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The optimization process is divided into the following parts: Project preparation and startup Single site verification RF optimization Parameter Optimization Customer acceptanceOptimization report outputFor the live network, there are OMC statistic data that can be used to reveal the network performance. On the other side, the influence to the network should be taken into consideration for any adjustment. That is the reason for adding of the simulated loading and why the changes of the parameter must be done at night if necessary.

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Before the network optimization, the RNO manager should take some preparation ,The following work is requiredUnderstanding of the Existing NetworkCluster Division and Optimization Team Establishment Optimization Tools and Software

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Before the network optimization, the RNO manager should be acquainted with the existing network to make the working plan. And the information of the existing network can be acquired from this document.

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The optimization manager needs to establish the optimization teams by estimating the workload, deciding the human resource and tools requirements and making the time schedule ,as shown in this diagramIf the NodeBs involved are more than 20 or the test time of the target area exceeds 3 hours, we should divide the target area into parts before the optimization. Cluster refers to a set of NodeBs in one part. An area of a cluster should contain a complete test route and the time for one test should be less than three hours. In addition, the test time of each cluster should be similar.

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Each team should be equipped with a set of drive test tools, including:1. UMTS Scanner: Agilent E6474A with E6455C(version upper 6.0) scanner2.UMTS Test UE: Huawei U636 / UA6Qualcomm TM6200 (version upper 5.0)/or Motorola A8353.GPS and data line: the E6455C has built-in GPS

More than one set of equipments below are required and shared in a large project team:1.YBT250: For identifying the location of the interference2.Digital camera: Used to record special propagation environment

The following software is required for each team: 1.Post processing tool: HUAWEI Assistant2.MapInfo: For some self-definition analysis of drive test data

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In WCDMA RNO, completing automatic check and test of functions of equipment in each site is necessary and ensures that the basic functions (such as access and call) of each cell and site in the area to be optimized are normal. So after sites are constructed and tested, the network optimization starts from the single site verification stage

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By single site verification, you can achieve the following goals:To distinguish the call drops and access problems due to poor coverage from those due to equipment performance.To familiarize the site location and configuration, the ambient radio environment.

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In the stage of preparations before test, you must input the Radio Parameter Planning Data Table and check it which has been output in radio network planning (RNP) stage. After check configured data, output the Radio Parameter Configuration Data Table and select proper test points and test route.In the stage of single site test, output the Single Site Verification Checklist according to the template.In the stage of solving problems, on-site engineers and product support engineers will solve the function problems.Because the project dimensioning, staff, site distribution, and work division vary, The single site verification is completed by both on-site engineers and RNO engineers.

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For each cell to be measured, check by LMT or M2000 the following indexes:Whether each cell has been set up.Whether cell Data Validity Indicator is Valid.Whether cell BAM Status is UnblockedWhether HSDPA function is properly configured and activated for HSDPA cells.Query the following indexes by execute the related command:Query cell status by executing DSP CELL MML of RNC LMT.Query cell HSDPA configuration by executing LST CELLHSDPA.Activate cell HSDPA function by executing ACT CELLHADPA.The on-site engineers and product support engineers must check that each network element (MSC, SGSN, GGSN, and so on) of core network (CN) has no alarms.

Before site test, you must collect data for RNP configuration and other data for RNC database, and check whether the data configured is consistent with the planned data, include NODEBNAME,LOCELL ID, MAXTXPOWER, LAC, RAC, Scrambling code PSCRAMBCODE, Frequency UARFCNDOWNLINK, and Others

To ensure that the services to be tested are provided by the cell to be measured, you must test cell equipment functions by selecting a test point of target cell, the most ideal method is to disable power

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Press the application key to start testing mode of the handset. Then the handset displays testing mode. The handset will displays the basic information of the serving network, including the uplink and downlink frequency number . Check whether the ID of the serving cell is consistent with the planned one in frequency check. If not, the UE might receive signals from other cells .In test mode, the handset will also displays the basic information include the primary scramble (P-SC) information, LAC,RAC, Check whether the CPICH RSCP and CPICH Ec/Io received by UE are greater than the threshold. Check whether there are problems, such as abnormal power amplifier, abnormal connection of antenna-feeder, inconsistent of antenna tilt/azimuth from the planned one, and blocking by buildings.

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For Voice Service and VP Service test, Use two handsets to call each other for five times. Record the originating and terminating connection conditionsFor PS Service test, Before test, check whether you can go online with the test UE in normal cells. If the handset is available for online service, type the website address in the browser. It is a symbol for connection of PS services that the handset is available for online services and browsing web pages.

