Iub Overbooking Description(2008!05!30)

RAN

Iub Overbooking Description Issue 01

Date 2008-05-30

Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd

Huawei Technologies Co., Ltd. provides customers with comprehensive technical support and service. For any assistance, please contact our local office or company headquarters.

Huawei Technologies Co., Ltd. Address: Huawei Industrial Base

Bantian, Longgang Shenzhen 518129 People's Republic of China

Website: http://www.huawei.com

Email: [email protected]

Copyright Huawei Technologies Co., Ltd. 2008. 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 information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute the warranty of any kind, express or implied.

Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd

RAN Iub Overbooking Description Contents

Issue 01 (2008-05-30) Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd

i

Contents

1 Iub Overbooking Change History..........................................................................................1-1

2 Iub Overbooking Introduction................................................................................................2-1

3 Iub Overbooking Algorithms..................................................................................................3-1 3.1 Iub Overbooking Key Principles...................................................................................................................3-2

3.1.1 Voice Service Capacity and Congestion Probability of Iub Overbooking............................................3-2 3.1.2 PS Service Capacity and Congestion Probability of Iub Overbooking................................................3-3 3.1.3 Iub Transmission Bandwidth for Iub Overbooking..............................................................................3-4 3.1.4 Transmission Priority of Iub Overbooking...........................................................................................3-5

3.2 Iub Overbooking Flow Control Algorithms ..................................................................................................3-6 3.2.1 Flow Control Algorithm 1 for Iub Overbooking..................................................................................3-6 3.2.2 Flow Control Algorithm 2 for Iub Overbooking..................................................................................3-8

4 Iub Overbooking Reference Documents...............................................................................4-1

RAN Iub Overbooking Description 1 Iub Overbooking Change History


1-1

1 Iub Overbooking Change History Iub Overbooking Change History provides information on the changes between different document versions.

Document and s

T t versions

Product Version

able 1-1 Document and produc

Document Version RAN Version RNC Version NodeB Version

01 (2008-05-30) 10.0 V200R010C01B051 V100R010C01B049V200R010C01B040

Draft (2008-03-20) 10.0 V200R010C01B050 V100R010C01B045

There are two types of changes, which are defined as follows:

Feature change: refers to changes in the Iub overbooking feature of a spz ecific product version.

Editorial change: refers to changes in information that has already been included, or the n.

01 (2008-05-30This is the document for the first commercial release of RAN10.0.

Compared with draft (2008-03-20) of RAN10.0, issue 01 (2008-05-30) of RAN10.0 incorporates the changes described in the following table.

zaddition of information that was not provided in the previous versio

)

1 Iub Overbooking Change History RAN

Iub Overbooking Description

1-2 Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd

Issue 01 (2008-05-30)

Change Type

Change Description Parameter Change

Feature change

None The parameters that are changed to be non-configurable are listed as follows: z AEU Board Port Flow Control Switch z AOU Board Port Flow Control Switch z UOI Board Port Flow Control Switch z GOU Board Port Flow Control Switch z FG2 Board Port Flow Control Switch z POS Board Port Flow Control Switch z re-TX monitor period[ms] z re-TX measure filter coef z Event A time to trigger z RLC Rate Limit Coeff[%] z HSDPA Rate Limit Coefficient z Event A pending time after trigger z Event B time to trigger z RLC Rate Recover Coeff[%] z HSDPA Rate Recover Coefficient z Event B pending time after trigger z Rate Limit Coeff for Congestion[%] z Congestion threshold of queue 0 [ms] z Congestion threshold of queue 1 [ms] z Congestion threshold of queue 2 [ms] z Congestion threshold of queue 3 [ms] z Congestion threshold of queue 4 [ms] z Congestion threshold of queue 5 [ms] z Packet discard threshold of queue 0 [ms]z Packet discard threshold of queue 1 [ms]z Packet discard threshold of queue 2 [ms]z Packet discard threshold of queue 3[ms] z Packet discard threshold of queue 4 [ms]z Packet discard threshold of queue 5 [ms]z Quick Rate Limit Coeff for Cong[%] z Rate Up Step[bps] z Cycle of increasing the rate[10ms] z Recover threshold of queue 0 [ms] z Recover threshold of queue 1 [ms] z Recover threshold of queue 2 [ms] Recover threshold of queue 3 [ms]



