hsupa description

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RAN

HSUPA Description Issue 02

Date 2008-07-30

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RAN HSUPA Description Contents

Issue 02 (2008-07-30) Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd

i

Contents

1 HSUPA Change History.......................................................................................................1-1

2 HSUPA Introduction ............................................................................................................2-1

3 HSUPA Principles.................................................................................................................3-1 3.1 HSUPA Protocol Architecture ................................................................................................................. 3-1 3.2 HSUPA Channel Mapping ...................................................................................................................... 3-2

3.2.1 Mapping of Services onto The E-DCH ........................................................................................... 3-2 3.2.2 Mapping of Logical Channels onto Transport Channels .................................................................. 3-2 3.2.3 Mapping of Transport Channels onto Physical Channels ................................................................. 3-3

3.3 HSUPA Physical Channels...................................................................................................................... 3-4 3.3.1 E-DPCCH ..................................................................................................................................... 3-4 3.3.2 E-DPDCH ..................................................................................................................................... 3-6 3.3.3 E-AGCH ....................................................................................................................................... 3-6 3.3.4 E-RGCH........................................................................................................................................ 3-9 3.3.5 E-HICH....................................................................................................................................... 3-12

3.4 HSUPA Physical Channel Timing ......................................................................................................... 3-13 3.4.1 E-DPDCH/E-DPCCH Timing Relative to the DPCCH ................................................................. 3-13 3.4.2 E-AGCH Timing Relative to the P-CCPCH.................................................................................. 3-13 3.4.3 E-RGCH Timing Relative to the P-CCPCH.................................................................................. 3-14 3.4.4 E-HICH Timing Relative to the P-CCPCH ................................................................................... 3-15 3.4.5 Association Between Frames of Different Physical Channels ........................................................ 3-15

3.5 HSUPA Key Technologies .................................................................................................................... 3-17 3.5.1 HSUPA HARQ ............................................................................................................................ 3-17 3.5.2 HSUPA Short TTI........................................................................................................................ 3-19 3.5.3 HSUPA Fast Scheduling............................................................................................................... 3-19

3.6 MAC-e PDU Generation....................................................................................................................... 3-19 3.6.1 MAC-e PDU Overview................................................................................................................ 3-19 3.6.2 MAC-e PDU Generation Process ................................................................................................. 3-20 3.6.3 MAC-e PDU Encapsulation ......................................................................................................... 3-25

4 HSUPA Algorithms...............................................................................................................4-1 4.1 Overview of HSUPA Related Algorithms ................................................................................................ 4-1

4.1.1 Algorithm of HSUPA Fast Scheduling............................................................................................ 4-1 4.1.2 Algorithm of Flow Control............................................................................................................. 4-1


Contents RAN

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4.1.3 Algorithm of CE Allocation ........................................................................................................... 4-1 4.1.4 Relation Among HSUPA Algorithms.............................................................................................. 4-2

4.2 HSUPA Fast Scheduling ......................................................................................................................... 4-2 4.2.1 Overview of HSUPA Scheduling.................................................................................................... 4-2 4.2.2 User Queuing in the Scheduling Algorithm..................................................................................... 4-4 4.2.3 AG UP Processing in the Scheduling Algorithm ............................................................................. 4-6 4.2.4 RG UP Processing in the Scheduling Algorithm ............................................................................. 4-9 4.2.5 GBR Processing in the Scheduling Algorithm................................................................................. 4-9 4.2.6 MBR Processing in the Scheduling Algorithm.............................................................................. 4-10

4.3 HSUPA Flow Control ............................................................................................................................4-11 4.3.1 Overview of HSUPA Flow Control................................................................................................4-11 4.3.2 Adjusting the Maximum Available Bandwidth of the Iub Port ....................................................... 4-12 4.3.3 Adjusting the Available Bandwidth of HSUPA ............................................................................. 4-14 4.3.4 Handling Iub Buffer Congestion................................................................................................... 4-14

4.4 Dynamic CE Resource Management ..................................................................................................... 4-15 4.5 Other HSUPA Related Algorithms......................................................................................................... 4-20

4.5.1 HSUPA Cell Load Control ........................................................................................................... 4-20 4.5.2 HSUPA DCCC............................................................................................................................. 4-20 4.5.3 HSUPA Power Control................................................................................................................. 4-21 4.5.4 HSUPA Mobility Management..................................................................................................... 4-21 4.5.5 HSUPA Directed Retry ................................................................................................................ 4-22

5 HSUPA Parameters ...............................................................................................................5-1

6 HSUPA Reference Documents ............................................................................................6-1


RAN HSUPA Description 1 HSUPA Change History


1-1

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

Document and Product Versions

Table 1-1 Document and product versions

Document Version RAN Version RNC Version NodeB Version

02 (2008-07-30) 10.0 V200R010C01B061 V100R010C01B050 V200R010C01B041

01 (2008-05-30) 10.0 V200R010C01B051 V100R010C01B049 V200R010C01B040

Draft (2008-03-20) 10.0 V200R010C01B050 V100R010C01B045

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

l Feature change: refers to the change in the HSUPA feature of a specific product version. l Editorial change: refers to changes in information that has already been included, or the

addition of information that was not provided in the previous version.

