Huawei Technologies Co
Guide Guide to Indoor WCDMA Coverage DesignFor internal use
only
Product NameConfidentiality Level
WCDMA RNPFor internal use only
Product VersionTotal 93 pages
3.1
Guide to Indoor WCDMA Coverage Design(For internal use
only)Prepared byChen LeiDate2006-03-20
Reviewed byXie Zhibin, Wu Zhong, Hu Wensu, Yang Shijie, and Ai
HuaDate2006-03-22
Reviewed byYao JianqingDate2006-03-25
Approved byDate
Huawei Technologies Co., Ltd.All Rights Reserved.Revision
HistoryDateRevision VersionDescriptionAuthor
2002-12-301.00Completed the first draft and revised some
contents according to review comments. Gu Jufeng
2004-10-292.00Added the analysis on a multi-system shared
system, preliminary analysis on an IRS, and method of calculating
the WCDMA service thresholds by GSM signals. Discussed handoff
problems in an indoor system. Supplemented and perfected other
projects according to relevant data of project S and domestic
experimental offices. Zhang Junhui
2004-12-102.01Revised some contents according to review
comments. Zhang Junhui
2006-3-203.00Added the following chapters: Planning concepts of
an indoor coverage system Indoor and outdoor interference control
Indoor and outdoor handoff design Design requirements of an indoor
distributed system manufacturer Review on the design scheme of an
indoor distributed system Investment evaluation of an indoor
distributed system Expansion and evolution of an indoor distributed
system Cases of designing an indoor distributed systemRevised some
contents in other chapters. Chen Lei
2006-5-293.1Added the following contents: Indoor coverage
strategy for the HSDPA Analysis on the coverage and capacity
influences of the existing R99 network Methods of indoor HSDPA
coverageLiao Zhengzhong
Table of Contents111 Overview
2 Planning Concepts of an Indoor Distributed System112.1 Design
Flow of an Indoor Coverage System112.2 Key Issues in Different
Phases of Indoor Coverage132.3 How to Help Operators with the
Design of an Indoor Coverage System132.4 Comparison Between
Intra-frequency and Inter-frequency Networking Solutions for an
Indoor Distributed System132.5 Planning Concepts of Different
Application Scenarios142.5.1 Airports, Bus Stations, and
Docks142.5.2 Shopping Centers and Large Supermarkets152.5.3
Exhibition Centers, Convention Centers, and Gymnasiums152.5.4
Office Buildings and Hotels152.5.5 Government Offices and
Companies163 Design for an Indoor Distributed System163.1
Collecting Coverage Target Information163.1.1 Collecting Coverage
Information (Mandatory)163.1.2 Collecting Service Information
(Mandatory)173.1.3 Collecting Capacity Information
(Mandatory)173.1.4 Analyzing Requirements of System Transmission
Resources (Mandatory)183.2 Surveying and Testing the Indoor
Distributed System183.2.1 Surveying the Existing Network of the
Indoor Distributed System (Mandatory)183.2.2 Preparing Coverage
Area Drawings (Mandatory)193.2.3 Surveying the Indoor Structure of
a Building (Mandatory)193.2.4 Indoor CW Tests (Optional)213.3
Estimating the Coverage and Capacity of an Indoor Distributed
System223.3.1 Link Budget of an Indoor WCDMA Distributed System
(Mandatory)223.3.2 Estimating the Capacity of a Single Indoor WCDMA
Distributed System (Mandatory)253.3.3 Link Budget of an Indoor
WCDMA and DCS 1800 Shared Distributed System263.4 Choosing a Signal
Source for an Indoor Distributed System283.4.1 Choosing a Proper
Signal Source According to Capacity and Coverage Requirements
(Mandatory)283.4.2 Repeater Influences on an Indoor Distributed
System (a Key Issue)293.5 Designing Indoor and Outdoor
Handoffs323.5.1 Designing Intra-WCDMA System Handoffs
(Mandatory)323.5.2 Planning Neighbor Cells for an Indoor Coverage
System (Mandatory)333.6 Analyzing a Shared Indoor Distributed
System and Control the Interference343.6.1 Analyzing a Shared
Indoor Distributed System of the Operator (Mandatory)343.6.2
Controlling the Interference in a Shared Indoor Distributed System
of the Operator (Mandatory)353.6.3 Analyzing an IRS ( a Shared
Indoor Distributed System of Multiple Operators (Optional)403.6.4
Analyzing Interference Between WCDMA Systems of Different Operators
(Optional)423.6.5 Methods of Controlling Indoor and Outdoor
Interference (Mandatory)453.7 Designing Parameters of an Indoor
Distributed System (Mandatory)453.8 Choosing Components
(Mandatory)453.8.1 Choosing a Combiner and a Filter for an Indoor
Distributed System453.8.2 Choosing Antennas for an Indoor
Distributed System (Mandatory)473.8.3 Choosing Feeders for an
Indoor Distributed System (Mandatory)503.8.4 Choosing a Power
Splitter and a Coupler for an Indoor Distributed System
(Mandatory)513.8.5 Choosing a Trunk Amplifier for an Indoor
Distributed System523.8.6 Choosing Feeder Connectors for an Indoor
Distributed System (Mandatory)533.8.7 Replacing and Adding
Components in an Indoor Distributed System (Mandatory)533.9
Designing a Detailed Solution for an Indoor Distributed
System543.9.1 Requirements on Design Reports of Indoor Distributed
System Manufacturers (Mandatory)543.9.2 Reconstruction Concepts and
a Schematic Diagram of an Indoor Distributed System
(Mandatory)543.9.3 Antenna Layout Plan of Floors in an Indoor
Distributed System553.9.4 Transmit Power Budget of Antenna Ports in
an Indoor Distributed System (Mandatory)553.9.5 Detailed Network
Topological Diagram of an Indoor Distributed System563.9.6 Detailed
Cabling Diagram of an Indoor Distributed System573.9.7 Material
List of an Indoor Distributed System573.10 Testing and Verifying an
Indoor Distributed System and Improving the Solution
(Optional)603.11 Evaluating the Investment of an Indoor Distributed
System (Mandatory)613.11.1 Main Cases of the Investment of an
Indoor Distributed System613.11.2 Investment Model of an Indoor
Distributed System623.11.3 Investment Estimate of an Indoor
Distributed System643.12 Reviewing the Design Solution for an
Indoor Distributed System (Mandatory)654 Expansion and Evolution of
an Indoor Distributed System664.1 Methods of Expanding the Capacity
of an Indoor Distributed System664.2 HSDPA Strategy in an Indoor
Distributed System664.2.1 Influences of HSDPA on the Original
Indoor R99 Coverage674.2.2 Influences of HSDPA on the Original
Indoor R99 Capacity704.2.3 Design of HSDPA Indoor Coverage
Solution715 Optimization for an Indoor Distributed System765.1
Optimizing the Coverage of an Indoor Distributed System765.2
Optimizing the Handoff of an Indoor Distributed System765.3
Optimizing the Interference of an Indoor Distributed System766
Cases of Designing an Indoor Distributed System766.1 Analyzing
Target Determination for an Indoor Distributed System776.1.1
Analyzing Coverage Targets776.1.2 Analyzing Service
Requirements796.1.3 Analyzing Requirements of Transmission
Resources796.2 Surveying and Testing an Indoor Distributed
System796.2.1 Surveying the Existing Network796.2.2 Surveying the
Inside of the Building796.3 Making Link Budget and Estimating the
Capacity of an Indoor Distributed System806.3.1 Making Link Budget
for an Indoor WCDMA Distributed System806.3.2 Estimating the
Capacity of an Indoor Distributed System816.4 Choosing Signal
Sources for an Indoor Distributed System836.5 Designing the Handoff
of an Indoor Distributed System836.6 List of Newly-Added Main
Devices of an Indoor Distributed System846.7 Detailed Solution for
an Indoor Distributed System846.7.1 Concepts of Reconstructing an
Indoor Distributed System846.7.2 Schematic Diagrams of the
Networking of an Indoor Distributed System856.7.3 Detailed Network
Topological Diagram of an Indoor Distributed System887 Summary897.1
Improvement Based on V2.0189
List of TablesTable 2-1 Comparison between intra-frequency and
inter-frequency networking solutions for an indoor distributed
system14Table 3-1 Values of the distance loss coefficient of
ITU-R.P 1238 model23Table 3-2 Values of the floor penetration loss
coefficient of ITU-R.P 1238 model24Table 3-3 Reference values of
indoor WCDMA penetration losses25Table 3-4 Service threshold
calculation of an indoor WCDMA and DCS 1800 shared distributed
system27Table 3-5 Design for Intra-frequency handoffs in and out of
an elevator32Table 3-6 Analyzing spurious interference of GSM 900M
BTS in the band of a WCDMA BTS according to the protocol38Table 3-7
Analyzing spurious interference of DCS 1800M BTS in the band of a
WCDMA BTS according to the protocol39Table 3-8 Analyzing spurious
interference of PHS BTS in the band of a WCDMA BTS according to the
protocol39Table 3-9 Example of IRS specifications41Table 3-10
Estimated thresholds of the interference of operator B's macro cell
BTS with operator A's indoor distributed system43Table 3-11
Estimated thresholds of the interference from operator A's own
equipment44Table 3-12 Antenna models of an indoor distributed
system47Table 3-13 Attenuation of feeders in an indoor distributed
