RF
Optimization
Once all the sites are installed and verification is
complete, RF optimization starts. In some situations for a tight schedule, RF optimization
might start after the construction of partial sites is complete. RF
optimization is usually performed after 80% of total sites in a cluster are
constructed.
RF optimization stage is one major stage of RNO. It aims at
the following aspects:
l Optimizing
signal coverage
l Control
pilot pollution
l Control
SHO Factor based on DT
RF optimization also involves optimizing list of neighbor
cells.
When the ind exes
like DT and traffic measurement after RF adjustment meets KPI requirements, RF
optimization stage ends. Otherwise you must reanalyze data and adjust
parameters repeatedly until all KPI requirements are met. After RF
optimization, RNO comes to parameter optimization stage.
Process of RF Optimization
RF optimization includes the following four parts:
l Test
preparations
l Data
collection
l Problem
analysis
l Para meter adjustment
Deciding
Optimization Goal
The key of RF optimization is to solve problems as below:
l
Weak
coverage
l
Pilot
pollution
l
High SHO
Factor based on DT
Actually, different operators might have different standards
on KPI requirements, ind ex
definition, and attention. Therefore the RF optimization goal is to meet the
coverage and handover KPI requirements in the contract (commercial deployment
offices) or planning report (trial offices).
Define the ind exes
as required by contract as below:
The index definition is the percentage ratio of the sampling
points with the index (such as CPICH Ec/Io) greater than the reference value in
all sampling points.
Index
|
Reference
|
Remarks
|
Coverage rate
|
≥ 95%
|
Test on the acceptance route
The planned continuous coverage service:
l CPICH
Ec/Io ≥ –12 dB
l
CPICH RSCP ≥ –95 dBm
|
CPICH Ec/Io ≥
–12dB
|
≥ 95%
|
Test result by scanner in outdoor unloaded conditions
|
CPICH RSCP ≥
–95dBm
|
≥ 95%
|
Test result by scanner in outdoor unloaded conditions
|
SHO Factor based on DT
|
30%–40%
|
The SHO Factor based on DT should be
5% to 10% lower than the goal, because the following optimizations cause the
soft handover factor to increase
|
Pilot pollution ratio
|
≤ 5%
|
–
|
1.2 Dividing
Clusters
According to the features of UMTS technologies, the coverage
and capacity are interactional and the frequency reuse factor is 1. Therefore
RF optimization must be performed on a group of or a cluster of NodeBs at the
same time instead of performing RF optimization on single site one by one. This
ensures that interference from intra-frequency neighbor cells are considered
during optimization. Analyze the impact of the adjustment of an ind ex on other sites
before adjustment.
Dividing clusters involves approval by the operator. The
following factors must be considered upon dividing clusters:
l According
to experiences, the number of NodeBs in a cluster depends on the actual
situation. 15–25 NodeBs in a cluster is recommended. Too many or few NodeBs in
a cluster is improper.
l A
cluster must not cover different areas of test (planning) full coverage
services.
l Refer
to the divided clusters for network project maintenance of the operator.
l Landform
factor
Landforms affect signal propagation. Mountains block signal propagation, so they are natural borders for dividing clusters. Rivers causes a longer propagation distance, so they affect dividing clusters in various aspects. If a river is narrow, the signals along two banks will interact. If the transportation between two banks allows, divide sites along the two banks in the same cluster. If a river is wide, the upstream and downstream will interact. In this situation, the transportation between two banks is inconvenient, dividing clusters by the bank according to actual situation.
Landforms affect signal propagation. Mountains block signal propagation, so they are natural borders for dividing clusters. Rivers causes a longer propagation distance, so they affect dividing clusters in various aspects. If a river is narrow, the signals along two banks will interact. If the transportation between two banks allows, divide sites along the two banks in the same cluster. If a river is wide, the upstream and downstream will interact. In this situation, the transportation between two banks is inconvenient, dividing clusters by the bank according to actual situation.
l A
cell-like cluster is much usual than a strip-like cluster.
l Administrative
areas
When the coverage area involves several administrative areas, divide clusters according to administrative areas. This is easily acceptable by the operator.
