Transmission resource management

Transmission Resource Management
SRAN5.0

Feature Parameter Description

Issue

03

Date

2011-09-30

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2011. All rights reserved.
No part of this document may be reproduced or transmitted in any form or by any means without prior
written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions
and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.
All other trademarks and trade names mentioned in this document are the property of their respective
holders.

Notice
The purchased products, services and features are stipulated by the contract made between Huawei and
the customer. All or part of the products, services and features described in this document may not be
within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements,
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The information in this document is subject to change without notice. Every effort has been made in the
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Huawei Technologies Co., Ltd.
Address:

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Website:

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SingleRAN

Contents

Contents
1 Introduction ................................................................................................................................1-1
1.1 Scope ............................................................................................................................................ 1-1
1.2 Intended Audience ........................................................................................................................ 1-1
1.3 Change History.............................................................................................................................. 1-1

2 Overview of TRM .......................................................................................................................2-1
2.1 Definition of TRM........................................................................................................................... 2-1
2.2 Structure of TRM Functions .......................................................................................................... 2-1
2.3 Similarities and Differences Between 2G, 3G, and Co-Transmission Systems ............................ 2-3
2.3.1 Transmission Resources ...................................................................................................... 2-3
2.3.2 Load Control ......................................................................................................................... 2-3
2.3.3 User Plane Processing and QoS.......................................................................................... 2-4
2.3.4 Differences of Co-TRM From 2G TRM and 3G TRM ........................................................... 2-5
2.4 Benefits of TRM ............................................................................................................................. 2-5

3 Transmission Resources ........................................................................................................3-1
3.1 Overview of Transmission Resources ........................................................................................... 3-1
3.2 Physical Transmission Resources ................................................................................................ 3-3
3.2.1 Physical Layer Resources for ATM Transmission ................................................................ 3-4
3.2.2 Physical Layer Resources for TDM Transmission................................................................ 3-4
3.2.3 Physical and Data Link Layer Resources for HDLC Transmission ...................................... 3-4
3.2.4 Physical and Data Link Layer Resources for IP Transmission............................................. 3-4
3.3 Logical Ports and Resource Groups ............................................................................................. 3-5
3.3.1 Introduction to LPs................................................................................................................ 3-5
3.3.2 ATM LPs at the RNC ............................................................................................................ 3-7
3.3.3 IP LPs at the BSC/RNC/MBSC ............................................................................................ 3-8
3.3.4 LPs at the NodeB ................................................................................................................. 3-9
3.3.5 LPs at the BTS ................................................................................................................... 3-10
3.3.6 Resource Groups at the BSC/RNC .................................................................................... 3-10
3.4 Path Resources ........................................................................................................................... 3-10
3.4.1 AAL2 Paths ......................................................................................................................... 3-10
3.4.2 IP Paths .............................................................................................................................. 3-10
3.5 Networking Application ................................................................................................................ 3-12
3.5.1 2G and 3G Networking ....................................................................................................... 3-12
3.5.2 Co-Transmission Networking ............................................................................................. 3-13

4 Quality of Service .....................................................................................................................4-1
4.1 Overview ....................................................................................................................................... 4-1
4.2 Transport Priorities ........................................................................................................................ 4-1
4.2.1 DSCP .................................................................................................................................... 4-1
4.2.2 VLAN Priorities ..................................................................................................................... 4-2

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Contents

4.2.3 Priority Queues ..................................................................................................................... 4-4
4.2.4 Priority Queues and Rate Limiting in the NodeB .................................................................. 4-5
4.3 Service QoS .................................................................................................................................. 4-6
4.4 Transmission Resource Mapping .................................................................................................. 4-6
4.4.1 Traffic Bearers ...................................................................................................................... 4-6
4.4.2 Transport Bearers ................................................................................................................. 4-7
4.4.3 Mapping from Traffic Bearers to Transport Bearers ............................................................. 4-7
4.5 Summary ..................................................................................................................................... 4-12

5 Load Control ..............................................................................................................................5-1
5.1 Overview of Load Control .............................................................................................................. 5-1
5.2 Definition and Calculation of Transmission Load .......................................................................... 5-2
5.3 Calculation of Reserved Bandwidth .............................................................................................. 5-2
5.3.1 Calculation of Bandwidth Reserved for 2G Signaling .......................................................... 5-2
5.3.2 Calculation of Bandwidth Reserved for Traffic ..................................................................... 5-3
5.4 Load Thresholds............................................................................................................................ 5-4
5.5 Admission Control ......................................................................................................................... 5-4
5.5.1 Admission Process ............................................................................................................... 5-5
5.5.2 Admission Strategy ............................................................................................................... 5-5
5.5.3 Load Sharing ........................................................................................................................ 5-8
5.5.4 Load Balancing ..................................................................................................................... 5-9
5.5.5 Preemption ......................................................................................................................... 5-11
5.5.6 Queuing .............................................................................................................................. 5-12
5.6 Load Reshuffling and Overload Control ...................................................................................... 5-12
5.6.1 Congestion Detection ......................................................................................................... 5-12
5.6.2 Overload Detection ............................................................................................................. 5-13
5.6.3 Congestion and Overload Handling ................................................................................... 5-14
5.7 Summary ..................................................................................................................................... 5-15

6 User Plane Processing ............................................................................................................6-1
6.1 Overview of User Plane Processing.............................................................................................. 6-1
6.2 Scheduling and Shaping ............................................................................................................... 6-2
6.2.1 RNC/BSC Scheduling and Shaping ..................................................................................... 6-2
6.2.2 NodeB Scheduling and Shaping .......................................................................................... 6-3
6.2.3 BTS Shaping ........................................................................................................................ 6-3
6.3 Iub Overbooking ............................................................................................................................ 6-3
6.4 Congestion Control of Iub User Plane .......................................................................................... 6-4
6.5 Downlink Iub Congestion Control Algorithm .................................................................................. 6-5
6.5.1 Overview of the Downlink Iub Congestion Control Algorithm ............................................... 6-5
6.5.2 RNC RLC Retransmission Rate-Based Downlink Congestion Control Algorithm ................ 6-6
6.5.3 RNC Backpressure-Based Downlink Congestion Control Algorithm ................................... 6-8
6.5.4 NodeB HSDPA Adaptive Flow Control Algorithm ................................................................. 6-9
6.6 Uplink Iub Congestion Control Algorithm .................................................................................... 6-12

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Contents

6.6.1 Overview of the Uplink Iub Congestion Control Algorithm ................................................. 6-12
6.6.2 NodeB Backpressure-Based Uplink Congestion Control Algorithm (R99 and HSUPA)..... 6-13
6.6.3 NodeB Uplink Bandwidth Adaptive Adjustment Algorithm .................................................. 6-14
6.6.4 RNC R99 Single Service Uplink Congestion Control Algorithm ......................................... 6-15
6.6.5 NodeB Uplink Congestion Control Algorithm for Cross-Iur Single HSUPA Service ........... 6-15
6.7 Dynamic Bandwidth Adjustment Based on IP PM ...................................................................... 6-16

7 Engineering Guidelines...........................................................................................................7-1
7.1 Configuring Co-TRM (with GSM BSC and UMTS RNC Combined) ............................................. 7-1
7.2 Using Default TRMLOADTH Table ................................................................................................ 7-1

8 Parameters .................................................................................................................................8-1
9 Counters ......................................................................................................................................9-1
10 Glossary ..................................................................................................................................10-1
11 Reference Documents .........................................................................................................11-1

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1 Introduction

1 Introduction
1.1 Scope
This document mainly describes the management of transmission resources at the base station
controller. The transmission resources refer to those carried on the Abis interface of the 2G system and
on the Iub interface of the 3G system, and those shared by the Abis and Iub interfaces of the common
transmission (co-transmission) system.
This document merges the Transmission Resource Management (TRM) feature descriptions of the 2G,
3G, and co-transmission systems. It describes transmission resources, Quality of Service (QoS), load
control, user plane processing, and associated parameters. It is applicable for R99, HSDPA, and HSUPA.
In this document, HSDPA transport resource management (WRFD-01061014 HSDPA Transport
Resource Management) and HSUPA transport resource management (WRFD-01061207 HSUPA
Transport Resource Management) mainly refer to the transmission resource mapping and load control.


The base station controllers of the 2G, 3G, and co-transmission systems are BSC, RNC, and Multi-Mode Base Station
Controller (MBSC) respectively.



MBSC is the GSM+UMTS multi-mode base station controller introduced in Huawei SRAN3.0 solution.



SRAN3.0 supports the co-transmission resource management (Co-TRM) feature (corresponding to MRFD-211503
Co-Transmission Resources Management on MBSC) only in the co-transmission scenario where the MBSC is
deployed on the base station controller side, and the MBTS is deployed on the base station side. In this scenario,
Co-TRM refers to the common management of IP logical ports (LPs) transmission resources when the 2G system and
the 3G system implement IP-based co-transmission on the Abis and Iub interfaces. Co-TRM improves the usage of
transmission resources and provides the QoS services. In the Co-TRM feature, Abis and Iub share IP LPs, and IP LPs
share IP physical transmission resources. The 2G IP paths are independent of the 3G IP paths. Co-TRM implements
the common load control and traffic shaping within the shared LPs.



SRAN5.0 also supports the Co-TRM feature in the scenario where the GSM BSC and the UMTS RNC are deployed
separately, and IP-based co-transmission is implemented on the base station side. In this scenario, Abis and Iub do not
share LPs and physical ports. Co-TRM improves the transmission bandwidth utilization in the GSM and UMTS
co-transmission scenario. For details, see Bandwidth Sharing of MBTS Multi-Mode Co-Transmission Feature
Parameter Description.