system50Table 3-14 Parameter indexes of Kathrein coupler51Table
3-15 Parameter indexes of Kathrein power splitter51Table 3-16 A
material list of an indoor distributed system58Table 3-17 Use scale
model of devices and components of an indoor distributed
system62Table 3-18 Example of calculating the reconstruction costs
of a single-site indoor coverage system63Table 3-19 Example of
estimating Investments of an indoor distributed system64Table 3-20
Key issues of a design review on the solution for an indoor
distributed system65Table 4-1 Changes of dynamic power distribution
in the case of the downlink load change of indoor coverage68Table
4-2 Influences of HSDPA indoor coverage on the original R99 network
coverage69Table 4-3 Influences of HSDPA on the original R99 network
capacity71Table 4-4 Merit and demerit comparison between
independent networking and hybrid networking72Table 4-5
Recommendation of networking solutions in various scenarios72Table
4-6 Merit and demerit comparison between the two modes of
allocating power resources in an indoor scenario74Table 4-7 Merit
and demerit comparison between the two modes of allocating code
resources in an indoor scenario75Table 6-1 Details about the floors
in the coverage target78Table 6-2 Elevators of the coverage
target78Table 6-3 GSM traffic and number of WCDMA users81Table 6-4
Service model81Table 6-5 Traffic model values82Table 6-6
Distribution features of PS bearing types82Table 6-7 Indoor WCDMA
traffic model82Table 6-8 Choosing signal sources for an indoor
distributed system83Table 6-9 List of newly-added main devices of
an indoor distributed system84Table 6-10 List of coverage areas of
GSM and WCDMA signals86
List of Figures12Figure 2-1 Flow chart of designing an indoor
distributed system
Figure 3-1 Floor plan example of a building19Figure 3-2 Example
of an indoor photo21Figure 3-3 Influence of a repeater on the noise
floor of a BTS30Figure 3-4 Interference between operator A's indoor
distributed system and operator B's outdoor BTS terminal42Figure
3-5 Interference from operator A's own equipment44Figure 3-6 Sample
of a combiner46Figure 3-7 Indoor antennas47Figure 3-8 Leakage
cables48Figure 3-9 Log-per antennas49Figure 3-10 A power splitter
and a coupler52Figure 3-11 A trunk amplifier52Figure 3-12 A
schematic diagram of reconstructing an indoor distributed
system55Figure 3-13 An antenna layout plan55Figure 3-14 Detailed
network topological diagram of an indoor distributed system56Figure
3-15 A detailed cabling diagram of an indoor distributed
system57Figure 3-16 Example of an onsite test and verification in a
floor61Figure 6-1 Illustration of coverage targets77Figure 6-2
Indoor photo of the building79Figure 6-3 Calculation of indoor slow
fading margin80Figure 6-4 Reconstructing an indoor distributed
system85Figure 6-5 Part of the design for WCDMA signal sources
(1)85Figure 6-6 Part of the design for WCDMA signal sources
(2)86Figure 6-7 Vertical area coverage method of the small
commodity market87Figure 6-8 Detailed network topological diagram
of an indoor distributed system89
Guide to Indoor WCDMA Coverage DesignKeywordsDesign of indoor
distribution system, signal source, link budget, interference
analysis, IRS, handoff, parts selection, and investment
evaluationAbstractFrom the aspects of planning concept and design
flow, this guide describes the planning design process and
attention points of an indoor distribution system as a reference of
indoor WCDMA distribution system project. Acronyms and
abbreviationsAbbreviationFull Spelling
BCCHBroadcasting Channel
DASDistributed Antenna System
DCS 1800Digital Cellular System at 1800 MHz
HSDPAHigh Speed Down Packet Access
IRSIntegrated Radio System
POIPoint of Interface
RRURemote Radio Unit
1 OverviewThis document is used to guide the planning design of
an indoor WCDMA distributed system. The guide consists of the
following chapters: 1 "Overview"
2 "Planning Concepts of an Indoor Distributed System"
3 "Design for an Indoor Distributed System"
4 "Expansion and Evolution of an Indoor Distributed System"
5 "Optimization for an Indoor Distributed System"
6 "Cases of Designing an Indoor Distributed System"
7 "Summary"
2 Planning Concepts of an Indoor Distributed System2.1 Design
Flow of an Indoor Coverage SystemThe design for an indoor
distributed system falls into the following three types: Design for
a single indoor WCDMA distributed system Design for a multi-system
shared indoor distributed system of a single telecom operator
Design for an integrated radio system (IRS) of multiple telecom
operatorsThis guide mainly describes the design scenario of the
first type and briefs key design points of the second and third
types. Figure 2-1 shows the design flow based on the key design
points of an indoor distributed system.
Figure 2-1 Flow chart of designing an indoor distributed
system2.2 Key Issues in Different Phases of Indoor CoveragePhase 1:
In the phase of network design, the Ec of edge coverage is the main
focus point for the network design and acceptance. Phase 2: In the
phase of early network optimization, the Ec/Io of a pilot in indoor
cells is the main focus point. Phase 3: In the phase of network
operation and optimization, the soft handoff ratio of edge areas or
special areas is the main focus point. 2.3 How to Help Operators
with the Design of an Indoor Coverage System1) Huawei Network
Planning Department helps an operator and a design institute
prepare a networking solution, design report template, and review
template for an indoor WCDMA coverage system. 2) The concerned
manufacturer designs an indoor distributed system accordingly. 3)
Huawei Network Planning Department helps the operator and the
design institute review the design report of the indoor distributed
system. The manufacturer optimizes the system based on review
comments. 4) The design report passing the review is sent to the
operator for filling. Then the operator declares the project
implementation. 2.4 Comparison Between Intra-frequency and
Inter-frequency Networking Solutions for an Indoor Distributed
SystemSuggested strategy: Control the interference and realize the
coverage through a dominant intra-frequency solution and a
secondary inter-frequency solution. Table 2-1 Comparison between
intra-frequency and inter-frequency networking solutions for an
indoor distributed systemIntra-frequency Coverage Solution for Both
Indoor and Outdoor SystemsInter-frequency Coverage Solution for
Both Indoor and Outdoor Systems
MeritsHandoffs between entrances and exits of a building or an
elevator entrance and exit are soft handoffs. The soft handoff
success rate is high and the spectrum resources are used
effectively. Indoor and outdoor interference is small and the
system capacity is large.
DemeritsIn dense urban areas, the large intra-frequency
interference between indoor and outdoor cells in high buildings
affect the quality and capacity. Additional frequencies must be
added. The hard handoff success rate is lower than that of soft
handoff.
Applicable scenarios Early phase of network construtction
Low buildings
Indoor scenarios with small intra-frequency interference
Indoor scenarios with low traffic
Terminals not supporting inter-frequency hard handoffs High
buildings Scenarios with large intra-frequency
Scenarios with heavy traffic Scenarios with abundant frequency
resources
Strategy suggestionsIn the early phase of network construction,
the indoor and outdoor intra-frequency interference is small and
the traffic is also small. Therefore, use the intra-frequency
strategy. Clear the intra-frequency interference by optimizing the
network. Then use the inter-frequency solution to control
interference. Use the inter-frequency coverage strategy for meeting
capacity requirements. In a mature network, this strategy can help
solve indoor or outdoor interference and capacity problems.
2.5 Planning Concepts of Different Application ScenariosDesign
principles and attention points for an indoor distributed system
vary with different scenarios classified by user distribution and
building functions. 2.5.1 Airports, Bus Stations, and Docks
Coverage scenariosAirports, bus stations, and docks Coverage
featuresBoth the social value and the economic value of indoor
coverage are high. The traffic density is heavy. Dominant common
voice service users move frequently in such open places. VIP areas
in such places as an airport require seamless coverage of data
services. Generally, outdoors BTSs cover these areas. Key design
pointsIndoor coverage is a supplement of dead zones and hot spots
covered by outdoor BTSs. Interference control is a major problem in
these areas. In outdoor BTSs, cells with redundant capacity can be
cascaded to an RRU to cover indoor areas, thus making full use of
CE resources and ensuring softer handoffs for indoor and outdoor
users.