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Change Change Description Parameter Change Type

z Recover threshold of queue 5 [ms] z Time to start re-TX monitor

Editorial change

General documentation change: z The Iub Overbooking

Parameters is removed because of the creation of RAN10.0 parameter reference.

z The structure is optimized.

None

Draft (2008-03-20) This is the first commercial release of RAN10.0.

Compared with issue 03 (2008-01-20) of RAN6.1, this issue incorporates the changes described in the following table.

Change Type

Change Description Parameter Change

Feature change

The description of Iub transmission bandwidth for Iub overbooking is updated in 1.3.1 Iub Overbooking Key Principles.

The SET DEFAULTFACTORTABLE command has been added. The following parameters of the ADD ADJMAP command have been deleted: z Gold user factor table index z Silver user factor table index z Bronze user factor table index The following parameters of the SET USERGBR command have been deleted:z Uplink GBR for Gold Interactive

R99 RAB[kbit/s] z Downlink GBR for Gold Interactive

R99 RAB[kbit/s] z Uplink GBR for Silver Interactive

R99 RAB[kbit/s] z Downlink GBR for Silver

Interactive R99 RAB[kbit/s] z Uplink GBR for Copper Interactive

R99 RAB[kbit/s] z Downlink GBR for copper

interactive R99 RAB[kbit/s] z Uplink GBR for Gold Interactive




Issue 01 (2008-05-30)


HSPA RAB[kbit/s] z Downlink GBR for Gold Interactive

HSPA RAB[kbit/s] z Uplink GBR for Silver Interactive

HSPA RAB[kbit/s] z Downlink GBR for Silver

Interactive HSPA RAB[kbit/s] z Uplink GBR for Copper Interactive

HSPA RAB[kbit/s] z Downlink GBR for Copper

Interactive HSPA RAB[kbit/s] z Uplink GBR for Gold Background

R99 RAB[kbit/s] z Downlink GBR for Gold

Background R99 RAB[kbit/s] z Uplink GBR for Silver Background

R99 RAB[kbit/s] z Downlink GBR for Silver

Background R99 RAB[kbit/s] z Uplink GBR for Copper

Background R99 RAB[kbit/s] z Downlink GBR for Copper

Background R99 RAB[kbit/s] z Uplink GBR for Gold Background

HSPA RAB[kbit/s] z Downlink GBR for Gold

Background HSPA RAB[kbit/s] z Uplink GBR for Silver Background

HSPA RAB[kbit/s] z Downlink GBR for Silver

Background HSPA RAB[kbit/s] z Uplink GBR for Copper

Background HSPA RAB[kbit/s] z Downlink GBR for Copper

Background HSPA RAB[kbit/s] The following parameters of the SET USERGBR command have been added: z Traffic Class z Traffic Handler Priorty Class z Bear Type z User Priority z Uplink GBR for BE service[kbit/s]



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z Downlink GBR for BE service[kbit/s]

The description of flow control Algorithm 1 is updated in 1.3.2.1 Flow Control Algorithm 1 for Iub Overbooking.

The parameters added are as follows: z RLC mode selection z RLC AM mode parameters selectionz RLC Rate Limit Coeff[%] z RLC Rate Recover Coeff[%] The IUB_OVERBOOKING parameter value has been replaced with the FLOWCONTROL_PARA parameter value.

Flow Control Algorithm 2 is supported on IP interface boards is added. The description of flow control method 2 is updated in 1.3.2.2 Flow Control Algorithm 2 for Iub Overbooking.