When the coverage area involves several administrative areas, divide clusters according to administrative areas. This is easily acceptable by the operator.
l DT
workload
The DT must be performed within a day for a cluster. A DT takes about four hours.
The DT must be performed within a day for a cluster. A DT takes about four hours.
Deciding Test Route
Confirm the KPI DT acceptance route with the operator before
DT. If the operator already has a decided DT acceptance route, you must
consider this upon deciding the KPI DT acceptance route. If the objective
factors like network layout cannot fully meet the coverage requirements of
decided test route by the operator, you must point this out.
The KPI DT acceptance route is the core route of RF
optimization test routes. Its optimization is the core of RF optimization. The
following tasks, such as parameter optimization and acceptance, is based on KPI
DT acceptance route. The KPI DT acceptance route must cover major streets,
important location, VIP, and VIC. The DT route should cover all cells as
possible. The initial test and final test must cover all cells. If time is
enough, cover all streets in the planned area. Use the same DT route in every
test to compare performances more accurately. Round-trip DT is performed if
possible.
Consider actual factors like lanes and left-turn restriction
while deciding test route. Before negotiating with the operator, communicate
these factors with local drivers for whether the route is acceptable.
1.4 Preparing
Tools and Data
Prepare necessary software (listed in Table 3-2),
hardwar e
(listed in Table 3-3),
and various data (listed in Table 3-4),
because the following test and analysis are based on them.
1.4.1 Preparing
Software
Table 3-2
lists the recommended software for RF optimization
No.
|
Software
|
Function
|
Remarks
|
1
|
Genex Probe
|
DT
|
–
|
2
|
Genex Assistant
|
Analyzing DT data and checking neighbor cells
|
–
|
3
|
Genex Nastar
|
Analyzing performance, checking health, and locating
problems
|
–
|
4
|
Mapinfo
|
Displaying maps and generating route data
|
–
|
Preparing Hardware
list of the recommended hardwar e
for RF optimization
No.
|
Device
|
Specification
|
Remarks
|
1
|
Scanner
|
DTI Scanner
|
–
|
2
|
Test terminal and data line
|
U626, Qualcomm, and so on
|
At least two test terminals
|
3
|
Laptop computer
|
PM1.3G/512M/20G/USB/COM/PRN
|
–
|
4
|
Vehicle mounted inverter
|
DC to AC, over 300W
|
–
|
Preparing Data
lists the data to be collected before optimization
No.
|
Needed data
|
Whether is necessary
|
Remarks
|
1
|
List of engineering parameters
|
Yes
|
–
|
2
|
Map
|
Yes
|
By Mapinfo or in paper
|
3
|
KPI requirements
|
Yes
|
–
|
4
|
Network configuration parameters
|
Yes
|
–
|
5
|
Survey report
|
No
|
–
|
6
|
Single site verification checklist
|
No
|
–
|
7
|
Floor plan of the target buildings
|
Yes
|
For indoor test
|
Data Collection
During RF optimization stage, the key is the optimization of
radio signals distribution, with the major means of DT and ind oor test. Before test, confirm with the customer
care engineers the following aspects:
l Whether
the target NodeBs, RNCs, and related CN are abnormal due to being disabled,
blocked, congested, and transmission alarms.
l Whether
the alarms have negative impact on the validity of test result data.
If the alarms exist, solve the problems before test.
If the alarms exist, solve the problems before test.
DT is a major test. Col lect
scanner and UE data of radio signals by DT test. The data is applicable in
analyzing coverage, handover, and pilot pollution problems.
l Indoor
coverage areas
Indoor coverage areas include inside buildings, department stores, and subways.
Indoor coverage areas include inside buildings, department stores, and subways.
l Inside
areas of important facilities
Inside areas of important facilities include gymnasiums and government offices.
Inside areas of important facilities include gymnasiums and government offices.
l Areas
required by the operator
Areas required by the operator include VIC and VIP.
