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HSDPA Packet Scheduling WCDMA RAN
Feature Guide
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HSDPA Packet Scheduling Feature Guide
ZTE Confidential Proprietary © 2010 ZTE Corporation. All rights reserved. I
HSDPA Packet Scheduling Feature Guide
Version Date Author Approved By Remarks
V4.5 2010-10-15 Wang Yue Peng Bei ,Hu Ye,
© 2010 ZTE Corporation. All rights reserved.
ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE.
Due to update and improvement of ZTE products and technologies, information in this document
is subjected to change without notice.
HSDPA Packet Scheduling Feature Guide
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TABLE OF CONTENTS
1 Functional Attribute ............................................................................................ 1
2 Overview .............................................................................................................. 1
2.1 HSDPA Fast Scheduling....................................................................................... 2
2.2 HSDPA Flow Control ............................................................................................ 3
3 Technical Description......................................................................................... 3
3.1 HSDPA Resource Allocation Scheme .................................................................. 3
3.2 HSDPA Scheduling Algorithms ............................................................................ 4
3.2.1 MAX C/I Algorithm ................................................................................................ 5
3.2.2 RR Algorithm ......................................................................................................... 5
3.2.3 PF Algorithm ......................................................................................................... 5
3.2.4 Summary of Scheduling Algorithms ..................................................................... 7
3.3 HSDPA TFRC Selection Algorithm....................................................................... 8
3.3.1 HS-SCCH Code and Power Selection ................................................................. 8
3.3.2 TBSIZE, Number of HS-PDSCH Channelization Codes, Modulation and Power Selection.................................................................................................... 9
3.4 HSDPA Flow Control Algorithm .......................................................................... 12
3.4.1 Flow Control Implementation Method................................................................. 12
3.4.2 Flow Control Algorithm........................................................................................ 13
3.5 Measure of HS-DSCH Required Power ............................................................. 16
3.6 Impact of HSPA+ on Scheduler.......................................................................... 17
3.6.1 Impact of introducing 64QAM Modulation Technology on Scheduler................ 17
3.6.2 Impact of introducing MIMO on Scheduler ......................................................... 20
3.6.3 Impact of introducing DC-HSDPA on Scheduler ................................................ 22
3.7 Dynamic power sharing in Multi-carrier .............................................................. 22
4 Parameter Description ..................................................................................... 24
4.1 HSDPA Scheduling Algorithm Parameters ........................................................ 24
4.1.1 Channel Quality Weight ...................................................................................... 24
4.1.2 SPI_0 SPI_1...SPI_15......................................................................................... 25
4.1.3 HS-PDSCH Total Downlink Power Allocation Method ....................................... 25
4.1.4 HS-PDSCH Measurement Power Offset ............................................................ 25
4.1.5 Support Type of RLC Flexible PDU Size Format ............................................... 26
4.1.6 Non-Conversational service Maximum MAC-d PDU Size Extended ................. 26
4.1.7 Conversational service Maximum MAC-d PDU Size Extended......................... 26
4.2 Dynamic Power Sharing in Multi-carrier Parameters ......................................... 27
4.2.1 Transmission Power ........................................................................................... 27
4.2.2 Power-sharing Ratio ........................................................................................... 27
5 Weight Mapping Table...................................................................................... 28
6 Glossary ............................................................................................................. 29
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FIGURES
Figure 2-1 n of Node B HSDPA ............................................................................................... 2
Figure 3-1 Resource allocation during UE scheduling .......................................................... 10
Figure 3-2 Flow control procedure......................................................................................... 13
Figure 3-3 Leaky bucket flow control scheme ....................................................................... 14
Figure 3-4 Static power sharing in Multi-carrier .................................................................... 23
Figure 3-5 Downlink power after introducing HSDPA ........................................................... 23
TABLES
Table 3-1 HS-PDSCH start code Nos ................................................................................... 18
Table 4-1 Parameter settings in OMMB ................................................................................ 24
Table 4-2 Parameter settings in OMMR ................................................................................ 24
Table 4-3 OMMB configuration parameters filed .................................................................. 27
Table 5-1 CQI weight mapping table ..................................................................................... 28
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1 Functional Attribute
System version: [RNC V3.09, Node B V4.09, OMMR V3.09, OMMB V4.09]
Attribute: [Optional functions]
Involved NEs:
UE Node B RNC MSCS MGW SGSN GGSN HLR
√ √ √ - - - - -
Note:
*-: Not involved.
*√: Involved.
Dependency: [None]
Mutual exclusion: [None]
Remarks: [None]
2 Overview
After the High Speed Downlink Packet Access (HSDPA) technology is introduced to
WCDMA, the MAC-hs layer is added to both Node B and UE. The HSDPA of Node B
implements the following functions:
1 Receiving and storing HS-DSCH data frames from UE on lub interface.
2 Performing cell-based multi-UE fast scheduling.
3 The Adaptive Modulation and Coding (AMC) provides HS-PDSCH air interface
transmission format (Number of channelization codes, modulation mode, and TB
size).
4 Transmitting HS-SCCH control information and HS-DSCH data information.
5 Demodulating messages such as ACK, NACK and CQI carried on HS-DPCCH.
6 Performing downlink HS-DSCH flow control.
The following figure shows the functional implementation of MAC-hs:
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Figure 2-1 n of Node B HSDPA
FP
AMC
Hsdpa
Scheduler
Harq
Entity
HSDPCCH
ACK/NACK/CQI
MACD PDU
Data PoolACK/NACK
CQI
Select Tbsize
Retrans
QueSelect Sch
UE/Que
HSSCCH Info
FP
AMC
Harq
Entity
HSDPCCH
ACK/NACK/CQI
MACD PDU
Data Pool
ACK/NACK
CQI
Select Tbsize
Retrans
Que
Select Sch
UE/Que
HSSCCH Info
HSDSCH DataUu
UE1
UE2
Iub
Flow
Control
Entity
Flow
Control
Entity
<=Hsdpa Capa
Alloc Frame
=>Hsdpa Capa
Request Frame
<=Hsdpa Capa
Alloc Frame
The implementation procedure of Node B MAC-hs is as follows:
1 Upon receiving the Frame Protocol (FP) data from lub interface, MAC-hs stores FP
data in the buffer area of each UE.
2 Hsdpa Scheduler selects the UE with data to be transmitted based on the
scheduling algorithm and selects idle HARQ PORCESS of UE through Harq Entity.
3 Hsdpa Scheduler selects appropriate HS -PDSCH air interface transmission format
in the AMC module based on channel quality, terminal capability, available power
and code resources of UE, and then transmits FP data over air interface.
MAC-hs of Node B also implements real-time flow control of downlink HS-DSCH data
frames on lub interface based on the air interface rate and channel quality of UE to
realize sharing of air interface and lub interface bandwidth among multiple UEs.
This document focuses on the description of Hsdpa Scheduler and Flow Control Entity,
that is, the components in grey in Figure 1.
2.1 HSDPA Fast Scheduling
The scheduling procedure at MAC-hs layer: Select the UE with data to be transmitted
based on scheduling algorithm; determine transmission format based on the channel
quality, available code and power resources of UE; transmit downlink data to UE over
HS-SCCH and HS-PDSCH; UE returns data receiving information to MAC-hs of Node B
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over HS-DPCCH. If UE returns data receiving failure to MAC-hs, MAC-hs layer of Node
B needs to retransmit the data that originally fails to be received by UE.
The Transmission Time Interval (TTI) of HS-PDSCH is 2 ms as stipulated in the protocol,
which means the scheduling time of MAC-hs layer must be controlled within 2 ms.
Compared with the minimum TTI of R99-10 ms, the scheduling rate of MAC-hs layer
improves by 5 times.