02 (2008-07-30) This is the document for the second commercial release of RAN10.0.

Compared with 01 (2008-05-30) of RAN10.0, issue 02 (2008-07-30) of RAN10.0 incorporates the changes described in the following table.

Change Type

Change Description Parameter Change

Feature change

Dynamic CE Resource Management is optimized For details, refer to 4.4 Dynamic CE Resource Management

l The parameters that are changed to be non-configurable are listed as follows:

l Happy bit delay time l HSUPA service rate extend scale


1 HSUPA Change History RAN

HSUPA Description

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Change Type


l E-TFCI Table Index l E-RGCH 3-Index-Step Threshold l E-RGCH 2-Index-Step Threshold

Editorial change

A parameter list is added. See chapter 5 HSUPA Parameters.

None.

01 (2008-05-30) This 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.

Change Type


Feature change

None. The parameters that are changed to be non-configurable are listed as follows: l HARQ Info for E-DCH l HSUPA Scheduling Info power

offset

Editorial change

General documentation change: l The HSUPA Parameters is

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

l The structure is optimized.

None.

Draft (2007-03-20) This is a draft of the document for the first commercial release of RAN10.0.

Compared with issue 03 (2008-01-20) of RAN 6.1, this issue incorporates the changes described in the following table:

Change Type


SRB can be carried on E-DCH. None.

The algorithm of HSUPA scheduled transmission is changed. None.

The algorithm of HSUPA flow control is changed. None.

Feature change

The algorithm of HSUPA CE scheduling is introduced. None.


RAN HSUPA Description 1 HSUPA Change History


1-3

Change Type


Editorial change

General documentation change is as follows: l Implementation information has been moved to a separate

document.

None.


RAN HSUPA Description 2 HSUPA Introduction


2-1

2 HSUPA Introduction HSUPA (High Speed Uplink Packet Access) is an important feature of 3GPP R6. As an uplink (UL) high speed data transmission solution, HSUPA provides a theoretical maximum uplink MAC-e rate of 5.73 Mbit/s on the Uu interface. The MAC-e peak data rate supported by Huawei RAN10.0 is 5.73 Mbit/s.

The main features of HSUPA are as follows:

l 2 ms short frame: It enables less Round Trip Time (RTT) in the Hybrid Automatic Repeat reQuest (HARQ) process, which is controlled by NodeB. It also shortens the scheduling response time.

l HARQ at the physical layer: It is used to achieve rapid retransmission for erroneously received data packets between the User Equipment (UE) and NodeB.

l NodeB-controlled UL fast scheduling: It is used to increase resource utilization and efficiency.

HSUPA improves the performance of the UMTS network in the following aspects:

l Higher UL peak data rate l Lower latency: enhancing the subscriber experience with high-speed services l Faster UL resource control: maximizing resource utilization and cell throughput l Better Quality of Service (QoS): improving the QoS of the network l UL peak rate: 5.73 Mbit/s per user l 10 ms and 2 ms TTI l Maximum 60 HSUPA users per cell l Soft handover and softer handover l Multiple RABs (3 PS) l Dedicated/co-carrier with R99 l UE categories 1 to 6 l Basic load control l OLPC for E-DCH l Iub flow control l CE scheduling l Power control of E-AGCH/E-RGCH/E-HICH


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Network Elements Involved The following table describes the Network Elements (NEs) involved in HSUPA.

Table 2-1 NEs involved in HSUPA

UE NodeB RNC MSC Server MGW SGSN GGSN HLR

NOTE l = NE not involved l = NE 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

Impact l Impact on System Performance

Compared with 3GPP R99, 3GPP R6 introduces HSUPA to provide a significant enhancement in the uplink in terms of peak data rate and cell throughput, a shorter latency, and a good balance between downlink and uplink.

l Impact on Other Features The impact of HSUPA on the other features is as follows: HSUPA does not affect the effectiveness of the other features. The implementation of HSUPA requires the support of power control, load control,

admission control, and mobility management. HSUPA and the other features have an impact on each other. For detailed information,

see Other HSUPA Related Algorithms.