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Before checking site, you need to inquiry product support engineers whether alarms exist, whether problems are solved, and whether the cell is in normal status. You must pay attention to intermittent alarms (such as, transmission alarms automatically reset, but this causes network to become unstable and affects services)

The testing route needs to cover the coverage are of primary serving cell to be measured as possible, as well as all major street around the NodeB to be measured. The testing route involves consideration of local driving habit and avoids waiting for traffic lights during testing.

Testing cell coverage and HSDPA access function in area verification requires a quick schedule. If the method is improper, the test of an index might terminate due to one or two abnormal cells. For a proper schedule, you must read the details of test, know the content, and avoid wasting time due to abnormalities.

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To check coverage by DT, proceed as below:Prepare the NodeB location map. Familiarize the points with poor

coverage.Connect the scanner to the laptop computer and test the signals of the

target cell according to the selected testing route.You need to cover all major streets around the NodeB as possible.

Output area coverage map based on the pilot signals received by scanner. Compare the CPICH RSCP and Ec/Io distribution of each cell.

You must pay special attention to the cells with weak RSCP and Ec/Io.

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To test HSDPA functions, you must use the testing software supporting HSDPA (such as Probe 1.3).

The HSDPA threshold of downlink BE service is defined as the rate judgment threshold of background/interactive services loaded on HS-DSCH in PS domain.

Fixed Maximum Transmit Power of UE, measure the RTWP of the cells:

In the cell to be measured, make the UE transmit signals at the fixed maximum power and the RTWP of the cell to be measured and the neighbor cells increases, In this way, you can judge whether the diversity of the receiver antenna is problematic.

Checking Antennas by Exchanging Feeders:Connect the Tx/Rx feeder to the Rx ports and the Rx feeder to the

Tx/Rx port. Compare the CPICH RSCP before and after exchanging feeders. If they are the same, the problem is not about reverse connection of antenna feeders (normally after exchanging feeders the difference of CPICH RSCP before and after exchanging feeders is less than 2 dB).

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The method for UE to transmit signals at the fixed maximum power is a recommended method of test and operation, but it is restricted from whether the UE supports related functions. To exchange antenna feeders, you must repeatedly adjust the antenna-feeder system. Adjustment requires abundant labor and is difficult to implement, so engineers must cooperate well with each other in test.

If RNO engineers find problems about product function, such as originating or terminating failure, call drop, quality of talk, they must retest to check whether the problem occurs again. In addition, RNO engineers must ask product support engineers to solve problems and tracing the solving of problems until problems are solved and closed.

If the problems are about engineering installation, ask on-site engineers to solve them. Meanwhile RNO engineers must trace them until they are solved and closed.

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On-site engineers must cooperate well with RNO engineers to ensure quality of projects.

On-site engineers complete the verification by test UE in idle mode and connected mode , RNO engineers complete the verification based on distribution of new site.

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After single site verification, optimization comes to RF optimization

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Pilot signal coverage optimization includes the following two parts:1.Weak coverage optimization for ensuring seamless coverage by pilot signals in the network2.Primary pilot cell optimization for ensuring proper coverage areas by each primary pilot cell, clear edge of primary pilot cells, and that alternation of primary pilot cells is reduced as possible.

Pilot pollution refers to those excessive pilots of approximately equivalent strength cover an area without a primary pilot. Pilot pollution might cause increasing of downlink interference, call drop due to frequent handover, low network capacity. The problems must be solved by adjusting engineering parameters.

Handover optimization consists of two parts:Checking missing neighbor cells, verifying and perfecting list of neighbor cells, solving handover, call drop, and downlink interference problems.Ensuring proper SHO Factor based on DT by adjusting engineering parameters properly.

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RF optimization includes the following four parts:Test preparations, Data collection, Problem analysis, Parameter adjustmentthe data collection, problem analysis, and parameter adjustment might be repeatedly performed according to optimization goal and actual on-site situations until RF indexes meet KPI requirements.

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Different operators might have different standards on KPI requirements , 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).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. 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.

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RF optimization objectives in R99 networks are listed in the table

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According to experiences ,1525 NodeBs in a cluster is recommendedOne cluster must not cover areas with different full coverage services.Refer to the divided clusters for network project maintenance of the operator.Landforms affect signal propagation. Mountains block signal propagation, so they are natural borders for dividing clusters. A cell-like cluster is much usual than a strip-like cluster.When the coverage area involves several administrative areas, divide clusters according to administrative areas The DT must be performed within a day for a cluster. A DT takes about four hours.he 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, are 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.