The scheduling algorithms of MAC-hs layer includes the Round Robin (RR), Maximum
Carrier to Interference (MaxC/I) and Proportional Fairness (PF) algorithms. These
algorithms have a great impact on the performance including cell service fairness,
throughput of single UE and cell throughput. As a tradeoff of the RR and MaxC/I
algorithms, the PF algorithm can help achieve large throughput and better service
fairness.
2.2 HSDPA Flow Control
The air interface rate of HSDPA UEs is subject to multiple ever -changing factors such as
UE channel quality, number of UEs to be scheduled in a cell, and code/power resources
of a cell. Therefore, the scheduler necessitates flow control to administrate the incoming
rate of downlink HS-DSCH data frames of each UE to make it consistent with the
outgoing rate of air interface to avoid either excess or insufficient data volume of UE on
Node B side.
On lub interface, the HSDPA scheduler informs RNC to control the transmit rate of
certain UE through the Capacity Allocation Frame (CAF). When certain UE in RNC fails
to receive the CAF within a specified time, RNC will voluntarily send a Cap acity Request
Frame (CRF) to HSDPA scheduler. The HSDPA scheduler then sends a CAF to RNC in
response.
The downlink rate for RNC to transmit data frames to certain UE of Node B scheduler
will not exceed the rate specified in the CAF.
3 Technical Description
3.1 HSDPA Resource Allocation Scheme
HSDPA UEs are scheduled by Node B, while R99 UEs are scheduled by RNC. This
brings about the resource (including code and power) sharing issue among HSDPA and
R99 UEs in the same cell.
The Spreading Factor (SF) of HS-PDSCH is 16, and downlink HSDPA service data is
carried on HS-PDSCH. Maximum number of HS-PDSCH code can be configured to 15
in each cell. RNC informs Node B of the number of HS-PDSCHs that can be used by
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certain cell through the Physical Shared Channel Reconfiguration Request signaling of
NBAP.
Node B implements the mechanism of cell power sharing among HSPA and R99 UEs.
As the downlink power control of R99 is implemented in RNC and Node B cannot control
power of R99 UEs, ZTE UMTS Node B HSPA scheduler is designed to support the
function of voluntarily bypassing R99 channel downlink transmit power, that is, the
maximum available power of related HSPA downlink channel shall not exceed the
maximum cell transmit power minus downlink transmit power of R99 channels. The
voluntary bypass function enables cell power sharing among HSPA and R99 UEs.
The procedure for HSPA scheduler to voluntarily bypass R99 channel downlink transmit
power: In each TTI of 2 ms, the cell TSSI reported through RF minus the power
consumed by HSDPA and HSUPA leaves the R99 power at this moment. Then the
available HSPA power in next 2ms TTI can be obtained by subtracting R99 power from
the maximum cell transmit power.
The RNC parameter HSPA Total Downlink Power Allocation Method
(HsdschTotPwrMeth) can be set to RNC Static Assigning Mode(0), RNC Dynamic
Assigning Mode(1), or Node B Assigning Mode(2). The voluntary power bypass of Node
B always takes effect no matter how the parameter HsdschTotPwrMeth is set. This
parameter is set to Node B Assigning Mode(2) by default, that is, Node B is
responsible for controlling power sharing so as to utilize cell transmit power to the
greatest extent.
When HsdschTotPwrMeth is set to RNC Static Assigning Mode(0) or RNC Dynamic
Assigning Mode(1), RNC can exercise control over the maximum available power of
HSPA, that is, the total HSPA power cannot exceed the value specified by RNC. For
details about RNC controlling total HSPA power, see ZTE UMTS Power Control FD.
3.2 HSDPA Scheduling Algorithms
The chief objective of scheduling algorithms is to calculate the relative priority of all UEs
in each TTI of 2ms, prioritize them and schedule those with higher priority first. The
scheduling algorithms implemented by ZTE UMTS Node B include MAX-C/I, RR and PF
algorithms.
MAX C/ I algorithm focuses on the maximum throughput of a cell. RR algorithm gives
equal scheduling opportunity for all UEs. PF algorithm is a tradeoff of MAX C/I and RR
algorithms.
Among these three algorithms, only the PF algorithm takes into account the HSDPA
service attributes.
For class-I/ -B and SRB over HS-DSCH services, the QoS is guaranteed by setting
different Schedule Priority Indicators (SPIs) in RNC.
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For Guaranteed Bit Rate (GBR) configured services, the PF algorithm preferentially
schedules UEs with GBR not satisfied.
Note: UEs with retransmitted data must be scheduled preferentially no matter which
scheduling algorithm is adopted.
The principles of above three scheduling algorithms are introduced as follows:
3.2.1 MAX C/I Algorithm
The MAX C/I algorithm only takes into account the channel quality to maximize cell
throughput. The relative priority of MAX C/I algorithm is given by:
RelativePriority = CQI * TBSIZE
The Channel Quality Indicator (CQI) is fed back by HS-DPCCH of UE. The maximum
MAC-hs Transmission Block Size (TBSIZE) of UE is obtained by querying the CQI
mapping table for UE categories provided by TS 25.214 based on current CQI, UE
categories and number of available HS-PDSCH channelization codes.
3.2.2 RR Algorithm
The relative priority of RR algorithm is given by:
RelativePriority = Current Time – Last Time of UE Scheduling
The unit of time in the above equation is TTI 2ms. Current Time: Refers to current
scheduling time;
It is obvious that RR algorithm has the longest scheduling waiting time.
3.2.3 PF Algorithm
The PF algorithm takes into account both the channel quality and history traffic. That is,
the PF algorithm takes into account both cell throughput and user fairness. As a tradeoff
between fairness and cell throughput, the PF algorithm is generally adopted by default.
The relative priority of PF algorithm is given by:
RelativePriority =WeightofSPI Rate (1+HistoryFlux)
The Schedule Priority Indicator (SPI) refers to the UE scheduling priority configured
through NBAP signaling, and ranges between 0 and 15. The SPI is related to the
services used by UE. WeightofSPI refers to the weight obtained through SPI mapping
which is configured through the parameter SPI_0 SPI_1…SPI15. The values of SPI_0,
SPI_1…SPI15 ranges between 1 and 2000, moreover, the value of SPI_n should less
than the values of SPI_n+1 (n=0, 1, 2…14), the reason for this request is that the
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mapping relationship between SPI and WeightofSPI should be accordant, otherwise
RNC configured SPI will be different with the real scheduled priority level. The
recommended default value of SPI_0, SPI_1…SPI15 is set to
[10,12,14,17,21,25,30,36,43,52,62,74, 89,107,128,154] by default. It is not suggested to
randomly configure SPI_0 SPI_1…SPI15 not compliant to the request of SPI_n less
than SPI_n+1, because this will result in difference of RNC configured SPI and the real
scheduled priority level, thereby bringing network service priority chaos.
Generally, Rate presents the current instant speed rate. The calculation of Rate is
different for traditional UE, MIMO UE and DC UE, with it’s formula as following:
For traditional UE and MIMO UE single stream:
Rate= 1(CQI_s) TBSIZE(CQI_s) w
For MIMO UE double sreams:
Rate= 2(CQI_1) TBSIZE(CQI_1)+ 2(CQI_2) TBSIZE(CQI_2)w w
For DC-HSDPA UE:
Rate= 1(CQI_n) TBSIZE(CQI_n) w
CQI_s is the CQI reported by traditional UE and MIMO UE under single stream
scheduling. CQI_1 and CQI_2 is the CQI for primary and secondary stream
reported MIMO UE under double stream scheduling. CQI_n is the CQI for related
carrier reported by DC UE. TBSIZE(CQI_s) , TBSIZE(CQI_1) , TBSIZE(CQI_2)
and TBSIZE(CQI_n) are obtained by querying the CQI mapping table for UE
categories provided by TS 25.214 based on current CQI.