RAN HSUPA Description 3 HSUPA Principles


3-1

3 HSUPA Principles The principles of HSUPA cover the technical aspects of the feature:

l HSUPA Protocol Architecture l HSUPA Channel Mapping l HSUPA Physical Channels l HSUPA Physical Channel Timing l HSUPA Key Technologies l MAC-e PDU Generation

3.1 HSUPA Protocol Architecture HSUPA Protocol Architecture describes the protocol architecture of HSUPA.

Figure 3-1 shows the HSUPA protocol architecture.

Figure 3-1 Protocol architecture of HSUPA

To enhance the Access Stratum (AS), HSUPA is implemented in the following ways:

l A new MAC entity (MAC-es/MAC-e) is added to UE below the MAC-d to handle HARQ retransmission, scheduling, MAC-e multiplexing, and E-DCH Transport Format Combination (E-TFC) selection.


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l A new MAC entity (MAC-e) is added to NodeB to handle the HARQ retransmission, scheduling, and MAC-e demultiplexing.

l A new MAC entity (MAC-es) is added to SRNC to combine signals from different NodeBs in soft handover and deliver data to the MAC-d in sequence.

l A new transport channel (E-DCH) is added to transfer data blocks between NodeB MAC-e and SRNC MAC-es.

The HSUPA data flow is as follows:

Step 1 The MAC-es/MAC-e of the UE sends the MAC-e PDUs to the physical layer (PHY) of UE.

Step 2 The MAC-e of NodeB sends the MAC-es PDUs through E-DCH FP to the MAC-es of SRNC.

Step 3 The E-DCH FP of Iub interface controls the data flow between NodeB MAC-e and SRNC MAC-es.

Step 4 The MAC-es of SRNC sends MAC-d PDUs to SRNC MAC-d.

----End

With HSUPA, the Universal Terrestrial Radio Access Network (UTRAN) supports higher-rate transmission. Accordingly, the Packet Switched Core Network (PS CN) requires a higher rate of service assignment, user plane transmission, and switching.

3.2 HSUPA Channel Mapping HSUPA Channel Mapping describes the following:

l Mapping services information on the E-DCH, l Mapping of logical channels onto the transport channels l Mapping of transport channels onto the physical channels

3.2.1 Mapping of Services onto The E-DCH When the UE sends a service request, the RNC determines whether to map the service onto the E-DCH according to the factors, such as, the traffic class, service rate, scheduling scheme, cell HSUPA capability and UE HSUPA capability.

For detailed information on mapping of signaling and traffic onto transport channels, see Mapping of Signaling and Traffic onto Transport Channels in Radio Bearers.

3.2.2 Mapping of Logical Channels onto Transport Channels Both Dedicated Control Channel (DCCH) and Dedicated Traffic Channel (DTCH) can be mapped onto the E-DCH in HSUPA.




3-3

Figure 3-2 Mapping of logical channels onto transport channels on the UE side

Figure 3-3 Mapping of logical channels onto transport channels on the UTRAN side

3.2.3 Mapping of Transport Channels onto Physical Channels After the coding and multiplexing on the E-DCH are performed, the subsequent data streams are mapped sequentially (first in, first out) and directly onto the physical channels.



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Figure 3-4 Mapping of transport channels onto physical channels

3.3 HSUPA Physical Channels HSUPA Physical Channels describes five types of HSUPA physical channels:

l E-DPCCH l E-DPDCH l E-AGCH l E-RGCH l E-HICH

3.3.1 E-DPCCH The E-DCH Dedicated Physical Control Channel (E-DPCCH) carries the control information associated with the E-DCH. Each radio link has at most one E-DPCCH. The spreading factor of the E-DPCCH is 256.




3-5

Figure 3-5 Frame structure of the E-DPCCH

The E-DPCCH carries the following control information:

l Retransmission Sequence Number (RSN): 2 bits l E-TFC Indicator (E-TFCI): 7 bits l Happy Bit: 1 bit

Retransmission Sequence Number (RSN): 2 Bits RSN is transmitted on the E-DPCCH and used to convey the uplink HARQ transmission number.

E-TFCI: 7 Bits E-TFCI is used on the current E-DPDCH. There are four transport block size tables defined in 3GPP 25.321. Each TTI has two tables, the details for which are as follows:

l 2 ms TTI E-DCH Transport Block Size Table 0 l 2 ms TTI E-DCH Transport Block Size Table 1 l 10 ms TTI E-DCH Transport Block Size Table 0 l 10 ms TTI E-DCH Transport Block Size Table 1

Table 0 or Table 1 is selected according to the signaling from the RNC.The E-TFCI Table Index is 0 for Voip service and 1 for all the others. With the table, the E-TFCI can be mapped to a transport block size.

