) By using frequencies' from macro layer: o
no need for a dedicated bandwidth for micro cells, except for BCCH planning,. The RCS for TCH is smaller.
o
Having a smaller RCS for TCH lead to an increased traffic capacity.
For micro cells is recommended to use a reuse
xl
-
.
The conclusion on strategy used for frequency hoppin g is presented in the Table 7. Table 7 FH implementation for Micro Cells
Hopping Mode
Usage for micro cells I
5.2
Advantages
Drawbacks I
I
BBH
Not recommended for less than 3 frequencies in the hop ping sequence.
Improve network
Higher effort for frequency planning (dedicated bandwidth for micro cells)
RFH
Reuse
Capacity increase while keeping a goo d
Requires good cell planning, with small overlap (possible for micro cells)
x l,
using
I
Inputs preparation Setting of Parameters to Reflect FP Strategy In case of sporadic implementation of micro cells the frequency planning can be done manually. In case of network wide implemen tation AFP is used for micro cell frequency plannin g. This step is performed as described in Chapter 4.4.1.
6 FP PROCESS FOR DUAL BAND N E T W O R K S In this chapter only the particularities of dual band frequency planning related to classical frequency planning are presented.
6.1
FP Strategy
6.1.1 Spectrum Partitioning The feature multiband cell is available since This feature brings a new strategy for du al ban d networks frequency planning . Therefore, the frequency planning fo r dual band networks can use two different strategies. One strategy for partitioning is for dual BCCH solution and the other for single BCCH solution. "
"
Dual BCCH. For dual BCCH cells there are no constraints related to partitioning. The frequency plann ing process can be seen as two different processes, independent on each other. Therefore, the frequency plan ning is performe d the same as for classical network for each band. Single BCCH. In this case (multiband cell) the BCCH is assigned to a dual band cell only from one band. Therefore, the spectrum partitioning between BCCH and TCH has to be don e only in o ne frequency band. Between BCCH and TCH band a guard band or frequencies must be reserved. Usually the BCCH frequency 1
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band is the customer classical band, and the preferred band will contain only TCH frequencies. A simple solution is to use one band only for BCCH and the other band for TCH. The advantage is that there is no need for a guard band. An example fo r single BCCH spectrum partitio ning is presented below:
514 514
Figure 7
Partitioning Dual Band Single BCCH
7 FP PROCESS FO R C ON CEN TRI C CELLS Concentric cells are used a low cost solution to decrease the blocking rate on congested cells and to deploy temporarily investments in new sites, if traffic growth is moderate. Also concentric cells can be used to free up some frequencies in the macro layer and implement additional (for example for micro cellular layer). In this chapter the particularities for concentric cells frequency plan ning a re presented. 7.1 FP Strategy
7.1.1 Spectrum Partitioning Concentric cells [9]
are introduced in the network to:
minimize the overall interference to keep the same interference using a smaller reuse cluster size. There are two different cases for concentric cell implementation: hot spot and network wide implementation.
-
Hot spot implementation i s performed only in some specific congested area, in order to increase the number of due to capacity reasons. In this case there is no need for a dedicated bandwidth for inner zones of concentric cells and the frequency planning can be done manually.
-
wide for concentric cells requires more careful frequency planing. Therefore, in order to have a proper frequency plan, for concentric cells, it is recommended to keep a dedicated bandwi dth f or in ner zones of concentric cells. Typically, 6 or 7 frequencies are enough for inner zone and a reuse of 3 (non consecutive frequencies) can theoretically be achieved on three sectorized cells. Frequencies can be reused between inner zones of any pair of cell if these cells are not on the first ring of neighbors.
For concentric cell network wide implementation, the frequency planni ng is supported by A91 55
8 F P PROCE SS F O R H O P P I N G N E T W O R K S In this chapter only the particularities of hopping networks related to classical frequency planning are presented.
