umts iub dimensioning principle and procedure v1[1].5-20100901

UMTS Iub Dimensioning Principle and Procedure Internal Open

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UMTS RNP For Internal Use Only

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RAN 12.0

UMTS Iub Dimensioning Principle and

Procedure

Prepared by UMTS RNP Date 2010-9-1

Reviewed by Date yyyy-mm-dd

Reviewed by Date yyyy-mm-dd

Granted by Date yyyy-mm-dd

Huawei Technologies Co., Ltd.

All rights reserved

2010-05-17 All rights reserved , Total14


Important Notice:Please send us your comments or requests via [email protected] .We will improve the quality of the material to meet your requirements ASAP.

Revision RecordDate Version CR ID Revision Description Author

2006-11-30 1.1 Initial transmittal Xu Haihong

2008-03-29 1.2 Add IP RAN Dimension Part Xu Haihong

2008-07-14 1.3 根据部分CR对文档进行修改 Xu Haihong

2010-05-17 1.4 Update according to RAN12.0 features Li Yuesheng

2010-09-01 1.5 Modify service IUB bandwidthLi Yuesheng

Change Request (CR) Record

CR ID

CR Originator

CR Date CR Description CR

Feedback

1 徐登宇

1、表1第二列的抬头应该“ATM over E1/T1”，而不是“ATM over IP”；2、4.6.2节，就算公共信道带宽时，为什么要乘以3 ？

Accept

2 耿飞1、在IUB口的计算原则指导书上，出现“IP over ATM”2、在下一个版本的指导书和工具上，能否直接把HSDPA的峰值速率考虑进去？

Accept



Table of Contents

1 Introduction..............................................................................................................................42 Iub Dimensioning Procedure...................................................................................................52.1 Iub dimensioning procedure..............................................................................................52.2 Iub dimensioning procedure for three main Iub transport scenarios.................................6

2.2.1 Protocol structure comparisons...................................................................................62.2.2 Service Iub bandwidth/overhead..................................................................................7

3 Iub Bandwidth Dimensioning Methodology.............................................................................93.1 CS and CS/voIP over HSPA services peak Iub bandwidth...............................................93.2 CS and CS/voIP over HSPA services Average Iub bandwidth........................................103.3 PS Iub bandwidth.............................................................................................................113.4 HSUPA Iub bandwidth.....................................................................................................113.5 HSDPA Iub bandwidth.....................................................................................................11

3.5.1 Iub bandwidth for average traffic model.....................................................................113.5.2 Iub bandwidth for HSPA End-user Experience Rate Bandwidth requirement...........12

3.6 Iub bandwidth for CCH and O&M....................................................................................123.6.1 Iub bandwidth for common control channels (CCH)..................................................123.6.2 Iub bandwidth for O&M..............................................................................................12

4 Case Study of Iub Bandwidth Dimensioning.........................................................................134.1 Input for Iub bandwidth dimensioning..............................................................................134.2 CS and CS over HSPA services peak Iub bandwidth.....................................................134.3 CS and CS over HSPA services Average Iub bandwidth................................................144.4 R99 PS Iub bandwidth.....................................................................................................144.5 HSDPA Iub bandwidth.....................................................................................................144.6 Iub bandwidth for MBMS, CCH and O&M.......................................................................15

4.6.1 Iub bandwidth MBMS.................................................................................................154.6.2 Iub bandwidth for CCH...............................................................................................154.6.3 Iub bandwidth for O&M..............................................................................................15

4.7 Total Iub bandwidth..........................................................................................................15



UMTS Iub Dimensioning Principle and ProcedureAbstract: This article presents an overview of UMTS Iub dimensioning principle and

procedure. It briefly introduces the usage of multidimensional ErlangB model in Iub

dimensioning of CS and CS/VoIP over HSPA services and that of the best effort

characteristic in Iub dimensioning of PS&HSPA services. Dimensioning methods based on

different Iub transport techs, like ATM and IP are introduced.

1 IntroductionIub is the interface between RNC and NodeB. There are mainly three kinds of Iub transport

scenarios: ATM over E1/T1, IP over E1/T1 and IP over Ethernet. Figure 1 and Figure 2

illustrates the scenario of ATM/IP over E1/T1 and IP over Ethernet.