1.2 Intended Audience
This document is intended for:


Personnel who are familiar with WCDMA or GSM basics



Personnel who need to understand the TRM feature of the 2G, 3G, and co-transmission systems



Personnel who work with Huawei products

1.3 Change History
This section provides information on the changes in different document versions.
There are two types of changes, which are defined as follows:


Feature change: refers to the change in the Transmission Resource Management feature.



Editorial change: refers to the change in wording or the addition of the information that was not
described in the earlier version.

Document Issues
The document issues are as follows:


03 (2011-09-30)

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

02 (2011-03-30)



01 (2010-05-15)



1 Introduction

Draft (2010-03-30)

03 (2011-09-30)
This is the document for the third commercial release of SRAN5.0.
Compared with 02 (2011-03-30) of SRAN5.0, this issue incorporates the following changes:
Change Type

Change Description

Parameter Change

Feature change

None

None.

Editorial change

The algorithm for NodeB backpressure-based uplink
None.
congestion control is optimized. For details, see the
section "NodeB Backpressure-Based Uplink Congestion
Control Algorithm (R99 and HSUPA)."

02 (2011-03-30)
This is the document for the second commercial release of SRAN5.0.
Change Type

Change Description

Parameter Change

Feature change

None

None.

Editorial change

Optimized the description of principles of load
balancing. For details, See "Principles of Load
Balancing".

None.

01 (2010-05-15)
This is the document for the first commercial release of SRAN5.0.
Compared with Draft (2010-03-30) of SRAN5.0, this issue optimizes the description.

Draft (2010-03-30)
This is the draft of the document for SRAN5.0.
Change Type

Change Description

Parameter Change

Feature change

The description of LPs at the BTS is added.

None.

The description of Co-TRM in the MBTS
None.
co-transmission scenario where the GSM BSC and the
UMTS RNC are deployed separately is added.
Editorial change

None.

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2 Overview of TRM

2 Overview of TRM
2.1 Definition of TRM
TRM is the management of transmission resources on the interfaces in various networking modes. The
transmission interfaces of the 2G system include Abis, Ater, and A; the transmission interfaces of the 3G
system include Iub, Iur, Iu-CS, and Iu-PS. Compared with the transmission on the other interfaces, the
transmission on the Abis and Iub interfaces has higher costs, more complicated networking modes, and
greater impact on system performance. Therefore, this document mainly describes the TRM for the Iub
and Abis interface. In the co-transmission system, TRM implements common management of
transmission resources shared by the Abis and Iub interfaces and so TRM is also focused on the Abis
and Iub interfaces. TRM in the co-transmission system is called Co-TRM.
Transmission resources are one type of resource that the radio network access provides. Closely related
to TRM algorithms are Radio Resource Management (RRM) algorithms, such as the scheduling
algorithm and load control algorithm for the Uu interface. The TRM algorithm policies should be
consistent with the RRM algorithm policies.

2.2 Structure of TRM Functions
Figure 2-1 shows the structure of TRM functions.

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2 Overview of TRM

Figure 2-1 Structure of the TRM functions

As shown in Figure 2-1, the TRM feature covers the following aspects:


Transmission resources involved in TRM include physical and logical resources. For details, see
section 3 "Transmission Resources."



Load control is applied to the control plane in TRM. It includes admission control, load reshuffling
(LDR), and overload control (OLC). For details, see section 5 "Load Control."



QoS priority mapping, shaping, and scheduling, dynamic bandwidth adjustment based on IP
Performance Monitor (PM), and congestion control are applied to the user plane in TRM. For details,
see section 4 "Quality of Service" and 6 "User Plane Processing."

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2 Overview of TRM

2.3 Similarities and Differences Between 2G, 3G, and
Co-Transmission Systems
2.3.1 Transmission Resources
Overview


In the SingleRAN 3.0 solution, the related concepts and configurations of the 2G and 3G systems in IP
transmission mode are almost the same.
− The

2G and 3G systems can use the same physical transmission resources, data link layer protocols,
and IP-based interface boards. For details, see section 3.2.4 "Physical and Data Link Layer
Resources for IP Transmission."

− The

concepts and functions of LPs, resource groups, and paths for the 2G and 3G systems are the
same. For details, see section 3.3 "Logical Ports and Resource Groups."

− The

2G and 3G systems can use the same commands to configure LPs, resource groups, and IP
paths. For details, see section 3.3.3 "IP LPs at the BSC/RNC/MBSC", 3.3.6 "Resource Groups at the
BSC/RNC", and 3.4.2 "IP Paths."



The Abis interface of the 2G system and the Iub interface of the 3G system are applied to almost the
same networking scenarios, which include direct connection, bandwidth variation, and convergence.
For details, see section 3.5.1 "2G and 3G Networking."

Characteristics of 2G TRM
The 2G system supports the TDM and HDLC transmission modes. For details about available
transmission resources, see section 3.2.2 "Physical Layer Resources for TDM " and 3.2.3 "Physical and
Data Link Layer Resources for HDLC Transmission."



The 3G system supports the ATM transmission mode. Transmission resources of the 3G system are
classified into physical transmission resources, LPs, resource groups, and path resources. For details,
see section 3.2.1 "Physical Layer Resources for ATM ", 3.3.2 "ATM LPs at the RNC", 3.3.6 "Resource
Groups at the BSC/RNC", and 3.4.1 "AAL2 Paths."



The LPs of the 3G system can also be applied in RAN sharing scenario for transmission resource
admission control. For details, see section 3.3.1 "Introduction to LP."



The 3G system also supports configuration of NodeB LPs. For details, see section 3.3.4 "LPs at the
NodeB."



For the Iub hybrid IP transmission mode, non-QoS paths can be further classified into high-quality
paths and low-quality paths. For details, see section 3.4.2 "IP Paths."



The Iub interface of the 3G system supports the ATM&IP dual stack networking and hybrid IP
networking. For details, see section 3.5.1 "2G and 3G Networking."

2.3.2 Load Control
Overview


The 2G system and the 3G system perform load control in respective control planes. Their load control
methods include admission control, LDR, and OLC. For details, see section 5 "Load Control."
− For

the ATM, IP, and HDLC transmission modes, the definitions and calculation methods of
transmission load of the 2G and 3G systems are the same. For details, see section 5.2 "Definition
and Calculation of Transmission Load."

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− Both

2G system and 3G system make requests for admission of services according to the bandwidth
reserved for services, and both calculate the bandwidth reserved for services based on activity
factors. For different services of the 2G and 3G systems, the reserved bandwidth differs. For details,
see section 5.3.2 "Calculation of Bandwidth Reserved for Traffic."

− In

the process of transmission resources admission control, the 2G and 3G systems have the same
admission processes, the same admission strategies, and the same principles of preemption and
queuing. Switches and actions of preemption and queuing in the 2G and 3G systems are different.
For details, see section 5.5 "Admission Control."

− In

the processes of LDR and OLC, the principles of congestion and overload detection for the 2G and
3G systems are the same, but the procedures for handling congestion and overload are different. For
details, see section 5.6 "Load Reshuffling and Overload Control."



In the SRAN3.0 solution:
− The

2G and 3G systems use the same load threshold table template and use the same command to
configure the table. For details, see section 5.4 "Load Thresholds,"

− The

2G and 3G systems use the same activity factor table template and use the same command to
configure the table. For details, see section 5.3.2 "Calculation of Bandwidth Reserved for Traffic."

The 2G Abis signaling needs to calculate the reserved bandwidth. For details, see section 5.3.1
"Calculation of Bandwidth Reserved for 2G Signaling."



The GBR of BE services of the 3G system are configurable. For details, see section 5.3 "Calculation of
Reserved Bandwidth."



In Iub hybrid transmission mode, the admission of primary and secondary paths is supported in the
process of transmission resource admission. For details, see section 5.5.4 "Load Balancing."

2.3.3 User Plane Processing and QoS
Overview


The 2G and 3G systems implement leaf LP shaping and hub LP scheduling functions in respective
user planes. The related concepts and principles are the same. For details, see section 6.2
"Scheduling and Shaping."



The 2G and 3G systems implement the adjacent-node-oriented mapping from services to
transmission resources in respective user planes. The related concepts such as DSCP and queue
priority are the same. For details, see 4.2 "Transport Priorities." In the SRAN3.0 solution, the 2G and
3G systems use the same TRMMAP table template and use the same command to configure the
mapping from services to transmission resources. For details, see section 4.4 "Transmission
Resource Mapping."



In HDLC transmission mode, the HDLC also supports shaping and scheduling functions. For details,
see section 6.2.1 "RNC/BSC Scheduling and Shaping."



The mapping from 2G Abis signaling services to transmission resources is not oriented to adjacent
nodes and therefore needs to be configured separately. For details, see "Mapping from Abis Signaling
Traffic to Transmission Resources."

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

The NodeB of the 3G system also supports shaping and scheduling functions. For details, see section
6.2.2 "NodeB Scheduling and Shaping."



The Iub interface of the 3G system implements a series of congestion control algorithms in the user
plane. For details, see section 6.3 "Iub Overbooking."



When the mapping from services to transmission resources is configured, the 3G services are
differentiated by user priority, traffic priority, and type of radio bearer. The 3G system also supports
configuration of primary and secondary paths. For details, see sections 4.3 "Service QoS" and 4.4
"Transmission Resource Mapping."