2.5.2 Shopping Centers and Large Supermarkets Coverage
scenariosShopping centers and large supermarkets Coverage
featuresCS users are dominant. The traffic is distributed
regularly, that is, in evenings or on the whole days of a vacation.
The traffic density is large in peak hours. Key design pointsIn
scenarios of this type, the structure is complex and coverage is
the main problem. Handoffs between entrances and exits of a hall
must be considered. Generally, use RRUs or micro BTSs as the major
signal source. 2.5.3 Exhibition Centers, Convention Centers, and
Gymnasiums Coverage scenariosExhibition centers, convention
centers, and gymnasiums Coverage featuresThe traffic is mainly
triggered by events. Sufficient margins must be reserved during
capacity estimate. Key design pointsCapacity is a key point for the
indoor design of the scenarios of this type. Do not set handoff
areas in traffic peak zones or auditoriums. Ensure good coverage
and smooth handoff for the entrances and exits of such places.
Generally, use macro cells to cascade RRUs for coverage, making
full use of CE resources. A news center may have many coverage
requirements on the data service. Use multi-cell and multi-carrier
configuration or the HSDPA function.
2.5.4 Office Buildings and Hotels Coverage scenariosOffice
buildings and hotels Coverage featuresIn scenarios of this type,
high-end users are more. Mainly consider users' requirements on the
coverage of data services. Key design pointsIn business areas and
shopping areas, the traffic is larger, whereas the traffic is
smaller in guest rooms. Consider the differences. Generally, use
RRUs or micro BTSs as the signal source. The drip irrigation
technique of the multi-antenna with small power is commonly used in
the scenarios of this type. Ensure the good coverage of CS services
in such places as elevators, entrances and exits of a hall, and
garages. 2.5.5 Government Offices and Companies Coverage
scenariosGovernment offices and companies Coverage
featuresScenarios of this type requires excellent network coverage.
Voice services are dominant and high-end users take a large
proportion. Key design pointsEnsure seamless coverage of voice
services and the coverage of data services in VIP areas. The
coverage is crucial. Generally, use macro cells or RRU for
coverage. 3 Design for an Indoor Distributed System3.1 Collecting
Coverage Target Information3.1.1 Collecting Coverage Information
(Mandatory)The operator offers opinions and the concerned
manufacturer collects coverage information. 1) Determine whether to
build a new indoor coverage system or to reuse the original one. 2)
Determine the specific floor where the coverage target is located.
3) Determine the requirements of coverage probability. For a
specific coverage floor, specify coverage probability requirements,
which vary with different requirements of design margin. If the
indoor coverage probability is 90% and the standard deviation of
shadow attenuation estimated indoors is 6 dB, the relevant design
margin is 5 dB. After collecting coverage information, make a link
budget for the indoor distributed system. 3.1.2 Collecting Service
Information (Mandatory)The operator offers suggestions. Comments
offered by Huawei are for your reference. 1) Determine types of
service object requirementsRequirements of WCDMA services vary in
the service threshold and system capacity. Therefore, during the
design of an indoor distribution system, confirm that the WCDMA
services require seamless coverage. 2) Determine the service
thresholds after making sure of basic service requirements. The
collected service information is a reference of link budget and
capacity estimate of the indoor distributed system. 3.1.3
Collecting Capacity Information (Mandatory)The concerned
manufacturer collects capacity information according to the
opinions offered the operator or referring to Huawei calculation
methods. 1) Collect the capacity information of a newly-built
indoor WCDMA distributed system. a) Predict the number of users of
the coverage target. b) Decide the traffic model with the operator.
2) Collect the capacity information of a shared Indoor GSM
distributed system. For an existing indoor GSM distributed system,
you can predict the capacity of indoor WCDMA distributed system
according to GSM traffic. a) From the operator, obtain the traffic
of the indoor GSM distributed system in the building. b) Get the
traffic percentage by the ratio of the GSM traffic in the building
to the total GSM traffic in the area. After collecting the capacity
information, calculate the capacity of indoor distributed system.
3.1.4 Analyzing Requirements of System Transmission Resources
(Mandatory)The concerned manufacturer analyzes the requirements of
system transmission resources by referring to Huawei analysis
methods. 1) Check whether E1 cables or optical fibers are used for
the transmission of WCDMA coverage in the building. 2) Decide
whether transmission resources are properly used according to the
calculated capacity and the type of signal source. If transmission
resources are limited due to the operator's transmission
conditions, duly communicate with the operator to prevent disputes
caused by transmission bottlenecks due to increased capacity. 3.2
Surveying and Testing the Indoor Distributed System3.2.1 Surveying
the Existing Network of the Indoor Distributed System (Mandatory)I.
Outdoor WCDMA BTSs Covering IndoorsIf the existing WCDMA network
still covers around the building designed for indoor coverage, the
outdoor cells may interfere with the indoor distributed system
later built. The main interference is pilot pollution. Generally,
the higher the floor is, the more serious pilot pollution becomes.
Therefore, you need to test the pilot signals of outdoor BTSs in
the indoor environment and to record the quantity and strength of
pilots and the distribution of pilot signals in the building. The
test result is a reference of edge field strength design of the
indoor distributed system. In actual engineering, the strength of
pilot signals of dominant indoor cells is higher in the design
margin than that of the strongest pilot signals of outdoor cells.
The edge field strength of indoor cell signals is about 5 dB higher
than that of outdoor cell signals. The test can be made selectively
inside the building. For example, choose one or two floors at the
bottom of the building, one or two floors in the middle, and one or
two floors at the top. The test needs Agilent-E6474A or Huawei
PROBE for indoor measurement. II. No Outdoor WCDMA BTSs Covering
IndoorsIf no WCDMA BTSs covers outdoors but a GSM distributed
system covers the inside of a building, record the coverage level
of the indoor GSM distributed system, pay attention to the places
or floors with poor indoor GSM distributed coverage, and make
handoff tests relevant to the GSM system. During the design for an
indoor WCDMA system, refer to the results of GSM network tests.
Make GSM signal level tests in different areas. The test items
include floor information, location information of the floor, and
CELL_ID, signal strength, and neighbor BCCH frequency and signal
strength of the serving cells of the test point. Make handoff tests
in major indoor and outdoor handoff areas, especially entrances of
halls and elevators. Record such information as signal strengths of
main serving cells and neighbor cells, and form a GSM signal
distributed diagram or table for the reference of indoor WCDMA
coverage design. 3.2.2 Preparing Coverage Area Drawings
(Mandatory)The operator or the indoor distributed system
manufacturer provides coverage area drawings. Obtain detailed
building drawings, including the floor plan for each coverage
target and elevational drawing of each direction. Try to obtain an
electronic copy in the AutoCAD format and a scanned copy of
engineering blueprint. In addition, obtain the construction
drawings of electrical and communication equipment rooms in the
building and mark the locations of allowable cabling holes and the
available transmission lines.
Figure 3-1 Floor plan example of a building3.2.3 Surveying the
Indoor Structure of a Building (Mandatory)The design institute and
the indoor distributed system manufacturer jointly complete an
indoor survey of a building. I. Main Tasks of an Indoor
SurveyPrepare information for the planning design of an indoor
distributed system. Through indoor survey and communications with
the concerned property management company, fulfill the following
tasks: Decide the coverage scope and specify coverage requirements
and differences of the floors in the building. Take enough digital
photos to show the indoor structure and outline of the building.
Decide the materials and thickness of the inner walls, floors, and
ceilings to estimate the penetration loss. For the penetration
loss, refer to Table 3-3. Decide available transmission, power, and
cabling resources and confirm the construction requirements of the
concerned property management company. Decide the installation
space for the equipment room, antennas, and feeders required by BTS
equipment. Know the usage of each floor and estimate the number of
users on each floor. If an indoor GSM distributed system already
exists, check the original design scheme during the indoor survey,
using it as a reference of designing a shared indoor distributed
system. II. Survey on Indoor Cabling ResourcesDuring a survey on
cabling resources, know the bearing capacity and curve radius of
the cabling environment. Pay attention to the following two points
about the survey on the curve radius: III. If the property
management company provides PVC pipelines for cabling, know the
curve radius at the corners of the PVC pipelines. Know the curve
radius from teh vertical cabling rack of the building to the
cabling corner of each floor. Indoor Structure ShootingChoose model
floors before taking photos indoors to ensure efficient
photographic tasks and to provide enough feature information of the
building. Suppose that there are 25 floors in the target building.
According to the building structure and floor layout, take the
first floor as a model floor. Choose one as a model floor from
floors 2 to 5, which are of the same structure and layout.
Similarly, choose one from floors 6 to 25, which are of the same
structure and layout. After choosing model floors, begin to take
indoor photos. The number of photos to be taken for each model
floor must meet the following requirements: Two to four photos:
Embody the floor layout. One or two photos: Embody the structure of
the ceiling. One or two photos: Show the locations for antennas.