Happy Bit: 1 Bit Happy Bit is a single bit field that is, passed from the MAC to the physical layer for the E-DPCCH inclusion. This field takes two values: Unhappy and Happy, which indicate whether the UE wants more resources.

The Unhappy value indicates a higher data rate than that supported by the current SG, due to the sufficient data in the buffer and enough power in the UE. Otherwise, the Happy Bit is set to Happy.



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For every E-DCH transmission, the Happy Bit is set to Unhappy if the following conditions are met:

l The UE transmits as much scheduled data as allowed by the current SG during E-TFC selection.

l The UE has enough power to transmit data at a higher rate. l Based on the same power offset as the one selected during E-TFC selection to transmit

data in the same TTI as the Happy Bit, the Total E-DCH Buffer Status (TEBS) may require more than Happy bit delay time which equals to 50 ms to be transmitted with the current SG multiplied by the ratio of the number of active processes to the total number of processes.

The ratio mentioned in the third criteria is always 1 for 10 ms TTI.

3.3.2 E-DPDCH The E-DCH Dedicated Physical Data Channel (E-DPDCH) carries the data associated with the E-DCH. Each radio link can have none, one, or several E-DPDCHs. The spreading factor of the E-DPDCH ranges from 2 to 256.

RAN10.0 provides a maximum of four E-DPDCHs with two SF4s and two SF2s.

Figure 3-6 Frame structure of the E-DPDCH

Generally, the E-DPDCH and the E-DPCCH are transmitted simultaneously, except with the power scaling as described in 3GPP TS 25.214, the E-DPCCH is transmitted discontinuously.

3.3.3 E-AGCH The E-DCH Absolute Grant Channel (E-AGCH) carries AGs for uplink E-DCH scheduling. The E-AGCH is a common downlink physical channel with a fixed rate of 30 kbit/s. The spreading factor of the E-AGCH is 256.

The E-AGCH is a shared channel for all HSUPA UE in the serving E-DCH cell.




3-7

Figure 3-7 Frame structure of the E-AGCH

An E-DCH AG has to be carried by one E-AGCH subframe or one E-AGCH frame, depending on the E-DCH TTI is 2 ms or 10 ms.

The information transmitted on the E-AGCH includes a 5-bit field of the AG value and a 1-bit field of the AG scope.

l The AG value indicates the maximum power ratio of the E-DPDCH to the corresponding DPCCH. The mapping of AG values is described in Table 3-1.

l The AG scope indicates whether the HARQ process activation or deactivation will affect one or all of the processes. The AG scope can take two different values: "Per HARQ process" or "All HARQ processes". "Per HARQ process" means that the AG is for one HARQ process. "All HARQ processes" means that the AG is for all HARQ processes.

When the E-DCH is configured with 10 ms TTI, only the value "All HARQ processes" is valid.

For detailed information on SG update, see HSUPA Serving Grant Update (subclause 11.8.1.3 in 3GPP 25.321).

The RNC-assigned sequence of 16-bit CRC on the E-AGCH is masked with either a primary or a secondary E-RNTI. Here, the E-RNTI stands for E-DCH Radio Network Temporary Identifier.

l The primary E-RNTI is unique for each UE. l The secondary E-RNTI is usually for a group of UEs.

When the UE demodulates the E-AGCH, the E-AGCH will again mask the CRC with the primary or secondary E-RNTI. Only the UE having the same E-RNTI can demodulate the information correctly.

Only the primary E-RNTI is used in the current RAN version.



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Table 3-1 Mapping of AG values

Absolute Grant Value Index

(168/15)2 x 6 31

(150/15)2 x 6 30

(168/15)2 x 4 29

(150/15)2 x 4 28

(134/15)2 x 4 27

(119/15)2 x 4 26

(150/15)2 x 2 25

(95/15)2 x 4 24

(168/15)2 23

(150/15)2 22

(134/15)2 21

(119/15)2 20

(106/15)2 19

(95/15)2 18

(84/15)2 17

(75/15)2 16

(67/15)2 15

(60/15)2 14

(53/15)2 13

(47/15)2 12

(42/15)2 11

(38/15)2 10

(34/15)2 9

(30/15)2 8

(27/15)2 7

(24/15)2 6

(19/15)2 5

(15/15)2 4

(11/15)2 3

(7/15)2 2




3-9

Absolute Grant Value Index

ZERO_GRANT 1

INACTIVE 0

3.3.4 E-RGCH The E-DCH Relative Grant Channel (E-RGCH) carries RGs for uplink E-DCH scheduling. The E-RGCH is a dedicated downlink physical channel with a fixed rate of 60 kbit/s. The spreading factor of the E-RGCH is 128.