2.3.4 Differences of Co-TRM From 2G TRM and 3G TRM
Characteristics of Co-TRM in SRAN3.0:


The Abis interface of the 2G system and the Iub interface of the 3G system share IP LPs, and IP LPs
share physical IP transmission resources.



Within a shared LP, common load control is implemented based on common load thresholds, that is,
common admission strategies and common congestion and overload detection.



In the process of handling overload caused by LP admission, the 2G and 3G systems reserve
bandwidth proportionally. For details, see section 5.6.3 "Congestion and Overload Handling."



Common traffic shaping is implemented within a shared LP.



Co-TRM is applicable only to one of the co-transmission networking scenarios. For details, see section
3.5.2 "Co-Transmission Networking."

In SRAN5.0, the Co-TRM in the scenario where the GSM BSC and the UMTS RNC are deployed
separately, and the GSM and UMTS systems do not share the LPs. In Co-TRM, the management of
GSM and UMTS transmission resources is similar to 2G TRM and 3G TRM. The only difference is that
Co-TRM has special requirements for BSC or RNC configurations to improve transmission bandwidth
utilization.
Co-TRM inherits the concepts, principles, and functions of 2G TRM and 3G TRM, which include
concepts and functions of paths and LPs, definition and calculation of load, calculation of bandwidth
reserved for services, principles and methods of load control, transmission resource mapping, and LP
shaping and scheduling. In the Co-TRM feature:


2G IP paths and 3G IP paths are mutually independent.



The 2G system and the 3G system implement transmission resource mapping separately.



The 2G system and the 3G system calculate reserved bandwidth separately.



The 2G system and the 3G system set preemption and queuing switches separately, and take
preemption and queuing actions separately.



The 2G system and the 3G system handle congestion and overload separately.

2.4 Benefits of TRM
TRM increases the system capacity with the QoS guaranteed and provides differentiated services.


Real-time (RT) services, such as conversational and streaming services
RT services do not allow packet loss and are sensitive to delay. The activity of RT services follows an
obvious rule. When multiple services access the network, the total actual traffic volume is relatively
stable.

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− Through

the transmission resource mapping, RT services can be mapped to high-priority paths and
thus be transmitted preferentially when congestion occurs. This reduces packet loss and
transmission delay. For details, see section 4 "Quality of Service."

− RT

services are admitted at the Maximum Bit Rate (MBR). With appropriate activity factors
configured, the access of more users are allowed under the condition that the QoS is guaranteed.
Overload control and preemption can achieve differentiated services. For details, see section 5 "Load
Control."



Non-real-time (NRT) services, such as interactive and background services
NRT services do not have strict requirements for bandwidth. When transmission resources are
insufficient, the data can be buffered to reduce the traffic throughput. The activity of NRT services does
not follow an obvious rule. When multiple services access the network, the total actual traffic volume
fluctuates significantly.
− Through

transmission resource mapping, NRT services can be mapped to low-priority paths and thus
the QoS of RT services can be guaranteed preferentially. For details, see section 4 "Quality of
Service."

− The

TRM feature provides the Guaranteed Bit Rate (GBR) and a user plane congestion control
algorithm, which allow the access of more users under the condition that the QoS is guaranteed. For
details, see section 6 "User Plane Processing."

− Through

the Scheduling Priority Indicator (SPI) weighting, bandwidth allocation for NRT services can
be differentiated. For details, see section 6 "User Plane Processing."
SPI is used to indicate the scheduling priorities of services, and SPI weighting is used to adjust the
queuing priorities of scheduling services or to proportionally allocate bandwidth to services in Iub
congestion control. A larger SPI weight indicates a higher queuing priority or a higher bandwidth
allocated to the Iub interface.



Signaling, such as Signaling Radio Bearer (SRB), Session Initiation Protocol (SIP), Network Control
Protocol (NCP), Communication Control Port (CCP), and Abis interface signaling
The traffic volume of signaling is low and its performance is closely related to Key Performance
Indexes (KPIs) of the network. Therefore, through transmission resource mapping, signaling can be
mapped to high-priority paths and the transmission of signaling takes precedence, thus preventing
packet loss and transmission delay.

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3 Transmission Resources

3.1 Overview of Transmission Resources
The 2G, 3G, and co-transmission systems can use the transmission resources described in Table 3-1.
Table 3-1 Transmission resources used by the 2G, 3G, and co-transmission systems
Transmission
Resource

2G System

3G System

Co-Transmission System

TDM

√

-

-

HDLC

√

-

-

IP

√

√

√

ATM

-

√

-

ATM transmission resources and IP transmission resources can be further classified into physical
resources, logical ports, resource groups, and paths.
In TDM and HDLC transmission, the user plane data is carried on the timeslots of physical ports.
Figure 3-1, Figure 3-2, Figure 3-3 and Figure 3-4 show examples of different transmission resources.
Figure 3-1 ATM transmission resources

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Figure 3-2 IP transmission resources of the 3G system

Figure 3-3 IP transmission resources of the 2G system

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Figure 3-4 IP transmission resources of the co-transmission system

3.2 Physical Transmission Resources
Table 3-2 describes the physical transmission resources used by the 2G, 3G, and co-transmission
systems.
Table 3-2 Physical transmission resources used by the 2G, 3G, and co-transmission systems
Physical
2G TDM
2G HDLC
2G IP
3G ATM
3G IP
Co-Transmissio
Transmissio Transmissio Transmissio Transmissio Transmissio Transmissio n System
n Resource n
n
n
n
n
E1/T1
√
electrical port

√

√

√

√

√

FE/GE
electrical port

-

√

-

√

√

GE optical
port

-

-

√

-

√

√

Unchannelize d
STM-1/OC-3c
optical port

-

-

√

√

-

Channelized √
STM-1/OC-3
optical port

√

√

√

√

√

Flex Abis
√
resource pool

-

-

-

-

-

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3.2.1 Physical Layer Resources for ATM Transmission
The physical ports for ATM transmission are as follows:
Physical Port

Transmission Mode

E1/T1 electrical port



IMA



UNI



Fractional ATM



IMA



UNI



Fractional ATM

Channelized STM-1/OC-3 optical port

Unchannelized STM-1/OC-3c optical port NCOPT

3.2.2 Physical Layer Resources for TDM Transmission
The physical ports for TDM transmission are as follows:





Channelized STM-1/OC-3 optical port

In TDM transmission on the Abis interface, Abis timeslots can be shared as a Flex Abis pool within the
BSC. For details about Flex Abis, see Flex Abis Feature Parameter Description of the GBSS.

3.2.3 Physical and Data Link Layer Resources for HDLC
Transmission
HDLC resources include physical layer resources and data link layer resources, which are listed as
follows:


Physical layer resources include E1/T1 electrical port and channelized STM-1/OC-3 optical port.



Data link layer resources refer to HDLC channels.

3.2.4 Physical and Data Link Layer Resources for IP Transmission
Table 3-3 describes the physical ports and data link layer protocols for IP transmission.
Table 3-3 Physical ports for IP transmission
Physical Port

Data Link Layer
Protocol

2G System 3G System

Co-Transmission
System


PPP/MLPPP

√

√

-

FE/GE electrical port

Ethernet

√

√

√

GE optical port

Ethernet

√

√

√

Unchannelized
STM-1/OC-3c optical port

PPP/MLPPP

-

√

-

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Physical Port

Data Link Layer
Protocol

2G System 3G System

Co-Transmission
System

Channelized STM-1/OC-3
optical port

PPP/MLPPP

√

√

√

3.3 Logical Ports and Resource Groups
Logical Ports (LPs) and resource groups are applicable to the 2G, 3G, and co-transmission systems, as
described in Table 3-4.
Table 3-4 LPs and resource groups applicable to the 2G, 3G, and co-transmission systems
LP and
2G TDM
2G HDLC
2G IP
3G ATM
3G IP
Co-Transmission
Resource Transmission Transmission Transmission Transmission Transmission System
Group
ATM LP

-

-

-

√

-

-

IP LP

-

-

√

-

√

√

Resource group

-

√

√

√

-

3.3.1 Introduction to LPs
LPs are used to configure bandwidth at transmission nodes and perform bandwidth admission and traffic
shaping to prevent congestion.
After the physical ports and paths are configured, the system can start to operate and services can be
established. There are problems, however, in the following scenarios:


Transmission aggregation
− Transmission

aggregation exists either on the transport network (for example, aggregation of NB1
and NB2, as shown in Figure 3-5) or at the hub NodeB or hub BTS (for example, aggregation of NB3
and NB4 at NB1, as shown in Figure 3-5).

− If

only physical ports and paths are configured, the bandwidth constraints at the aggregation nodes
are unavailable. As shown in Figure 3-5, the total available bandwidth BW0 of NB1 through NB4 is
known, but the values of BW1 through BW4 are unknown. Thus, the admission algorithm does not
work properly. For example, if the total reserved bandwidth at NB2 exceeds BW2, in the downlink the
total volume of data sent to NB2 may exceed BW2, and congestion and packet loss may occur.

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Figure 3-5 Transmission aggregation on the Iub or Abis interface

NB: NodeB or BTS



BW: bandwidth

BW0: bandwidth of physical ports on the RNC
or BSC or MBSC

RAN sharing in the RNC
− In

this scenario, operators share the bandwidth at one NodeB and the bandwidth needs to be
configured for each operator so that the bandwidth used by each operator does not exceed their
respective reserved bandwidth.

− If

only physical ports and paths are configured, the preceding requirement cannot be fulfilled.

To solve the preceding problems, the LP concept is introduced to the TRM feature.