One or two photos: Embody the features of outer walls and windows.
One or two photos: Embody the features of corridors and elevators.
One or two photos: Show unusual structures such as large metal
objects, and unusual equipment rooms (possible interference
sources). One or two photos: Show the panorama and outline of the
building.
Figure 3-2 Example of an indoor photo3.2.4 Indoor CW Tests
(Optional)Generally, the calibration of indoor propagation models
is not recommended. The current planning software cannot calibrate
propagation models. You can use the existing propagation models. If
the operator requires CW tests on a typical building, the indoor
distributed system manufacturer and Huawei can jointly complete the
tests. Making an indoor CW test is to obtain the indoor propagation
feature information of the coverage target. After a CW test,
analyze test data and obtain the penetration loss values of
separation walls, floors, and ceilings in the building. You can use
the GATOR signal source as the signal source of an indoor CW test.
The output power is about 5 dBm, which can meet the requirements of
an indoor test. For transmitting antennas, use common vehicle
antennas. In a CW test, transmitting antennas must be placed near
the chosen locations for antennas, where antennas may be installed
in actual engineering. For more details about a CW test, see WCDMA
Test Guide. 3.3 Estimating the Coverage and Capacity of an Indoor
Distributed System3.3.1 Link Budget of an Indoor WCDMA Distributed
System (Mandatory)The indoor distributed system manufacturer
completes a link budget of an indoor distributed system by
referring to the operator's comments and the calculating methods of
Huawei. I. Choosing an Indoor Propagation Model Keenan-Motley
indoor propagation modelBased on the free space propagation model,
the Keenan-Motley model is added with the penetration loss of walls
and floors. This model uses the following formula:
: frequency, its unit: MHz
: distance between a UE and a transmitter, its unit: km
: reference value of wall loss
: number of wallsIn this formula, multipath effects are not
considered, the penetration loss is regarded only as the product of
the number of walls and the reference value of wall loss, and all
walls use the same penetration loss value. Therefore, the result of
this formula is inaccurate. The following is another formula
improved from the above one. A finer model considers the
penetration losses of walls and floors of different types.
: number of type- floors penetrated
: number of type- walls penetrated
: penetration loss of type- floors
: penetration loss of type- walls
: number of floor types
: number of wall typesRelevant experiments show that the typical
value of attenuation through floors is 12 dB to 32 dB and the value
of attenuation through walls depends on the type of separation
walls used. If typical soft separation walls are used, the
attenuation value is 1 dB to 5 dB, whereas the value is 5 dB to 20
dB for hard separation walls. ITU-R P.1238 indoor propagation
modelCurrently, the industry recommends the ITU-R P.1238 indoor
propagation model. This model divides the propagation scenarios
into NLOS and LOS. For NLOS, the model uses the following
formula:
: coefficient of distance losses
: frequency, its unit: MHz
: distance between an UE and a transmitter, its unit: m,
: coefficient of floor penetration losses
: slow fading margin, whose value is relevant to the coverage
probability requirements and the standard deviation of indoor slow
fading For LOS, the model uses the following formula:
The applicable frequency range of the model is 1800 MHz to 2000
MHz. Table 3-1 Values of the distance loss coefficient of ITU-R.P
1238 modelCoefficient of Distance Losses
Frequency (GHz)ResidencesOfficesShops
1.8-GSMHz283022
Table 3-2 Values of the floor penetration loss coefficient of
ITU-R.P 1238 modelCoefficient of floor Penetration Losses
FrequencyResidencesOfficesShops
900 MHz-9 (1 floor)
19 (2 floors)
24 (3 floors)-
1.8-GSMHz4 n15 + 4 (n - 1)6 + 3 (n - 1)
Note: "n" denotes the number of the floors to be penetrated,
larger than or equal to 1. II. Estimating the Indoor Edge Field
Strength and the Antenna Transmit Power Estimating the indoor edge
field strength if outdoor BTSs are builtAccording to the results of
indoor pilot tests, design the edge field strength of indoor cell
signals higher than the indoor pilot Ec of outdoor cells by 5 dB,
which is regarded as an experience reference value. In addition,
consider the Ec and Ec/Io requirements of the lowest access
thresholds of a service. Considering the above two points,
determine the indoor edge field strength. Estimating the indoor
edge field strength if outdoor BTSs are not enabled According to
the results of outdoor BTS coverage prediction, input the longitude
and latitude where the building with an indoor distributed system
to be built is located into the coverage predication result
diagram. Then you can see the pilot Ec of outdoor cells outside the
building. Design the edge field strength of indoor cell signals
higher than the pilot Ec of outdoor cells outside the building by 5
dB, which is regarded as an experience reference value. In
addition, consider the Ec and Ec/Io requirements of the lowest
access thresholds of this service. Considering the above two
points, determine the indoor edge field strength. III. Deciding the
Path loss According to the Chosen Indoor Propagation ModelIV.
Getting the Transmit Power of Antenna Port by Adding the Path Loss
and the Design Value of Edge Field StrengthV. Statistic Reference
Values of Indoor Penetration Loss TestsTable 3-3 Reference values
of indoor WCDMA penetration lossesItemSignal typeReference
valueTheoretical value or industrial empirical valueUnit
Penetration loss through an elevator doorWCDMA22.62030dB
Average of the penetration loss through an indoor brick
separation wall WCDMA71010dB
Average of the penetration loss through a reinforced concrete
wall WCDMAAbout 201530dB
Penetration loss through thin glass (on an ordinary glass
window)WCDMAAbout 11dB
Penetration loss through thick glass (WCDMAAbout 33dB
3.3.2 Estimating the Capacity of a Single Indoor WCDMA
Distributed System (Mandatory)The indoor distributed system
manufacturer estimates the capacity of a single indoor distributed
system by referring to the operator's comments and the calculating
methods of Huawei. I. Estimating the Capacity of a Newly-Built
Indoor WCDMA Distributed System1) During a building survey, predict
the number of users in the coverage target and the traffic model
confirmed by the operator (busy hour traffic and throughput of a
single user). 2) Calculate the number of CEs, number of uplink and
downlink demodulation boards, and number of E1 links required by a
single site according to the single-site CE calculation by using
the RND tool. The calculated numbers of CEs and uplink and downlink
demodulation boards required by a site of an indoor distributed
system can be taken as a reference of choosing a signal source of
the indoor distributed system. Compare the calculated number of E1
links with the original transmission resources of the operator. If
the transmission resources are limited, remind the operator in
time. II. Estimating the Capacity of a Shared Indoor GSM
Distributed SystemIf the operator regards that the percentage of
the indoor GSM traffic to the total GSM traffic is the same as the
percentage of the indoor WCDMA traffic to the total WCDMA traffic
in the same building, use the following calculating methods.
Otherwise, predict the number of users in the coverage target
before other tasks. 1) Determine the building that needs a shared
distributed system. 2) From the operator, obtain the traffic of the
indoor GSM distributed system in the building. 3) Traffic of the
indoor GSM distributed system / Total GSM traffic in the area =
Percentage of the traffic of the indoor GSM distributed system to
the total traffic4) Total predicted number of WCDMA users in the
area x Percentage of the traffic of the indoor GSM distributed
system to the total traffic = Number of WCDMA users of the indoor
distributed system5) Determine with the operator the traffic model
of the indoor distributed system (busy hour traffic and throughput
of a single user). 6) Calculate the number of CEs, number of uplink
and downlink demodulation boards, and number of E1 links according
to the single-site CE calculation by using the RND tool. The
calculated numbers of CEs and uplink and downlink demodulation
boards required by a site of an indoor distributed system can be
taken as a reference of choosing a signal source of the indoor
distributed system. Compare the calculated number of E1 links with
the original transmission resources of the operator. If the
transmission resources are limited, remind the operator in time.