1(CQI_s)w and 2(CQI_1)w refer to the weight obtained through CQI mapping which
is configured through the parameter Channel Quality Weight (ConditionWgt). The value of
ConditionWgt ranges between 1 and 6, and is set to 3 by default. The larger the value of
ConditionWgt, the steeper the mapping relation between Weight of CQI and CQI, that is,
the more scheduling chance the UEs with high CQI have. 1w is for single stream
mapping, 2w is for double stream mapping. For detailed mapping table, see Chapter 5.
The history flux of UE is calculated at intervals of 2 ms, and the accumulated newly
transmitted data increases by TBSIZE, as given in the following equation:
For traditional UE:
HistoryFlux(n) = HistoryFlux (n-1) * 0.96 + TBSIZE, where, TBSIZE is a variable
because the data volume scheduled each time varies. n refers to the times of
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history scheduling. HistoryFlux(n) refers to the history flux after n times of
scheduling. TBSIZE refers to the TBSIZE of last scheduling.
For MIMO UE:
HistoryFlux(n) = HistoryFlux (n-1) * 0.96 + TBSIZE1+TBSIZ2, where, TBSIZE1
and TBSIZ2 refer to the transmit block size of primary and secondary stream of
MIMO, if primary or secondary stream is not scheduled or retransmitted in this TTI,
TBSIZE1 or TBSIZ2 is 0.
For DC UE:
HistoryFlux(n) = HistoryFlux (n-1) * 0.96 + TBSIZE1+TBSIZ2, where, TBSIZE1
and TBSIZ2 refer to the transmit block size of two carriers, if it’s not scheduled or
retransmitted in this TTI in the related carrier, TBSIZE1 or TBSIZ2 is 0. This is main
idea of the joint scheduling algorithm for DC UE cross two carriers comparing to
traditional UE’s independent scheduling algorithm on single carrier.
If a UE is stream class user, Guaranteed Bit Rate(GBR) is configured by RNC; If a UE is
I/B class user, a minimal GBR is configured by RNC, It’s named Nominal Bit Rate, NBR
value generally is 16K. Both GBR is get by scheduler through Mac-hs Guaranteed Bit
Rate IE of NBAP. In order to discriminate stream class and I/B class, we defined that if
Discard Timer IE of NBAP is configured, scheduler treat the UE as stream class
service; If Discard Timer IE is not configured, scheduler treat the UE as I/B class service.
HSDPA Scheduler first schedule GBR not satisfied stream class UEs, then schedule
GBR not satisfied I/B class UEs, and schedule GBR satisfied UEs and non-GBR UEs
last.
For the GBR not satisfied UEs, they are prioritized and scheduled by the GBR not
satisfied degree.
The non-GBR UEs and GBR satisfied UEs shall be prioritized and scheduled based on
their relative priorities obtained by adopting the PF algorithm.
3.2.4 Summary of Scheduling Algorithms
The MAX C/I algorithm focuses on the maximum cell throughput, but is seldom adopted
in practice.
The PF algorithm is the most widely used and complicated scheduling algorithm, and
also has the best comprehensive effect.
The RR algorithm is rather simple and generally adopted for comparison test with the PF
algorithm.
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3.3 HSDPA TFRC Selection Algorithm
When selecting several appropriate UEs for scheduling in each TTI, the scheduler needs
to determine Transport Format and Resource Combination (TFRC) required for each UE,
for example, TBSIZE, HS-PDSCH code information (start code No. and number of
channelization codes), HS-PDSCH power, HS-SCCH code No. and HS-SCCH power.
For UEs with retransmitted data, the TFRC is selected based on the principle of
retaining TBSIZE, number of HS-PDSCH channelization codes and power and HS-
SCCH power.
For UEs requesting transmission of new data, the TFRC is selected starting from UEs
with high relative priority until code or power resources are used up in the cell.
3.3.1 HS-SCCH Code and Power Selection
The selection of HS-SCCH channelization codes is rather simple. An arbitrary code can
be assigned to HS-SCCH of UE unless according to the protocol, the same HS -SCCH
code must be adopted in the event of scheduling in two consecutive TTIs.
Two types of power control algorithms are provided for HS-SCCH. One of them is
constant power algorithm, that is, 1/4 pilot power is adopted constantly, and the other is
CQI-based outer loop power control algorithm. The former is used for testing and the
latter is set by default. The basic principle of the CQI-based outer loop power control
algorithm is as follows:
The power selection of HS-SCCH is given by:
Pdelta/9hs/s NohspdschEsscchNoEPP CPICHHSSCCH
Where,
PCPICH: Refers to the receive power of pilot channel (Unit: dBm).
Es/Nohsscch is constantly 1.2dB.
Γ: refers to the Measurement Power Offset (MeasPwrOffset) configured for
NBAP signaling.
Es/Nohspdsch = -4.5 + CQI dB;
Pdelta refers to the value obtained based on HS-SCCH BLER outer loop
adjustment.
The maximum HS-SCCH power cannot exceed pilot power, and the minimum HS-SCCH
power cannot be less than -16dB of pilot power.
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3.3.2 TBSIZE, Number of HS-PDSCH Channelization Codes, Modulation and Power Selection
Two types of HS-DSCH power control algorithms are provided. One of them is the
average power control algorithm, that is, the average available power of all UEs that can
be scheduled in one TTI, and the other is MPO power control algorithm. The former is
generally used for testing and the latter is used by default. The MPO power control
algorithm is described as follows:
The TBSIZE, number of HS-PDSCH channelization codes, modulation mode and power
selection are closely related to CQI, and the target BLER of UE at the time when CQI is
generated is 10%. The CQI reported by various manufacturers, however, are inacc urate
due to the implementation differences or measurement errors, and therefore must be
corrected. Node B adjusts target CQI by using the CQI reported by UE as well as
decoding results, that is, Node B performs outer loop adjustment of CQI reported by UE
so as to minimize impact brought by measurement errors and implementation difference
among different manufacturers.
Basic concept of HSDPA CQI adjustment algorithm: The CQI offset of UE is initialized to
0, MAC-hs TB decoding results are accumulated. The CQI offset of UE increases by
0.01 each time ACK signal is detected, and decreases by 0.09 each time NACK signal is
detected. The adjusted CQI is obtained by adding the CQI reported by UE to the CQI
offset of UE.
The TBSIZE, number of channelization codes, modulation mode and Reference Power
Adjustment can be obtained by querying CQI mapping table for UE categories provided
in TS 25.214 based on adjusted CQI.
CPICHHSPDSCH PP
Where,
PCPICH: Refers to the receive power of pilot channel (Unit: dBm).
Γ: refers to the Measurement Power Offset (MeasPwrOffset) configured for
NBAP signaling.
Reference Power Adjustment obtained after querying the CQI mapping
table for UE categories (unit: dB).
For example, suppose UE category is 8, Γ is set to 6dB and adjusted CQI is 27, we can
obtain the following information by querying the CQI mapping table for UE categories:
TBSIZE: 14411; number of HS-PDSCHs: 10; modulation mode: 16QAM; is -2dB. If
PCPICH is 33 dBm, then HS-PDSCH power is 37 dBm (33 + 6 - 2). If the number of
available HS-PDSCH channelization codes in a cell is not less than 10, available power
is not less than 37 dBm and the UE data volume to be scheduled is larger than 14411,
then TBSIZE is 14411, the number of HS-PDSCH channelization codes is 10,
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modulation mode is 16QAM, power is 37dBm and the to-be-scheduled data of UE is
transmitted.