The parameters deleted are as follows: z Congestion threshold of NRTVBR

[ms] z Recover threshold of NRTVBR [ms]z Packet discard threshold of

NRTVBR [ms] z Congestion threshold of UBR [ms] z Recover threshold of UBR [ms] z Packet discard threshold of UBR

[ms] The parameters added are as follows: z UOP Board Port Flow Control

Switch z GOU Board Port Flow Control

Switch z FG2 Board Port Flow Control

Switch z Flow control parameter index z Priority queue number z Congestion threshold of queue 1

[ms] z Recover threshold of queue 1 [ms] z Packet discard threshold of queue 1

[ms] z Congestion threshold of queue 2






Issue 01 (2008-05-30)









[ms]

Editorial change

General documentation change: Implementation information has been moved to a separate document. For information on how to implement Iub overbooking, refer to Configuring Iub Overbooking in RAN Feature Configuration Guide.

None.

RAN Iub Overbooking Description 2 Iub Overbooking Introduction


2-1

2 Iub Overbooking Introduction Introduction

rface.

e convtraffi

z

If the Radio Network Controller (RNC) allocates the maximum bandwidth to the subscriber is unused.

sed.

g to the Guaranteed Bit Rate (GBR). Data transmission use transmission priorities, congestion detection and flow control after services are admitted In this way, the maximum number of users with the minimum number of activity request to use voice and PS Best Effort (BE) services can access the network, thus achieving a

tte dth.

Impact ance

n bandwidth usage and saves the cost of transmission.

r Features

The Iub overbooking feature considers the statistic multiplexing of service activities and multiple users. Through the admission of more users, Iub overbooking increases the resource utilization on the Iub inte

Th Universal Mobile Telecommunications System (UMTS) supports four traffic classes: ersational, streaming, interactive, and background. The transmission rate varies with the c class as follows:

For Circuit Switched (CS) conversational services, the channel transmits voice signals at a certain rate (for example, 12.2 kbit/s) during a conversation and only transmits SilenceDescriptors (SIDs) at intervals when there is no conversation.

z For Packet Switched (PS) interactive and background services, such as web browsing, there is data transmitted during data downloading. After a web page has been downloaded, and when the user is reading the page, however, there is very little data to transfer.

when a service is established, a large proportion of the Iub transmission bandwidth For example, downloading a 50 KB page takes only about one second, but reading this page needs dozens of seconds. Thus, over 90% of the Iub transmission bandwidth is not u

To save the Iub transmission bandwidth for operator use, Huawei provides the Iub overbooking function, which applies an admission control mechanism to access the service. Services are admitted according to the different activity factors. PS interactive and background services can be admitted accordin

be r utilization of transmission bandwi

z Impact on System PerformIub overbooking increases the Iub transmissio

z Impact on OtheThis feature has no impact on other features.

2 Iub Overbooking Introduction RAN



Issue 01 (2008-05-30)

Network ElemT - the rk s) i ook

Table 2-1 NEs involved in Iub overbooking

ents Involved able 2 1 shows Netwo Elements (NE nvolved in Iub overb ing.

UE NodeB RNC MSC Server MGW SGSN GGSN HLR

-

N

z : involved UE = User Equipment, RNC = Radio Network Controller, MSC Server = Mobile Service Switching Center Server, MGW = Media Gateway, SGSN = Serving GPRS Support Node, GGSN = Gateway GPRS Support Node, HLR = Home Location Register

OTE: z : not involved

RAN Iub Overbooking Description 3 Iub Overbooking Algorithms


3-1

3 Iub Overbooking Algorithms About Thi

T co

s Chapter

he following table lists the ntents of this chapter.

Section Describes

3.1 Iub Overbooking Key Iub Overbooking Key Principles provides information on the Principles activity factors, GBR for PS BE services, the transmission

bandwidth for Iub overbooking, the different transmission priorities, congestion detection, and the flow control.

3.2 Iub Overbooking Flow Control Algorithms

Iub Overbooking Flow Control Algorithms describes two flow control algorithms, namely, flow control algorithm 1 and flow control algorithm 2. The two algorithms are applied to the congestion that is caused by Iub overbooking.