3.3.3 Link Budget of an Indoor WCDMA and DCS 1800 Shared
Distributed SystemWhen making a link budget for an Indoor WCDMA and
DCS 1800 shared distributed system, consider the frequency loss
differences between different systems and the insertion loss
differences during the access to a shared distributed system. This
section describes the reuse of the existing DCS 1800 system,
covering the differences of WCDMA and DCS 1800 shared distributed
system. Figure out the BCCH receiving level relevant to the DCS
1800 system required for satisfying the service access thresholds
of WCDMA system. That is, through the BCCH receiving level test of
the existing DCS 1800 system, you can evaluate whether the system
can satisfy the service threshold requirements after direct WCDMA
signal combination in the future. Table 3-4 Service threshold
calculation of an indoor WCDMA and DCS 1800 shared distributed
systemMinimum SigLvl requirements based on link budget
VoiceCS64kPS64/384PS128/384PS144/384PS384/384
max CL in UL (dB)
a142.7137.4137.7134.9134.4130.2
max CL in DL (dB)
b144.1138.8139.1136.3135.8131.6
Tx Power P-CPICH
c333333333333
minimum P-CPICH RSCP requirements (dBm)
d=c-b-111.1-105.8-106.1-103.3-102.8-98.6
design margin (dB)
e555555
indoor coverage P-CPICH target (dBm)
F=d+e-106.1-100.8-101.1-98.3-97.8-93.6
Tx Power of BCCH of co-site GSM BTS (dBm)
g393939393939
Coupling loss difference between UMTS and GSM1800 band (dB)
h2.52.52.52.52.52.5
Additional loss to connect NodeB into existing GSM DAS (dB)
i0.50.50.50.50.50.5
Min BCCH target (dBm)
j=f+g-c+h+i-97.1-91.8-92.1-89.3-88.8-84.6
In Table 3-4, the parts in pink are output results, those in
green are input values, and those colorless are constant items. To
get the link budget values in Table 3-4, we suppose as follows: The
Tx Power P-CPICH of the BTS in the indoor WCDMA system is 33 dBm.
The Tx Power of BCCH of the co-site GSM BTS in an indoor GSM system
is 39 dBm. The coupling loss difference between UMTS and GSM1800
band refers to the uplink frequency loss difference. The additional
loss to connect NodeB into existing GSM DAS refers to the insertion
loss caused by the combiner when the WCDMA signal source is
introduced into the indoor GSM distributed system. The maximum
transmit power of GSM BTS signals must be set according to facts.
By referring to the actually-tested level of the indoor GSM
distributed system, you can know whether the indoor GSM distributed
system can meet the access threshold requirements of WCDMA services
if the WCDMA and DCS 1800 systems combine directly. If not,
reconstruct the indoor distributed system accordingly. This link
budge is for the reference of calculating the WCDMA service
threshold levels by using the existing the GSM system. 3.4 Choosing
a Signal Source for an Indoor Distributed System3.4.1 Choosing a
Proper Signal Source According to Capacity and Coverage
Requirements (Mandatory)The indoor distributed system manufacturer
chooses a proper signal source by referring to the operator's
comments and Huawei solution. According to coverage and capacity
requirements in different scenarios, choose relevant devices for
the signal source of an indoor distributed system. Choosing indoor
coverage signal sources of small buildingsA small building is lower
than 10 floors and its total area is smaller than 10,000 m2. If
coverage and capacity requirements are met, use the microcell
BTS3801C to combine with the original system and reconstruct the
combined system. Choosing indoor coverage signal sources of medium
sized buildingsA medium sized building is of 10 to 20 floors and
its total area is smaller than 20,000 m2. If coverage and capacity
requirements are met, use one BBU3806 and two RRU3801Cs to combine
with the original system and reconstruct the combined system.
Choosing indoor coverage signal sources of large sized buildingsA
large sized building is of 20 to 30 floors and its total area is
smaller than 30,000 m2. If coverage and capacity requirements are
met, use one BBU3806 and three RRU3801Cs to combine with the
original system and reconstruct the combined system. Choosing
indoor coverage signal sources of ultra-large buildingsAn
ultra-large building is of over 30 floors, having skirt buildings.
Its total area is larger than 30,000 m2. If coverage and capacity
requirements are met, use two BBU3806s and multiple RRU3801Cs or
one BBU and multiple pico RRUs to combine with the original system
and reconstruct the combined system. Choosing signal sources for
both indoor and outdoor coverage scenariosFor the scenarios
requiring both indoor and outdoor coverage, use one BBU plus one
RRU or a macro BTS plus one RRU to make full use of CE resources of
signal sources. 3.4.2 Repeater Influences on an Indoor Distributed
System (a Key Issue)The indoor distributed system manufacturer
chooses a proper signal source by referring to the comments of the
operator and Huawei. Restrict the use of repeaters and trunk
amplifiers in an indoor distributed system to control the
interference and to reduce the influence on the capacity of the
system. I. Merits, Demerits, and Use Suggestions of a Repeater
Radio frequency (RF) repeaterMerits: Requires no transmission
resources. Demerits: Insufficient isolation between the donor
antenna and the service antenna may cause self-excitation. The
repeater causes pilot pollution easily, thus affecting the network
quality. It may also increase the noise level of donor BTS
receiver, thus reducing the capacity and the coverage radius of the
system. In addition, the repeater affects RRM algorithms such as
power control, handoff, and admission algorithms. Fiber
repeaterMerits: Transmitting signals through fibers, a fiber
repeater is stabler than an RF repeater. Tx and Rx isolation does
not need to be considered and self-excitation does not occur
easily. Demerits: A fiber repeater may increase the noise level of
donor BTS receiver, thus reducing the capacity and the coverage
radius of the system. It may cause longer delay, thus affecting the
location service. In addition, the repeater affects RRM algorithms
such as power control, handoff, and admission algorithms.
Suggestions: Do not use an RF repeater as a signal source of an
indoor distributed system in urban areas. A fiber repeater can be
used only in the scenarios with low capacity requirements, such as
a close underground parking garage. II. Repeater Influences on the
Noise Floor Rise of a Donor BTS
Figure 3-3 Influence of a repeater on the noise floor of a BTSIn
Figure 3-3, the x-axis is the noise increment factor (dB) and the
y-axis is the noise increment (dB) including the BTS noise
increment and the repeater noise increment .
dB (1)
dB (2)
dB (3)
Noise coefficient (dB) of a repeater
Noise coefficient (dB) of the donor BTS
Uplink gain (dB) of the repeater
Path loss (dB) from the uplink Tx port of the repeater to the Rx
port of the donor BTS, including the cable loss, antenna gain, and
space path loss
Net gain (dB)Formulas (1) and (2) show that a repeater can
increase the uplink noise floor of the donor BTS by 3 dB when the
noise increment factor is 0. Meanwhile, the noise floor of the
repeater also increases by 3 dB. The noise floor increase means the
decrease of the receiving sensitivity, increase of the UE transmit
power, and reduction of the uplink coverage radius. A repeater can
increase the noise floor of both the donor BTS and the repeater
itself. The noise floor is balanced when is 0. The key factor of a
repeater to the noise increase of the donor BTS is the uplink gain
of the repeater. Reducing the uplink gain of the repeater may
reduce the noise increase of the donor BTS. Because uplink losses
cannot be totally made up, however, the noise floor of the repeater
itself increases. UEs in the repeater coverage area must increase
the transmit power to make up the loss difference value. 3.5
Designing Indoor and Outdoor Handoffs3.5.1 Designing Intra-WCDMA
System Handoffs (Mandatory)I. Designing Handoffs Between the
Entrances and Exits of a Hall The size of an handoff area at the
entrances and exits of a hall depends on the settings of handoff
parameters and the Ec and Ec/Io of the edge field strength.
Generally, use Huawei default settings of the baseline parameters.
To avoid too much indoor signal leakage, ensure that the pilot Ec
outdoors five to seven meters away from the door is smaller than
-95 dBm. Generally, the handoff area at the entrance and exit of a
hall is within the range of five to seven meters outdoors away from
the hall door. The handoff area cannot be close to the road or deep
indoors. II. Designing Handoffs at the Entrance and Exit of an
Indoor ElevatorFor the entrance and exit of an elevator, use
intra-frequency soft handoffs. If you use the indoor and outdoor
inter-frequency solution, use the inter-frequency coverage solution
for the entire building. Table 3-5 Design for Intra-frequency
handoffs in and out of an elevator BuildingDesign for elevator
coverage and handoff
Small building (of less than 10 floors)Use a directional antenna
at the top of the elevator shaft. Vertically downward, the antenna
directly covers the elevator shaft. No handoff exists in a same
cell.
Medium sized building (of 10 to 20 floors)Install a small
directional antenna every several floors in the elevator shaft to
vertically cover the elevator shaft. If the building is covered by
two cells, use the cell signals of lower floors to cover the
elevator shaft. On lower floors or at the exit of the elevator on
the first floor, UEs are in a same cell. Therefore, no handoff is
triggered.
Large building (of 20 to 30 floors)The signals of two cells are
introduced to cover the elevator shaft. It is recommended that the
system cover the elevator shaft by different segments, which are
the same as the floors. During the moving of the elevator, soft
handoffs between two cells are performed in the elevator.
Ultra-large building (of over 30 floors)Cover the elevator shaft
by segments, which are the same as the floors. Soft handoffs are
performed in the elevator. You can also use leakage cables for
elevator coverage.