An LP indicates the bandwidth constraints between paths or between other LPs.



An LP can be comprised of only paths. Such an LP is called a leaf LP. A physical port can be a leaf LP.



An LP can also be comprised of only other LPs. Such an LP is called a hub LP. A physical port can be
a hub LP.



One key characteristic of LPs is the bandwidth. For an LP, the uplink bandwidth can be different from
the downlink bandwidth.

LPs can be classified into the following types:


ATM LP: used for bandwidth admission and traffic shaping. Multiple levels of ATM LPs are supported.



IP LP: used for bandwidth admission and traffic shaping. Multiple levels of IP LP are supported.

In the 3G TRM, LPs need to be configured on both the RNC and NodeB sides; in the 2G TRM, LPs need
to be configured only on the BSC side; in the Co-TRM, LPs need to be configured only on the MBSC
side.
LPs are configured on the RNC or BSC or MBSC side for the following purposes:


To implement admission control in the aggregation or RAN sharing scenario in the RNC



To implement traffic shaping in the downlink

LPs are configured on the NodeB side for the following purposes:


To achieve fairness between local data and forwarded data in the aggregation scenario

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


To implement traffic shaping in the RAN sharing scenario

For details about LP shaping, see section 6.2 "Scheduling and Shaping."

3.3.2 ATM LPs at the RNC
ATM LPs, also called Virtual Ports (VPs), provide the functions of ATM traffic shaping and bandwidth
admission. They can be configured on ATM interface boards through the ADD ATMLOGICPORT
command. These LPs have the following attributes:


Types of LP: hub LP and leaf LP



Bandwidth: The downlink bandwidth is used for traffic shaping and bandwidth admission, and the
uplink bandwidth is used for bandwidth admission only.



Resource management mode: SHARE or EXCLUSIVE, which indicates whether operators in the RAN
sharing scenario share the Iub transmission resources.

When the ADD AAL2PATH, ADD SAALLNK, or ADD IPOAPVC command is executed to specify the
bearer type of an AAL2 path, an SAAL link, or an IPoA PVC as ATMLOGICPORT, the path, link, or PVC
can be set to join an LP.
The parameters associated with ATM LPs are as follows:


LPNTYPE



TXBW



RXBW



RSCMNGMODE

In the ATM transmission aggregation scenario, LPs need to be configured for each NodeB and at each
aggregation node; in the RAN sharing scenario, an LP needs to be configured for each operator that
shares the NodeB.
As shown in Figure 3-6, below is an example of transmission aggregation.

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Figure 3-6 Transmission aggregation at LPs

NB: NodeB

BW: bandwidth

BW0: bandwidth of the physical
port on the RNC



The leaf LPs, that is, LP1, LP2, LP3, and LP4, have a one-to-one relationship with the NodeBs. The
bandwidth of each leaf LP is equal to the Iub bandwidth of each corresponding NodeB.



The hub LP, that is, LP125, corresponds to the hub NodeB. The bandwidth of the hub LP is equal to
the Iub bandwidth of the hub NodeB.



The actual rate at a leaf LP is limited by the bandwidth of the leaf LP and the scheduling rate at the hub
LP and physical port.



In the transmission resource admission algorithm, the reserved bandwidth of a leaf LP is limited by not
only the bandwidth of the leaf LP but also the bandwidth of the hub LP and the bandwidth of the
physical port. That is, the total reserved bandwidth of all the LPs under a hub LP cannot exceed the
bandwidth of the hub LP.

The RNC supports multi-level shaping (a maximum of five levels), which involves leaf LPs and hub LPs.

3.3.3 IP LPs at the BSC/RNC/MBSC
IP LPs have the functions of IP traffic shaping and bandwidth admission. They can be configured on IP
interface boards through the ADD IPLOGICPORT command. These LPs have the following attributes:


Types of LP: hub LP and leaf LP



Bandwidth: The downlink bandwidth is used for traffic shaping and bandwidth admission, and the
uplink bandwidth is used for bandwidth admission only.



Resource management mode: SHARE or EXCLUSIVE, which indicates whether operators in the RAN
sharing scenario share the Iub transmission resources.

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When the ADD IPPATH command is executed to specify the bearer type of IP path as IPLGCPORT, or
when the RNC and MBSC bind the IP LPs through the ADD SCTPLNK command, the path or link can
be set to join an LP.
IP LPs are similar to ATM LPs in terms of principles and application. The current version supports a
maximum of five levels of IP LPs.
The parameters associated with IP LPs are as follows:


LPNTYPE



RSCMNGMODE



CIR



OAMFLOWBW

3.3.4 LPs at the NodeB
LPs at the NodeB have the function of traffic shaping, which are mainly used to differentiate operators in
the RAN sharing scenario. ATM or IP LPs can be configured on the interface board through the ADD
RSCGRP command. The LPs have the following attributes:


Types of LPs: ATM and IPv4



Transmit bandwidth: used for traffic shaping



Receive bandwidth: used to calculate the remaining bandwidth for backpressure-based flow control



Port types
− For ATM
− For

LPs, the port types are IMA, UNI, fractional ATM, and unchannelized STM-1.

IP LPs, the port types are PPP, MLPPP group, and Ethernet port.

In ATM transmission mode, when the ADD AAL2PATH, ADD SAALLNK, or ADD OMCH command is
executed to add an AAL2 path, an SAAL link, or an OM channel respectively, the path, link, or channel
can be set to join an LP.
In IP transmission mode, when the ADD IPPATH command is executed to add an IP path, the path can
be set to join an LP so as to add the data traffic volume carried on the path of the local NodeB to the LP.
The MML command ADD IP2RSCGRP is executed to bind an LP to the target IP network segment. The
command is executed to join the signaling stream, OM traffic, and forwarded data traffic to a specified
LP.
The parameters associated with LPs at the NodeB are as follows:


BEAR



PT



TXBW



RXBW

The LP capabilities of NodeB interface boards are as follows:


Each physical port of the NodeB supports a maximum of four IP LPs.



When a Main Processing & Transmission interface board (WMPT) is configured, each interface board
supports a maximum of 4 ATM LPs or a maximum of 8 IP LPs.



When other interface boards are configured, each interface board supports a maximum of 16 ATM LPs
or a maximum of 8 IP LPs.

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3.3.5 LPs at the BTS
In IP over FE/GE transmission mode, you can run the MML command ADD BTSIPLGCPORT to
configure LPs at the BTS. The TXBW parameter is used for traffic shaping in the GSM and UMTS
co-transmission to reduce the impact of GSM uplink traffic on the UMTS uplink traffic.
The MML command ADD BTSIPTOLGCPORT is used to bind the LPs to the target IP addresses of LPs.
The command is executed to join the signaling stream, OM traffic, and data traffic to the LPs.

3.3.6 Resource Groups at the BSC/RNC
Resource groups support bandwidth admission but do not support traffic shaping. Resource groups are
applicable to ATM and IP transmission modes. Multiple levels of transmission resource groups are
supported. To add a resource group, run the ADD RSCGRP command. To join an IP path to a resource
group, run the ADD IPPATH command. To associate with ATM paths, run the ADD AAL2PATH
command.
On the RNC or BSC side, LPs cannot contain transmission resource groups, and transmission resource groups cannot
contain LPs either.

3.4 Path Resources
Path resources comprise paths in the control plane, user plane, and management plane. The paths in
the user plane, that is, AAL2 paths for ATM transmission and IP paths for IP transmission, are key
resources. The allocation and management of transmission resources are based on paths.
Table 3-5 describes the path resources that can be used by the 2G, 3G, and co-transmission systems.
Table 3-5 Path resources that can be used by the 2G, 3G, and co-transmission systems
Path
2G TDM
2G HDLC
2G IP
3G ATM
3G IP
Co-Transmission
Resource Transmission Transmission Transmission Transmission Transmission System
AAL2 path -

-

-

√

-

-

IP path

-

√

-

√

√

-

3.4.1 AAL2 Paths
In ATM transmission mode, the following types of AAL2 path can be configured:


CBR



RT-VBR



NRT-VBR



UBR

The AAL2 path can be configured through the ADD AAL2PATH command. When an AAL2 path is
configured, the TXTRFX and RXTRFX parameters need to be set by running ADD ATMTRF command.
These parameters determine the type of the AAL2 path.

3.4.2 IP Paths
IP paths can be classified into QoS paths and non-QoS paths.

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


On QoS paths, different services share the bandwidth of paths. The Per Hop Behavior (PHB) of IP
paths is determined by transmission resource mapping. For details about transmission resource
mapping, see section 4.4 "Transmission Resource Mapping."
PHB is the next-hop behavior of the IP path. Services can be prioritized based on the mapping from
PHB to DSCP.



On non-QoS paths, different services do not share the bandwidth of IP paths. The PHB of IP paths is
determined by the path type. Non-QoS paths can be further classified into high-quality paths and
low-quality paths. The low-quality path, denoted as LQ_xxx, is applicable to only hybrid IP
transmission on the Iub interface. In hybrid IP transmission mode, if the physical port is an PPP or
MLPPP port, high-quality paths are configured; if the physical port is an Ethernet port, low-quality
paths are configured.
For details about the hybrid IP transmission on the Iub interface, see section 3.5.1 "2G and 3G
Networking."