3 Iub Overbooking Algorithms RAN



Issue 01 (2008-05-30)

3.1 Iub Overbooking Key Principles Iub Overbooking Key Principles provides information on the activity factors, GBR for PS BE services, the transmission bandwidth for Iub overbooking, the different transmission priorities, congestion detection, and the flow control.

3.1.1 Voice Service Capacity and Congestion Probability of Iub Overbooking

The service behavior of voice service is about 50%. That is, at a given moment of a conversational situation, data is usually transmitted either on the uplink (UL) or the downlink (DL) channel.

Without Iub overbooking (the activity factor is 100%), one E1 supports about 54 users with Adaptive Multi Rate (AMR) at 12.2 kbit/s. After the Iub overbooking is introduced, when the activity factor is set to 70%, the E1 supports up to 77 users with AMR at 12.2 kbit/s. In this case, the congestion probability is only 1.1E-4. Compared with the target Block Error Rate (BLER) of voice service, 1E-3, the quality deterioration caused by congestion is negligible.

For the AMR service at 12.2 kbit/s, the capacity and congestion probability on one E1 are listed in Table 3-1.

Table 3-1 Voice service capacity and congestion probability of Iub overbooking

Service Behavior

Activity Factor

Number of Users Supported

Congestion Probability

Bandwidth Saved

100% 54 0.00E+00 0%

90% 60 5.20E-12 10%

77% 70 8.30E-07 23%

70% 77 1.10E-04 30%

68% 80 5.30E-04 32%

64% 85 4.40E-03 36%

60% 90 2.20E-02 40%

50%

54% 100 1.80E-01 46%

The smaller the activity factor is set, the more users can access the network. Thus, the usage of the Iub transmission resources can be increased. The congestion probability, however, is also higher. Therefore, the activity factor needs to be set appropriately to get trade-off between capacity and congestion probability.



3-3

3.1.2 PS Service Capacity and Congestion Probability of Iub Overbooking

Without Iub overbooking, only a limited number of BE services can access the network. Since the available bandwidth is occupied by the accessed BE services, new PS services cannot be admitted, even if there is no data transmitted for the accessed services. Although Dynamic Channel Configuration Control (DCCC) is available for dynamic channel configuration, the bandwidth usage is still low, that is, lower than 50%.

Iub overbooking enables statistical multiplexing of transmission bandwidth, thus allowing admission of more PS services and achieving better utilization of the transmission bandwidth.

For example, one E1 supports up to three PS users with a DL rate of 384 kbit/s and a UL rate of 64 kbit/s without Iub overbooking. With Iub overbooking, when the service behavior is 10% and the activity factor is 17%, eighteen PS users (DL: 384 kbit/s; UL: 64 kbit/s) can be supported. Here, the congestion probability is 9.8%.

For the PS service, the capacity and congestion probability on one E1 is shown in Table 3-2.

Table 3-2 PS service capacity and congestion probability of Iub overbooking

Service Behavior

Activity Factor

Number of Users Supported

Congestion Probability

Bandwidth Saved

10% 30 35.30% 90%

13% 24 21.40% 87%

17% 18 9.80% 83%

10%

25% 12 2.60% 75%

25% 12 35.10% 75%

33% 9 16.60% 67%

50% 6 3.80% 50%

25%

100% 3 0.00% 0%

33% 9 74.60% 67%

50% 6 34.40% 50%

60% 5 18.80% 40%

50%

75% 4 6.30% 25%




Issue 01 (2008-05-30)

z Since the service behavior for actual PS services is not fixed, the congestion probability may vary

after bandwidth admission. In this situation, congestion detection and flow control are applied. z To ensure that the maximum number of users with the minimum number of activity request to use

PS BE services is able to access the network, and to prevent resource shortage, GBR is introduced, and three user levels (gold, silver, and copper) are available for user priority differentiation. The services configured with GBR are usually admitted on the basis of GBR. Therefore, the activity factors of these services are usually set to 100%.