III. Designing Handoffs at the Indoor Windows of a High
BuildingOutdoor cell signals are easy to get into the windows of a
high building. As a result, pilot pollution and ping-pong handoffs
occur, which cause call drop easily. Therefore, the pilot power at
the antenna port near the windows of a high building must be
designed 5 dB margin higher than the signals of outdoor cells for
the control of handoffs between indoor and outdoor cells of the
high building. 3.5.2 Planning Neighbor Cells for an Indoor Coverage
System (Mandatory)For the neighbor planning of an indoor
distributed system, because an indoor coverage area is relatively
closed, consider the signal strength of the actual handoff area
when setting the neighborship. The basic principle is that the
neighborship must be as simple as possible. I. Choosing Neighbor
Cells in Indoor and Outdoor Intra-frequency and Inter-frequency
CasesMake a choice according to the planning emulation results and
the neighborship of the co-site indoor GSM distributed system. If
outdoor BTSs are built, take the site survey results as a reference
and choose the outdoor cells with good and stable Ec and Ec/Io as
mutual neighbors of indoor cells. II. Choosing Neighbor Cells for
the Cells of a High Building Planning phaseIn this phase, it is
hard to tell stable cells with strong signals from unstable cells
with weak signals. Considering the complexness of indoor
environment and the uneven distribution of indoor signals of a same
outdoor cell, Huawei recommends two-way neighbor planning based on
the results or logical relations of an indoor signal survey.
Optimization phaseA one-way neighbor solution is that the indoor
cells of a high building are not used as neighbors of the outdoor
cells. After an indoor distributed system comes into operation, if
it is found during optimization that the large fluctuation of
outdoor signals of a high building causes frequent indoor and
outdoor handoffs and thus affects the network quality, you can use
the one-way neighbor solution as an optimization means. 3.6
Analyzing a Shared Indoor Distributed System and Control the
Interference3.6.1 Analyzing a Shared Indoor Distributed System of
the Operator (Mandatory)The indoor distributed system manufacturer
analyze the shared indoor distributed system by referring to the
comments of the operator and Huawei. Generally, the operator may
choose a shared indoor distributed system to save costs. The
following are the key points for a shared indoor distributed
system: Reducing influences on the original systemTry to reduce
changes and influences on the original system. According to the
results calculated by the detailed topological diagram of the
system design, the indoor distributed system manufacturer evaluates
influences on the original system. The network reconstruction must
try to solve such problems as serious signal leakage or coverage
insufficiency of the original system. Referring to the design of
the original systemFor the design of a new system, refer to the
solution and actual test data of the original system. Refer to the
design solution of the original system and offer the most proper
reconstruction ideas. In the new system, avoid such problems as
handoff failure, call drop, and interference occurring in the
indoor tests of the original system
Transforming componentsReuse the passive components of the
original system that have good performance and satisfy frequency
requirements. The combiner must meet the requirements of isolation
and intermodulation perforation index. Try to use trunk amplifiers
less. Mainly, use 1/2-inch feeders. For some trunks or distribution
cables with large losses, use 7/8-inch feeders. Choosing signal
sourcesAccording to the coverage and capacity requirements in the
system design, choose a proper signal source. For urban areas, be
careful to choose a repeater as the signal source of the indoor
coverage system. Controlling costsTry to save costs in engineering
reconstruction. State reasons before replacing or adding
components. 3.6.2 Controlling the Interference in a Shared Indoor
Distributed System of the Operator (Mandatory)Interference in a
shared indoor distributed system involves three aspects: Congestion
interference Intermodulation interference Spurious interferenceTo
clear outband interferences, the simplest way is to add a filter to
the receiver. To clear inband interference, however, you may reduce
the power of the transmitter or add a filter to the transmitter.
Space isolation is effective for spurious interference, receiver
congestion, and intermodulation interference. The isolation size
depends on the maximum isolation required by various interferences.
For an indoor distribution system, to reduce transmitting
intermodulation interference and suppress spurious interference is
to add a filter to the transmitter. For more details about
interference control, see Guide to WCDMA Antenna and Feeder
Design-20060323-A-3.0. I. Congestion InterferenceDefinition: If
interference signals are too strong, they may congest the WCDMA
receiver and exceed the working scope of the amplifier and the
frequency mixer, thus making the receiver fail to demodulate
signals normally and interfering with the operation of the
receiver. Congestion falls into inband congestion and outband
congestion. Congestion interference has fewer impacts on the
system. Solution: To relieve inband congestion, add a filter to the
transmitter. To relieve outband congestion, add a filter to the
receiver. For the requirements of filter isolation, see the methods
of calculating isolation in the following examples.
For example: Calculate the inband congestion interference caused
by the spurious signals of GSM 900M BTS in bands 1920 MHz to1980
MHz. Spurious signals of GSM 900M BTS in non-GSM frequency band:
-30 dBm / 3 MHzMaximum transmit power of a GSM 900M BTS: 46 dBm /
200 KHzRequired congestion of a WCDMA receiver: ( -40 dBm (inband)(
-15 dBm (outband)( -16 dBm (GSM and DCS inband)Because the spurious
signals of GSM 900M BTS in the WCDMA receiving frequency band is
-30 dBm / 3 MHz (equal to -29 dBm / 3.84 MHz) and the WCDMA inband
congestion is required equal to or less than -40 dBm, the isolation
of an antenna must be: -29 dBm / 3.84 MHz (-40 dBm / 3.84 MHz) = 11
dB Calculate the inband congestion interference caused by the
spurious signals of DCS 1800M BTS in bands 1920 MHz to1980 MHz.
Spurious signals of DCS 1800M BTS in non-DCS frequency band: -30
dBm / 3 MHzMaximum transmit power of a DCS 1800M BTS: 46 dBm / 200
KHzRequired congestion of a WCDMA receiver: ( -40 dBm (inband)( -15
dBm (outband)( -16 dBm (GSM and DCS inband)Because the spurious
signals of DCS 1800M BTS in the WCDMA receiving frequency band is
-30 dBm / 3 MHz (equal to -29 dBm / 3.84 MHz) and the WCDMA inband
congestion is required equal to or less than -40 dBm, the isolation
of an antenna must be: -29 dBm / 3.84 MHz (-40 dBm / 3.84 MHz) = 11
dB
Calculate the inband congestion interference caused by the
spurious signals of PHS BTS in the band of a WCDMA BTS. Required
congestion of a WCDMA receiver: ( -40 dBm (inband)Strictly, the
maximum transmit power of a PHS BTS is 27 dBm. Then, the required
isolation of an antenna is calculated as follows: 27 (-40) = 67
dB
If the adjacent channel interference is considered when a WCDMA
BTS works in band 1920 MHz, the adjacent-channel congestion signal
allowed by the WCDMA receiver is -52 dBm. The isolation between the
systems that meets the congestion condition is: 27 (-52) = 79 dBII.
Intermodulation InterferenceDefinition: If multiple systems
coexist, intermodulation products may be generated between
different frequencies of different systems, thus causing
interference. If the antenna system uses improper components, when
signals of different frequencies pass through the components,
intermodulation occurs. Due to the nonlinearity of a transmitter,
the signals generate intermodulation products together with
transmitting signals of the transmitter. The transmission of
intermodulation products and useful signals together through an
antenna may cause interference with the receiver. Solution: A
rational frequency plan can reduce intermodulation interference to
a tolerable scope. For component intermodulation interference,
restrain it through component index selection and engineering
standards, or clear it by replacing the components with lowered
performance. To relieve inband intermodulation interference, add a
filter to the transmitter. To relieve outband intermodulation
interference, add a filter to the receiver. For the requirements of
filter isolation, see the methods of calculating isolation in the
following examples.
For example: Calculate the isolation according to the
intermodulation interference arising from other WCDMA signals and
the spurious signals of GSM 900M BTS in bands 1920 MHz to 1980 MHz.
Interference signals in the band of a receiver required by the
WCDMA receiving intermodulation features: ( -48 dBmSpurious signals
of GSM 900M BTS in bands 1920 MHz to 1980 MHz, stipulated in the
protocol: -30 dBm / 3 MHzTherefore, the required isolation is: -30
dBm / 3MHz (-48 dBm / 3.84 MHz) + (10log (3.84 MHz / 3 MHz)) = 19
dB
Calculate the isolation according to the intermodulation
interference arising from other WCDMA signals and the spurious
signals of DCS 1800M BTS in bands 1920 MHz to 1980 MHz.
