OptimizationPrimary colours:
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RN 2002
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Presentation / Author
Module objectives
After completing this learning element, the participant will be able to:
Theory:
Sketch the (E)GPRS Optimisation process and the main optimisation tasks
List the most important tools for (E) GPRS planning and optimisation
Know some important KPIs
GSM Network Optimization
(E)GPRS Network Optimization
Data Rate
End to End (E2E) data rate (applications)
Mobility improvement
Presentation / Author
* © Nokia Siemens Networks
GSM Network Optimization
The optimal GSM network from PSW services point of view has:
As high signal level as possible
It means that even the indoor signal level should be high enough to have MCS9 for getting the highest data rate on RLC/MAC layer.
As low interference as possible
The aim of having high C/I is to avoid throughput reduction based on interference.
Enough capacity
Enough BSS hardware capacity (interface and connectivity) is needed to provide the required capacity for PSW services in time. Both CSW and PSW traffic management should be harmonized with the layer structure and long term plans.
As few cell-reselection as possible
The dominant cell coverage is important to avoid unnecessary cell-reselections for mobility. The PCU allocation can help to reduce the inter PCU cell reselections.
Dominant cell structure can help to maximize the signal level and reduce the interference, too.
Features
All the features should be used which can improve the PSW service coverage, capacity and quality in general. Examples:
Since S14 it is possible to use (E)GPRS on DFCA TRXs
The (E)GPRS coverage can be used in the extended area
Before any (E)GPRS optimization related activities the GSM network should be optimized!!!
Presentation / Author
GSM Network Optimization - features
The following information should be collected related to the volume of network element and connectivity usage of network elements:
of BSCs
# of Gb links size/PCU or PSE
The connectivity limits can be estimated based on the list above.
The following information should be collected related to terminals used in the network:
Ratio of AMR capable terminals
Ratio of R97, R98, R99, R4, R5, R6, R7 capable terminals
Ratio of the different tsl capability terminals (like 1+2, 4+2, dual carrier capable, etc)
The capacity requirements and feature possibilities can be analyzed by the list above
Presentation / Author
(E)GPRS Network Optimization - Netact
NetAct Reporter is a family of applications for processing, analysing, and visualising performance data that is coming from different sources. Raw data becomes meaningful information that is visualised in graphical and textual reports. NetAct Reporter gives a view of the network and service performance and makes it possible to analyse network data, create reports based on the data and distribute the information.
NetAct
BSC
(E)GPRS Network Optimization - KPI
NetAct reporter counter and KPI analysis gives exact picture about network performance.
The analysis of KPIs can be based on the following list:
Signaling related KPIs
Network usage (RLC Payload, Packet Erlangs, etc)
Data rate (CS - MCS selection, retransmission, UL BLER, throughput, etc.)
Blocking (timeslot sharing, soft blocking, hard blocking, EDAP congestion, PCU congestion, Gb congestion, etc)
Mobility related KPIs
TBF release due to flash
Features like NCCR and NACC will not only increase the performance of the network in general, additionally better statistics will get available, helping again to increase the performance of the system!
Presentation / Author
Tools for (E)GPRS Planning
The field measurements and drive tests are usually used for analyzing accessibility, data rate measurements in stationary and mobility environment to see the end-users perception.
PSW (Packet Switched) accessibility analysis
The PSW accessibility measurements measure the success rate and time period of access to the PSW core (GPRS attach and PDP context activation), as well as the access to BSS (TBF establishment).
- Accessibility measurements contain GPRS attach/detach, PDP context activation and TBF establishment/release measurements.
- The attach/detach, PDP context activation/deactivation and Routing Area Update are LLC related measurements (MS-SGSN) and can be measured and trouble shooted.
Presentation / Author
TCP/IP measurements
Useful commands in IP networks to estimate end to end performance:
1. Ping: The command Ping can be used to check the network Round Trip Time to one or several remote hosts. The command runs an application which generates an ICMP (Internet Control Message Protocol) Echo Request data packet (this is an IP packet with Protocol = 1, Type field = 8) which is sent to the host. An Echo Reply is expected from the host (this is an IP packet with Protocol = 1, Type field = 0
Example: Ping 0.0.0.0 – 1000 where 0.0.0.0 is an IP address and 1000 the size of the ping package in Bytes
2. Tracert: The Tracert (trace route) tool checks the route to a destination by sending ICMP (Internet Control Message Protocol) Echo Request data packets with different TTL (time to live) values starting with TTL=1 for the first packet, then TTL=2 for the next packet,…
Example: tracert 0.0.0.0 where 0.0.0.0 is an IP address
3. PathPing: The tool PathPing extends the features of the Ping and Tracert commands and offers more information than those commands do.
During a certain time, data packets are sent to each node contained in the path to a certain destination. Statistics are calculated based on the data packets which are sent back from these nodes. Since the PathPing command shows losses of packets for each of the nodes and each connection, this command can be used to localize those nodes and/or connections making problems.
Example: pathping 0.0.0.0 where 0.0.0.0 is IP address
Presentation / Author
- MCS distribution
- RX Level
- Cell reselection latency
- Retransmission based on cell reselection
The throughput analysis is always the analysis of signal level and C/I, because low data rate can be caused by signal, capacity and interference issues
Presentation / Author
As supplement to drive tests from network side protocol analyzer provide real-time monitoring and analysis on different interfaces. Several vendors supported by NSN
Nethawk
Tektronix
Agilent
Other post-processing tools can help to analyze the measurements captured by the drive test tools, protocol analyzers and application testers.
Presentation / Author