3.1.3 Iub Transmission Bandwidth for Iub Overbooking The following formulas are applied to calculate the required Iub transmission bandwidth for a UE:

z Required Iub downlink transmission bandwidth = required DL Common Channel (CCH) bit rate x General common channel service downlink factor[%]+ required DL Multimedia Broadcast Multicast Service (MBMS) CCH bit rate x MBMS common channel service downlink factor[%]+ required DL Radio Resource Control (RRC) signaling bit rate x SRB service downlink factor[%]+ required DL AMR voice maximum bit rate x AMR voice service downlink factor[%]+ required DL CS conversational maximum bit rate x R99 CS conversational service downlink factor[%]+ required DL CS streaming maximum bit rate x R99 CS streaming service downlink factor[%]+ required DL R99 PS conversational maximum bit rate x R99 PS conversational service downlink factor[%]+ required DL R99 PS streaming maximum bit rate x R99 PS streaming service downlink factor[%]+ required DL R99 PS interactive GBR x R99 PS interactive service downlink factor[%]+ required DL R99 PS background GBR x R99 PS background service downlink factor[%]+ required DL RRC signaling bit rate of High Speed Packet Access (HSPA) x HSDPA signal downlink factor[%]+ required DL High Speed Downlink Packet Access (HSDPA) conversational maximum bit rate x HSDPA conversational service downlink factor[%]+ required DL HSDPA streaming maximum bit rate x HSDPA streaming service downlink factor[%]+ required DL HSDPA interactive GBR x HSDPA interactive service downlink factor[%]+ required DL HSDPA background GBR x HSDPA background service downlink factor[%]

z Required Iub uplink transmission bandwidth = required UL CCH bit rate x General common channel service uplink factor[%]+ required UL RRC signaling bit rate x SRB service uplink factor[%]+ required UL AMR voice maximum bit rate x AMR voice service uplink factor[%]



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+ required UL CS conversational maximum bit rate x R99 CS conversational service uplink factor[%]+ required UL CS streaming maximum bit rate x R99 CS streaming service uplink factor[%]+ required UL R99 PS conversational maximum bit rate x R99 PS conversational service uplink factor[%]+ required UL R99 PS streaming maximum bit rate x R99 PS streaming service uplink factor[%]+ required UL R99 PS interactive GBR x R99 PS interactive service uplink factor[%]+ required UL R99 PS background GBR x R99 PS background service uplink factor[%]+ required UL RRC signaling bit rate of HSPA x HSUPA signal uplink factor[%]+ required UL High Speed Uplink Packet Access (HSUPA) conversational maximum bit rate x HSUPA conversational service uplink factor[%]+ required UL HSUPA streaming maximum bit rate x HSUPA streaming service uplink factor[%]+ required UL HSUPA interactive GBR x HSUPA interactive service uplink factor[%]+ required UL HSUPA background GBR x HSUPA background service uplink factor[%]

For details about admission control for Iub transmission bandwidth and the parameters for GBR, see Admission Control.

When the factor table configuration is executed without using the ADD FACTORTABLE command, the default active factor table is available. The default factor table can be modified using the SET DEFAULTFACTORTABLE command.

The factor table is used when an adjacent mapping is added or modified, and the parameter involved is Factor Table Index.

The GBR for the BE services can be configured. The parameters for GBR are as follows:

z Traffic Class z Traffic Handler Priorty Class z Bear Type z User Priority z Uplink GBR for BE service[kbit/s] z Downlink GBR for BE service[kbit/s]

3.1.4 Transmission Priority of Iub Overbooking The RNC provides different priorities for different services on the Iub interface. Videophone or voice is transmitted with high priority and PS data with low priority.

By this means, when the congestion occurs in Iub transmission, the quality of the videophone or voice does not deteriorate.




Issue 01 (2008-05-30)

3.2 Iub Overbooking Flow Control Algorithms Iub Overbooking Flow Control Algorithms describes two flow control algorithms, namely, flow control algorithm 1 and flow control algorithm 2. The two algorithms are applied to the congestion that is caused by Iub overbooking.