Interference signals in the band of a receiver required by the
WCDMA receiving intermodulation features: ( -48 dBmSpurious signals
of DCS 1800M BTS in bands 1920 MHz to 1980 MHz, stipulated in the
protocol: -30dBm/3MHzTherefore, the required isolation is: -30 dBm
/ 3 MHz (-48 dBm / 3.84 MHz) + (10log (3.84 MHz / 3 MHz)) = 19
dB
III. Spurious InterferenceDefinition: The unideal features and
broadband noises of the frequency mixer, filer, and power amplifier
in a transmitter may generate many useless outband signals, called
spurious signals. When transmitted from an antenna, spurious
signals interfere with the receiver of another system. Spurious
interference affects the system most greatly. Solution: To relieve
inband spurious interference, add a filter to the transmitter. To
relieve outband spurious interference, add a filter to the
receiver. For the requirements of filter isolation, see the methods
of calculating isolation in the following examples. For example:
Calculate the isolation and the spurious interference of GSM 900M
BTS in the receiving band of WCDMA BTS. Table 3-6 Analyzing
spurious interference of GSM 900M BTS in the band of a WCDMA BTS
according to the protocolValueDescription
Spurious interference value (dBm / 3.84 MHz)-29-30 dBm / 3 MHz
(required by the protocol)
Permissible value (dB) of sensibility drop of the interfered
system< 0.1 dB< 0.8 dB< 3 dB< 6 dB< 10 dB-
Permissible interference value (dBm / 3.84 MHz) of the
interfered system -121-112-105-100-96-105 dBm / 3.84 MHz
(noises)
Required isolation between systems9283767167-
Calculate the isolation and the spurious interference of DCS
1800M BTS in the receiving band of WCDMA BTS. Table 3-7 Analyzing
spurious interference of DCS 1800M BTS in the band of a WCDMA BTS
according to the protocolValueDescription
Spurious interference value (dBm / 3.84 MHz)-29-30 dBm / 3 MHz
(required by the protocol)
Permissible value (dB) of sensibility drop of the interfered
system< 0.1 dB< 0.8 dB< 3 dB< 6 dB< 10 dB-
Permissible interference value (dBm / 3.84 MHz) of the
interfered system -121-112-105-100-96-105 dBm / 3.84 MHz
(noises)
Required isolation between systems9283767167-
Calculate the isolation and the spurious interference of PHS BTS
in the receiving band of a WCDMA BTS. Table 3-8 Analyzing spurious
interference of PHS BTS in the band of a WCDMA BTS according to the
protocolValueDescription
Spurious interference value (dBm / 3.84 MHz)-38 dBm-26 dBm / 60
MHz (required by the protocol)
Permissible value (dB) of sensibility drop of the interfered
system< 0.1 dB< 0.8dB< 3 dB< 6 dB< 10 dB-
Permissible interference value (dBm / 3.84 MHz) of the
interfered system -121-112-105-100-96-105 dBm /3.84 MHz
(noises)
Required isolation between systems8374676258-
3.6.3 Analyzing an IRS ( a Shared Indoor Distributed System of
Multiple Operators (Optional)Operators choose the mode of a shared
indoor distributed system. There is a special phenomenon about the
indoor coverage outside China: Multiple operators share an indoor
distributed system, antenna system, and equipment room, due to too
expensive expenses such as rents and property management fees. They
call such a site IRS. We rarely see such a case in China. Each IRS
has a leader operator, who manages the shared parts. Other
operators pay the leader operator and directly connect their
feeders and cables to the POI. The leader operator is responsible
for the rest, including commissioning and guarantee. Generally, an
IRS connects with multiple systems, such as GSM, DCS, CDMA, and
WCDMA. With fiercer competition in mobile communications, more
operators will consider using an IRS to build their networks for
cost saving. Especially, because the property problem is hard to be
solved, more and more IRSs will come forth. This document takes an
indoor WCDMA distributed system outside China as an example,
indicating the issues to be considered when a signal source is
introduced into an IRS. Generally, different system signals of
different operators are led into the IRS through POIs. Currently,
POIs fall into two types from the aspect of application: passive
POI and active POI. An active POI is relevant to signal
amplification. That is, it is added with a power amplifier. A
passive POI is simpler in design, similar to a more complex
multi-system combiner. A POI system designer needs to consider the
influence that the noise coefficient of an active POI may have on
the sensitivity of the system, as well as the spurious and
congestion interference between systems. Let us describe the issues
to be considered for designing and using a POI system from the
following two angles: As the leader of the POI systemWhen designing
the POI system, consider the POI selection first. Such materials
are scare currently. Generally, assume various conditions to deduce
the threshold levels of services. Secondly, consider dividing the
transmission and reception of the whole POI system. If many signals
are introduced, spurious interference and intermodulation
interference become unpredictable. To maximally reduce
intermodulation and spurious interference, do consider dividing
transmission and reception when designing a POI system. As a user
of the POI systemThe leader completes the design of the POI system.
What a user does is to introduce signals according to the POI
specifications provided by the leader. Generally, the design
results meet the requirements of service threshold levels in the
POI specifications. Table 3-9 lists the WCDMA IRS specifications
that operator A provides for operator B. Table 3-9 Example of IRS
specificationsSpecifications of WCDMA IRS
Downlink Requirement
ItemDescriptionDataUnit
DL-1Data Rate384kbps
DL-2Maximum no. of carriers3no.
DL-3Cut-in Common Pilot Channel (CPICH) power per
carrier30dBm
DL-4Maximum composite power to POI43dBm
DL-5Minimum Carrier-to-Intermodulation45dBc
DL-6Minimum CPICH signal level* (MinDownLev) at user terminal
per carrier-85dBm
DL-7Minimum percentage of time of measurements >
MinDownLev90%
DL-8Minimum percentage of area of measurements >
MinDownLev90%
Uplink Requirement
ItemDescriptionDataUnit
UL-1Data Rate384Kbps
UL-2Transmit power at user terminal21dBm
UL-3Maximum noise received power level at no load at 3840kHz at
POI-98dBm
UL-4Minimum Carrier-to-Intermodulation33dBc
UL-5Minimum uplink signal level** (MinUpLev) at POI -90dBm
UL-6Minimum percentage of time of measurements >
MinUpLev90%
UL-7Minimum percentage of area of measurements >
MinUpLev90%
In the above example, operator B's WCDMA signal sources are
introduced into operator A's IRS. If the pilot power of each
carrier of operator B's WCDMA input signals is ensured to be larger
than 30 dBm but less than 43 dBm, the downlink receiving Ec for
PS384K services can be larger than -85 dBm and the uplink receiving
Ec of the BTS larger than -90 dBm within 90% of the time in 90% of
the coverage areas. During the design of an IRS, the main task for
a user is to analyze whether the IRS specifications provided by the
leader can meet users' requirements. 3.6.4 Analyzing Interference
Between WCDMA Systems of Different Operators (Optional)Surely, the
existing network does not have only one WCDMA operator. Therefore,
the problem of interference between systems of different operators
must be considered during the design phase of an indoor distributed
system. Generally, consider the interference between two operators'
systems in adjacent bands. Suppose that operator A and operator B
are in the adjacent bands. When designing operator A's indoor
distributed system, analyze how to mitigate interference in each of
the following three scenarios: Between operator A's indoor
distributed system and operator B's outdoor macro cell BTS, the
former may receive the uplink interference from operator B's
outdoor BTS terminal. Scenario 1:
Figure 3-4 Interference between operator A's indoor distributed
system and operator B's outdoor BTS terminalIn such a scenario,
consider the minimum coupling loss between operator B's terminal
and operator A's indoor distributed system, including the first
adjacent channel leakage ratio (ACLR) and the second ACLR. Operator
A can try to avoid the first adjacent channel interference (ACI) to
obtain better network quality. When analyzing and deciding the ACI,
you can calculate the WCDMA interference thresholds according to
the test signal levels of operator A's existing GSM system. For
details, see Table 3-10. Table 3-10 Estimated thresholds of the
interference of operator B's macro cell BTS with operator A's
indoor distributed system
In Table 3-10, the noise rise tolerated (30 dB) is derived from
section 7.2 of protocol TS 25.104. The parameter describes the
dynamic receiving scope of a NodeB receiver. The suggested maximum
interference tolerated in the protocol is -73 dB. That is, the
noise rise tolerated above the noise floor is 32 dB.
Conservatively, set the noise rise tolerated to 30 dB. Based on
Table 3-10, we can conclude: According to the actual signal test
results of the indoor GSM distributed system, if the BCCH receiving
level exceeds the point of -23.5 dBm, the distributed system may be
interfered. In this case, change the configuration, that is,
enlarge the minimum coupling loss. Operator A's terminal may
interfere in operator A's indoor distributed system. Scenario
2:
Figure 3-5 Interference from operator A's own equipmentIf a UE
of operator A is close to the antenna of its own indoor distributed
system, the noise rises suddenly at the receiving end of NodeB.
Within the minimum transmit power, the UE cannot restrict noise
rise through power control. Therefore, pay attention to the minimum
coupling loss that may affect the system. You can judge possible
influences through the equivalent GSM signal receiving level to the
minimum WCDMA coupling loss. For details, see Table 3-11. Table
3-11 Estimated thresholds of the interference from operator A's own
equipment
A UE farer away from the antenna has a larger path loss.
