EGPRS OPTIMIZATION

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(E)GPRS Network Optimization

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1 © Nokia Siemens Networks RN20024EN14GLN1

RN 2002(E)GPRS Explain: Chapter 4(E) GPRS Network optimization

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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

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(E)GPRS BSS Network Optimization - Structure

GSM Network Optimization• Coverage maximization • Interference reduction• Capacity optimization (air interface and connectivity)

(E)GPRS Network Optimization• Signaling capacity & resource allocation improvement• Data Rate

– Connectivity Capacity (MS-SGSN)– TSL data rate improvement and multislot usage maximization (BSS)– End to End (E2E) data rate (applications)

• Mobility improvement

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GSM Network OptimizationThe 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!!!

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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 PCU/BSC ratio• # of BCF/PCU ratio• # of Cells/PCU• # of Abis TSLs/PCU • # of DAP/PCU• Average DAP size/BCF• # of Gb links size/PCU or PSEThe 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

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(E)GPRS Network Optimization - Netact

BSCNetAct

Measurement data

Measurement administration

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.

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(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

CCCH usage and congestionTRXSIG congestionBCSU load

Data rate and Territory related KPIsNetwork 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 KPIsTBF 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!

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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.

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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 address3. 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

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Throughput analysis – Stationary- Average throughput (RLC/MAC and Application)- MCS distribution- RX Level- BLER - C/I ratio

Throughput analysis – Mobility (intra/inter PCU and RAU cell-reselection)- Cell reselection latency

- RLC/MAC- LLC- Application level

- 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

Tools for (E)GPRS Planning

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Tools for (E)GPRS PlanningAs 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-AgilentOther post-processing tools can help to analyze the measurements captured by the drive test tools, protocol analyzers and application testers.

Documents

EGPRS OPTIMIZATION