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8.1 8.1
FP Strategy
Spectrum Partitioning BBH. There are no different aspects related to frequency planning and spectrum partitioning for Base Band Hopping . The frequen cy planning, fo r these networks, is performe d the same as for classical network (Chapter 4.2.1). RFH. In the same way, as for the method de scribed in chapter 4.2.1, a separati on between BCCH and TCH frequencies is perfo rmed. The frequency planning for BCCH frequencies is performed in the same way as for classical networks, since these BCCH frequencies do not hop. To avoid ad jacent interferen ce is recomme nded t o keep one channel separation between BCCH and TCH sub-bands. If the planning area contains hopping and non-hopping areas, the available resources have to be divided in hopping and non -hopping frequencies, for TCH carriers. These two sub -bands must have at least one channel separation between them, in order to avoid interference. The separation between sub-bands can be used afterwards as frequencies. An example for spectrum partitioning in a real network is presented below. This example is taken from Jakarta frequency planning, for Satelindo customer. For this network, there are defined two areas: inner area, very dense, wit h RFH hopp ing TCH
Figure 8
Partitioning for Hopping Networks
8.1.2 Decision on Frequency Hopping Implementation The primary goal of frequency hopping is to decrease the network interference and therefore, a n increased network One major benefit of frequency hopping is the fading reduction. Fading effects occurs in urban environments due to reflections and diffraction on different propagation paths. Frequency hopping introduces frequency diversity and combats multipath fading: different frequencies experience different fading. Therefore, the mobile at each burst and stay in fading notch for a shorter time. experience different The frequency hopping results in an increased receiver sensitivity under fading conditions and therefore in improved quality in uplink and downlink direction compared to a non -hopping configuration. Since there are defined two hopping modes: BBH and RFH there are different approaches for each of them.
BBH. There i s no other aspect related to frequency plannin g for BBH network than for classical network. The BBH i s preferred instead of RFH since the frequency plan of a BBH network includes intelligence by using tools and different algorithms. By using it i s very difficult to increase the traffic capacity and keeping a good When this point is reached, no capacity improvement is possible it is time to choose RFH. RFH. Usually RFH i s chosen when there is congestion in traffic, there are not available any additional resources for capacity improvement, and there is 1
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impossible to face any TRX extension. For RFH there is a possibility to increase traffic capacity, with the condition to keep the bellow a maximum value. There are different reuse strategies for RFH: 1 and The advantages and drawbacks for each type of hopping and reuse are presented in Table 8. Table 8 Hopping Modes Advantages and Drawbacks
Reuse scheme
Benefits
Drawbacks
Higher
Minimum interference + benefits of interferer and
BBH
for frequency planning
frequency diversit y Radio Design errors can be hidden by frequency
Allow o re-use of the hopping frequencies (for the
RFH
1
microcells).
Need a good
design of the network (same teight of the sites, regular
Ease the transition between hopping
and
hopping area. From interference reduction
RFH
From interference
azimuth of the antennas, fl at area, ca reful tilt tuning) to be fully efficient.
the requirement to
Good cell planning
coverage over lap
same antenna height and a careful tilt tuning is even allowed. as for 1x3, whereas there is n o requirement for same azimuth
No
re-utilization
of
the
hopping
frequencies
possible (for example for More difficult transition
hopping area and
non-hopping area.
A detailed explanation on how to create hopping groups Also, the method used in Cape Town to create
each reuse is explained i n groups is presented in
In the Table 9 there are presented the improvement network (Portugal), for different hopping modes. Table 9 FrequencyHopping ModesComparison
obtained in a running
Reuse indicators SDCCH drop RTCH assign fail Cali-drop success rate HO causes
nterference bands in band 1)
Reuse 1x3
Discrete
Baseband
1.2% 0.6%
1.0% 0.5 %
hopping 1.2% 0.6%
hopping 0.8% 0.4%
1. l %
1. 1 %
96.2%
98 %
1. l % 96.2%
0.9% 96.4%
Better-cell: 43% Qual HO: 34% Level HO: 54%
Better-cell: 47% Qual HO: 23% Level HO: 28%
Better-cell: 42% Qual HO: 29% Level HO: 23% 68%
?seer-cell: 41% HO: 32% HO: 22% 61%
0.64
0.76
0.61
I,
Note: Discrete hopping is like a BBH, but where the As i t can be seen from the table a better quality can be the same of frequencies. These gains are strongly cell planning and antenna diversity gain.
