3.WCDMA RNP RNC Area Planning Guidance-20040716-A-1.1

Huawei Technologies Co. Ltd.

Product version Confidentiality level

V100R001 For internal use only

Product name: WCDMA RNP Total pages: 19

WCDMA RNP RNC Area Planning

Guidance For internal use only

Prepared by URNP-SANA Date 2003-08-21

Reviewed by Date

Reviewed by Date

Approved by Date

Huawei Technologies Co., Ltd.

All rights reserved

WCDMA RNP RNC Area Planning Guidance For internal use only

10-4-30 Confidential Page 2 , Total 19

Revision Record

Date Revision version

Change Description Author

2003-08-21 1.00 Initial transmittal Zhou Xinjie

2003-09-03 1.10 Revision based on review opinions Zhou Xinjie



Table of Contents

1 Overview .................................................................................................................................. 6

2 RNC Area Planning Procudures .............................................................................................. 7

3 RNC Area Restriction Factor Analysis ..................................................................................... 8

3.1 RNC Processing Capability Restriction .............................................................................. 9

3.2 Administration Area Restriction ........................................................................................ 11

3.3 Transmission Interface Restriction ................................................................................... 12

3.4 Core Network (CN) Capacity Restriction ......................................................................... 12

3.5 Reserving Resource for Network Expansion ................................................................... 12

4 RNC Area Planning Rule ....................................................................................................... 16

4.1 Continuous Coverage Rule .............................................................................................. 16

4.2 Reducing Signaling/Data Traffic between RNCs ............................................................. 17

4.3 Traffic Balancing ............................................................................................................... 17

5 Summary of Pending Problems ............................................................................................. 18



List of Figures

Figure 1 Location of RNC in the network and the peripheral interfaces .................................... 6

Figure 2 RNC area planning procedures .................................................................................... 8

Figure 3 Scheme 1: Before expansion ..................................................................................... 13

Figure 4 Scheme 1: After expansion ........................................................................................ 13





Figure 9 RNC area planning: continuous coverage ................................................................. 16

Figure 10 RNC area planning: Discontinuous coverage .................................................. 17

Figure 11 RNC area planning: traffic balanced ................................................................. 18

Figure 12 RNC area planning: traffic unbalanced............................................................. 18



WCDMA RNP RNC Area Planning Guidance

Key words: WCDMA, RNC area, network planning

Abstract: This document introduces RNC area planning in the WCDMA radio network planning,

including the definition, identification, functions of RNC area, as well as the RNC area

planning process, the factors determining the RNC area size and other issues to be

discussed in the RNC area planning.

List of abbreviations:

Abbreviations Full spelling

RNP Radio Network Planning

WCDMA Wideband Code Division Multiple Access

PLMN Public Land Mobile Network

UTRAN UMTS Terrestrial Radio Access Network

RNC Radio Network Controller

GSM Global System for Mobile communications

BSC Base Station Controller

CRNC Control RNC

SRNC Serving RNC

WRBS WCDMA RNC Business Subrack

WFMR WCDMA RNC radio frame processing board

WOSE WCDMA RNC Single mode Optical interface board of E1/T1

WXIE WCDMA RNC general E1/T1 Interface board



1 Overview

RNC (Radio Network Controller) is an NE controlling the UTRAN radio

resources, just like the BSC in the GSM system. The RNC is connected to the

NobeB, 3G CN (including 3G MSC and 3G SGSN) and other RNCs with the Iub

interface, Iu interface and Iur interface respectively. The RNC mainly implements the

L2 processing and RRC processing of the Uu interface, as well as the control plane

and user plane processing of the Iu/Iub/Iur interface, implements connection and

disconnection, and realizes the radio resource management functions of handover,

power control and call admission.

Figure 1 Location of RNC in the network and the peripheral interfaces

RNC area refers to a radio coverage area [1] composed of one or more cells

controlled by the same RNC. Different RNCs are identified by RNC-Id. The RNC-Id

together with the PLMN-Id uniquely identifies an RNC in the whole world, that

means,

Global RNC-Id = PLMN-Id + RNC-Id

RNC-Id or Global RNC-Id is used to identify an RNC in the Iu, Iub or Iur

interface.