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Genex Probe: air interface DT softwareGenex Assistant: Analyzing DT data and checking neighbor cells Genex Nastar: Analyzing performance, checking health, and locating problems Mapinfo: Displaying maps and generating route data

Scanner :DTI Scanner Test terminal : U626, E620, Qualcomm, and so on Laptop:PM1.3G/512M/20G/USB/COM/PRN

Map can be mapinfo map or paper mapFloor plan of the target buildings is necessary for indoor test

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The DT and indoor 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 or HSDPA 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 the above services.

According to different full coverage services in the planned areas, DT might be one of the following:3G ONLY continuous call test by using scanner + unloaded VPAccording 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.3G ONLY continuous call test by using scanner + unloaded voice service3G ONLY continuous call test by using scanner + unloaded PS384K

Indoor test consists of walking test and vertical test. Perform walking test to obtain horizontal signals distribution inside buildings. Perform vertical test to obtain vertical signals distribution.

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)

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Most of the coverage and interference issues could be resolved through adjusting sites parameters, such as (in order of priority):Antenna tiltAntenna azimuthAntenna locationSplit sectorRemove sectorCombine sectorAntenna heightAntenna typeTMARRUSite locationNew site

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If possible, we should survey the relative sites, otherwise, we can check the former site survey report or photos. It is very necessary to know the condition of the sites and then probably we can give the applicable advice If it is impossible to survey the site, we can take the former survey report for reference

do the RF adjusting and test the result at the same time, so as to avoid reworking the tasks.

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Weak coverage refer to that the RSCP of pilot signals in a coverage area is less than -95 dBm. overshoot coverage refers to that the coverage range of some NodeBs is beyond the planned range and discontinuous primary pilot coverage areas form in coverage areas of other NodeBs.Unbalanced between uplink and downlink refers to the following situations in uplink and downlink symmetric services No primary pilot areas refer to the areas with no primary pilot or the primary cell changes frequently

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Downlink coverage analysis involves analyzing CPICH RSCP and CPICH Ec/Io obtained by drive test.Uplink coverage analysis is analyzing UE transmit power obtained in DT.

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Downlink coverage analysis involves analyzing CPICH RSCP obtained by drive test.The quality standard of CPICH RSCP must be combined with the optimization standard , Usually, the strongest RSCP received by each scanner in the coverage area must be above -95 dBm.

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Start Assistant. Analyze scanner-based RSCP for 1st Best Service Cell, and you can obtain the distribution of weak coverage area In this Figure, there was weak coverage areas with RSCP smaller than -95 dBm in the DT route

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In parallel with the analysis of RSCP coverage, the Ec/Io plot should also be analysed The -8 dB threshold takes into account the expected future interference increase as a result of increased traffic.

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Because the RSCP Level is poor, and the fundamental cause of low Ec/Io is poor coverage

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RSCP level is good, the poor Ec/Io will imply strong system interference

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An example Ec/Io plot is shown in this FigureComparisons of the Ec/Io plots from the scanner and UE should be made. Areas where UE Ec/Io is significantly lower than that of the scanner may imply a problem of missing neighbour or delayed soft handoff which can be associated with call drops.

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Analyze scanner-based RSCP for SC, and you can obtain the signal distribution of each cell (scramble). According to DT data, if the scramble signals of a cell are not present, probably some sites cannot transmit signals during test. If a cell cannot transmit signals during DT, the DT of relative areas must be re-performed.Very weak coverage might be result of blocked antennas, so you must check the survey report of the site and check installation of on-site antennas. No (poor) coverage cell might be due to that the DT route does not cover the cell coverage area. In this case, reevaluate the DT route for the rationality and perform DT again.Analyze scanner-based RSCP for SC, and you can obtain the signal distribution of each cell (scramble). If the signals of a cell are widely distributed, even in the neighbor cells and the cells next to its neighbor cells, the signals of the cell is present, the cell encounters a cross-cell coverage which might be due to over high site or improper down tilt of antenna. The cross-cell coverage cells interferes neighbor cells, so the capacity declines. Analyze scanner-based SC for 1st Best ServiceCell, and you can obtain the scramble distribution of the best cell. If multiple best cells changes frequently in an cell, the cell is a no primary pilot cell,

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as shown in the Figure, No primary pilot cell forms due to the following causes:Cross-cell non-seamless coverage due to over high sitePilot pollution in some areasCoverage voids at edges of coverage areasTherefore intra-frequency interferences forms which causes ping-pong handover and affects performances of service coverage.

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Missing neighbor cells, improper parameters of soft handover, cell selection and reselection cause the inconsistent between scanner primary pilot cell and camped cell in idle mode or Best Service Cell in the active set in connection mode of UE.