3.2.1 Flow Control Algorithm 1 for Iub Overbooking Flow control algorithm 1 for Iub overbooking is based on the Radio Link Control (RLC) retransmission ratio, and is available for all Iub interface boards.

The procedure of flow control algorithm 1 for Iub overbooking is as follows:

Step 1 Configure relative parameters:

z For R99 BE services, set the sub-parameter IUB OVERBOOKING SWITCH of Channel class algorithm switch to ON by using the SET CORRMALGOSWITCH command.

z For HSDPA BE services, set the sub-parameter HSDPA_FLOW_CONTROL_SWITCH of Hspa algorithm switch to ON by using the SET CORRMALGOSWITCH command.

Step 2 The RNC starts monitoring the retransmission ratio of the RLC Protocol Data Units (PDUs) periodically. The monitoring period is 1000ms. The RNC calculates the retransmission ratio as shown in the following formula:

Fn = (1 a) x Fm + a x Mn

z Fn: the retransmission ratio to be calculated z Fm: the retransmission ratio calculated previously z n = m + 1 z Mn: the retransmission ratio measured currently z a = 0.5

Step 3 When the retransmission ratio is higher than Event A threshold [0.1%] in specified consecutive periods, whose length is 2 x monitoring period 1000ms, event A is triggered.

z For R99 BE services, the RNC reduces the current transmission rate, and the new transmission rate is current transmission rate x 50%.

z For HSDPA BE services, the RNC reduces the current transmission rate, and the new transmission rate is the current transmission rate x 50%.

After event A is triggered, there is a pending time period, during which the RNC stops monitoring the retransmission ratio. The length of the pending time is one monitoring period 1000ms.

Step 4 When the retransmission ratio is lower than Event B threshold [0.1%] in specified consecutive periods, whose length is 14 x monitoring period 5000ms, event B is triggered.

z For R99 BE services, the RNC increases the current transmission rate, and the new transmission rate is current transmission rate x 130%.

z For HSDPA BE services, the RNC increases the current transmission rate, and the new transmission rate is the current transmission rate x 130%.



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After event B is triggered, there is a pending time period, during which the RNC stops monitoring the retransmission ratio. The length of the pending time is one monitoring period 1000ms.

Figure 3-1 shows the flow chart of BE services flow control algorithm 1.

Figure 3-1 Flow chart of BE services flow control algorithm 1

By flow control algorithm 1, the transmission rate of the RNC is matched with the bandwidth of the Iub interface, as shown in Figure 3-2.




Issue 01 (2008-05-30)

Figure 3-2 BE services flow control in Iub congestion

The other parameters used in flow control algorithm 1 are as follows:

z RLC mode selection z RLC AM mode parameters selection

3.2.2 Flow Control Algorithm 2 for Iub Overbooking Flow control algorithm 2 for Iub overbooking is based on the back pressure of the interface boards. Flow control algorithm 2 also needs to apply for the necessary licenses in accordance with the different networking modes.

The licenses flow control algorithm 2 can apply for are as follows:

z Asynchronous Transfer Mode (ATM) Iub overbooking function, which is used for ATM non-hub networking

z Hub Iub overbooking function, which is used for ATM hub networking z IP Iub overbooking function, which is used for IP networking

The procedure of flow control algorithm 2 for Iub overbooking is as follows:

Step 1 The license is obtained and the Iub overbooking feature is activated.

