3g inteference test and solution report
TRANSCRIPT
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
3G Uplink
Interference and
Solution Report
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
CONTENTS
1 OBJECTIVE..................................................................................................................... 3
2 EXECUTIVE SUMMARY.............................................................................................. 3 2.1 TYPES OF INTEFERENCE ...............................................................................................4
3 TOOLS ............................................................................................................................. 4
4 TEST DETAILS BY HUAWEI. ...................................................................................... 4 4.1 TEST PROCEDURES ........................................................................................................4 4.2 OBSERVATION..................................................................................................................5 4.3 RECOMMENDED SOLUTION ...........................................................................................6
5 TEST DETAILS BY ERICSSON .................................................................................... 6 5.1 METHODOLOGY ...............................................................................................................7 5.2 PROCEDURE.....................................................................................................................7 5.3 OBSERVATION & SOLUTION...........................................................................................8
6 RECOMMENDATION.................................................................................................... 9
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
1 OBJECTIVE
� Confirm the level of inteference on the UL spectrum of the allocated Band D
(1950 MHz – 1960MHz) spectrum granted to Celtel Nigeria. The test was
conducted by Celtel’s two major vendors for 3G, they are:
� Messrs Huawei Technologies Ltd conducted test Port-Harcourt, South South
region.
� Messrs Ericsson conducted test in Lagos, Lagos Region.
2 EXECUTIVE SUMMARY
Spectrum Assignment in Nigeria
Figure 1: Spectrum Assignment of Celtel and CDMA operator
NCC had assigned 1950~1960MHz to Celtel UMTS Rx band, while 1960~1970MHz
has already been assigned to Starcomms CDMA Tx band. Interference possibility
exists between CDMA Downlink and UMTS uplink because the two frequency
bands are very close to each other.
1960
1970 1880 1890
BS
1950 10MHz
Celtel Up Celtel Down
10MHz
1960
10MHz
2150 10MHz 2140
CDMA
operator Down
CDMA
operator Up
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
2.1 TYPES OF INTEFERENCE
There are three types of interferences between CDMA1900 downlink and
UMTS2100 uplink.
� Spurious emission
� Blocking
� Intermodulation.
3 TOOLS
• R&S FSH3 spectrum Analyzer.
• TEMS Drive test kit.
• Vendors’ (Huawei and Ericsson) Network statistics monitoring tools.
4 TEST DETAILS BY HUAWEI.
Huawei conducted the Interference test in Port-Harcourt where twenty four 3G sites are
operational. The test procedure is shown below
4.1 TEST PROCEDURES
Objective
The test purpose is to verify if it can solve the interferences between Starcomms
CDMA downlink and the Celtel WCDMA uplink after installing filters on both
Starcomms sites and Celtel sites.
Test network figure
Prerequisites
The tested WCDMA site works normally.
Procedure Expected result
1. Collect all the sectors’ RTWP (Received total wideband
power) without any filter and select a sector which is suffering
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
serious interference (RTWP>-90dBm) to test.
2、Install Celtel WCDMA receive filter on selected sector and
then collect RTWP again.
3、Uninstall Celtel WCDMA receive filter and install CDMA
transmit filter on the selected sector, then collect RTWP.
4、Install both WCDMA receive filter and CDMA transmit
filter on selected sector and then collect RTWP.
5、Connect YBT250 to the tested sectors antenna without any
filter.
6、Set YBT250 span range from 1920~1970MHz and record
the result (save the spectrum figure).
7、Set YBT250 span range from 1950~1960MHz and record
the result (save the spectrum figure).
8、Connect WCDMA receive filter on YBT250 and then
connect selected sector antenna to filter.
9、Repeat steps 5 and 7.
10、Change to another antenna of same sectors.
11、Repeat steps 5 to 9.
Remarks
In this test, CDMA filter be installed on WCDMA sector (in real network, it should be
installed on Starcomms CDMA site), but the effect is the same because of the filter is
still on the same link.
4.2 OBSERVATION
Test was carried out using the RTWP (Received Total Wideband Power) measurement
function of the Huawei Node B for all 72 sectors. For a sector to be free from Uplink
interference the RTWP < -102dBm. 32 sectors out of the 72 sectors tested failed this test.
Therefore, Huawei used the above procedure to treat the affected cells using the designed
filter and the Uplink interference was observed to have been eliminated for the affected
site. An indication that the major source of interference is the blocking from Starcomms’
CDMA sites.