The above example is only an ideal situation. In practice, code, power and data volume
all may fall short of the requirements of CQI mapping table. On the other hand, UEs are
scheduled in a descending order of relative priority in one TTI. We try to guarantee
resources for UEs with high relative priority and use up code and power resources in a
cell when selecting the number of HS-PDSCH channelization codes and power for one
UE.
As shown in the following figure, suppose UE category, Γ configuration and CQI of both
UEs are identical, for example: UE category: 8; Γ: 6dB; adjusted CQI: 27, and to-be-
scheduled data volume is sufficient. The number of HS-PDSCH channelization codes is
15, and available power of the cell is 6 W. Ten HS -PDSCH channelization codes and
5W power are used for scheduling of the first UE, leaving the rest 5 HS-PDSCH
channelization codes and 1W power. In such a case, the available TBSIZE for the
second UE decreases to 4664.
Figure 3-1 Resource allocation during UE scheduling
HS-PDSCH 10
16QAM
TBSIZE 14411
POWER 37Dbm(5W)
HS-PDSCH 15
POWER 6W
HS-PDSCH 5
POWER 1WHS-PDSCH 5
16QAM
TBSIZE 4664
POWER 30Dbm(1W)
The specific processing is described as follows:
The extended CQI mapping table is called CQI mapping extension table. The CQI
mapping extension table contains the number of channelization codes, modulation mode,
TBSIZE and Es/No. For example, suppose the number of channelization codes is 10
and modulation mode is 16QAM, then the corresponding TBSIZE and Es/No table
entries are listed as follows:
TBSIZE Es/No
6554 14.56
7041 15.00
7430 15.36
7840 15.62
8272 15.89
8729 16.19
9047 16.39
9546 16.71
9894 16.94
10440 17.42
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11017 17.93
11625 18.46
12048 18.78
12713 19.26
13177 19.60
13904 20.12
14411 20.50
Assume the power meets the requirement during UE scheduling, and Es/No is given by
the following equation:
Es/No = -4.5 + CQI +
If CQI is 27, then the value of Es/No is 20.5. We can obtain TBSIZE, which is 14411, by
querying the CQI mapping extension table based on the number of channelization codes
(10) and modulation mode (16QAM). The power required in this case is 37dBm.
If the power is insufficient, for example, it is only 36 dBm, Es/No ne eds to be adjusted to
(20.5 – 1), that is, 19.5. Suppose the number of channelization codes is 10, we can
obtain TBSIZE and Es/No, which are 12713 and 19.26 respectively, by querying the CQI
mapping extension table. Then we can calculate the HS -PDSCH power through the
following equation:
HS-PDSCH power = 36 – (19.5 (Adjusted Es/No) – 19.26 (Es/No obtained by querying
the table)) = 35.76 dBm
If the number of available channelization codes is insufficient, we can obtain the
corresponding TBSIZE and Es/No in the similar way as above by querying the CQI
mapping extension table based on the number of available channelization codes and UE
Es/No. Then we can calculate HS-PDSCH power based on Es/No.
If the to-be-scheduled data volume of UE is less than the selected TBSIZE, continue
query of the CQI mapping extension table and lower TBSIZE until it is slightly larger than
the to-be-scheduled data volume of UE according to the HS-PDSCH power (Es/No), the
number of channelization codes and the modulation by the above steps. The principle of
querying the CQI mapping extension table: Firstly, based on the fixed modulation and
fixed number of channelization codes, query the CQI mapping extension table through
decreasing the HS-PDSCH power. If it can’t find out suitable TBSIZE, then continue
query of the CQI mapping extension table through decreasing the number of
channelization codes. If it can’t find out suitable TBSIZE through decreasing number of
channelization codes still, at last, continue query of the CQI mapping extension table
through decreasing the modulation, for example 64QAM down to 16QAM, 16QAM down
to QPSK.
Note: If is less than 0 (for example, UE category: 8; CQI > 25), to reach the testing
standard that the download rate is 85% of the air interface rate, that is, BLER is less
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than 10%, the HS-PDSCH power will remain unchanged, that is, PCPICH + Γ. And this is
a non-standard solution.
3.4 HSDPA Flow Control Algorithm
The HSDPA scheduler is essentially used to implement the downlink packet transfer
function, that is, to receive UE data over the lub interface and then transmit it through
the air interface.
HS-PDSCH is shared among multiple UEs in a cell, and the total number of UEs as well
as the channel quality of each UE ever change, resulting in constant change of the
transmit rate over every UE air interface. Therefore, a flow control mechanism is
required to control the UE packet receiving rate over the lub interface to realize a
balance between inflow and out flow of packets in scheduler.
3.4.1 Flow Control Implementation Method
Flow control is implemented through Frame Protocol (FP) on user plane over the lub
interface by using downlink HS-DSCH Capacity Request Control Frame and uplink the
HS-DSCH Capacity Allocation Control Frame.
RNC will send a CRF to the Node B, when necessary, to trigger the flow control. Node B
will also send a CAF to RNC, when necessary, to control the UE packet inflow rate. For
specific formats of the CAF and CRF, see TS 25.435 protocol.
Here are three trigger mechanisms available for flow control, namely, the flow control will
be triggered in one of the following cases:
1 The Node B receives a CRF from the RNC.
2 The number of stacked packets on UE side exceeds the maximum or minimum
threshold.
3 The UE flow control timer times out.
Where, in the first mechanism, it is the RNC that initiates the flow control, while in the
rest ones, it is the Node B that initiates the flow control.
After the flow control is triggered, the RNC data receiving rate of UE -Vin is estimated
first based on the air interface rate of UE; then the parameters in relation to the CAF are
calculated according to Vin; finally, a CAF is sent. The flow control procedure is as
follows:
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Figure 3-2 Flow control procedure
Flow Control
Trigger Event
Caculate Vin
Get credits interval
repetition period by Vin
Send Capacity
Allocation Frame
End
To avoid frequent trigger of flow control, we set the minimum interval of UE flow control
to 60 ms.
3.4.2 Flow Control Algorithm
As mentioned above, flow control aims at maintaining a balance between UE packet
input and output. Furthermore, flow control also needs to assure there are sufficient
packets during UE scheduling to make full use of the transmitting capability of UE air
interface. In view of these objectives, we design a flow control algorithm as follows:
We regard each packet buffer area of UE as a leaky bucket. As shown in Figure 4, inV
denotes the inflow rate over the lub interface of every UE, corresponding to the RNC
data transmitting rate. outV BufferTimeVoutH *aim is the transmit rate (outflow
rate) of every UE through the Uu interface. The target height of the leaky bucket can be
computed by BufferTimeVoutH *aim . BufferTime indicates buffer time. Generally
the larger the number of to-be-scheduled UEs, the less outflow rate
BufferTimeVoutH *aim .
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Figure 3-3 Leaky bucket flow control scheme
PDU BUFFER
RNC
Node B Capacity Allocation
inV = ),,(AIMDIFFERout
HHVF
outV
CURRENTH
AIMH
DIFFERH = AIMH – CURRENTH
DIFFERH
inV
When inV > outV , the bucket height increases; when inV = outV , the bucket height
remains the same; when inV < outV , the bucket height reduces.
Take 80% of aimH as a median, Node B does not voluntarily initiate the flow control
when the inflow rate falls within the upper and lower thresholds of this median. If inV
exceeds the upper threshold that is usually set to 90% of the bucket height, Node B will
initiate the flow control to decrease the inflow rate inV ; if aimH is less than the lower
threshold that is usually set to 70% of the bucket height, Node B will also initiate the flow
control to increase the inflow rate inV .
Note: The BufferTime of UE leaky bucket is constant, and at present is set to 150 ms by
taking into account various factors. HSDPA scheduler offers a buffer area with constant
size of less than 150M bit for sharing among all UEs. Assume BufferTime is 150 ms, the
buffer area far exceeds current air interface capability requirement: 1000M bit/s.