Areas required by the operator include VIC and VIP.
Test the previous areas to locate, analyze, and solve the RF
problems.
Indoor test also involves in optimizing handover of ind oor and outdoor
intra-frequency, inter-frequency, and inter-system.
The DT and ind oor
test during RF optimization stage is based on VP service. According to the
contract (commercial deployment offices) and planning report (trial offices),
if seamless coverage by VP service is impossible in areas, such as, suburban
areas and rural areas, the test is based on voice services. For areas with
seamless coverage by PS384K service required by the contract (commercial
deployment office) or planning report (trial office), such as office buildings,
press centers, and hot spot areas, the test is based on PS384K service.
Drive
Test
DT Types
According to different full coverage services in the planned
areas, DT might be one of the following:
l
3G ONLY
continuous talk test by using scanner + unloaded VP
According to simulation result and experiences, if the test result meets requirements on VP service coverage, the test result will also meet identical coverage requirements of PS144K, PS128K, and PS64K services.
According to simulation result and experiences, if the test result meets requirements on VP service coverage, the test result will also meet identical coverage requirements of PS144K, PS128K, and PS64K services.
l
3G ONLY
continuous talk test by using scanner + unloaded voice service
l
3G ONLY
continuous talk test by using scanner + unloaded PS384K
Setting DT Indexes
The following paragraphs take VP service for example.
Setting DT ind exes
proceeds as below:
1)
Start Genex
Probe 1.3 software
2)
Select Configuration > System Config > Test Plan
For setting DT, see the following table.
Index
|
Meaning
|
Enable
|
Whether to implement this index. True for implementation. False for non-implementation. The
recommended value is True.
|
Call Number
|
Called number. Whether the called
terminal supports VP must be confirmed.
|
Setup Time (s)
|
The maximum time for setting up
calls. It ranges from 20–30s. The recommended value is 25s.
|
Calling Time (s)
|
The time for a single call from
call start to normal end of call. Set it great enough according to actual DT
route. The recommended value is 99999s.
|
Idle Time (s)
|
Call internal time. The
recommended value is 10s.
|
Call Count
|
Total call times. Set it great
enough according to actual DT route. The recommended value is 999 times.
|
Collect call data tracing at RNC side while performing drive
test. This help to locate and analyze problems.
Data to be collected includes:
l Traced
signaling messages of single subscriber
Indoor
Test
GPS signals are unobtainable in door test. Ob tain
the plan of the target area before test.
Indoor test consists of walking test and vertical test.
Perform walking test to obtain horizontal signals distribution inside buildings
by selecting Indoor Measurement >
Walking Test. Perform vertical test
to obtain vertical signals distribution by selecting Indoor Measurement > Vertical
Test. For the detailed method, see WCDMA
Test Guide 3.0.
Collecting RNC Configuration Data
During RF optimization stage, collect neighbor cell data of
network optimization and other data configured in RNC database. In addition,
check whether the configured data is consistent with the previously
checked/planned data.
While checking configured data, feed back the improperly
configured data (if found) to product support engineers. During checking, pay
special attention to handover reselection parameters and power setting
parameters, as listed in Table 4-1.
Type
|
Content to be checked
|
Handover reselection parameter
|
IntraFreqNCell (intra-frequency neighbor cell)
InterFreqNCell (inter-frequency neighbor cell)
InterRATNCell (inter-system neighbor cell)
|
Power configuration parameter
|
MaxAllowedULTxPower (maximum uplink transmit power of UE)
PCPICHPower (PCPICH transmit power)
|
For handover reselection parameters, check list of neighbor
cells, including intra-frequency, inter-frequency, and inter-system neighbor
cells.
Output an updated Radio
Parameter Configuration Data Table and parameter revision records. This is
useful in problem analysis and following optimization stages.
4) Start
RNC LMT
5) Col lect MML scripts
6) Convert
neighbor cell configuration data in MML scripts to Excel files by using Nastar
7) Save
the data in the format in which the data can be imported to Assistant.
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