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1
8.1.3
and
I
-
Non-GPRS networks In case of Base Band Hopping in non -GPRS networks, the is not used, since the g oal is t o use all frequencies fro m one cell and ho p between them. There is a particularity for Synthesized Frequency Hopping. The parameter can be used to reduce the RF Load of the cell, by setting a higher priority for BCCH frequencies. Therefore, the traffic is distributed on the BCCH frequency, less interfered, and the RF Load for hopp ing frequencies is lower. Default value of is The proposed values for BCCH is 7, for TCH less interfered 5 and for interfered frequencies the proposed value is 0.
I
-
GPRS networks The assignment.
and
will have no impact on PS TS
8.1.4 RF Load The RF Lood (see chapter calculation is evaluated for RFH networks, since for the other networks RF load w ill be al l the time 100%. As explained in and for reuse 1x3, RF Load should be maximum value 50% to avoid intra site interference, and for a reuse of 10 - 1 2%, with the maximum value of 16.6%.
with its it must be
By using these maximum values, the maxi mum numb er o f frequencies that can be assigned to a cell are fou nd.
I
More detailed information o n RF Load calculation can be found i n Frequency Coordination a t the
and
Border
Frequency coordination at the planning border -
-
BBH the strategy
the planning border is the same described in Chapter 4.2.6.
RFH the strategy is to remove fr om the FHS (Frequency Hop pin g Sequence) the frequencies used in the vicinity of the pl anni ng border. The problems might appear if the area outside planning border is not hopping and is using the some frequency band for TCH. If there is a separation between area and the surroundings, the frequency can done on the planning border. This was the case for Cape Town
Reuse 7x3. In case that the same frequency ban d is used in b oth areas, is achieved an easier transition from hoppi ng area to non -hopping area .
Reuse In case of reuse the transition can be done if a dedicated bandwidth is kept for plonning at the hopping border (is like a buffer). The optimization of frequency pla n is performed manually, when using RFH. Frequency coordination at the country border -
For BBH the strotegy at the country bo rder is the same described in Chapter 4.2.6.
-
For RFH: In case that the thresholds presented in chapter 4.2.6 are not exceeded there is no need for
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If the thresholds are exceeded, the strategy is to from the FHS (Frequency Hopping Sequence) the frequencies used on the country border, by the other GSM operator. 8.1.6Frequency Coordination at Co-Existence of Several Systems
-
. . . : '
.
.-
For RFH the forbidden frequencies are calculated like in Chapter 4.2.7. The difference is that the forbidden frequencies are extracted from the FHS (Frequency Hopping Sequence).
..
:
For BBH networks the strategy is the same as described in Chapter 4.2.7.
-
3
. .
.
8.2 Inputs prepara tion 8.2.1Experience Database
:
.
The creation of the experience database for hopping networks is the same as for classical network, described in chapter 4.3.4.
BBH. For BBH networks the experience database is used the same as for classical network, since there is no difference f rom classical frequency planning.
RFH. In case of RFH, the experience databa se must be used besides BCCH frequency allocation also during gro up allocat ion for hopping TCH. 8.3
Creatio n of Frequency Plan
8.3.1Setting of Parameters to Reflect FP Strategy AFP parameters settings for hopping networks, is performed the same as presented in Chapter There is a difference in case of RFH and consists in FHS definition. As described in a new cell type is defined containing the frequency sub -band allocated for hopping TCH (described in spectrum partitionin g chapter) an d provide the FHS. Before launching the
hopping mode must be set as described in
8.4 Post Implementation Tasks 8.4.1 Update Experience Database The main difference from the classical network configuration is that for TCH frequencies of RFH network, the experience database is not used. Experience database is used only for BCCH planning. All constraints found, both from BCCH and TCH frequency planning optimization, or some specific channel separation for problematic cell couples must be added in experience matrix.
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9 FREQUENCY PLANNING
TOOLBOX
This chapter wants to a view of the context of frequency planning related tools that are in the whole frequency planning world. The tools used within
are:
A9 1 55 Radio Network Planning
(which includes Piano tool) SONAR RADAR
A91 55 i s the only tool that followed Alcatel PLC. The other tools are not officials and can be used if needed, but cannot be provided to the customer. The disadvantage i s the more tools are used, the probability of inconsistency i s higher.