All UEs share the air interface capability in a cell, so whether there are one or several
UEs in a cell does not make much of a difference for the required buffer area. The value
of BufferTime is constant, so the higher the air interface rate of UE, the more the buffer
data packets used by UE or vice versa.
Otherwise, we employ two aspects processing in HSDPA packet scheduling to
cooperate HSDPA flow control algorithm.
A. According to characteristics of different services, RNC will configure and sending two
parameters to Node B: DISCARDTIMERPRE and DISCARDTIMER, Node B will employ
these two parameters in different services scheduling process. When data packet can’t
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be scheduled by Node B in the specific UE ’s data buffer in the predefined time duration,
these data packet will be discarded to ease the congestion in the data buffer of Node B.
We will not configure DISCARDTIMER parameter for services which need accurate data
transmission, such as Interactive and Background class services. But for services which
have high time-delay requirement such as Streaming and Conversation(VoIP over
HSDPA) class, we can configure DISCARDTIMER parameter selectively for them to
discard data packet that can’t be scheduled in time. And the DISCARDTIMER time
duration can be different, for example, 4s for Streaming class and 60-80ms for
Conversation class with higher time-delay QOS requirement.
B. Introducing sliding window management and T1 timer mechanism to stop related
MAC-hs PDU retransmission which couldn’t be accepted by UE even with multiple
retransmission.
Node B sliding window management is a algorithm for MAC-hs PDU transmission
management in scheduling process. And the purpose is to avoid UE receiving MAC-hs
PDU with unclear TSN. At the same time, Node B scheduling algorithm can employ T1
timer to stop MAC-hs PDU retransmission which couldn’t be accepted by UE even with
multiple retransmission.
T1 timer and window size parameter MACHSWINSIZE of MAC-hs transmission and
receiving side can be configured by RNC OMM, and delivered to Node B and UE
through signaling respectively.
Sliding window management is to wait MAC-hs PDU at lower edge of the the window
received accurately, or until retransmission times and T1 timer expiring, the window will
slide forward. Assuming TrsWindow_LowerEdge is the lower edge of the the window,
TrsWindow_LowerEdge represents minimum TSN of the MAC-hs PDU which is waiting
for ACK response. If receiving ACK response of this MAC-hs PDU successfully or
discarding this MAC-hs PDU because of retransmission times and T1 timer expiring,
TrsWindow_LowerEdge will slide to the next minimum TSN of the MAC-hs PDU which is
waiting for ACK response. MAC-hs PDU with smaller TSN than TrsWindow_LowerEdge
will not be retransmitted, and MAC-hs PDU with bigger TSN than
TrsWindow_LowerEdge + MACHSWINSIZE also can’t be transmitted(waiting to be
transmitted) .
For example, MACHSWINSIZE is 12,TrsWindow_LowerEdge is 0,as the following figure,
TSN=12,13,14 MAC-hs PDU outside of window are not allowed to be transmitted, if
receiving NACK response for TSN=0 MAC-hs PDU and discarded because of
retransmission times and T1 timer expiring, receiving ACK response for TSN=1
MAC-hs PDU and NACK for TSN=2 MAC-hs PD, TrsWindow_LowerEdge will silde to 2,
TSN=12,13 MAC-hs PDU now are allowed to be transmitted, TSN=14 MAC-hs PDU is
still waiting to be transmitted, TSN<2 MAC-hs PDU is not allowed retransmitted again.
The default configuration for MACHSWINSIZE is 16, and specially for MIMO dual stream
transmission service, MACHSWINSIZE is configured 32 defaultly.
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1 2 3 4 5 6 7 8 9 10 11 12
TRANSMIT_WINDOW_SIZE
TRANSMIT_WINDOW_SIZE
0 13 14
Node B can employ T1 timer to stop ret ransmission of related MAC-hs PDU.
Firstly, at the UE side, if no timer T1 is active, the timer T1 shall be started when a MAC-
hs PDU with TSN > next_expected_TSN is correctly received, that is to say, UE will start
T1 based on successfully receiving next TSN MAC-hs PDU. But Node B does not know
accurately whether UE received next TSN MAC-hs PDU or not, so Node B will start T1
after receiving ACK response for next TSN MAC-hs PDU from UE. ACK response delay
or lost will result in Node B starting T1 later than UE, so Node B will properly postpone
discarding related PDU. On mechanism of retransmission priority and retransmission
number limitation, Node B will guarantee to discard specific MAC-hs PDU in time which
can’t be transmitted and will not block next TSN PDU transmission significantly.
T1 timer range is 【10ms-400ms,…】and the default configuration is 50ms at RNC
OMM.
3.5 Measure of HS-DSCH Required Power
According to TS25.433, there are three types of common measure: Transmitted carrier
power of all codes not used for HS -PDSCH or HS-SCCH transmission, HS-DSCH
Required Power, HS-DSCH Provided Bit Rate. Among these common measures, HS-
DSCH Required Power is a key refrence parameter of RNC admission control. Here is
detailed description of HS-DSCH Required Power.
According to TS25.433, HS-DSCH Required Power Value indicates the minimum
necessary power for a given priority class to meet the GBR for all UEs belonging to this
priority class. It is expressed in thousandths of the cell max transmission power.
The basic principle is to pre-calculate required power for GBR rate with 100ms time
duration according to recent historical power and throughput rate.
Node B can schedule multiple packet data QUEs for every UE. For one scheduled
packet data QUE, the required power is the sum of HS-SCCH required power and
HS-DSCH required power. HS-SCCH required power can be calculated by HS-
SCCH reserved power/QUE number. And HS-DSCH required power calculation
process as following:
1. Get CQI according to GBR:
GbrTbSize = GBR / 500,check TS25.214 CQI table, get GbrCqi according to
GbrTbSize.
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2. Statistics of scheduled packet data QUE every 100ms:
HS-DSCH accumulated power: AccuDschPwr
Accumulated transmitted BITNumber: AccuSchBitNum
3. According the actual scheduling, calculate the actual corresponding CQI:
SchTbSize = AccuSchBitNum / SchNum, thereinto, SchNum is the scheduled
times in 100ms, check TS25.214 CQI table, get SchCqi according to SchTbSize.
4. Calculate HS-DSCH required power.
The actual average HS-DSCH power is: SchDschPwr = AccuDschPwer /
SchNum
HS-DSCH required power = SchDschPwr - (SchCqi - GbrCqi)
At the same time, pay attention that HS-DSCH required power can’t higher than
pilot power+MPO, and can’t lower than pilot power -10dB。
5. Filtering HS-DSCH required power, then report to RNC:
The current reported HS-DSCH required power = last time reported HS-DSCH
required power * (1- gdfMeasFilterCoeff) + current calculated HS-DSCH
required power * gdfMeasFilterCoeff, thereinto the filtering factor
gdfMeasFilterCoeff = 0.015625.
3.6 Impact of HSPA+ on Scheduler
3.6.1 Impact of introducing 64QAM Modulation Technology on Scheduler
After introducing the HSDPA and HSUPA technologies respectively in R5 and R6
protocol versions, 3GPP organization is now introducing new technologies in R7 and
subsequent versions to enhance HSPA performance. After the HSDPA technology is
introduced to WCDMA, the MAC-ehs layer is added to both Node B and UE and
compatible with all functions of original MAC-hs layer. For the HSDPA scheduler of Node
B, R7 is primarily characterized by two technologies: 64QAM and improved L2.
Introducing of HSPA+ technology does not have any impact on the HSDPA scheduling
and flow control algorithms. But it has certain impact on HS-SCCH/HS-PDSCH code
selection, and packetization of MAC-ehs PDU.
