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BSC3153 Nokia GSM/EDGE BSS, Rel. BSS13, BSC and TCSM, Rel. S13, Product Documentation, v.1

BSS (BSC) Traffic Handling Capacity, Network Planning and Overload Protection

DN9812388 Issue 9-0 en 29/02/2008

# Nokia Siemens Networks

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BSS (BSC) Traffic Handling Capacity, Network Planning and Overload Protection

The information in this document is subject to change without notice and describes only the product defined in the introduction of this documentation. This documentation is intended for the use of Nokia Siemens Networks customers only for the purposes of the agreement under which the document is submitted, and no part of it may be used, reproduced, modified or transmitted in any form or means without the prior written permission of Nokia Siemens Networks. The documentation has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. Nokia Siemens Networks welcomes customer comments as part of the process of continuous development and improvement of the documentation. The information or statements given in this documentation concerning the suitability, capacity, or performance of the mentioned hardware or software products are given as is and all liability arising in connection with such hardware or software products shall be defined conclusively and finally in a separate agreement between Nokia Siemens Networks and the customer. However, Nokia Siemens Networks has made all reasonable efforts to ensure that the instructions contained in the document are adequate and free of material errors and omissions. Nokia Siemens Networks will, if deemed necessary by Nokia Siemens Networks, explain issues which may not be covered by the document. Nokia Siemens Networks will correct errors in this documentation as soon as possible. IN NO EVENT WILL NOKIA SIEMENS NETWORKS BE LIABLE FOR ERRORS IN THIS DOCUMENTATION OR FOR ANY DAMAGES, INCLUDING BUT NOT LIMITED TO SPECIAL, DIRECT, INDIRECT, INCIDENTAL OR CONSEQUENTIAL OR ANY LOSSES, SUCH AS BUT NOT LIMITED TO LOSS OF PROFIT, REVENUE, BUSINESS INTERRUPTION, BUSINESS OPPORTUNITY OR DATA, THAT MAY ARISE FROM THE USE OF THIS DOCUMENT OR THE INFORMATION IN IT. This documentation and the product it describes are considered protected by copyrights and other intellectual property rights according to the applicable laws. The wave logo is a trademark of Nokia Siemens Networks Oy. Nokia is a registered trademark of Nokia Corporation. Siemens is a registered trademark of Siemens AG. Other product names mentioned in this document may be trademarks of their respective owners, and they are mentioned for identification purposes only. Copyright Nokia Siemens Networks 2008. All rights reserved.

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# Nokia Siemens Networks

DN9812388 Issue 9-0 en 29/02/2008

Contents

ContentsContents 3 List of tables 4 List of figures 5 Summary of changes 7 1 2 3 3.1 3.2 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Planning the cellular network 9 BSC nominal capacity and dimensioning 13 Planning of basic GSM radio network parameters 19 Location Area Definition and CCCH Parameters 19 Abis LAPD link and CCS7 link dimensioning 26 BSS overload protection and flow control 29 BSS overload protection 29 System throughput versus offered load 34 Overload protection mechanisms 35 How to know when the system is running above the nominal load? AS7 overload protection implementation 46 The LAPD counters used to check the LAPD load statistics 46 Indications on overload protection mechanisms 47 Timers 50 Parameters 50

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BSS (BSC) Traffic Handling Capacity, Network Planning and Overload Protection

List of tables Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Connectivity of logical PCUs 17

Extreme case 1: theoretical maximum (maximum paging capacity in radio interface, TMSI4 in use, for example 4 TMSIs in each paging) 20 Extreme case 2: theoretical minimum (minimum paging capacity in radio interface, IMSI1 in use only, for example 1 IMSI in each paging) 21 Parameter values for the LA size for small cells 22 23

Parameter values for the LA size for medium size cells Parameter values for the LA size for large cells 23

Parameter values for the LA size for extra large cells LA with 2 cells Combined and 8 cells Noncombined

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# Nokia Siemens Networks

DN9812388 Issue 9-0 en 29/02/2008

List of figures

List of figures Figure 1. Figure 2. BSS block diagram 30 34

System throughput versus offered load

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# Nokia Siemens Networks

DN9812388 Issue 9-0 en 29/02/2008

Summary of changes

Summary of changes

Changes between document issues are cumulative. Therefore, the latest document issue contains all changes made to previous issues.

Changes made between issues 9-0 and 8-0In chapter Planning of basic GSM radio network parameters, more information on 32 kbit/s LAPD links and CCS7 links has been added to section Abis LAPD link and CCS7 link dimensioning.

Changes made between issues 8-0 and 7-1Modified the name of chapter BSS overload protection to BSS overload protection and flow control and included the information from Flow and Overload Control document into it. Structural changes in chapter BSC nominal capacity and dimensioning. Updated the Traffic Handling Capacity information with data for the new BSC3i variants. Updated the PCU Capacity and Overload Protection topic with changes due to the introduction of (E)GPRS Inactivity alarm.

Changes made between issues 7-1 and 7-0Editorial changes.

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# Nokia Siemens Networks

DN9812388 Issue 9-0 en 29/02/2008

Planning the cellular network

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Planning the cellular networkThis is an overview of how to plan and configure the GSM/EDGE network implemented by the Nokia base station subsystem (BSS) in such a way that the performance experienced by the end-users is not limited by an overload in the BSS. The general procedure of radio network planning is explained, with a detailed description of CCCH parameters. Note that the network planning examples are just generic examples and as such they do not necessarily represent the optimal solution for any particular network. Commonly cellular network (BSS) planning has the following main targets:.

to achieve the required radio coverage with the maximum time and location probability (more than 90%) to maximise the network capacity (Erl/km2) with a limited frequency band (MHz) by reusing frequencies to reach a good quality of service (QoS) with a minimum level of interference to minimise the number of network elements and transmission needed (MSC, BSC, BTS, ...) and therefore the cost of the network infrastructure

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The described network planning process is an optimisation process which needs information about network elements, system properties (GSM, GPRS, EDGE), planning of the environment, topography of the service area, existing facilities of the operator, distribution of the subscribers, and the estimated future growth of subscribers. Network dimensioning is done so that the coverage and capacity requirements based on subscriber growth forecast are fulfilled. After the number of network elements and commercial aspects is available, the business plan can be made.

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BSS (BSC) Traffic Handling Capacity, Network Planning and Overload Protection

An important activity of network planning is the base station subsystem (BSS) parameter planning and radio network verification and optimisation. This is based on experience gained during the trial period of the network. The general results and documents from network planning are:.

List of sites and network elements Coverage predictions and measurements Frequency plan and interference analysis Capacity calculations BSS parameter plan Transmission network plan

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During the network's existence, knowledge about its operation and subscriber behaviour will improve. The network will also expand in terms of capacity and coverage because of continuous subscriber growth. Therefore, network planning is also a continuous process which tries to minimise the modifications to the existing network while preparing extension plans. Testing and tuning are also needed at each new stage of the network to ensure good quality of service. In the planning and optimisation phase we also need to verify that all the network elements and the interfaces between them have enough capacity for the given network configuration providing good quality for all subscribers with their estimated reference call mix. The following planning aspects should also be checked: 1. BSC erlang capacity load (for example the BSC traffic handling (erlang)) capacity must be large enough for the planned network configuration and traffic load. The optimised location area (LA) and routing area (RA) size and the common control channel (CCCH) structure (for example combined, noncombined CCCH) is defined for the given network in order to keep the paging load in the required physical limits in the BSC Abis LAPD links (16 kbit/s, 32 kbit/s, or 64 kbit/s) and in the radio interface.

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