9.1 Short Description of A91 55 A9155 RNP i s the Alcatel software dedicated to radio network planning for networks working under the GSM UMTS technology, from initial design to densification and optimization. A91 55 allows the following tasks:
-
Radio Measurement Evaluotion an d Propagation Model Calibration
-
Radio network Coverage Plonning
-
Analysis
-
Neighborhood Plonning
-
Frequency and
-
BS System Data Interfacing
Planning
The frequency planning process for A91 55 is on Automatic Frequency Planning During frequency allocation process AFP takes into account, module (AFP) besides standard channels separation: Interference matrix, based on coverage predictions Capacity Analysis From frequency planning point of view A91 55 i s performing: Enhanced frequency plan analysis for all kind of radio configurations Consistency checks against given resources analysis for overall
check and local optimizations
Efficient visualization functions for manual network check and frequency plan modifications Enhanced algorithms for fast, efficient and reliable resource planning Automatic Frequency planning in non-hopping, base-band and synthesized frequency hopping networks Automatic MAL,
and HSN planning
Automatic
planning
Standardized
Interface
to
BS
system
for
frequency
implementation
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plan
A91 55 can be used as a standalone to ol also for a frequency planning campaign. This can be seen in Table 10. A91 55 works on Windows NT, 200 0 platfo rm. Detailed information can
[email protected]. E
9.2
be
retrieved
from
A9155
support
team,
Short Description of EasyRNP is an add itional RNP tool, which can be used on top of A91 55 RNP fool. The Piano (an old frequency planning tool) functionality is included in The tool provides a visual interface for radio network planners to operate RNP data in graphical way. The main application of this tool is seen in operational networks during optimization of: - frequency plan
a
a
-
neighbors planning
EasyRNP features are:
-
-
-
EasyRNP provides a visual and effective interface of site DB to operate RNP data in a gr aphical way (Piano functionality). 80 measurement reports can be imported. EasyRNP provides SONAR functionality cell by cell. SONAR functionality is based on counters and provides the HO traffic between cells. If the HO traffic between two cells is high, the channel separation has to be high as well. Channel separation assignment for the entire network. These results can be exported to A91 for automatic frequency planning . The possibilities are: a) From scratch, with no and neighbors constrains b) Based on
information, based on site co-cell, co -channel
counters
EasyRNP does not have the feature of automatic frequency allocation. Therefore, the tool can be used only during a frequency plan manual optimization and to create inputs to A91 55 (interference and channel separation matrix). EasyRNP works on Windows NT, 20 00 Detailed information can be retrieved from the support team:
-9.3 Short Description of SONAR SONAR was developed out of necessity to identify missing neighbors relationships, in the networks. The tool can be used dur ing frequency pla n optimiza tion campaigns. SONAR uses a web interface and needs live connection with OMC -R, to have access to weekly and daily HO statistics. Therefore, the tool is not easy to be installed. The tool inputs are:
-
Neighbo r H O statistics
-
Configuration data from OMC-R
The main features of SONAR are:
-
Neighbor analysis a)
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b)
neighbor analysis
c) Global neighbor analysis Automatic frequency ollocation, based on
-
SONAR works on Windows, server and Perl.
counters (HO statistics)
and Linux platform and requires Apache Web
Detailed information con be retrieved from Richard lvanov and Wayne who developed it:
9.4
and
Short Description of RADAR RADAR is an evolution of SONAR, by including indicators for frequency planning. RADAR uses measurements in order to evaluate the probability of interference between any given cell and all others in the network. This probability is then used to select or allocate frequencies. RADAR is currently a C GI script and can b e accessed with a web browser. RADAR relies on a large amount of pre -computed data and requires a database to be populated daily with RMS binary files. In order to facilitate timed data collection processing, a Linux PC is used. The back -end database is RADAR is written i n Perl but uses a few Bourne shell scripts for OMC connection and crontab handling . RMS does not by itself provide enough information for a frequency plan, because mobiles that ar e in dedicated mode o n a particul ar cell, scan only BCCH frequencies defined in the neighbour list. Therefore it is necessary to implement dummy neighbours in the network in order to scan all BCCH frequencies, and thus pick up potential interferers cells that are not neighbours. These dummy neighbours are created as external OMC cells with an impossible H O mar gin (127 ). The dummy neighbour management i s part of RADAR. "
"
As inputs RADAR uses the binary PMRES files of types AClE RNL export files. The frequency plan output is in files).