The IP path can be configured through the ADD IPPATH command.
For details about the classification of non-QoS paths, see Table 3-6.
Table 3-6 Classification of non-QoS paths
High-Quality Path

Low-Quality Path

BE

LQ_BE

AF11

LQ_AF11

AF12

LQ_AF12

AF13

LQ_AF13

AF21

LQ_AF21

AF22

LQ_AF22

AF23

LQ_AF23

AF31

LQ_AF31

AF32

LQ_AF32

AF33

LQ_AF33

AF41

LQ_AF41

AF42

LQ_AF42

AF43

LQ_AF43

EF

LQ_EF

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NOTE


On the Iu-PS interface, even if IPoA transmission is used, IP paths still need to be configured.



High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA) services can be carried
on the same IP path, with HSDPA services carried in the downlink and HSUPA services carried in the uplink.

3.5 Networking Application
3.5.1 2G and 3G Networking
The typical networking scenarios for the Iub interface are as follows:


Direct connection: The RNC is directly connected to a NodeB through a physical port, the bandwidth of
which is exclusively occupied by this Iub interface.



Transmission aggregation: As shown in Figure 3-5, the Iub traffic volume of more than one NodeB is
converged, for example, on the transport network or at the hub NodeB.



Bandwidth being variable: The bandwidth on the transport network might be variable. For example, the
bandwidth of Asymmetric Digital Subscriber Line (ADSL) transmission is variable.



ATM&IP dual stack: Both ATM and IP transmission resources are available for one Iub interface so
that the transmission cost is reduced.



Hybrid IP: Both high-QoS transmission (such as IP over E1) and low-QoS transmission (such as IP
over FE) are applicable to one Iub interface so that differentiated management of services is
implemented.



RAN sharing: Operators share the physical bandwidth. In this scenario, bandwidth should be reserved
for each operator.



The typical networking scenarios for the Abis interface are similar to the Iub interface, except that networking scenarios
such as dual stack, hybrid IP, and RAN sharing are not applied to the Abis interface.



For details about the 2G and 3G networking, see the IP BSS Feature Parameter Description of the GBSS and the IP
RAN Feature Parameter Description of the RAN.

Table 3-7 lists the types of transmission applicable to each interface.
Table 3-7 Types of transmission applicable to each interface
Interface

ATM

TDM

HDLC

IP

ATM&IP Dual Stack

Hybrid IP

Iub

√

-

-

√

√

√

Iur

√

-

-

√

-

-

Iu-CS

√

-

-

√

-

-

Iu-PS

-

-

-

√

-

-

Abis

-

√

√

√

-

-

A

-

√

-

√

-

-

Ater

-

√

-

√

-

-

Pb

-

√

-

-

-

-

Gb

-

√

-

√

-

-

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The IP transmission mode of the Ater interface supports only TDM networking on IP over E1.

3.5.2 Co-Transmission Networking
Co-TRM is applied to the following co-transmission networking scenarios:
Figure 3-7 Co-transmission scenario where the GSM BSC and the UMTS RNC are combined

GSM+UMTS MBSC deployed and GSM+UMTS MBTSs deployed
GSM+UMTS MBTS sharing IP LP transmission resources over the Abis and Iub
interfaces

Figure 3-8 Co-transmission scenario where the GSM BSC and the UMTS RNC are deployed separately

BSC and RNC separately deployed, without sharing physical ports
GSM+UMTS MBTS deployed, sharing physical ports

For details about the co-transmission networking, see the Common Transmission Feature Parameter
Description.

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4 Quality of Service

4.1 Overview
The purpose of TRM algorithms is to guarantee the Quality of Service (QoS). Different types of service
have different QoS requirements.


The Iub or Abis control plane and the Uu signaling require reliable transmission. Packet loss rate and
delay may affect KPIs such as connection delay, handover success rate, access success rate, and call
drop rate.



CS services have requirements for delay and packet loss rate. For example, speech services are
sensitive to end-to-end latency, and data services are sensitive to packet loss.



NRT services are relatively insensitive to delay, but in some scenarios, they are sensitive to delay.
When the load is light, the requirement for delay should be fulfilled. whereas when the load is heavy,
the requirement for delay can be lowered to a certain extent to guarantee the throughput.

The transport layer provides various transport bearers and transport priorities. The appropriate type of
transport bearer and transport priority should be selected according to the traffic classes, user priorities,
traffic priorities, and radio bearer type of service. High-priority services take precedence in transmission
when congestion occurs. This reduces packet loss and transmission delay.
Transmission resource mapping maps services of different QoS requirements to different transport
bearers. Transmission resource mapping (WRFD-050424 Traffic Priority Mapping onto Transmission
Resources) is an important method to guarantee the QoS and differentiate the users and services. It
mainly involves data in the user plane.
This section describes transmission resource mapping and associated concepts such as transport
priorities and service QoS. For the differences in implementing QoS-related services in the 2G TRM, 3G
TRM, and Co-TRM, see the following sections.

4.2 Transport Priorities
Transport priority-related concepts include Differentiated Service Code Point (DSCP), Virtual Local Area
Network (VLAN) priority, and Priority Queue (PQ).

4.2.1 DSCP
The DSCP is carried in the header of each IP packet to inform the nodes on the network of the QoS
requirement. Through the DSCP, each router on the propagation path knows which type of service is
required. DSCP provides differentiated services (DiffServ) for layer 3 (L3).
When entering the network, services are differentiated and subject to flow control according to the QoS
requirement. In addition, the DSCP fields of the packets are set. The DSCP field is in the header of each
IP packet. On the network, DiffServ is applied to different types of traffic according to the DSCP values
and services for the traffic are provided. The services include resource allocation, queue scheduling, and
packet discard policies, which are collectively called PHB. All nodes within the DiffServ domain
implement PHB according to the DSCP field in each packet.
Policies for using DSCP are as follows:


The traffic carried on QoS paths uses the DSCPs mapped from services. For details, see "Mapping
from TC to PHB or PVC" and "Mapping from PHB to DSCP."



The traffic carried on the non-QoS path uses the DSCP that the PHB of the IP path corresponds to.
For details, see "Mapping from PHB to DSCP."

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It is recommended that you set the path type to QoS path when configuring the IP path. This ensures
simple configuration, better multiplexing, and higher QoS.

4.2.2 VLAN Priorities
VLAN provides services of different priorities to isolate different users and enhance security of IP
transport network. VLAN provides differentiated services for layer 2 (L2). The principles of VLAN
priorities are similar in the 2G and 3G systems. This section takes the VLAN solution of the 3G system
as an example.
Figure 4-1 shows a typical example of the VLAN solution on the Iub interface. In this solution, the
Multi-Service Transmission Platform Network (MSTP) provides two Ethernets carried on two different
Virtual Channel (VC) trunks.


One Ethernet is a private network for RT services of multiple NodeBs. The RT services in this Ethernet
are not affected by other services and thus used for carrying high-priority services.



The other Ethernet is a public network for NRT services of multiple NodeBs. It can be shared by other
services. The NRT services in this Ethernet might be affected by other services and thus used for
carrying low-priority services.

Figure 4-1 Typical example of solution of the VLAN on the Iub interface

Red line: private
network

Blue line: public
network

Black line: connection between routers

Each NodeB or RNC provides an Ethernet port that connects to the MSTP network. The MSTP transmits
the Ethernet data of different QoS to either of the VC trunks according to the VLAN priority in the frame
header of Ethernet data. On the same VC trunk, different NodeB data is distinguished by VLANID.
Figure 4-2 shows an example of using VLAN priorities.

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Figure 4-2 Example of using VLAN priorities

The RNC, NodeB1, and NodeB2 are connected to the same L2 network. Data of NodeB1 (VLAN 10) and
NodeB2 (VLAN 20) is isolated according to different VLANIDs. VLANIDs are attached to data of different
traffic classes sent from the Ethernet port.
Data of different traffic classes use VLAN priorities mapped from DSCP. Then, the L2 network provides
differentiated services based on the VLAN priorities. When IP paths are configured, the VLANFLAG
parameter specifies whether a VLAN is available.
Table 4-1 describes the default mapping from DSCP to VLANPRI.
Table 4-1 Default mapping from DSCP to VLANPRI
DSCP

VLANPRI

0-7

0

8-15

1

16-23

2

24-31

3

32-39

4

40-47

5

48-55

6

56-63

7

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You can run the SET DSCPMAP command to dynamically configure the mapping from DSCP to
VLANPRI.

4.2.3 Priority Queues
At each ATM port (such as IMA, UNI, fractional ATM, or NCOPT port) or leaf LP of the RNC, there are
five types of priorities, as shown in Figure 4-3. The scheduling order is as follows: CBR > RT-VBR >
UBR+ (MCR) > WRR (NRT-VBR, UBR) > UBR+ (non-MCR), where MCR refers to Minimum Cell Rate.
Figure 4-3 Queues at each ATM port or leaf LP of the RNC

At each IP port (such as PPP/MLPPP or Ethernet port) or leaf LP of the RNC, BSC or MBSC, there are
six types of priorities, as shown in Figure 4-4. The default scheduling order is as follows: Queue1 >
Queue2 > WRR (Queue3, Queue4, Queue5, and Queue6), where WRR refers to Weighted Round
Robin.
Figure 4-4 Queues at each IP port or leaf LP of the RNC

Different types of services enter queues of different priorities for transmission. In this way, services are
differentiated. For details, see section 4.4.3 "Mapping from Traffic Bearers to Transport Bearers."
At each ATM port (such as IMA, UNI, fractional ATM, or NCOPT port) or LP of the NodeB, there are four
types of priorities, as shown in Figure 4-5. The scheduling order is as follows: CBR or UBR+ (MCR) >
RT-VBR > NRT-VBR > UBR or UBR+ (non-MCR).