Figure 1 ATM/IP over E1/T1

Figure 2 IP over Ethernet

The purpose of Iub dimensioning is to estimate the required Iub bandwidth and the

corresponding number of E1 pairs or IP transport bandwidth.

This document is organized as follows:

Section 1 is the introduction;

Section 2 introduces the Iub dimensioning principle and procedure and compares the

protocol structure and Iub overhead for ATM/IP over E1/T1 and IP over Ethernet;

Section 3 introduces the detailed procedure of Iub bandwidth dimensioning for services,

CCH and O&M;

Section 4 gives a case study for IP over Ethernet transmission mode.



2 Iub Dimensioning Procedure

2.1 Iub dimensioning procedure

For the multi-services in UMTS, Huawei has carried out in-depth research in the field of

multi-service network dimensioning and adopts multidimensional ErlangB model to estimate

the Iub bandwidth of CS, CS/VoIP over HSPA multi-services.

Apart from services bandwidth, Iub bandwidth dimensioning includes calculation of Iub

bandwidth occupied by MBMS, common channels and O&M. Figure 3 shows the Iub

dimensioning procedure.

Figure 3 Iub dimensioning procedure

For mixed CS, CS/VoIP over HSPA, PS and HSPA services Iub bandwidth dimensioning,

best effort characteristic of PS and HSPA is used. In other words, the spare part of Iub

bandwidth which is not used by CS services can be utilized by PS and HSPA services.

Figure 4 illustrates sharing of Iub bandwidth by CS, CS/VoIP over HSPA, PS and HSPA.


CS Traffic Voice Traffic VP TrafficCS/VoIP over HSPA TrafficGoS Requirements

Subscribers Subs per NodeB

PS Traffic PS64 Throughput PS128 Throughput PS384 ThroughputPS Retransmission

HSPA Traffic

CS, CS/VoIP over HSPA Iub Peak Bandwidth

PS Iub Bandwidth

Service Iub Bandwidth

HSPA Iub Bandwidth

Common Channel Bandwidth

O&M Bandwidth

Iub Bandwidth

Input Iub Dimensioning Output

MBMS Channel Number

MBMS Iub Bandwidth

HSPA End-user Experience Rate Bandwidth

CS, CS/VoIP over HSPA Iub Average Bandwidth

MAX

MAX


Figure 4 CS, CS/VoIP over HSPA and PS sharing resource

Therefore, the total Iub bandwidth can be obtained through the following formula:

The ultimate Iub configuration is decided by the larger one of uplink and downlink Iub

bandwidth.

2.2 Iub dimensioning procedure for three main Iub transport scenarios

2.2.1 Protocol structure comparisons

The Iub dimensioning procedures given in Figure 3 is applicable for ATM over E1/T1, IP

over E1/T1 and IP over Ethernet. In other words, the dimensioning procedure for different

Iub transport scenarios are the same though the Iub overheads may varies.

Figure 5 shows the protocol structure of three main Iub transport scenarios. From the

protocol structure, it can be seen that the service Iub overheads for three main Iub transport

scenarios are:

FP overhead, AAL2 overhead and ATM overhead for ATM over E1/T1

FP overhead, UDP/IP overhead and PPP overhead for IP over E1/T1

FP overhead, UDP/IP overhead and MAC overhead for IP over Ethernet

On the other hand, Only ATM over E1/T1 has ALCAP protocol layer.2010-05-17 All rights reserved , Total14

PS & HSPA Occupied Bandwidth

O & M Bandwidth

CCH & MBMS Bandwidth

CS, CS/VoIP over HSPA Occupied Bandwidth

Time

CS, CS/VoIP over HSPA Average Bandwidth

CS, CS/VoIP over HSPA Peak Bandwidth

Total Bandwidth


Figure 5 Protocol Structure of ATM,IP over E1/T1 and IP over Ethernet

2.2.2 Service Iub bandwidth/overhead

Based on the protocol structure, the Iub bandwidth/overhead for R99, CS/VoIP over HSPA

and HSPA service could be calculated and the results are given in Table1.