After optimization, the Ec/Io for 1st Best Service Cell of UE and scanner is consistent. In addition, the coverage map of UE is marked by clear bordering lines of Best Service Cell

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For areas with poor index, judge whether the increasing of UE transmit power is due to call drop or poor uplink coverage. Geographically displayed on the map, the former is as a point of sudden increment with call drop while the latter is an area with seamless coverage unnecessarily with call drop.Mark the areas with weak coverage or large common seamless coverage for further analysis. Check whether downlink CPICH RSCP coverage voids exist in the areas with uplink coverage voids. Solve the problem with both uplink and downlink weak coverage by analyzing downlink coverage analysis. If only the uplink coverage is poor without uplink interference (see WCDMA Interference Solution Guide), solve the problems by adjusting down tilt and azimuth of antenna, and adding TMAs.

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In this Figure , UE transmit power is lower than 10 dBm normally. Only when uplink interference and coverage area edge exist will the UE transmit power increase sharply to 21 dBm (Some UEs that support HSDPA, such as E620, with a power class of 3, the maximum transmit power is 24 dBm), and the uplink is restricted. Comparatively restricted uplink coverage occurs much easily in macro cells than in micro cells.

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If some cells are frequently seen as polluters (e.g. >8% time) should bemarked and investigated.Usually, the max number of active cell is 3, so if number of strong pilot ismore than 3,then it is a pilot pollution point.If (CPICH_RSCP1st - CPICH_RSCP4th) < 5dB ,it means the best serve cellis not dominant

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According to the conditions of Pilot Pollution, the SC4,SC5,SC6 are Pilot Pollution, the RSCP of SC6 is more then 5dB lower than the best serve cell, so it is not Pilot PollutionMargin is 5 dB

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Looking at the estimated active set based on the scanner data is a useful measurement of pilot pollution , In order to see areas of excessive SHO candidates, the estimated active set size is allowed to exceed maximum of 3 .Locations where there are more than 3 pilots in the active set should be marked and sources of the interference should be identified. This can be done in conjunction with the Pilot pollution analysis.

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An example of pilot pollution results is provided in the Table. This shows the % of time each cell was seen as a pilot polluter. Cells which are frequently seen as polluters (e.g. >8) should be marked and investigated.

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Due to restriction to site location and complex geographic environment, celldistribution might be improper. Improper cell distribution causes weakcoverage of some areas and coverage by multiple strong pilots in sameareas.If a NodeB is constructed in a position higher than around buildings, mostareas will be with in the line-of sight range. Therefore signals are widelytransmitted. Over high site cause difficult control of cross-cell coverage,which causes pilot pollution.The sector azimuth of each antenna is set to cooperate with each other. Ifthe azimuth is improperly set ,might lead to pilot pollution Therefore we mustadjust the antenna according to actual propagation.If the antenna down tilt is improper, signals are received in the areas whichare covered by this site. Therefore interferences to other areas causes pilotpollution. Even worse, interferences might cause call drop.When the NodeBs are densely distributed with a small planned coveragerang and the PICH power is over high, the pilot covers an area larger thanthe planned area. This causes pilot pollution.

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Multiple strong pilots interferes useful functional signals, so Io increases,Ec/Io decreases, BLER increases, and network quality declines.More than three strong pilots or no primary pilot exists in multiple pilots,frequent handover occurs among these pilots. This might cause call drop.The interference of the areas with pilot pollution increases, the systemcapacity declines.

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Start Assistant. Analyze scanner-based RSCP for 1st Best ServiceCell andEcIo for 1st Best ServiceCell. Select the areas with high RSCP and poorEc/Io as candidate areas with pilot pollution.Analyze scanner-based Whole PP. Select the areas corresponding tocandidate areas as the key areas with pilot pollution.Locate the cells that cause pilot pollution of the key areas.Based on RSCP for 1st Best ServiceCell, judge whether the pilot pollution is caused by existence of multiple strong pilots or lack of a strong pilot. For the former cause, you can solve the problem by weakening other strong pilots. For the latter cause, you can solve the problem by strengthening some strong pilot.Based on the actual environment, analyze the specific causes to pilot pollution. For specific causes, provide solutions to pilot pollution. While eliminating pilot pollution in an area, consider the influence to other areas and avoid causing pilot pollution or coverage voids to other areas.After the adjustment, we should take retest and analyze RSCP, Ec/Io and Whole PP. If they cannot meet KPI requirements, re-optimize the network by selecting new key areas until KPI requirements are met.