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Figure 4-5 Queues at each ATM port or LP of the NodeB

At each IP port (such as PPP/MLPPP or Ethernet port) or LP of the NodeB, there are six types of
priorities, as shown in Figure 4-6. The default scheduling order is as follows: Queue1 > WFQ (Queue2,
Queue3, Queue4, Queue5, and Queue6). Where, WFQ refers to Weighted Fair Queuing.
Figure 4-6 Queues at each IP port or LP of the NodeB

Priority queues are used for RNC backpressure-based downlink congestion control. For details, see
section 6.5.3 "RNC Backpressure-Based Downlink Congestion Control Algorithm."
In the 2G TRM, there are no priority queues at the BTS.

4.2.4 Priority Queues and Rate Limiting in the NodeB
The NodeB automatically configures priority queues (PQs). PQ and Rate Limiting (RL) supplement each
other. When the actual bandwidth exceeds the specified bandwidth, the NodeB buffers or discards the
congested data to ensure the bandwidth at the physical port. When the physical port is congested, the
NodeB discards low-priority packets according to the PQ rules.
Table 4-2 describes the PQ rules based on the Most Significant Bits (MSBs) of DSCP in the NodeB.
Table 4-2 PQ rules in the NodeB
MSB of DSCP

PQ

110 or 111

Default urgent queue; manual configuration of PQ is not required.

101

TOP

100 or 011

MIDDLE

010 or 001

NORMAL

0

BOTTOM

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Parameters associated with PQs in the NodeB are as follows:


SIGPRI



OMPRI



PTPPRI

4.3 Service QoS
For service QoS, the following aspects need to be taken into consideration:


Traffic classes at the radio network layer: conversational service, streaming service, interactive service,
and background service, which are in descending order of QoS requirement.



User priorities: Services of the same traffic class can be differentiated based on the ARP.
− The

radio access network (RAN) provides DiffServ for users with different priorities based on the
Allocation Retention Priority (ARP). ARP is a core network (CN) QoS parameter regarding user
priorities.

− There

are three user priorities, that is, gold, silver, and copper. The relation between user priority and
ARP can be set through SET UUSERPRIORITY command.

− Both

2G and 3G systems differentiate user priorities, but the 2G system uses the ARP for admission,
and there is no mapping from user priority to ARP.



Traffic Handling Priority (THP): Interactive services of the same ARP can be differentiated based on
the THP. THPs are classified into high priority, middle priority, and low priority. The transport network
layer of the 2G system does not differentiate THPs.



Types of radio bearer: Radio bearers represent the service types of bearers, including R99 and HSPA
(HSUPA and HSDPA). Interactive services of the same ARP and THP can be differentiated based on
the parameter CarrierTypePriorInd.

For details about user priorities and THP, see the Load Control Feature Parameter Description of the
RAN.

4.4 Transmission Resource Mapping
Transmission resource mapping refers to the mapping from traffic bearers to transport bearers. The
RNC and BSC support configuration of mapping to transport bearers according to the characteristics of
service QoS.

4.4.1 Traffic Bearers
For 2G services, traffic bearers refer to the traffic class (TC) of the 2G system; for 3G services, traffic
bearers refer to the combination of TC, ARP, THP, and type of radio bearer that corresponds to one
transport bearer.
The RNC provides the following traffic classes that can be used in transmission resource mapping
configuration:


Common channel



SRB



SIP



AMR speech service



CS conversational service



CS streaming service

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

PS conversational service



PS streaming service



PS interactive service




PS background service

The BSC provides the following traffic classes that can be used in transmission resource mapping
configuration:


Abis OML



Abis RSL



Abis ESL



Abis EML



CS speech service



CS data service



PS data service

2G Abis signaling traffic classes have higher QoS requirement than other traffic classes, except Abis
EML.

4.4.2 Transport Bearers
Transport bearers refer to transmission of traffic on a certain type of paths.
For details about the types of paths for transport bearers, see section 3.4 "Path Resources."
Priorities of paths are the basis of transmission resource mapping:


Priorities of ATM paths are specified by the Pre-defined Virtual Connection (PVC).



Priorities of IP paths are specified by PHB. PHB is then indicated by the DSCP priority.

4.4.3 Mapping from Traffic Bearers to Transport Bearers
Overview
For the mapping from traffic bearers to transport bearers, default or dynamic configuration and
adjacent-node-oriented or non-adjacent-node-oriented configuration are provided.
The keyword used for configuring transmission resource mapping is traffic type. In transmission
resource mapping:


For 2G services, each TC corresponds to one priority of transport bearer, as shown in Figure 4-7.



For 3G services, each combination of TC, ARP, THP, and type of radio bearer corresponds to one
priority of transport bearer, as shown in Figure 4-8.

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

Only the mapping of Abis signaling services in the 2G system is non-adjacent-node-oriented configuration. For details,
see "Mapping from Abis Signaling Traffic to Transmission Resources."



The transmission resource mapping of the RNC also supports configuration of primary and secondary paths. For details,
see section 5.5 "Admission Control."

Figure 4-7 2G transmission mapping

Figure 4-8 3G transmission mapping

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Mapping from TC to PHB or PVC
For each combination of interface type and transport type, a transmission resource mapping can be
configured by default. The RNC and BSC provide default transmission resource mapping tables
(TRMMAP tables) for various networking scenarios. The default TRMMAP table can be queried through
the LST TRMMAP command. Table 4-3 describes the default TRMMAP table, where IDs 0 to 8
represent Iub ATM, Iub IP, Iub ATM IP, Iub HYBRID IP, Iur ATM, Iur IP, Iu-CS ATM, Iu-CS IP, and Iu-PS of
the RNC respectively, and IDs 10 to 12 represent Abis IP, A IP, and Ater IP of the BSC respectively.
Table 4-3 Default TRMMAP table
Interface

ATM

IP

ATM&IP Dual Stack

Hybrid IP

Iub

0

1

2

3

Iur

4

5

-

-

Iu-CS

6

7

-

-

Iu-PS

-

8

-

-

Abis

-

10

-

-

A

-

11

-

-

Ater

-

12

-

-



In HDLC transmission mode, traffic is directly mapped to port queues.



The default TRMMAP table differentiates neither operators nor user priorities. If transmission resource mapping is not
dynamically configured, the default TRMMAP table is used.

To provide better differentiated services, the RNC and BSC support dynamic configuration of the
transmission resource mapping and thus traffic bearers can be mapped to transport bearers freely. The
RNC also supports separate configuration of transmission resource mapping under an Iub adjacent
node for a certain operator or a certain user priority.
To dynamically configure transmission resource mapping, do as follows:
Step 1 Run the ADD TRMMAP command to specify the mapping from the TCs of a specific interface
type and transport type to a transport bearer.
Step 2 Run the ADD ADJMAP command to use the configured TRMMAP table. When the RNC
ADJMAP is configured, the TRMMAP tables need to be specified for gold, silver, and copper
users respectively.


In the RAN sharing scenario, the operator index needs to be set to specify transmission resource mapping of the
operator under the adjacent node, if the resource management mode is set to EXCLUSIVE.



When the transmission mode on the Iub interface is ATM&IP dual stack or hybrid IP, the load balance index of primary
and secondary paths needs to be configured.

----End
The associated parameters are as follows:


ITFT

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

TRANST



CNMNGMODE



CNOPINDEX



TMIGLD



TMISLV



TMIBRZ



LEIGLD



LEISLV




LEIBRZ

Mapping from PHB to DSCP
The service QoS can be mapped to transport QoS by configuring the mapping between PHB and DSCP.
Table 4-4 describes the default mapping from PHB to DSCP.
Table 4-4 Default mapping from PHB to DSCP
PHB

DSCP (Binary)

DSCP (Decimal)

EF

101110

46

AF43

100110

38

AF42

100100

36

AF41

100010

34

AF33

11110

30

AF32

11100

28

AF31

11010

26

AF23

10110

22

AF22

10100

20

AF21

10010

18

AF13

1110

14

AF12

1100

12

AF11

1010

10

BE

0

0

You can run the SET PHBMAP command to dynamically configure the mapping from PHB to DSCP
(PHBMAP).


If the traffic is carried on a non-QoS path, the PHB of the path is determined by the path type. Run the
SET PHBMAP command to configure PHBMAP.



If the traffic is carried on a QoS path, the PHB of the path is determined by the TRMMAP. Run the ADD
TRMMAP command to determine the PHB of the path, and then run the SET PHBMAP command to
configure PHBMAP.

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Mapping from DSCP to Queue Priority
By configuring the mapping from DSCP to queue priority, you can achieve differentiated services for the
traffic classes with different DSCP values according to different queue priorities.
Table 4-5 describes the default mapping from DSCP to queue priority.
Table 4-5 Default mapping from DSCP to queue priority
Minimum DSCP

Queue Priority

40

0

32

1

24

2

16

3

8

4

0

5

You can run the SET QUEUEMAP command to dynamically configure the minimum DSCP value that
each queue at the IP port corresponds to.
The associated parameters are as follows:


Q0MINDSCP



Q1MINDSCP



Q2MINDSCP



Q3MINDSCP



Q4MINDSCP

The minimum DSCP value of queue 5 need not be set. The IP packet that meets the condition (0 <= DSCP value <
minimum DSCP value for queue 4) enters queue 5 for transmission.