Table1 R99, CS/VoIP over HSPA service Iub bandwidth



Notes:

The Iub bandwidth per link in above table already considered:

1) The activity factor of AMR12.2k and CS/VoIP over HSPA is 0.65, and that of the other services is 1;

2) The Iub bandwidth occupied by SRB (3.4kbps) is included and the SRB activity factor is 0.1;

3) The Duty Ratio of CS/VoIP over HSPA is 0.1.

Table2 HSPA service Iub Overhead

Notes:

1) Terminal Type 1: supports HSDPA( lower than 14.4Mbps) and phase 1 / phase 2 HSUPA( 1.96Mbps or

5.76Mbps);

2) Terminal Type 2: supports 64QAM or MIMO or 64QAM+MIMO or DC-HSDPA in downlink, and 16QAM

in uplink.

Table3 MBMS/O&M/CCH Iub bandwidth



3 Iub Bandwidth Dimensioning Methodology

3.1 CS and CS/voIP over HSPA services peak Iub bandwidth

CS and CS/voIP over HSPA services peak Iub bandwidth is calculated by multidimensional

ErlangB algorithm in Huawei. Multidimensional ErlangB can estimate the respective

blocking probability of various CS and CS/voIP over HSPA services. Under a fixed Iub

bandwidth, different services have different blocking probabilities, which depend on their Iub

bandwidth usages. Multidimensional ErlangB model is illustrated in Figure 6.

Figure 6 Multidimensional ErlangB model

The resource is shared by all services in multidimensional ErlangB model, which takes good

advantage of the fact that the probability of simultaneous bursts from many independent

traffic sources is very small. The following figure illustrates the gain when the resource is

shared compared to when the resource is partitioned.

Figure 7 Partitioning Resources vs. Resources Shared

Once we know the GoS requirement of CS and CS/voIP over HSPA services, the CS

and CS/voIP over HSPA traffic per NodeB (after considering soft handover ratio) and the

service Iub bandwidth, we can calculate the CS and CS/voIP over HSPA services peak



Iub bandwidth using multidimensional ErlangB（MDE）model. This idea is shown in

Figure 8.

Note:

Iub factors means Iub bearer bandwidth including FP, AAL2 and ATM or IP overhead for service i.

Figure 8 Estimate peak Iub bandwidth using multidimensional ErlangB model

3.2 CS and CS/voIP over HSPA services Average Iub bandwidth

Of course, the average Iub bandwidth for CS and CS/voIP over HSPA services can also be

obtained, which does not guarantee the GoS requirements. The formula below is used to

calculate CS and CS/voIP over HSPA services average bandwidth:

: Soft handover overhead which does not include softer handover;

: Iub bandwidths for CS and CS/voIP over HSPA service I, shown in Table1.

3.3 PS Iub bandwidth

The calculation for PS Iub bandwidth is almost the same as that for CS and CS/voIP over

HSPA services average Iub bandwidth except that PS traffic calculation should also

consider the PS characteristics, e.g. PS burstiness, retransmission. The formula below is

used to calculate PS Iub bandwidth:


GoS Requirements

Traffic & Service Iub Bandwidth

Peak Iub Bandwidth

MDE


: Retransmission factor of PS services, which is equal to BLER/(1-BLER);

: Burst ratio of PS services and this parameter reflects the Qos requirement of PS services.

3.4 HSUPA Iub bandwidth

HSUPA usually bears Best Effort (BE) services; the calculation procedure of Iub bandwidth

for HSUPA is almost same as that for PS. HSUPA Iub bandwidth is calculated by the below

formula:

: HSUPA service Iub Overhead, shown in Table2.

3.5 HSDPA Iub bandwidth

3.5.1 Iub bandwidth for average traffic model

The calculation procedure of Iub bandwidth for HSDPA is almost same as that for HSUPA.

However, it should be noted that HSDPA does not support SHO and therefore there is no

Iub SHO overhead for HSDPA. HSDPA Iub bandwidth is calculated by the below formula:

: HSDPA service Iub Overhead, shown in Table2.

