RAN Iub Overbooking Description Issue 01 Date 2008-05-30 Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd
Nov 24, 2015
RAN
Iub Overbooking Description Issue 01
Date 2008-05-30
Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd
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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
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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
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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]
RAN Iub Overbooking Description 1 Iub Overbooking Change History
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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
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Change Change Description Parameter Change Type
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]
RAN Iub Overbooking Description 1 Iub Overbooking Change History
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Change Change Description Parameter Change Type
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
[ms] z Recover threshold of queue 2 [ms] z Packet discard threshold of queue 2
[ms] z Congestion threshold of queue 3
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Change Change Description Parameter Change Type
[ms] z Recover threshold of queue 3 [ms] z Packet discard threshold of queue 3
[ms] z Congestion threshold of queue 4
[ms] z Recover threshold of queue 4 [ms] z Packet discard threshold of queue 4
[ms] z Congestion threshold of queue 5
[ms] z Recover threshold of queue 5 [ms] z Packet discard threshold of queue 5
[ms] z Congestion threshold of queue 6
[ms] z Recover threshold of queue 6 [ms] z Packet discard threshold of queue 6
[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
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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
Iub Overbooking Description
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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
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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.
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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.
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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%
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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.
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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.
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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
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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.
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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
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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