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According to the test, change pilot signal strength of an area with pilotpollution by adjusting antenna down tilt and azimuth. This changes thedistribution of pilot signals in the area. The principle for adjustment isenhancing primary pilot and weakening other pilots.Pilot pollution is caused by the coverage by multiple pilots. A direct method tosolve the problem is to form a primary pilot by increasing the power of a celland decreasing the power of other cells.If adjusting power and antenna is not effective to solving pilot pollution, use RRU or micro cells.Using RRU or micro cells aims to bring a strong-signal coverage in the area with pilot pollution, so the relative strength of other signals decreases.

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According to the test, change pilot signal strength of an area with pilotpollution by adjusting antenna down tilt and azimuth. This changes thedistribution of pilot signals in the area. The principle for adjustment isenhancing primary pilot and weakening other pilots.Pilot pollution is caused by the coverage by multiple pilots. A direct method tosolve the problem is to form a primary pilot by increasing the power of a celland decreasing the power of other cells.If adjusting power and antenna is not effective to solving pilot pollution, use RRU or micro cells.Using RRU or micro cells aims to bring a strong-signal coverage in the area with pilot pollution, so the relative strength of other signals decreases.

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Missing neighbor cells causes that a strong-pilot cell cannot be listed into the active set so the interference increases as strong as call drop occurs. For missing neighbor cell, you must add necessary neighbor cells. Redundant neighbor cells causes that the neighbor cell information is excessive and unnecessary signals cost occurs. When the neighbor cell list is fully configured, the needed neighbor cell cannot be listed. For this problem, remove redundant neighbor cells.

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This Excel-formatted report contains four sheets: Scanner Statistic, Scanner Result, Imported Config, and Scanner vs Config. Wherein, the Scanner vs Config sheet is for comparing neighbor cells generated by scanner and the configured neighbor cells.The Figure shows the result of missing neighbor cells. For the missing neighbor cells generated automatically by Assistant, you must check according to the location information of the cell on the map whether to add the missing neighbor cells to the neighbor cell list. For the missing neighbor cells due to cross-cell coverage, the primary task is to solve coverage problem by adjusting RF parameters. If this fails, you can temporarily solve the problem by adding neighbor cells.

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The spots with missing neighbor cells has a poor Ec/Io measured by UE and a strong Ec/Io scanned by scanner. Locate the areas for further analysis.Check the points with poor Ec/Io and check whether the strongest scramble by scanner is neither in active set nor in monitoring set. If yes, move to the third step for confirmation. If the scramble exists in the monitoring set, the problem is not about missing neighbor cell but about Ec/Io deterioration due to handover (reselection) delay and soft handover failure.Check the latest intra-frequency measurement control whether the neighbor cell list contains the strong scrambles by scannerYou can also directly check the neighbor cells continuation of the base cell under the RNC for deciding missing neighbor cells.

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No subscribers are using the network during RF optimization stage, so UE DT data of entire network in a time is used and geographically averaged by 5 meters. You can obtain the ratio of the points in soft handover state to all DT points. Set the scanner consistent to the system parameters with default configuration, such as 1A and 1B threshold. The SHO Factor based on DT during RF optimization stage must be 5%10% lower than the KPI target value, because the following optimizations cause SHO Factor based on DT to increase and brings difficulties in ensuring traffic measurement SHO Factor based on DT

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The success rates for event 1a, 1b & 1c and can be obtained from software (Assistant) as shown in the example below.

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The precondition for adjustment is that the adjustment will not cause new coverage voids, coverage blind zone, and more pilot pollution.

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Parameter optimization includes field test and statistics analysis. The field test can be divided into two parts: drive test on main road and test for special areas. Test for special areas is like walk survey for some indoor distributed cells.We can use scanner + UE log, RNC log, statistics counters and KPI, MSC & SGSN log to optimize the network

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Drive test is to get information on the service coverage on the main road and to optimize the problems as access failure, drop call, power control, handover and service quality. Unlike RF optimization drive test, for parameter optimization its not needed to do the service test for all sites. So its not necessary to stick to the idea of cluster.

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Access failure :system bugs, power control parameter, cell selection and reselection parameter etc. Reason for drop calls :system bugs, power control parameter, handover parameter etc. Reason for Service quality :system bugs, power control parameter, RLC parameter etc

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The influence caused by the cell parameters adjustment should be analyzed carefully by optimization engineer. The parameters adjustment to a live network should be performed when traffic is low (for example: at midnight). It is essential to do the service functional test after adjustment Sometimes its hard to predict accurately the impact of the parameter changes. So its necessary to benchmark before and after parameter changes. Its recommended to do the benchmark together with the statistics analysis for live network.

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The optimization report should be presented after the project passes the customer acceptance Besides the optimization report, the updated Site Configuration Parameter tableand Radio Part Parameters Table are required.

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