10, T31 and and the PRC format (12 AClE
RADAR provides the frequency plan faster since it does not contain before frequency pla n implementation. For more information contact
validation step,
or
.
9.5 Tool related FP steps The table below presents the tools used in each FP process step. The steps which are not tool related were ignored in this table. Table 10 FP Toolbox Tasks
A9 1 55
SONAR
RADAR
1. Analysis of existing FP 1.1 Download from OMC - R of FP
neighbourhood plan
PRC Generotor module
1.2 Import 180 counters 1.3
Frequency usage based on counters
T180
Load from
files
Interface
Interface
v
v
v
v
v
v
v
v
11.4
Determination of FP indicators weighted over area
,
1.4.2 C/I weighted over traffic
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Number of constrains violation
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RADAR
v
v
v
v
v
Manual exception list
Manual exception list
2. Def ine Targets
Not tool related
3. Defi ne Strategy
Not tool related
4. Preparation work 4.1
Support for any spectrum partitioning strategy (diff erent subbands)
v
Treatment of exception sites (fixed frequencies)
v
Possibilities for Frequency Hop ping implementati on (BBH, RFH)
v
Implementation coordination solutions
v
4.2
4.3
of
4.4
frequency
Logical parameter system (ACIE)
fr om
4.5
4.6
Neighb ors retrieval from system
4.7
Neighbors Planning
v
BBH and RFH
PRC Generator modu le PRC Genera tor module Automatic
Load from xls files
manually
v
v
v
v
Automatic
v
Manual 4.8
OMC Neighbors relationships
v
counters consideration
4.9
4.10
Interference automatically
4.12
Interference matrix
4.13
Check
v
v
Manual experience matrix
v
v
v
v
v
v
v
v
v
v
v
v
v
v
Experience database consi derati on
4.1 1
v
v
matrix
creation
v
v
monually
v
v
manually of frequency pla n
5.1
frequency plannin g
v
5.2
Automatic frequency plannin g
v
5.3
Automatic
v
planning
Only BCC
6. Frequency plan validation 6.1
Determination of indicators
6.2
7.
FP performance
Frequency plans co mparis on
v v
Frequency plan implement ation
PRC Generator module
8. Post implement ation tasks 9.
Only visual check of FP End user indicators End user indicators (after implementation) implementation) indicators End user indicators End user (after implementation) implementotion) External tool
via PRC
tool related
Reporting
Not tool related
10 PROPOSALS OF DIFFERENT FREQUENCY PL AN NI NG C ONFI GURA TIO NS
This chapter is providing some proposal frequency planning strategy based on available frequency spectrum and traffic capacity requests. Table 1 1 is presenting some
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hints but no t rules. It is very difficult to give general strategies on this issue, since each project is different an d dependent on network environment. Table 11 Proposed FP Strategies
Channels
Proposed FP strategy
Network configuration inputs
#
Calculated values
Observatio
I 2
Very small bandwidth
Due to limited bandwidth the traffic capacity can be fulfil by RFH reuse
Best solution is to deploy RFH reuse xl .
-
11
-
1 frequencyguard
frequencies for BCCH frequency
Requires: - small cells overlap -effort in planning transition from RFH and hopping
- Regular - Flat area Homogenous best server area
For high tr affic capacity deploy reuse 1 -
14
-
1
-
15 frequencies for
Same azimuths
Needs a very good RNP since RCS for BCCH is only
frequencies for BCCH
14.
frequency guard frequency
hopping TCHs Irregular pattern small cell overlap
-
14
-
1
-
-
Fewer constraints in network design -
No continuous micro cellular layer
1
CONFIDENTIAL
Needs the
Deploy reuse frequencies for BCCH
antenna
frequency guard frequency
for all sites.
15 frequencies for hopping TCHs
Problems to implement micro cells.
Deploy BBH -
17
-
22
Lower interference due to intelligent FP
frequencies for BCCH
frequencies for BBH TCH
Edition
Higher effort in frequency
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