RNC area planning is to plan the number of RNCs within the coverage range,

the number of cells controlled by each RNC and the coverage range of each RNC.

The RNC planning, a part of radio network planning [2], is to plan the RNC area

based on the planning result of the number of NodeB and the number of cells within

the coverage range, the coverage range and capacity of various cells, as well as the

interface traffic. For a complete radio network planning project, the final output of



Network Planning Report of XXX Project should contain the number of RNCs for

network planning and the dimensioning of RNC area.

This document depicts the RNC area planning process and the relevant factors.

Chapter 2 introduces the RNC area planning flow; Chapter 3 discusses the relevant

restriction factors in the RNC dimensioning; Chapter 4 describes the relevant rules

for the RNC area planning; Chapter 5 summarizes the pending problems.

2 RNC Area Planning Procudures

The RNC area planning includes the two parts: RNC number dimensioning and

RNC area planning. The former part calculates the number of RNCs required

according to the number of NodeBs, the number of cells, the capacity of each cell

and the interface traffic (including interface type and the number of links). It is a part

of radio network dimensioning. The latter part estimates the coverage range of a

RNC according to the number of RNCs and the coverage range of each cell in the

dimensioning result. As the coverage range of each cell is determined by means of

simulation output of the network planning, the coverage range of an RNC area can

be determined after the RNC that the cells belong to is identified.

Input of RNC area planning:

The Number of NodeBs and the number of cells in the coverage range, the

capacity of each cell, the coverage range of each cell and the planned interface

traffic

Output of RNC area planning:

The number of RNCs in the coverage range and the RNC-Id of the cells

Figure 2 shows the RNC area planning procedures.



Start

Determine the number of RNCs

based on the network operation and

maintenance organization structure

Calculate the actual processing capability

of the RNC (traffic/flow/the number of

cells/the number of NodeBs supported)

Whether RNC specification

supports?

The number of

RNCs

RNC cell split

The estimation result of

traffic/flow/the number of cell/

the number of NodeBs

RNC processing capability

Other restrictions (transport

resource/CN resource)

Cell converage range/site

distribution

Actual geotraphic

environment

RNC cell division

RNC_ID of each

cell

N

Y

End

Radio Network Calculation

Radion Network Planning

Figure 2 RNC area planning procedures

3 RNC Area Restriction Factor Analysis



Too small RNC area or too many RNCs will lead to more RNC relocation

procedures, which increases the signaling traffic and call drop rate. Moreover, the

over-small RNC area requires more transmission resources of the Iur/Iu interface,

and it may have influence on the performance of the radio resource management

algorithm. Therefore, this document only analyzes the restriction factors of the upper

limit in the RNC area planning (ignoring the restriction factors of the lower limit in the

RNC area planning.)

The influences of over-small RNC area on the radio resource management

algorithm are as followings:

Because the signaling exchange between different RNCs has delay, and

the bandwidth configured for the Iur interface is limited, the increase of the

RNCs may lower the performance of algorithms, for example, the soft

handover algorithm. On the other hand, if no Iur interface is configured

between RNCs or the Iur resource is restricted, the soft handover between

RNCs will be substituted by intra-frequency hard handover, which lowers

the handover success rate.

Some of radio resource management algorithms in the RNC are

implemented with internal signaling of the RNC and not supported by Iur

interface singaling. This results in that if the CRNC and the SRNC is not the

same one, some radio resource management algorithms do not function.

For example, the inter-frequency load balancing algorithm monitors loading

of cells and issues commands of handover to some UEs to achieve balance

among cells. The load monitoring is cell-oriented, and is implemented by

the CRNC; the handover is connection-oriented, and is implemented by the

SRNC. The command of handover based on load is internal signaling of

one RNC and there is no relevant message over Iur interface Therefore,

when the SRNC and the CRNC are respective ones, the inter-frequency

load balancing algorithm cannot be supported.