Therefore, suppose that such a UE has a power margin of 3 dB to
overcome the burst interference from a UE closer to the antenna.
Based on the supposition, the noise rise tolerated is 3 dB. If the
estimated power margin is larger than the assumed one, the data
calculated through the GSM signal level is more acceptable.
Generally, if the level of GSM signals distributed right below the
antenna is less than -19 dBm, no interference occurs. Conclusion:
For satisfying the minimum coupling loss, the antenna is generally
installed in a high location in actual engineering. In this way,
the pilot power of antenna port is equal to or less than 5 dBm. On
a lower building, the antenna is generally installed a little farer
away from the places where UEs are often used. 3.6.5 Methods of
Controlling Indoor and Outdoor Interference (Mandatory) Controlling
too many outdoor signals to go indoors In actual engineering, the
edge field strength of indoor cell signals must be about 5 dB
higher than that of outdoor signals. A: Adjust the downtilt and
azimuth angles of the antenna of an outdoor NodeB to control the
strength of outdoor NodeB signals going indoors. B: Reconstruct the
indoor distributed system or add an indoor antenna to enhance the
strength of indoor signals. C: Use a rational handoff solution and
set handoff parameters properly. For example, use the indoor and
outdoor inter-frequency solution. Controlling too many indoor
signals to leak outdoorsA: Lay out antennas rationally and allocate
the antenna port power rationally to prevent too many indoor
signals from leaking outdoors. B: Use the technique of drip
irrigation coverage with multiple small-power antennas to prevent
too many indoor signals from leaking outdoors. 3.7 Designing
Parameters of an Indoor Distributed System (Mandatory)When
designing an indoor distributed system, generally use Huawei
default settings of baseline parameters. 3.8 Choosing Components
(Mandatory)3.8.1 Choosing a Combiner and a Filter for an Indoor
Distributed SystemBy using the calculating methods described in
section 3.6.2 "Controlling the Interference in a Shared Indoor
Distributed System of the Operator (Mandatory)", calculate the
isolation required by the components of an indoor distributed
system. Then accordingly, choose a proper combiner and filter. When
choosing a combiner and a filter, note that the component
performance indexes include the following key indexes: Frequency
range Insertion loss Isolation Power tolerance Standing wave ratio
(SWR)Duplex filters are used in an actual indoor distributed
system. If a duplex filter cannot meet the isolation requirements,
add a filter to increase the isolation. A cross band coupler is a
dual-band combiner commonly used in an indoor distributed system.
The main performance indexes to be considered are: Isolation
between systems Insertion loss Third-order cross modulationThe
insertion loss cannot be too large; otherwise, the loss may greatly
affect the original system. A multi-band combiner and a POI are
also indoor combiners. Currently, in the application of an indoor
distributed system, a combiner falls into three types: Ordinary
two-in-one combiner All-in-one combiner Mixed combinerFigure 3-6
shows a sample of a two-in-one combiner.
Figure 3-6 Sample of a combiner3.8.2 Choosing Antennas for an
Indoor Distributed System (Mandatory)Indoor antennas differ from
outdoor ones because of the following factors: Close coverage
Restrictions by transmit power
Restrictions by installation space
Restrictions by visual pollutionAntennas of an indoor
distributed system are usually applied in the following application
scenarios: Indoors In subways and tunnels
In elevators and supermarketsI. Indoor ScenariosDue to the
characteristics of indoor coverage, antennas used indoors have
smaller gains, without detailed requirements on the half power
width of the beam. In a scenario with a smaller coverage area, use
omni-directional antennas. In a long and narrow open area, use
directional antennas. If multiple systems share an antenna, use a
broad frequency antenna. In an indoor application scenario,
generally use ceiling mount omni-directional antennas, which are of
a smaller size and a smaller gain (below 5 dBi). This type of
antenna is attractive in appearance.
Figure 3-7 Indoor antennasIn Figure 3-7, the first two are
ceiling mount omni-directional antennas, the third and fourth are
flat directional antennas, and the fifth is a stick
omni-directional antenna. Table 3-12 Antenna models of an indoor
distributed systemModelFrequency RangeAntenna
DescriptionAzimuthGainManufacturer
800 10137876960/17102500 MHzCeiling mount antenna of vertical
polarization and N female connector3602 dBiKathrein
TS-IAOMT-800/2400806960/14202400 MHzCeiling mount antenna of
vertical polarization and N female connector3602 dBiTelestone
TQJ-SA800/2500-3824960/ 17102500 MHzCeiling mount antenna of
vertical polarization and N female connector3602 dBiGuangdong
Shenglu
II. Subway and Tunnel ScenariosIn special indoor coverage
scenarios such as subways or tunnels, leakage cables are applied in
some long and narrow indoor coverage areas with limited antenna
installation space, for example, a subway, road railway tunnel,
underground market, and underground parking garage. Leakage cables
are relatively expensive (100 RMB/m typically). They are hard to
install.
Figure 3-8 Leakage cablesIII. Scenarios of Elevators and Some
Large Warehouse SupermarketsIn such application scenarios as an
elevator, large warehouse supermarket, and tunnel, two types of
narrow-beam directional antennas are used, that is, Yagi and
log-per antennas. They are often installed in places with little
attention to indoor decoration, for example, in an elevator or a
large warehouse supermarket. A Yagi antenna is a narrowband antenna
with a cheap price and a large gain (larger than 10 dBi). A log-per
antenna is a broadband antenna with a higher price and a smaller
gain (less than 10 dBi). Note that a Yagi antenna is recommended
for a single WCDMA system while a log-per antenna is recommended
for the multi-system combination of an operator.
Figure 3-9 Log-per antennasIV. Installation of an Indoor
AntennaThe selection of an indoor antenna depends on the
installation location and coverage target range of the antenna, and
the requirements of the concerned property management company on
the antenna (to avoid visual pollution and to ensure that the
antenna is in tune with the decoration near its location). The
selection principles are as follows: Wall-against installation:
Choose a flat directional antenna for intra-floor coverage. Ceiling
mounted installation: Choose a ceiling mount omni-directional
antenna tightly against the ceiling to cover a whole floor or even
the lower floor. Concealed installation: Choose a stick
omni-directional antenna installed above the ceiling to cover the
whole floor or even the upper floor. In such a case, the
penetration loss of the ceiling is introduced. Elevator shaft:
Choose a Yagi antenna or a log-per antenna, installed at the top of
the elevator shaft. That is because the bottom of an elevator is of
a full steel structure, hard to penetrate. The antenna lobe goes
downwards to cover the entire elevator shaft. Large warehouse
supermarket: Because the indoor decoration of such a place is not
important, install a Yagi antenna, log-per antenna, or wall-mounted
antenna for coverage. 3.8.3 Choosing Feeders for an Indoor
Distributed System (Mandatory)In the design of an indoor
distributed system, feeders are used for connecting all components.
Generally, use the following two types of feeders: 1/2-inch feeder:
large-loss, low-cost, easy to bend, applicable to distribution
cable connection of each floor 7/8-inch feeder: small-loss,
high-cost, hard to bend, applicable to trunk connection between
floorsTable 3-13 Attenuation of feeders in an indoor distributed
systemWCDMAGSM
Specification (m)1/2-inch feeder (dB)7/8-inch feeder
(dB)1/2-inch feeder (dB)7/8-inch feeder (dB)
50.5 0.3 0.4 0.2
101.1 0.6 0.7 0.4
151.6 0.9 1.1 0.6
202.1 1.2 1.5 0.8
252.7 1.5 1.9 1.1
303.2 1.8 2.2 1.3
353.7 2.1 2.6 1.5
404.3 2.4 3.0 1.7
454.8 2.7 3.3 1.9
505.4 3.1 3.7 2.1
555.9 3.4 4.1 2.3
606.4 3.7 4.4 2.5
657.0 4.0 4.8 2.7
707.5 4.3 5.2 2.9
758.0 4.6 5.6 3.2
808.6 4.9 5.9 3.4
859.1 5.2 6.3 3.6
909.6 5.5 6.7 3.8
9510.2 5.8 7.0 4.0
10010.7 6.1 7.4 4.2
3.8.4 Choosing a Power Splitter and a Coupler for an Indoor
Distributed System (Mandatory)The selection of a power splitter and
a coupler for an indoor distributed system is relatively simple.
Check that the component performance indexes meet the requirements
of bandwidth and isolation. Table 3-14 and Table 3-15 list some
performance parameters of optional components. Table 3-14 Parameter
indexes of Kathrein couplerModelCoupling AttenuationInsertion
LossVSWRdBcThird Order Intermodulation (dBc)MHzBand (MHz)
K 63 23 60617.0 / 1.0 dB< 0.05 dB< 1.15<
-1508002200
K 63 23 610110.4 / 0.4 dB< 0.05 dB