Mapping from Abis Signaling Traffic to Transmission Resources
You need to configure the mapping from Abis signaling traffic of the BSC to transmission resources
independently. Both the default configuration and the dynamically configuration are available for the
mapping. You can use the SET BSCABISPRIMAP command to dynamically configure the mapping.
Table 4-6 and Table 4-7 describe the default mapping from traffic to transmission resources.
Table 4-6 Mapping from traffic to transmission resources in IP transmission mode
TC

DSCP

ESL

48

OML

48

RSL

48

EML

0

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Table 4-7 Mapping from traffic to transmission resources in HDLC transmission mode
TC

Queue Priority

ESL

0

OML

0

RSL

0

EML

5

For IP transmission on the Abis interface, the associated parameters are as follows:


OMLDSCP



RSLDSCP



EMLDSCP



ESLDSCP

For HDLC transmission on the Abis interface, the associated parameters are as follows:


OMLPRI



RSLPRI



EMLPRI



ESLPRI

4.5 Summary
Table 4-8 describes the difference between traffic bearers in the 2G, 3G, and co-transmission systems.
Table 4-8 Difference between traffic bearers in the 2G, 3G, and co-transmission systems
Traffic Bearer

2G System

3G System

Co-Transmission System

TC

√

√

√

ARP

√

√

√

THP

√

√

√

Radio bearer type

×

√

√



The 2G system uses the ARP for admission, and there is no mapping from user priority to ARP.



The transport layer of the 2G system does not differentiate THPs.

Table 4-9 describes the adjacent-node-oriented transmission resource mapping of the 2G TRM, 3G TRM,
and Co-TRM.
Table 4-9 Adjacent-node-oriented transmission resource mapping of the 2G TRM, 3G TRM, and Co-TRM
Transmission Mode Adjacent-Node-Oriented Transmission Resource Mapping
3G ATM transmission From TC + ARP + THP + radio bearer type to PVC
3G IP transmission

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Transmission Mode Adjacent-Node-Oriented Transmission Resource Mapping
2G HDLC transmission From TC (excluding signaling traffic) to queue priority
2G IP transmission

From TC (excluding signaling traffic) to PHB, from PHB to DSCP to queue
priority

Co-transmission



For 2G services: from TC (excluding signaling traffic) to PHB, from PHB to
DSCP to queue priority



For 3G services: from TC + ARP + THP + radio bearer type to PHB, from PHB
to DSCP to queue priority



The mapping from signaling traffic of the Abis interface of the 2G system to transmission resources is not oriented to
adjacent nodes. It needs to be configured independently.



In TDM transmission mode of the 2G system, traffic is directly carried on the timeslot at the port. Thus, transmission
resource mapping is not required.



In IP transmission mode of the 3G system, configuration of primary and secondary paths is also supported.

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5 Load Control

5 Load Control
5.1 Overview of Load Control
Load control at the transport layer is used to manage transmission bandwidth and control transmission
load, for the purpose of allowing more users to access the network and increasing the system capacity
with the QoS guaranteed. Load control is responsible for management of data in the control plane.
Load control methods include admission control, LDR, and OLC.


Admission control is the basic method of load control. In the process of transmission resource
admission, admission control is used to determine whether the transmission resources are sufficient to
accept the admission request from a user. Admission control prevents excessive admission of users
and guarantees the quality of admitted services.



LDR is used to prevent congestion, reduce transmission load, and increase admission success rate
and system capacity.



OLC is used to quickly eliminate overload when congestion occurs, and to reduce the impact of
overload on high-priority users.

Differentiated services are implemented as follows:


Admission strategies: Different admission strategies are used for different types of users. During
admission based on transmission resources, differentiated services for user priorities are
implemented.



Preemption: High-priority users preempt bandwidth of low-priority users. Thus, differentiated services
for different service types and user priorities are implemented.



LDR: Different LDR actions are used for different services. During congestion, differentiated services
for different service types are implemented.



OLC: Bandwidth of low-priority users is released, which reduces the impact of overload on high-priority
users. In the case of overload, differentiated services for different service types and user priorities are
implemented.

Table 5-1 describes load control applied in the 2G TRM, 3G TRM, and Co-TRM.
Table 5-1 Load control applied in the 2G TRM, 3G TRM, and Co-TRM
Load Control

2G TRM

3G TRM

Co-TRM

Reserved bandwidth
admission

√

√

√

Load balancing

-

√

√

Preemption

√

√

√

Queuing

√

√

√

LDR

√

√

√

OLC

√

√

√

Admission
control

This section describes the definition and calculation of transmission load, calculation of reserved
bandwidth, and load thresholds in addition to admission control, LDR, and OLC. For differences of
implementing load control in the 2G TRM, 3G TRM, and Co-TRM, see the following sections.

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5 Load Control

5.2 Definition and Calculation of Transmission Load
Transmission load refers to transmission resources required by access users. In the ATM, IP, or HDLC
transmission mode, transmission resources are measured based on bandwidth, and load control
management is based on transmission bandwidth only.
Load is defined on the basis of reserved bandwidth. Bandwidth is reserved for each service in load
control. Load is the sum of bandwidth reserved for all services, and the uplink load and downlink load are
calculated separately.
Load of all paths and all LPs (including leaf LPs and hub LPs) needs to be calculated as follows:


Path load: The load on a path is equal to the sum of reserved bandwidth of all services.



Leaf LP load: The load on a leaf LP is equal to the sum of load of all paths.



Hub LP load: The load on a hub LP is equal to the sum of load of all LPs.

5.3 Calculation of Reserved Bandwidth
Reserved bandwidth is used for both load calculation and user admission. Therefore, calculation of
reserved bandwidth for each service should be specified.

5.3.1 Calculation of Bandwidth Reserved for 2G Signaling
This section describes the bandwidth reserved for signaling of the 2G Link Access Protocol on the D
channel (LAPD) link.
When the IP transmission mode is applied to the Abis interface, some LAPD links and user plane data
share the transport channels. The LAPD links include OML, ESL, and RSL. These links occupies a large
proportion of bandwidth and therefore the bandwidth of LPs needs to be reserved for LAPD links to
prevent congestion.
The calculation of bandwidth reserved for LAPD links is as follows:


Bandwidth reserved for uplink signaling = Average bandwidth for uplink OMLs and ESLs of the BTS +
Number of TRXs x Average bandwidth for uplink RSLs of the BTS



Bandwidth reserved for downlink signaling = Average bandwidth for downlink OMLs and ESLs of the
BTS + Number of TRXs x Average bandwidth for downlink RSLs of the BTS

You can adjust the bandwidth reserved for LAPD signaling of the BTSs using Abis IP. The associated
parameters are as follows:


OMLESLUL



OMLESLDL



RSLUL



RSLDL

In IP over E1 mode, the bandwidth reserved for LAPD signaling takes effect on LPs. To ensure the accuracy of admission
based on bandwidth for PPP and MLPPP links, you are advised to take one of the following measures:

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5 Load Control



Configure LPs on the PPP or MLPPP links with the same bandwidth as the PPP or MLPPP links



Configure IP paths of the QoS type: Bandwidth of IP path = Bandwidth of PPP or MLPPP - Max (Bandwidth reserved for
uplink signaling, Bandwidth reserved for downlink signaling)

5.3.2 Calculation of Bandwidth Reserved for Traffic
Bandwidth reserved for a service = Transport-layer rate of the service x Activity factor, where the
transport-layer rate of the service derives from the rate that the user applies for.
The RNC or BSC calculates the reserved bandwidth based on the activity factor and performs admission
control based on the reserved bandwidth.
The bandwidth reservation policies for different services are as follows:


For RT services: Reserved bandwidth = MBR x Activity factor



For 3G NRT services: Reserved bandwidth = GBR x Activity factor



For 2G NRT PDCH services (with the backpressure switch disabled): Reserved bandwidth = MBR x
Activity factor



3G signaling:
− Admission

of SRB at 3.4 kbit/s: The bandwidth for 3G SRB signaling is fixed at 3.4 kbit/s. This
admission mode is applicable to R99, HSDPA, and HSUPA services. For R99 services, if the
bandwidth of a transport channel varies between 3.4 kbit/s and 13.6 kbit/s, resource allocation and
resource admission do not need to be performed again.

− Admission


of IMS at the GBR

3G common channels:
− Bandwidth

reserved for E-FACH = GBR x Activity factor

− Bandwidth

reserved for other common channels = MBR x Activity factor

NOTE


For 2G PS services, the recommended activity factor is 1.



For 3G common channels or SRBs, the activity factors are identical for all users, instead of varying according to user
priorities.



In TDM transmission mode, the bandwidth is allocated in a fixed manner instead of based on activity factors.

Activity factors can be configured for different types of services and adjacent nodes:


Both default configuration and dynamic configuration are available for activity factors for different types
of service. The default configuration can be queried through the LST TRMFACTOR command. You
can run the ADD TRMFACTOR command to dynamically configure activity factors for different types
of service.



You can run the ADD ADJMAP command to configure the same activity factor table for an adjacent
node by specifying the FTI parameter.

For 3G BE services, the GBR can be set by running the SET UUSERGBR command, according to traffic
classes, traffic priorities, user priorities, and types of radio bearers. The associated parameters are as
follows:


TrafficClass



THPClass



BearType



UserPriority



UlGBR



DlGBR

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5 Load Control

5.4 Load Thresholds
In the admission process based on transmission resources, load and threshold are compared to
determine whether the admission is successful.
The thresholds can be configured through the parameters such as relative residual resource (%,
percentage of residual bandwidth to total bandwidth) or absolute residual resource (kbit/s, residual
bandwidth). Uplink and downlink thresholds are configured separately.