3.5.2 Iub bandwidth for HSPA End-user Experience Rate Bandwidth requirement

If HSPA End-user Experience Rate Bandwidth such as 3.6Mbps and 7.2Mbps is given, the

Iub bandwidth needed by peak rate can be calculated by the following formula:

It should be noted that the PeakRatePerNodeB is the application layer rate and the

relationship between application layer rate and physical layer rate is given in the following table:

Table1 Physical layer rate & application layer rate

Physical Layer Rate

Application Layer Rate

3.6Mbps 3.2Mbps7.2Mbps 6.4Mbps14.4Mbps 12.7Mbps



Notes:

Since peak rate is used for Iub calculation, there is no need to consider additional burst ratio;

3.6 Iub bandwidth for CCH and O&M

3.6.1 Iub bandwidth for common control channels (CCH)

Iub bandwidth for common channel mainly includes FACH and PCH for downlink while

RACH for uplink for one cell. The Iub bandwidth for downlink CCH depends on the

configurations of FACH and PCH. FACH and PCH are mapped onto the same physical

channel S-CCPCH. Generally, the typical configuration of RACH and S-CCPCH are both

one for each cell.

Herein, common Channels also includes NBAP, ALCAP consuming Iub bandwidth (For IP

transport, there is no ALCAP signaling). As the services speed gets bigger, the ratio of Iub

bandwidth consumed by NBAP, ALCAP gets so lower as to be ignored.

3.6.2 Iub bandwidth for O&M

O&M Iub bandwidth is configurable and the typical recommended value is 64kbps for both

uplink and downlink for one NodeB.

4 Case Study of Iub Bandwidth Dimensioning This chapter gives a case study for IP over Ethernet Iub bandwidth calculations. Since the

uplink and downlink Iub bandwidth calculation procedures are the same, only downlink Iub

bandwidth calculations are shown.

4.1 Input for Iub bandwidth dimensioning

The Iub bandwidth calculation is exemplified with a case study using the following traffic

model given in Table2 and the HSPA End-user Experience Rate Bandwidth (peak rate)

requirement of HSDPA is 7.2Mbps. Table2 Traffic Model

Traffic Model (Single User @ Busy Hour)Bearers Uplink Downlink GoS

AMR12.2k (Voice) 10 mErl 10 mErl 2%CS64k（Video） 1 mErl 1 mErl 2%

PS64k 1266 kbits 4227 kbits N/APS128k 0 456 kbits N/APS384k 0 380kbts N/AHSPA 3797 kbits 15188 kbits N/A



CS over HSPA 1 mErl 1 mErl 2%

Assumption:

NodeB configuration S111

Subscribers number per NodeB is 1000

Soft HO ratio is 20%

PS traffic burst ratio is 20%

HSDPA traffic burst ratio is 20%

HSDPA End-user experience rate: 7.2Mbps in Physical Layer, 6.4Mbps in

application Layer

HSDPA average Rate: 1920kpbs

HSDPA UE Type: Type 1

Retransmission ratio of PS services is 1%

Retransmission ratio of HSPA is 1%

MBMS channel number: 1 (128k)

4.2 CS and CS over HSPA services peak Iub bandwidth

For DL direction:

Voice traffic: Video call traffic:

CS over HSPA traffic:

Using MDE, the peak Iub bandwidth for CS and CS over HSPA services is

4.3 CS and CS over HSPA services Average Iub bandwidth

Average Iub needed by Voice:

Average Iub needed by Video Call:

Average Iub needed by CS over HSPA:

Average Iub needed by CS and CS over HSPA call is:

4.4 R99 PS Iub bandwidth



Average Iub needed by PS64k:



Average Iub needed by PS Services:

4.5 HSDPA Iub bandwidth

Average Iub bandwidth needed by HSDPA:

Since the 7.2Mbps physical layer rate corresponding to application layer rate 6.4Mbps,

Peak HSDPA Iub bandwidth for each NodeB is:

4.6 Iub bandwidth for MBMS, CCH and O&M

4.6.1 Iub bandwidth MBMS

Average Iub needed by MBMS:

4.6.2 Iub bandwidth for CCH

The typical Iub bandwidth of CCH (including NBAP) for S111 is

4.6.3 Iub bandwidth for O&M

The Iub bandwidth of O&M is 64kbps.

4.7 Total Iub bandwidth

DL total Iub bandwidth is:


umts iub dimensioning principle and procedure v1[1].5-20100901

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