3.1 RNC Processing Capability Restriction1

The size of the RNC area is mainly determined by some features of the RNC

itself, such as:

The capacity of the RNC (the number of equivalent voice users and the

number of CEs)

1 The RNC performance parameters in Section 3.1 “RNC Processing Capability” are based on the BSC6800

V100R002. However, the exact operation should refer to the latest specifications due to the version update.



The number of E1 links of the Iub interface that can be provided by the

RNC

The number of cells supported by the RNC

The number of NodeBs supported by the RNC

After the number of NodeBs, the number of cells and the capacity of various

cells are figured out by dimensioning, the RNC areas will be planned according to

these results.

1. Calculating the number of RNC2 based on the capacity of the RNC

(the number of equivalent voice users, or the number of Erlangs or the

number of CEs)

Each WFMR board supports up to 250 of 12.2K equivalent voice users, each

WRBS frame can be configured with up to 10 of WFMR cards, and each RNC

contains up to 16 of WRBS frames So one RNC can accommodate 40000

equivalent voice users at the maximum. Based on the planned number of equivalent

voice users to be supported by a RNC, the number of RNCs to be configured

RNC_1 can be calculated as followings:

RNC_1= [The number of equivalent users to be supported by the RNC /40000]

Or

RNC_1= [The number of Erlangs to be supported/40000] (if the number of

Erlangs is provided in the planning)

Or

RNC_1= [The number of CEs to be supported/40000] (if the number of CEs is

provided in the planning)

2. Calculating the number of RNCs34

based on the number of E1 links to

be provided by the Iub interfaces.

Generally, the Iub interface is realized with the WBIE or WOSE/WOME interface

board in the WRBS frame. Either two WBIE boards or two WOSE/WOME boards,

but not any mixture of them, can be configured in the same WRBS frame. One WBIE

2 In Huawei RNC, the number of CEs, the number of Erlangs and the number of equivalent voice users are

equivalent for 12.2k, without any difference. 3 Here is the calculation based on the number of E1 links of the Iub interface only. The Iub interface can also use

the ATM over STM-1 optical interface provided by the WLPU, which is seldom applied. 4 The Iur interface, a logic interface, can be connected through the fiber provided by the WLPU board, or through

the E1 of the WBIE/WOSE board, or connect different RNCs via the CN through the Iu interface. It depends on the specific situation. In the calculation of the RNC number based on the E1 number, the Iur interface traffic is not



board can provide 32 E1s, and one WOSE/WOME board can provide 63 E1s. One

RNC contains 16 WRBS frames at the maximum. Therefore, each RNC supports

2016 E1s at the maximum. Based on the planned number of E1 links in Iub interface

to be supported by the RNC, the number of RNCs to be configured RNC_2 can be

calculated as followings:

RNC_2= [The number of E1 links of the Iub interface to be supported/2016]

3. Calculating the number of RNCs based on the number of cells to be

supported

Each WFMR board supports 16 cells at the maximum, each WRBS frame can

be configured with 10 WFMR boards at the maximum, and each RNC contains 16

WRBS frames at the maximum, so one RNC can support 2560 cells at the maximum.

Based on the planned number of cells to be supported by the RNC, the number of

RNCs to be configured RNC_3 can be calculated as follows:

RNC_3= [The number of cells to be supported/2560]

4. Calculating the number of RNCs based on the number of NodeBs to be

supported

When NodeBs are not cascaded, each WBIE board can support 32 NodeBs at

the maximum, each WRBS frame is configured with two WBIE cards, and each RNC

contains 16 WRBS frames at the maximum, so one RNC can support 1024 NodeBs

at the maximum. Taking cascade of NodeB into account, one RNC can support 1280

NodeBs. Based on the planned number of NodeBs to be supported by the RNC, the

number of RNCs to be configured RNC_4 can be calculated as followings:

RNC_4= [The number of NodeBs to be supported/1280]

5. Finally, the number of RNCs required is MAX {RNC_1, RNC_2, RNC_3,

RNC_4}.