Admission threshold of a new user (handover reserved threshold)
This threshold controls the admission of a new user and can be configured through the parameters
FWDRSVHOBW, BWDRSVHOBW, FWDRESVHOTH, and BWDRESVHOTH.



Congestion threshold (admission threshold of a user requesting a rate increase)
This threshold triggers LDR and can be configured through the parameters FWDCONGBW,
BWDCONGBW, FWDCONGTH, and BWDCONGTH.



Congestion clear threshold
This threshold clears congestion and can be configured through the parameters FWDCONGCLRBW,
BWDCONGCLRBW, FWDCONGCLRTH, and BWDCONGCLRTH.



Overload threshold
This threshold triggers overload control and can be configured through the parameters
FWDOVLDRSVBW, BWDOVLDRSVBW, FWDOVLDTH, and BWDOVLDTH.



Overload clear threshold
This threshold clears overload and can be configured through the parameters
FWDOVLDCLRRSVBW, BWDOVLDCLRRSVBW, FWDOVLDCLRTH, and BWDOVLDCLRTH.
NOTE

In 2G TDM transmission mode, there are only congestion threshold and congestion clear threshold, which are configured
through the parameters TDMCONGTH and TDMCONGCLRTH.

The congestion threshold and congestion clear threshold, and the overload threshold and overload clear
threshold are used to prevent ping-pong effect. It is recommended that they should be set to different
values.
By running the ADD TRMLOADTH command, you can configure a load threshold table (TRMLOADTH
table) for paths, LPs, resource groups, or physical ports. By specifying the TRMLOADTHINDEX
parameter, the TRMLOADTH table can be referred to.
In ATM transmission, you can run the MML command ADD AAL2PATH or ADD ATMLOGICPORT
command to refer to the TRMLOADTH table.
In IP transmission, you can run the MML command ADD IPPATH or ADD IPLOGICPORT command to
refer to the TRMLOADTH table.
In TDM/HDLC transmission, you can run the MML command SET BSCABISPRIMAP to refer to the
TRMLOADTH table.
For details about the preceding thresholds, see sections 5.5 "Admission Control" and 5.6 "Load
Reshuffling and Overload Control."

5.5 Admission Control
Admission control is used to determine whether the transmission resources are sufficient to accept the
admission request from a user. If the transmission resources are sufficient, the admission request is
admitted; otherwise, the request is rejected. Admission control can prevent admission of excessive
users and guarantee the QoS.

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5.5.1 Admission Process
Figure 5-1 shows the admission control during the request for transmission resources.
Figure 5-1 Admission control during the request for transmission resources

As shown in Figure 5-1, when the users request transmission resources, the admission control process
is as follows:
1. The admission based on transmission resources is decided according to the admission strategy. If
the admission is successful, a user can obtain transmission resources. If the admission fails, go to
step 2. For details about the admission strategy, see section 5.5.2 "Admission Strategy."
2. The attempt to preempt resources is made. If the preemption is successful, a user can obtain
transmission resources. If the preemption fails or the preemption function is not supported, go to step
3. For details about preemption, see section 5.5.5 "Preemption."
3. The attempt for queuing is made. If the queuing is successful, a user can obtain transmission
resources. If the queuing fails or the queuing function is not supported, the admission based on
transmission resources fails. For details about queuing, see section 5.5.6 "Queuing."
After transmission resources are successfully admitted, bandwidth needs to be reserved on the
corresponding paths and ports. In addition, bandwidth needs to be updated to the load.

5.5.2 Admission Strategy
Overview
The principles of ATM/IP transmission resource admission are as follows:
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5 Load Control



Multiple levels of admission. After the user initiates a request for transmission resources, admission
based on transmission resources is decided in the sequence of paths -> LPs -> physical ports.



If a certain level of admission is not supported, you can directly perform the admission decision of transmission
resources of the next level. If the LP is not configured, the admission is performed in the sequence of paths -> physical
ports.



In multiple levels of admission, users can obtain transmission resources only when the admission based on all
resources is successful.



In TDM Flex Abis transmission, the transmission resource admission is performed from the Flex Abis resources of the
lowest-level base station step by step in an ascending order. In HDLC transmission, admission is based on HDLC links.



The service priorities need to be taken into consideration. New users, handover users, and users
requesting a rate increase use different admission strategies.

The admission based on transmission resources is determined according to the current load, bandwidth
requested by users, and admission thresholds. The admission strategy varies according to the types of
users.


For a new user
− Admission

based on paths

Path load + Bandwidth required by the user < Total configured bandwidth for the path - Path
bandwidth reserved for handover.
− Admission

based on LPs

The admission based on LPs is performed level by level. For each level of admission, the strategy is
as follows: LP load + Bandwidth required by the user < Total bandwidth for the LP - LP bandwidth
reserved for handover.


For a handover user
− Admission

based on paths

Path load + Bandwidth required by the user < Total bandwidth for the path.
− Admission

based on LPs

The admission based on LP resources is performed level by level. For each level of admission, the
strategy is as follows: LP load + Bandwidth required by the user < Total bandwidth for the LP.


For a user requesting a rate increase
− Admission

based on paths

Path load + Bandwidth required by the user < Total bandwidth for the path - Path congestion
threshold.
− Admission

based on LPs

The admission based on LPs is performed level by level. For each level of admission, the strategy is
as follows: LP load + Bandwidth required by the user < Total bandwidth for the LP - LP congestion
threshold.
NOTE

If no admission threshold is configured for the user, the admission strategy can be simplified as: Load + Bandwidth
required by the user < Total bandwidth configured.

Procedure for the Admission Based on Paths
One type of service can be mapped to multiple paths of the same type by configuring transmission
resource mapping. Figure 5-2 shows the procedure for the admission based on paths.

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Figure 5-2 Procedure for the admission based on paths

Step 1 Paths are selected according to transmission resource mapping. For details about transmission
resource mapping, see section 4.4 "Transmission Resource Mapping."
If no paths are available for use, for example, when the mapped path type does not exist, the
admission fails.
Step 2 The admission sequence for all paths is determined. For details, see the section "Sequence of
the Admission Based on Paths."
Step 3 According to the sequence, a path is selected to undergo admission decision.
If…

Then…

The admission succeeds.

The admission based on paths is complete.

The admission fails.

Go to Step 4.

Step 4 Whether there are still available paths is determined.
If…

Then…

There is no available path.

The admission fails, the admission based on paths
is complete.

There are still available paths.

Go to Step 3.

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Sequence of the Admission Based on Paths
During the admission process, the sequence of the admission based on the paths needs to be
determined after all paths available for a type of service are determined.


If the type of service requests a rate decrease, successful admission is directly performed on its
original path.



If the type of service requests a rate increase, an admission decision is preferentially performed on its
original path.



If a type of service is mapped to multiple paths of the same type,
− When

paths are configured as primary and secondary paths and load balancing algorithm is enabled,
firstly whether the admission is based on the primary paths or the secondary paths is determined
according to the algorithm of path load balancing. For details, see section 5.5.4 "Load Balancing."
Then the specific primary or secondary path to undergo admission decision is determined according
to the algorithm of path load sharing. For details, see section 5.5.3 "Load Sharing."
− Otherwise, the path to undergo admission decision is determined according to the algorithm of path
load sharing. For details, see section 5.5.3 "Load Sharing."

5.5.3 Load Sharing
As Figure 5-3 shows, the round robin path algorithm helps implement load sharing between paths.


One type of service can be mapped to multiple paths of the same type. The paths form a circular chain.
In the circular chain, the admission sequence for all paths is fixed.



A cursor is used to indicate the current path for admission decision.



If the admission succeeds, the cursor moves to the next path for use in the next admission procedure.



If the admission fails, the next path is chosen to undergo admission decision in the sequence of the
circular chain.

Figure 5-3 Path round robin

For example,


One type of service is mapped to five paths of the same type that are numbered path 1 to path 5. The
five paths form a circular chain: 1→2→3→4→5→1.



Assume that the type of service needs to be admitted for 100 times in response to 100 requests. The
times are respectively marked T1, T2, T3, …



Assume that the admission of T1 succeeds on path 1.

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

Then the admission of T2 is performed in the sequence of 2→3→4→5→1. Assume that the admission
succeeds on path 4.



Then the admission of T3 is performed in the sequence of 5→1→2→3→4. Assume that the admission
fails on all paths. In this case, the admission of T3 is rejected.



Then the admission of T4 is performed in the sequence of 5→1→2→3→4. …

If the admission of all the 100 times succeeds on the first path for admission decision, then the 100
service requests are respectively admitted on one of the five paths in the following way:

5.5.4 Load Balancing
In the admission control, load balancing is a method used to achieve the load balance between primary
and secondary paths.

Principles of Load Balancing
The principles of load balancing are as follows:


Load balancing between primary and secondary paths is applied only in the Iub hybrid transmission
scenario, including ATM&IP dual stack and hybrid IP transmission.



A service is not always preferably admitted based on the primary path. If the load of the primary path
exceeds the load threshold and the ratio of secondary path load to primary path load is lower than the
load ratio threshold, then the service is preferably admitted based on the secondary path to improve
the resource usage and user experience.

Calculation of the Load of Primary and Secondary Paths
The load of a path is calculated as follows: PathLoad = (PortUsed ÷ PortAvailable) x 100%
where:


PathLoad refers to the load of the path.



PortUsed refers to the total bandwidth of the admitted services at the physical port.



PortAvailable refers to the total available bandwidth at the physical port, including the used bandwidth.

Issue 03 (2011-09-30)


5-9

Transmission resource management

Transmission resource management

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