After the 64QAM modulation technology is adopted, 64QAM improves the modulation
efficiency by 50%, and accordingly, the peak rate of single UE increases by 50% and
reaches 21.6 Mbps compared with HS -DSCH of R5.
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After 64QAM technology is introduced, the major impact on HSDPA scheduler lies in the
change of modulation mode information carried on HS-SCCH and HS-PDSCH code-set
information.
The modulation mode information and HS-PDSCH code-set information carried on HS-
SCCH are defined as follows according to R5 TS25.212.
xccs,1, xccs,2, xccs,3 = min(P-1,15-P) P refers to the number of HS-PDSCH
channelization codes.
xccs,4, xccs,5, xccs,6, xccs,7 = |O-1-P/8 *15| O refers to the start code No. of HS-
PDSCH.
QAMif
QPSKifxms 161
01,
After 64QAM modulation mode is introduced, if xms,1 is 0, the modulation mode is QPSK;
if xms,1 is 1, the modulation mode is 16QAM or 64QAM.
otherwise
QPSKifxms 1
01,
To further differentiate between 16QAM and 64QAM modulation modes, the lowest BIT
xccs,7 in HS-PDSCH code information bits (xccs,4, xccs,5, xccs,6, xccs,7) is used. Specifically, if
xccs,7 is 0, the modulation mode is 16QAM; if xccs,7 is 1, the modulation mode is 64QAM.
QAMif
QAMifxccs 641
1607,
The lowest BIT position (xccs,7 in R5) of |O-1-P/8 *15| is subject to the even/odd
position of HS-SCCH code demodulated by UE. If HS-SCCH code position is 1, or 3,
xccs,7 is 1; if HS-SCCH code position is 2, or 4, xccs,7 is 0; That is, the following equation
must be met:
|O-1-P/8 *15| mod 2 = (HS-SCCH number) mod 2
If 16QAM or 64QAM modulation mode is selected, then the available HS-PDSCH start
code Nos. are listed as follows:
Table 3-1 HS-PDSCH start code Nos
Odd position of HS-SCCH code
Even position of HS-SCCH code
P >= 8 1 3 5 7 2 4 6
P < 8 2 4 6 8 10 12 14 1 3 5 7 9 11 13 15
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To break the downlink data transmission rate bottleneck caused by fixed AM RLC PDU
length and RLC transmit window size defined in R6 and earlier versions, the improved
L2 technology enables the RLC layer of RNC to support variable RLC PDU lengths. The
corresponding MAC-ehs SDU length changes, and the length field L in MAC-ehs PDU is
used to indicate MAC-ehs SDU length.
The multiplexing of logical channel data shifts from RNC to Node B, that is, several
dedicated logical channels are multiplexed into one MAC-d stream and distinguished
through Logical Channel IDs (LCH-IDs) in MAC-ehs PDU. When MAC-ehs is used, LCH-
ID multiplexing replaces C/T multiplexing in MAC-d. The HSDPA scheduler receives and
stores LCH-ID field from HS-DSCH DATA FRAME TYPE2, and forwards this field
through MAC-ehs PDU. For the frame format of HS-DSCH DATA FRAME TYPE2, see
TS25.435.
MAC-ehs SDUs are of variable lengths. To avoid failure in transmitting a complete MAC-
ehs SDU because the length of MAC-ehs SDU exceeds that of MAC-ehs PDU, MAC-
ehs PDU has a Segmentation Indication (SI) field added to support segmented
transmission of MAC-ehs SDU.
For detailed format of MAC-ehs PDU, see TS25.321.
When both Node B and UE support improved L2, RNC determines the type of signaling
and service, that is, fixed or flexible PDU size, based on the settings of the parameter
RlcSizeSuptType. This parameter is a switch used to indicate RLC PDU size type
configured for signaling and services. It has two values:
1: Signalling Fixed Mode, Service Flexible Mode
2: All Flexible Mode
The RLC information reassignment is required when a UE takes handover between cells
that support flexible size and those that do not or when transport channel type switches
between HS-DSCH and DCH or FACH. In the case of LI s ize inconsistency after
handover or switching, RESET or MRW procedure must be initiated to re-establish RLC.
To avoid signaling RB RLC reestablishment, fixed PDU Size is recommended for
signaling RB, RLC PDU size is set to 144bits and LI size is constantly 7bits. After new
technologies including 64QAM are used, flexible PDU size must be used for service RB,
so RlcSizeSuptType is set to 1 by default.
The maximum length of Data field in RLC PDU is 1504 bytes (including lengths of SN
and LI) as stipulated in the protocol. The actual maximum available SDU size is
configured by RNC through the parameter CMaxPDUSize and NonCMaxPDUSize.
CMaxPDUSize is configured for conversational service and NonCMaxPDUSize is
configured for non conversational service. In view of protocol header overhead at bottom
layer (FP layer, IP/UDP layer and so on) during data transmission, NonCMaxPDUSize is
set to 600 bytes (4800 bits) by default to avoid decrease of efficiency due to
segmentation at transmission layer.
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3.6.2 Impact of introducing MIMO on Scheduler
Impact of introducing MIMO in R7 on scheduler includes the following aspects: PF
scheduling algorithm needs to be modified according to MIMO UE; We need adding
MIMO single/dual stream selecting algorithm in front of scheduling priority calculation.
MIMO single/dual stream selecting algorithm is to preliminarily choose single or dual
stream transmission for the MIMO UE in the current TTI. Impact on TFRC selection
algorithm; And VAM technology.
Let’s expound these impact individually.
1.PF scheduling algorithm needs to be modified according to MIMO UE
Please refer to section 3.2.3 for details related to MIMO UE.
2. MIMO single/dual stream selecting algorithm
UE decides preferred precoding control indication (PCI) vector matrix pref
2
pref
1 , ww
combining with CQI and transmits to Node B through uplink HS-DPCCH signaling.
Based on PCI/CQI compositive report, Node B packet scheduling module will decide
and send to UE with single or dual stream transmission mode, TBSize, modulation mode
in next TTI. At the same time, Node B will inform UE precoding weight w2 which is put in
precoding weight indication bit in the first part of downlink HS-SCCH subframe.
Protocol defined PCI and CQI compositive coding format when UE is configured MIMO
working mode. And UE must support two types of CQI report: type A or type B CQI
report. Type A or Type B CQI report with CQI range (0~30) for single stream
transmission, Type A CQI report with CQI range(0~255)for dual stream transmission.
Type A CQI report is a CQI report format which UE decides transmission block
number(1 block or 2 blocks) according to current channel condition. When 1
transmission block is selected by UE, the preferred primary precoding vector(PCI) from
HS-DPCCH will be used in Node B to precode the primary transmission block. When 2
transmission blocks are selected by UE, the preferred primary precoding vector and
orthogonal precoding vector (PCI) will be used in Node B to precode the primary and
secondary transmission blocks. Type A CQI report will include 1 or 2 transmission format
according to the transmission block number.
Type B CQI report is a CQI report format which UE decides single transmission block
according to current channel condition. The preferred primary precoding vector(PCI)
from HS-DPCCH will be used in Node B to precode the primary transmission block, and
there is no secondary transmission block.
For these two different types of CQI report-type A and type B, UE will achieve different
report rate which is configured by RAN through the following method:
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Report rate for type A CQI report is N_cqi_typeA/M_cqi, rest(M_cqi-N_cqi_typeA) will
be used for type B CQI report. MIMO CQI report rate that can be used is the same as
SISO, which is the function of CQI feedback duration k and CQI repeating factor
N_cqi_transmit.
According to TS25.214v7.9.0, when the following formula is tenable:
_cqi_typeA _cqimod76802565
NMk
chipchipmCFN
with
)2( mskk , UE will send type A CQI report, otherwise send type B CQI report.