3.2 Administration Area Restriction

The size of the RNC is subject to the organization structure of the operator’s

network. Generally, the operator defines the network’s operation & maintenance

structure according to the administration areas. The RNC area planning should be

consistent with the network’s operation & maintenance structure. Please plan and

set the RNC area according to the network’s operation & maintenance structure after

well communicating with the operator.

considered for the moment.



Generally speaking, RNC is a part of the local access network. A RNC will not

be used crossing the local network. So the upper limit of RNC area is limited by the

administration area. Even though a RNC can support more cells with larger capacity,

it can act as the radio network controller only, being limited by the size of the

administration area of a certain level. This case occurs mostly in the area where

RNC capacity is available more than required.

3.3 Transmission Interface Restriction

An outstanding feature of the WCDMA is providing more high-rate data services.

This greatly increases the demand for the transmission resource of the Iu/Iur/Iub

interface. If the transmission resource that can be provided at the location of the

RNC is not enough, the processing capacity of the RNC will be limited, thus the size

of the RNC area is limited. The transmission interface resource restricts the size of

the RNC area as followings:

The number of Iu/Iur/Iub interfaces that can be provided -> The number of E1s

connected with the RNC ->Size of RNC area

3.4 Core Network (CN) Capacity Restriction

The CN capacity restriction means that the MSC/SGSN capacity restricts the

RNC capacity, which further restricts the size of the RNC area.

Generally speaking, if 3G MSC is used, the capacity of the MSC is sufficient,

and will not restrict the capacity of the RNC. However, if the operator considers the

factors of low cost and smooth upgrading, the 2G MSC scheme will be adopted for

the CN. When the 2G MSC is connected to the 3G RNC, the capacity of the 3G RNC

will be restricted. Generally, the capacity of the MSC of the existing 2G network is

400,000 of equivalent voice users. Suppose that the current percentage of utility is

60%, and in the remaining capacity 20% should be left for redundancy according to

the engineering experience, so there is the capacity of 80,000 of equivalent voice

users could be used for accessing 3G RNC. Therefore, the MSC will be the

bottleneck of the system capacity. Because the Iu-Flex mode is not available now (It

is the R5 feature, which can be hardly realized so far), it means one RNC cannot be

connected with multiple MSCs. So the capacity bottleneck of the MSC leads to the

capacity bottleneck of the RNC, which further limits the size of RNC area. The

MSC/SGSN capacity restricts the size of the RNC as followings:

SGSN/MSG capacity -> RNC capacity -> RNC area size

3.5 Reserving Resource for Network Expansion



With the popularization of the WCDMA network and the development of new

services, the number of users and the requirements for the capacity increase year by

year. The capacity expansion of NodeB can be realized by means of increasing the

transmit power, adding module, adding carrier frequency and splitting cells. The

capacity expansion of the RNC can be realized with one of the following three

schemes:

1. Installing new RNC, with new NodeBs

Area_2Area_1

Com3

RNC_1

NodeB_A1 NodeB_B1 NodeB_C1 NodeB_D1

Figure 3 Scheme 1: Before expansion

Area_2Area_1

Com3

RNC_1

NodeB_A1 NodeB_B1NodeB_C1

NodeB_D1

Com3

RNC_2

NodeB_A2 NodeB_B2

NodeB_C2NodeB_D2

Figure 4 Scheme 1: After expansion

Advantages: A small number of RNCs before expansion, without influence on

the existing NodeB.

Disadvantage: Large traffic between RNC

2. Installing new RNC, with cutovering some NodeBs



Area_2Area_1

Com3

RNC_1



Area_2Area_1

Com3

RNC_1


NodeB_D1

Com3

RNC_2

NodeB_A2 NodeB_B2

NodeB_C2NodeB_D2


Advantages: A small number of RNCs before expansion, and small traffic

between the RNCs.