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
The effect of installing filters(RTWP_M)
-120
-100
-80
-60
-40
-20
0
1 51 101 151 201 251 301 351 401 451 501 551 601
Samples
RTWP(dBm)
Without filters
With WCDMA Filter
With CDMA Filter
With both filters
Figure 2 The effect of installing filters (RI007_1, RTWP_M)
4.3 RECOMMENDED SOLUTION
In order to solve interference, Celtel needs to install filters on the affected site. The
filter tested during the trial has a 40dB attenuation range and the results are shown
below.
Case Average RTWP
Without filter -80.9dBm
With WCDMA filter -101.7dBm
With CDMA filter -82.9dBm
With both filter -105.6dBm
Figure 3 the effect of installing filters (RI007_1, RTWP_M)
With the expected growth of Celtel 3G network as well as the expansion of the
Starcomms network whose sites are potential interferers to Celtel’s WCDMA sites.
Huawei has recommended that 50% of WCDMA sites will need a filter to eliminate the
Uplink interference. However, the specific sites will be identified using the Huawei
RTWP tool.
5 TEST DETAILS BY ERICSSON
Ericsson conducted the Interference test in Lagos. The test procedure is shown below
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
5.1 METHODOLOGY
Some sites were identified.
� Record traces of the uplink (1950 – 1960 MHz) at identified site using R&S FSH3
spectrum Analyzer and taking a snap-shot of the graph.
� Collect statistics for a period of 3 hours in the day.
5.2 PROCEDURE
A spectrum analyzer was connected to an Omni antenna to scan measurement for the
uplink on a frequency range of 1920MHz to 1967MHz for us to get all the active
bandwidth before and after the bandwidth of 1950 MHz - 1960 MHz given to Celtel
Nigeria.
� Identify all sites to be tested as well as their addresses.
� Power on the Spectrum analyzer.
� Connect the Spectrum analyzer to the Car charging system
� Set the date and time to current date and time
� Set the start Frequency to 1920 MHz and Stop frequency to 1967 MHz.
� Set the Noise floor to -102dBm.
� Connect the Omni antenna to the RF input port of the Spectrum Analyzer.
� Set the sweep time to 10ms
� Check to ensure that the equipment is working normally and setup is complete.
� Drive around each operational site and save the RTWP for each site in the
memory of the Spectrum analyzer.
� After all sites RTWP has been saved; download the file for observation and
analysis.
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
5.3 OBSERVATION & SOLUTION
With the UL interference statistics, it can be seen that some cells experienced some
interference, which might have been caused by spurious emissions or blocking
interference from other parties as shown in the figure below.
Figure 4 Spectrum from 1950 to 1960 without filter
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
Figure 5 Spectrum from 1950 to 1960 with filter
Statistics was also collected on the network monitoring tool shows indication of
interference in some sites. The installation of the Test filters reduced the level of
interference.
Based on the above results and observations, conclusion was drawn that there is some
form of interference on the Uplink for certain 3G sites. We recommend that Celtel plan
for about 35% of the 3G sites to require filters. This is required as a safe-guard measure
for those sites that may experience interference. The other recommendation is to avoid
direct line of sight with the CDMA operational sites on future installations.
6 RECOMMENDATION.
Based on the finding during the interference test the following is recommended:
1. The blocking effect of Starcomms sites on the Celtel’s 3G sites to be reported to the
regulatory body – Nigerian communication Commission (NCC) for record purpose and
perhaps a regulatory action may emanate by reallocating frequencies to CDMA operators
to finally eliminate the blocking interference.
2. 339 sites are planned for the 3G year 1 rollout in 13 states of Nigeria as shown below:
Document Category Radio Equipment Trial Information Category 3G Uplink inteference
mitigation filter test
Development Status Final Document Owner Radio Planning
State Planned sites Starcomm's Presence
ABIA 9 YES
ANAMBRA 12 YES
CROSS-
RIVERS 9
Planned for 2008
DELTA 31 Planned for 2008
EDO 24 Towards Q4, 2007
ENUGU 8 No Known Plan
FCT 24 YES
IMO 12 No Known Plan
KADUNA 19 YES
KANO 34 YES
LAGOS 127 YES
RIVERS 30 YES
Grand Total 339
Since Starcomms is not stopping rollout and we do not know where next (citiy) they will
rollout new sites, coupled with the fact that NCC is not indicating withdrawing the
1960MHz – 1970 MHz from Starcomms. It is recommended we install the tested filters
on all 3G sites. For future 3G deployment in all cities; 3G Equipment Vendors should be
instructed to install the tested filter for all Node Bs. These filter need to be acquired as
soon as possible before the 3G commercial launch to improve the quality of service to
our potential 3G subscribers.