01 Wcdma Rnp&Rno Conspectus

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WCDMA RNP&RNO Conspectusfundamental of WCDMA, Optimization techniques.

Transcript of 01 Wcdma Rnp&Rno Conspectus

0HUAWEI TECHNOLOGIES Co., Ltd.
HUAWEI TECHNOLOGIES Co., Ltd.
Network Planning Scope
Transmission network
configuration between network elements.
WCDMA Core network planning (CS/PS domain)
WCDMA RNP tools development
Objectives of network planning
The RF Design of wireless system revolves four main principles. These principles are Coverage, Capacity, Quality and Cost. And further, adapt to the future network development and expansion.
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Adopts cellular network structure and frequency planning to guarantee intra/inter-frequency interference
Users supported can be calculated from carriers and timeslots if the interference meets the requirements.
Provides voice service
Realize 1×1 frequency reuse
The capacity per WCDMA cell is “soft” for it is related to environment and neighbor cell interference.
Supports multiple services with different speed rate and QoS, and each service has different coverage range.
GSM
WCDMA
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Determine the following information (network estimation input data) before performing radio network estimation:
Band class available to operators, traffic model, traffic density of the network, user growth prediction, actual coverage area, propagation environment, service and mobile terminal type to be supported by the network, operator’s requirements for indoor and outdoor coverage, coverage probability, blocking probability, and acceptable delay
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SHO Gain
In last slide, we discussed some concept in WCDMA, then how these concept applied in our link budget?
In this figure, I highlight the parameters that was decided by the capacity or quality , could you tell me which one is for capacity and which one is for quality? Yes the red one decided by , while …
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(sectorization, carriers,...)
Equal to
Nominal Planning
Based on the result of network dimension, preliminary design present Information of theoretical sites including following :
Site coordinates.
Engineering parameters such as Antenna height, azimuths and tilts.
Radio parameters such as scrambling code ,transmit power of different channels , etc.
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WCDMA simulation
About simulation
Unlike GSM network, in CDMA coverage and capacity are too inter-related to be predicted accurately, so we introduced Monte Carlo simulation to evaluate the performance of a radio network.
EcEc/Iopilot pollution distribution
Soft (softer) handover area analysis
UE transmit power
……
Monte Carlo is a static simulation
During Monte Carlo simulation, the performance of the network is analyzed over various instances in time (snapshot), where UEs are in statistically determined places with the given traffic model. The ability of each terminal to make its connection to the network is calculated through an iterative process.
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Best server plot
Access failure distribution and statistic of each service
Continuous coverage areas of each service
Cell load distribution of downlink and uplink
Pilot pollution distribution
+map
Performance summary based on the simulation result.
Annex: simulation output
In preliminary design stage, we choose initial sites, do network performance simulation, conduct adjustment according to the simulation result, until finally we get all performance requirements fulfilled, then we can output the <<XX project WCDMA Radio Network preliminary design Report>> with following contents:
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Site list
Radio network
Site Survey
For each theoretical site, a physical site will be acquired in this phase through following steps:
A suitable physical site
Give adequate radio coverage.
Be aesthetically and politically acceptable to the local community.
Have power nearby, good access and a co-operative owner.
Define search areas
Site Survey report
The surveyor will prepare a report listing the options, and following items will included in the report:
Accurate grid reference.
Photographs of the site.
360º panoramic photos from site or if obstructed from nearby location/structure.
From site survey report, RNP engineers can derive appropriate site location, antenna type,
height, azimuth, down tilt, etc.
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Verification by system simulation
It is an iterative process to verify the final design until all the requirements are fulfilled
Coverage prediction
RNP Planning
Frequency plan
Handover parameters
Access control parameters
Other radio parameters
After performance verification by simulation, we produce <<XX project RNP report>> with more detailed contents. In order to guide the project implementation, the report should also include following items
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Brief Introduction
Acceptance criteria
--- e.g. site installation, basic functions of the cell
RF optimization
To optimize coverage & 3G neighbor lists
Services test & para. optimization
To evaluate network performance
To optimize network parameters
To identify & solve new network issues
--- e.g. issues caused by traffic increase
Preparation
Phase 1
Phase 2
Phase 3
It should be noted that the phases given above are the general procedures but it does not mean that the previous phase is no need to do again when the next phase starts. For example, during the network optimization at phase 3, some issues may have to be solved through RF Optimization.
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To check service function
CS call & PS attach/detach
Before the single site verification, we should make sure that the following checks have been done and no remaining issues:
Alarm Check, Cell Status Check, and Parameter Check
Site Verification Items:
Installations: CPICH RSCP, CPICH Ec/Io, Rx Antenna Swap Test
Settings: Frequency & SC, Cell reselection parameters, LAC/RAC, Neighbor List.
Functions: LA/RA update, 3G<->2G Cell reselection, SMS (MT & MO), Voice (MT & MO), VP (MT & MO), PS Attach & Detach, PS service, Voice/VP/PS soft handover, Voice 3G->2G handover.
Site verification needs to check the service function before the optimization to ensure the basic service functions are normal for each site.
The check consists of signal strength, feeder connection, LA/RA update, PS attach, PS detach, voice service call setup, PDP activation , intra-frequency handover, 3G2G handover, 3G2G cell reselection.