When MIMO Activation Indicator in HS-DSCH FDD Information signaling is sent by RNC,
Node B will feed back MIMO N/M Ratio(N_cqi_typeA/M_cqi)to RNC in HS-DSCH
Information Response signaling. RNC will send MIMO N/M Ratio to UE through RRC
signaling. And UE will send type A and type B CQI report according to MIMO N/M Ratio,
Node B will also receive type A and type B CQI report according to MIMO N/M Ratio.
MIMO N/M Ratio value can be:1/2, 2/3, 3/4, 4/5, 5/6, 6/7, 7/8, 8/9, 9/10, 1/1. Now we
only consider to use MIMO N/M Ratio with 1/2 and 1,and it’s default configuration is 1,
that is to say UE will always report Type A CQI report.
MIMO single/dual stream selecting algorithm flow description is as following:
1) After outer loop process of the UE reported CQI, Node B will judge UE CQI report is
Type A or Type B. If it is Type A, go to step 2, if it is Type B, go to step 3.
2) For Type A CQI, if it’s single stream CQI, Node B will employ single stream
scheduling in the current TTI; If it’s dual stream CQI, Node B will employ dual
streams scheduling in the current TTI;
3) For Type B CQI, Node B will check the recent historical type A CQI report is single
stream or dual streams before the current TTI. If it ’s single stream, Node B will
employ single stream scheduling for UE in current TTI based on Type B CQI report.
If it’s dual stream, comparing the current TTI single stream TBSize and sum of
recent historical dual streams TBSize, if current TTI single stream TBSize is bigger,
Node B will employ single stream scheduling for UE in current TTI based on Type B
CQI report, otherwise Node B will employ dual streams scheduling based on Type
A CQI report;
4) Under small data buffer conditions, dual streams process will change into single
stream process.
3. Impact on TFRC selection algorithm
TFRC selection algorithm for MIMO UE single stream scheduling is the same as
traditional UE in section 3.3. But there is some difference for MIMO UE double stream
scheduling in TFRC selection algorithm:
1) Firstly, modify the CQI of MIMO primary and secondary stream individually with
the same principle as in section 3.3.
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2) According to modified CQI of primary and secondary stream, without
consideration of code and power resource, to select the TBSIZE of two streams,
then calculate the needed power, and calculate power per code channel and
code rate.
3) According to the cell rest power, to calculate UE code channel number that can
be used based on the principle of no change to power of per code channel
4) According to code channel number that can be used, to select the TBSIZE
based on no change to code rate
5) Finally to modify TBSIZE according to packet data volume waiting for
scheduling.
4. VAM technology
Primary and secondary pilot configuration with VAM (Virtual Antenna Mapping)
technology will be deployed when MIMO UEs and traditional non-MIMO UEs are
supported in mixed networking. VAM technology is mainly used for power balance
between two PAs and load balance between two transmission channels. And for MIMO
UE, under single stream scheduling condition, PCI codebook restrictions of
2
1
2
1pref
2
jjw on UE side is needed to assure two PAs power balance. In
order to reduce the affection of secondary pilot to traditional non-MIMO UEs, secondary
pilot power can be configured as half of primary pilot, but few MIMO commercial
terminals support this kind of configuration.
3.6.3 Impact of introducing DC-HSDPA on Scheduler
After introducing DC-HSDPA in R8, new joint PF scheduling algorithm will be used for
DC UE, and scheduling relative priority formula for DC UE need to be adjusted
accordingly. Please refer to section 3.2.3 for details related to DC UE.
The queuing and scheduling rule according UE relative scheduling priority:
On carrier1, single carrier UEs and DC UEs will be queued and scheduled according to
described relative priority;
In the same way, on carrier2, single carrier UEs and DC UEs will be queued and
scheduled according to described relative priority.
3.7 Dynamic power sharing in Multi-carrier
Dynamic power sharing in multi-carrier function will be supported with upgrading
software of Node B. The advantage of this technique is to improve utilization rate of
output power in multi carriers and improve quality of user service, increase downlink
capacity, and decrease TCO(Total Cost of Owernship).
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Traditional power sharing in multi-carrier is static, power of each carrier is the same. For
example, show as in figure 5. In practical field application, power of multi-carrier can not
be totally used. Load threshold of R99 is low, power of R99 is surplus most of the time.
After introducing HSDPA, HSDPA scheduler can adopt strategy of dynamic power
allocation, total output power of cell can keep a smooth level, and interference of
downlink is more stable, so load threshold of HSDPA can be higher, show as Figure 3-4.
Figure 3-4 Static power sharing in Multi-carrier
Pmax
Pmax/2carrier2carrier1R99
HSDPA+R99
Figure 3-5 Downlink power after introducing HSDPA
HS-DSCH (rate controlled)
DCH (power controlled)
Common channels
t
power
To
tal
cell
po
wer
To
tal
cell
po
wer
Common channels
DCH (power controlled)
Unused power
power
t
HS-DSCH with dynamic power allocationPower usage with DCH
R99 R5
For example, carrier1 is R99 service carrier, carrier2 is R99+HSDPA service carrier,
total output power of equipment is Pmax, Pmax-carrier1 and Pmax-carrier2 are max
power for each carrier . Pth is the power which can be shared between carriers, Pth=k*
min(Pmax-carrier1,Pmax-carrier2), k is sharing power ratio which can be configured
in OMM , such as 10% or 20%. Pmax and K corresponds to parameters of dynamic
power sharing in multi-carrier Transmission Power and Power-sharing Ratio in chapter
4.2。
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Then take an actual instance for example, each carrier of UMTS Node B is 20W. At time
T, output power of carrier1 is 13W, output power of carrier2 is 17W, but carrier2 need
more 4W for HSDPA service, and based on dynamic power sharing in multi-carrier, 4W
of carrier1 can share with carrier2 to satisfy HSDPA service requirement, and capacity of
network is also enhanced.
4 Parameter Description
4.1 HSDPA Scheduling Algorithm Parameters
Table 4-1 Parameter settings in OMMB
Abbreviated name Parameter name
ConditionWgt Channel Quality Weight
SPI_0 SPI_1…SPI_15 SPI Factor
Table 4-2 Parameter settings in OMMR
Abbreviated name Parameter name
HsdschTotPwrMeth HSPA Total Downlink Power Allocation Method
MeasPwrOffset HS-PDSCH Measurement Power Offset
RlcSizeSuptType Support Type of RLC Flexible PDU Size Format
NONCMAXPDUSIZE Non-Conversational service Maximum MAC-d PDU Size Extended(byte)
CMAXPDUSIZE Conversational service Maximum MAC-d PDU Size Extended(byte)
4.1.1 Channel Quality Weight
OMM Path
View->Configuration Management ->NodeB NE->Base Station Radio Resource
Management ->WCDMA Radio Resource Management->Baseband Resource Pool-
>Local Cell ->HSDPA parameter-> Channel Quality Weight
Parameter Configuration
This parameter indicates channel quality weight. The value of this parameter is [1 6]. Its
default value is 3.
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4.1.2 SPI_0 SPI_1...SPI_15
OMM Path
View->Configuration Management ->NodeB NE->Base Station Radio Resource
Management ->WCDMA Radio Resource Management->Baseband Resource Pool-
>Local Cell ->HSDPA parameter-> SPI_0 SPI_1…SPI_15
Parameter Configuration
This parameter indicates weight of Que SPI. The values of SPI_0, SPI_1…SPI15 may
be modified. The values of SPI_0, SPI_1…SPI15 ranges between 1 and 2000, moreover,
the value of SPI_n should less than the values of SPI_n+1 (n=0, 1, 2…14).
The default value of this parameter is [10, 12, 14, 17, 21, 25, 30, 36, 43, 52, 62, 74, 89,
107, 128, 154].