Disadvantages: Influence on the existing NodeB

3. Reserving some RNC resource in advance, and adding NodeBs



Area_2Area_1

Com3

RNC_1


Com3

RNC_2


Area_2Area_1

Com3

RNC_1


NodeB_D1

Com3

RNC_2

NodeB_A2 NodeB_B2

NodeB_C2NodeB_D2


At the initial stage of network construction, the capacity configuration of the

RNC hardware or that of the software License does not reach the maximum

specification of the RNC. The capacity expansion can be performed by means of

grand more license or adding hardware.

Advantage: Expansion imposes no influence on the existing NodeB; small traffic

between RNCs

Disadvantages: Several RNCs are to be configured at the initial stage.



Summarizing the analysis above, in order to avoid the influence of the

expansion of RNC and NodeB over the existing network, avoid service interruption

caused by cutover, and avoid excessive inter-RNC handover and Iur interface traffic,

the third scheme is preferable. When planning the RNC area, reserve resource for

network expansion according to the expectation of user and capacity increase. Then

calculate the number of RNCs based on the maximum capacity/the number of

cells/the number of NodeBs/the number of links after communicating and achieving

agreement with the customer.

4 RNC Area Planning Rule

In the RNC area planning process, the number of RNCs in a local network is

planned based on the restriction factors as mentioned in Chapter 3. In addition,

please conform to the following rules when determine which cell to be included in a

certain RNC area.

4.1 Continuous Coverage Rule

When planning a certain RNC area, the continuous coverage rule should be

followed, that means to put subordinate all the cells in a continuously covered area

into one RNC, avoiding discontinuous coverage of a RNC area (that is the area

covered by an RNC is not continuous). This rule can reduce the number of cells on

the edge of an RNC area, so as to reduce the RNC handover and increase the

handover success rate, thus lowering the signaling and data traffic between RNCs,

utilizing RRM algorithms as completely as possible, at last improving satisfaction

degree of end users.

Com3 Com3

RNC_Area_1RNC_Area_2

Figure 9 RNC area planning: continuous coverage



Com3 Com3

RNC_Area_1

RNC_Area_2 RNC_Area_2

Figure 10 RNC area planning: Discontinuous coverage

4.2 Reducing Signaling/Data Traffic between RNCs

In the planning of a RNC area, it is necessary to make use of the environmental

factors as much as possible to reduce the signaling/data traffic between RNCs, so

as to avoid frequent soft handover between RNCs.

In the city with high-volume traffic, if two or more RNC areas exist, the RNC

areas can be divided by the mountain or river within the city, so as to minimize the

overlap among cells of two RNC areas. If such a geographic feature is not available,

two RNCs area should not be bordered as parallel or vertical to streets or roads.

Moreover, the boundary should not be overlap a street or cross the place with

high-volume traffic (like shopping mall). In the border area of the urban and suburb,

the RNC boundary should be placed at the base station at the side of suburb instead

of the border are of high-volume traffic, so as to avoid frequent soft handover

between RNCs.

4.3 Traffic Balancing

In the city with high-volume traffic, if two or more RNC areas exist, the number

of cells and the traffic of each RNC should be balanced. This can avoid call

admission failure or call drop caused by RNC overload and resource restriction, and

lower the failure possibility of the equipment under high load.



Com3 Com3


Figure 11 RNC area planning: traffic balanced

Com3 Com3


Figure 12 RNC area planning: traffic unbalanced

5 Summary of Pending Problems

The pending problems at present are as followings:

The RNC processing capability includes the RNC processing capacity, the

number of NodeBs and the number of cells and the number of Iub links, but does not

include other uncertain factors with bottleneck, for example, the number of

always-online users in the PS domain supported by the RNC.



List of references:

[1] 3GPP TS 23.002 v3.6.0 (Release 99), 2002/09

[2] Wang Mingmin, WCDMA RNP RNC Operation Guide Ver 1.0, RNS Subdivision of Shanghai

Research Center 2003/04/23

Date post:	24-Oct-2014
Category:	Documents
Upload:	khurrambilal01
View:	123 times
Download:	9 times

3.WCDMA RNP RNC Area Planning Guidance-20040716-A-1.1

Documents