If there is any suspect like the low signal strength and wrong feeder connection (maybe Tx/Rx main antenna, maybe Rx diversity antenna), the optimization engineer needs to ask installation engineer to do the RF check.
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Purpose: identify equipment issues
Notes:
It is recommended that the test route should be near the site(~100m).
The CPICH RSCP and Ec/Io can be seen from scanner or Engineering UE.
Frequency/Scrambling Code/LAC/RAC can be read from engineering UE.
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Tool: NodeB LMT, engineering UE or scanner
Purpose: UL/DL interference investigation
PS attach/detach, PDP activation
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To optimize neighbor cell list
To resolve RF-related drop calls
RF optimization is an ongoing activity and needs to be revisited as traffic increases in the network and as new sites are deployed.
In addition, as the network matures, the optimization process should be enhanced to take into account statistical data and key performance indicators collected throughout the network.
it is crucial that the RF optimisation is carried out for groups or clusters of sites rather than on single site basis. This will ensure that the impact of all the sites in a given area on coverage as well as interference is taken into account.
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(1) Clutters
RF optimization carried out for groups or clusters of sites
(2) Drive Routes
Covering each cell
important locations
(3) Tools
To adjust antenna azimuth
To adjust antenna location
To adjust antenna height
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(2)Increase ant. height;
(3)Replace high-gain antenna;
(4)Add new cells;
Ways to optimize:
(2)Decrease ant. height;
(3)Adjust CPICH power
Ways to optimize:
(1)UL or DL coverage limited?
(2)Optimize UL or DL interference
It is also useful to examine the RSCP coverage on per cell bases in order to highlight any cells that have too large a footprint.
When comparing RSCP coverage from scanner and UE, it should be noted that the UE will have lower levels as a result of the in-car penetration loss and differences of antenna gain.
CPICH coverage: Suggestion Value
Good: RSCP ≥ -85 dBm
Poor: RSCP < - 95 dBm
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or to indicate antennas blocking
Cells with excessive or poor dominance
Due to non-optimum antenna tilts
or due to a high site
Areas of non-dominance
Cell dominance analysis:
Site visit needed
Cells with excessive or poor dominance:
Cells with too large dominance will be causing interference to adjacent cells resulting in poorer capacity.
Comparison between the UE and scanner SC plots.
Significant differences between the plots may indicate a missing neighbor or failed soft handoff problem.
Areas of non-dominance:
This refers to areas where there is not a single clear dominant cell and where the best server changes too frequently. Such conditions will result in excessive number of soft hand off events reducing the system efficiency and increasing the probability of call drops.
UE vs. Scanner scrambling codes:
It is also useful to perform visual comparison between the UE and scanner SC plots. Significant differences between the plots may indicate a missing neighbour or failed soft handoff problem.
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Pilot pollution definition:
(1) low signal quality
(2) decreased system capacity
(3) Call drops easier
(2) Pilot power optimization
Because of the radio propagation complexity, the signal can not be controlled as designed, which causes the pilot pollution.
Especially in dense urban, the pilot pollution is very easy to happen.
Pilot pollution will probably result in:
signal quality decreased (lower Ec/Io)
(2) Calls dropped. (because of frequent handover between the cells)
(3) System Capacity decreased.
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(1)Compare coverage difference b/w Scanner and UE
(2) Add missing neighbor cells
(3) Remove useless neighbor cells
Neighbor list classification:
(2) Cell Reselection
Drive test (service test):
Drop calls during moving
Careful consideration is needed prior to removing neighbours since the Actix results are drive route dependent.
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RF-related Drop Calls
Fast change of RF conditions usually causes drop calls, e.g. turning a corner.
Poor RSCP & Ec/Io
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Parameter Optimization improves network quality and solves network problems.
Parameter Optimization is a complicated procedure and needs parameter and algorithm knowledge.
Parameter Optimization will be combined with other optimization activities making network better !
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An effective way to reduce drop calls
The influence caused by the cell parameters adjustment should be analyzed carefully.
The following influences need to be considered:
(1) Evaluate influence on customer service and other networks
(2) Evaluate influence on OMC
Prepare Test Plan and Implement Changing
(1) Prepare Test schedule, Routes, Tools.
(2) Change Parameters and Make Records.
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Regular Drive Testing Target
To get benchmark of the performance of the network and users’ experience
To monitor the progress of on-going optimisation activities
To validate new features of the RAN
To identify degradation in coverage and/or increase in interference
call setup SR,
call drop rate,
As a result of increased traffic or changes in environment
Routine drive tests should be carried out (e.g. on monthly)
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To assess impact of parameter changes
To identify poorly performing cells
To provide triggers for network upgrade decisions
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Main reasons for failed RRC connection setups:
(1) poor coverage; (2) low FACH power
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(1) poor coverage; (2) no enough resource
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(1) poor coverage (e.g. SRB/TRB reset);
(2) Strong UL/DL interference
(3) Insufficient handover area
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KPI Analysis: Inter-RAT HO SR
Data discrepancies between 3G network and 2G network have direct impact on inter-RAT HO SR.
e.g. BSIC wrong configured
GeneX Nastar: analyzing network statistics (all performance indicators).
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network for Operator
experience for Subscribers
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Coverage DT

8Connection of PS services
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