4.1.3 HS-PDSCH Total Downlink Power Allocation Method
OMM Path
View->Configuration Management->RNC NE->RNC Radio Resource Management-
>Modify Advanced Parameter ->HSPA Configuration Information
Parameter Configuration
This parameter is an internal parameter of RNC. It indicates the method for allocation of
total HS-PDSCH power. Three allocation methods are supported:
0:RNC Static Assigning Mode
1:RNC Dynamic Assigning Mode
2:Node B Assigning Mode
By default, this parameter is set to 2: Node B Assigning Mode.
4.1.4 HS-PDSCH Measurement Power Offset
OMM Path
View->Configuration Management->RNC NE->Rnc Radio Resource Management-
>UtranCell->UtranCellXXX-> Modify Advanced Parameter ->Hspa Configuration
Information In A Cell
Parameter Configuration
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This parameter indicates the assumed HS-PDSCH power offset relative to P-CPICH/S-
CPICH power used for CQI measurement. The range of this parameter is [-6, 13] dB by
step 0.5dB.
Its default value is 6dB.
4.1.5 Support Type of RLC Flexible PDU Size Format
OMM Path
View->Configuration Management->RNC NE->RNC Radio Resource Management-
>Modify Advanced Parameter ->HSPA Configuration Information
Parameter Configuration
This parameter is a switch used to indicate RLC PDU size type configured for signaling
and services. It has 2 values:
1: Signalling Fixed Mode, Service Flexible Mode
2: All Flexible Mode
By default, this parameter is set to 1: Signalling Fixed Mode, Service Flexible Mode
4.1.6 Non-Conversational service Maximum MAC-d PDU Size Extended
OMM Path
View->Configuration Management->RNC NE->RNC Radio Resource Management-
>Advanced Parameter Manage->HSPA Configuration Information -> Non-
Conversational service Maximum MAC-d PDU Size Extended(byte)
Parameter Configuration
This parameter indicates the Non-Conversational service maximum size in octets of the
MAC level PDU when an extended MAC level PDU size is required. According to the
protocol, the maximum length of the Data field in an RLC PDU is 1504 bytes (12032 bits,
including the length of the SN and the length of the LI). Considering the protocol header
overheads of the bottom layer (FP layer, IP/UDP layer, etc.) during data transmission, the
RNC sets the Non-Conversational service maximum MAC-D PDU size to 600 bytes by
default so as to avoid low transmission efficiency caused by segmentation in the
transport layer.
4.1.7 Conversational service Maximum MAC-d PDU Size Extended
OMM Path
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View->Configuration Management->RNC NE->RNC Radio Resource Management->
Modify Advanced Parameter -> HSPA Configuration Information -> Conversational
service Maximum MAC-d PDU Size Extended
Parameter Configuration
This parameter indicates the Conversational service maximum size in octets of the MAC
level PDU when an extended MAC level PDU size is required. The RNC sets the
Conversational service maximum MAC-D PDU size to 65 bytes by default.
4.2 Dynamic Power Sharing in Multi-carrier Parameters
Table 4-3 OMMB configuration parameters filed
Abbreviated name Parameter name
Transmission Power Local Cell Transmission Power
Power-sharing Ratio Power-sharing Ratio
4.2.1 Transmission Power
OMM path
View->Configuration Management ->NodeB NE->Base Station Radio Resource
Management -> WCDMA Radio Resource Management->Sector Management->Sector-
> Local Cell ->Transmission Power
Parameter Configuration
This parameter is the maximum transmission power of local cell, with range of [0,200].
4.2.2 Power-sharing Ratio
OMM path
View->Configuration Management ->NodeB NE->Base Station Equipment Resource
Management ->Power-sharing Ratio
Parameter Configuration
This parameter is configured for power-sharing ration in dynamic power-sharing in multi-
carriers, with the range of [1, 50%].
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5 Weight Mapping Table
Table 5-1 CQI weight mapping table
Wgt1 Wgt2 Wgt3 Wgt4 Wgt5 Wgt6
Single stream CQI w1
1 1 1 1 1 1 1
2 1 2 4 1 1 1
3 1 3 9 1 1 1
4 1 4 16 1 1 1
5 1 5 25 1 1 1
6 1 6 36 2 1 1
7 1 7 49 3 2 2
8 1 8 64 5 4 3
9 1 9 81 7 7 6
10 1 10 100 10 10 10
11 1 11 121 13 15 16
12 1 12 144 17 21 25
13 1 13 169 22 29 37
14 1 14 196 27 38 54
15 1 15 225 34 51 76
16 1 16 256 41 66 105
17 1 17 289 49 84 142
18 1 18 324 58 105 189
19 1 19 361 69 130 248
20 1 20 400 80 160 320
21 1 21 441 93 194 408
22 1 22 484 106 234 515
23 1 23 529 122 280 644
24 1 24 576 138 332 796
25 1 25 625 156 391 977
26 1 26 676 176 457 1188
27 1 27 729 197 531 1435
28 1 28 784 220 615 1721
29 1 29 841 244 707 2051
30 1 30 900 270 810 2430
Double stream CQI w2
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Wgt1 Wgt2 Wgt3 Wgt4 Wgt5 Wgt6
0 1 21 426 84 197 510
1 1 21 426 84 197 510
2 1 22 479 124 254 769
3 1 26 620 142 374 780
4 1 27 692 178 392 786
5 1 27 732 203 524 1380
6 1 28 838 230 692 2068
7 1 30 880 280 823 2520
8 1 30 925 282 833 2534
9 1 32 958 330 989 2900
10 1 34 1042 386 1199 3786
11 1 35 1197 462 1579 5346
12 1 36 1278 510 1755 6204
13 1 37 1364 561 1917 7172
14 1 38 1449 599 2081 8162
6 Glossary
3GPP 3rd Generation Partnership Project
A
ACK ACKnowledgement
AMC Adaptive Modulation and Coding
ARQ Automatic Repeat Request
B
BLER Block Error Rate
C
CPICH Common Pilot Channel
CQI Channel Quality Indicator
C/I Carrier / Interference
D
DCH Dedicated Channel
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DL Downlink (Forward link)
F
FACH Forward Access Channel
G
GBR Guaranteed bit rate
H
HARQ Hybrid Automatic Retransmission Request
HS-DPCCH High Speed Dedicated Physical Control Channel
HS-DSCH High Speed Downlink Shared Channel
HS-PDSCH High Speed Physical Downlink Shared Channel
HS-SCCH High Speed Shared Control Channel
HSDPA High Speed Downlink Packet Access
HSPA High Speed Packet Access
HSPA + High Speed Packet Access Plus
HSUPA High Speed Uplink Packet Access
K
Kbps kilo-bits per second
M
MAC Media Access Control
Mbps Mega-bits per second
MPO Measure Power Offset
N
NACK Negative ACKnowledgement
NBR Nominal Bit Rate
O
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OMM Operations & Maintenance Management Center
OMMB OMM of the Node B
OMMR OMM of the RNC
P
P-CPICH Primary Common Pilot Channel
PDU Protocol Data Unit
Q
QAM Quadrature Amplitude Modulation
QoS Quality of Service
QPSK Quaternary Phase Shift Keying
R
RAB Radio Access Bearer
RLC Radio Link Control
RNC Radio Network Controller
RR Round Robin
RRC Radio Resource Control
S
S-CPICH Secondary Common Pilot Channel
SDU Service Data Unit
T
TFC Transport Format Combination
TFRC Transport Format and Resource Combination
TTI Transmission Time Interval
U
UE User Equipment
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UMTS Universal Mobile Telecommunications System
UTRAN Universal Terrestrial Radio Access Network
W
WCDMA Wideband Code Division Multiple Access