Step 2 Relative switches are set to ON:

z The parameter Flow control switch is set to ON as required, and the parameter Flow control parameter index is associated with the thresholds for flow control of ports. Therefore, the setting of Flow control switch is based on the ports.

z For ATM networking, the ports consist of UNILINK, IMAGRP, FRALNK, VP, and OPT. z For IP networking, the ports consist of LGCPORT, PPPLNK, MPGRP, OPT, and ETHPORT. z The ATM interface boards have five queues, while the IP interface boards have six queues. For IP

interface boards, you can set the number of queues that adopt the absolute priority scheduling algorithm (that is, resource allocation depends on the priority class to which a particular user belongs to) by using the parameter Priority queue number. The number of the remaining queues, which is yielded by six minus Priority queue number, adopts the Round Robin (RR) scheduling algorithm. That is, resources are allocated recursively, priority given first to the order of the queues, then the order of the tasks for each queue.

Step 3 The interface boards monitor the transmission buffers of the queues on the Iub interface.

Step 4 When the buffer length of a queue is greater than the congestion threshold, the queue enters the congestion state. When a queue on the port is congested, the port becomes congested



3-9

accordingly. The interface boards send congestion signals to the concerned DPUb boards, and the BE users of the port or the logical port (LP) enter the congestion state. The RNC downsizes the transmission rate of the BE users to GBR x 10%.

z For ATM interface boards, the four congestion thresholds are 30ms, 30ms, 30ms, 50ms. z For IP interface boards, the six congestion thresholds are 25ms, 25ms, 25ms, 25ms 50ms, 50ms.

Step 5 When the buffer length of the queue is greater than the packets discarding threshold, the RNC starts discarding data packets in the buffer.

z For ATM interface boards, the four packet discarding thresholds are 45ms, 45s, 45ms, 80ms. z For IP interface boards, the six packet discarding thresholds are 60ms, 60ms, 60ms, 60ms 80ms,

80ms. z The length of the discarded packets of queue is packet discarding threshold minus congestion

threshold.

Step 6 When the buffer length of the queue is smaller than the congestion recovery threshold, the port is recovered if all the queues leave the congestion state. The interface boards send congestion clearing signals to the concerned DPUb boardsand the BE users of the port or LP leave the congestion state. The RNC recovers the transmission rate.

z For ATM interface boards, the four recovery thresholds are 20ms, 20s, 20ms, 25ms. z For IP interface boards, the six recovery thresholds are 15ms, 15ms, 15ms, 15ms, 25ms, 25ms. z The length of the discarded packets of queue is packet discarding threshold minus congestion

threshold.

z The recovered rate is r x 95%. r in the previous formula is the latest transmission rate of the user prior to entering the congestion state.

Step 7 After the BE users leave the congestion state, the RNC upsizes its transmission rate every 10 ms according to the upsizing step until the BE users reach the Maximum Bit Rate (MBR). The value of MBR is carried on the Radio Access Bearer (RAB) from the Core Network (CN).

The initial upsizing step of the transmission rate is 2000bps x SPI Factor, and the step is doubled at intervals of 200ms.

----End

The result of BE services flow control algorithm 2 is as shown in Figure 3-3.




Issue 01 (2008-05-30)

Figure 3-3 Result of BE services flow control algorithm 2

The other parameters used in flow control algorithm 2 are as follows:Traffic ClassUser PriorityTraffic Handling PriorityScheduling Priority IndicatorBear Type

RAN Iub Overbooking Description 4 Iub Overbooking Reference Documents


4-1

4 Iub Overbooking Reference Documents Iub Overbooking Reference Documents lists the reference documents related to the feature.

There are no reference documents related to this feature.

Iub Overbooking Description.pdfCoverContents1 Iub Overbooking Change History 2 Iub Overbooking Introduction 3 Iub Overbooking Algorithms 3.1 Iub Overbooking Key Principles 3.1.1 Voice Service Capacity and Congestion Probability of Iub Overbooking 3.1.2 PS Service Capacity and Congestion Probability of Iub Overbooking 3.1.3 Iub Transmission Bandwidth for Iub Overbooking 3.1.4 Transmission Priority of Iub Overbooking

3.2 Iub Overbooking Flow Control Algorithms 3.2.1 Flow Control Algorithm 1 for Iub Overbooking 3.2.2 Flow Control Algorithm 2 for Iub Overbooking

4 Iub Overbooking Reference Documents