Figure 3-8 Frame structure of the E-RGCH

An RG is transmitted in 3, 12, or 15 consecutive slots. Each slot carries a sequence of 40 binary values.

l If the cell transmitting the E-RGCH is in the serving E-DCH Radio Link Set (RLS), then 3 or 12 slots are used, depending on the E-DCH TTI is 2 ms or 10 ms.

l If the cell transmitting the E-RGCH is not in the serving E-DCH RLS, 15 slots are used.

The RG commands are mapped to the RG values, as described in the following table.

Table 3-2 Mapping of RG commands

RG Command

RG Value (for Serving E-DCH RLS)

RG Value (for Non-Serving E-DCH RL)

UP 1 Not allowed

HOLD 0 0

DOWN 1 1

When the UE receives an RG command, the SG is adjusted upwards or downwards by one step. The step can be 1, 2, or 3 in the Scheduling Grant Table according to the current SG



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value, E-RGCH 3-Index-Step Threshold whose value is 17 for 2ms TTI and 9 for 10ms TTI, and E-RGCH 2-Index-Step Threshold. Wose value is 18 for 2ms TTI and 12 for 10ms TTI. The Scheduling Grant Table is provided in Table 3-3.

When the SG needs to be determined due to E-RGCH signaling:

l The UE determines the lowest power ratio and the corresponding index in the Scheduling Grant Table: SGIndexLUPR. The lowest power ratio is in the Scheduling Grant Table ( Table 3-3), and is equal to, or higher than the reference_ETPR. The reference_ETPR is the power ratio of E-DPDCH to DPCCH. The ratio is used for the E-TFC selected for the previous TTI in this HARQ process and calculated by the amplitude ratios prior to the quantization according to 4.5.3 HSUPA Power Control.

l If the UE receives a serving RG "UP", the UE determines the SG (based on the "3-index-step threshold" and "2-index-step threshold" configured by higher layers) as follows:

l If SGIndexLUPR < 3-index-step threshold, then SG = SG [MIN (SGLUPR + 3, 37)]. l For example, if SGIndexLUPR = 15 and 3-index-step threshold = 20, then the new SG

index is 18. l If 3-index-step threshold SGIndexLUPR < 2-index-step threshold, then SG = SG [MIN

(SGLUPR + 2, 37)]. l For example, if SGIndexLUPR = 21 and 2-index-step threshold = 25, then the new SG

index is 23. l If SGLUPR 2-index-step threshold, then SG = SG [MIN (SGLUPR + 1, 37)]. l For example, if the SGIndexLUPR = 28 and 2-index-step threshold = 25, then the new SG

index is 29. l If the UE receives an RG "DOWN", then SG = SG[MAX (SGLUPR - 1, 0)]. l SG = SG[SGIndex] which means to get an SG from the Scheduling Grant Table

according to the SGIndex.

Table 3-3 Scheduling Grant Table

Index Scheduled Grant

37 (168/15)2 x 6

36 (150/15)2 x 6

35 (168/15)2 x 4

34 (150/15)2 x 4

33 (134/15)2 x 4

32 (119/15)2 x 4

31 (150/15)2 x 2

30 (95/15)2 x 4

29 (168/15)2

28 (150/15)2

27 (134/15)2




3-11

Index Scheduled Grant

26 (119/15)2

25 (106/15)2

24 (95/15)2

23 (84/15)2

22 (75/15)2

21 (67/15)2

20 (60/15)2

19 (53/15)2

18 (47/15)2

17 (42/15)2

16 (38/15)2

15 (34/15)2

14 (30/15)2

13 (27/15)2

12 (24/15)2

11 (21/15)2

10 (19/15)2

9 (17/15)2

8 (15/15)2

7 (13/15)2

6 (12/15)2

5 (11/15)2

4 (9/15)2

3 (8/15)2

2 (7/15)2

1 (6/15)2

0 (5/15)2



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3.3.5 E-HICH The E-DCH Hybrid ARQ Indicator Channel (E-HICH) carries uplink E-DCH HARQ acknowledgement indicators. The E-HICH is a dedicated downlink physical channel with a fixed rate of 60 kbit/s. The spreading factor of the E-HICH is 128.

The frame structure of the E-HICH is the same as that of the E-RGCH. An HARQ acknowledgement indicator is transmitted in 3 or 12 consecutive slots and in each slot a sequence of 40 binary values is transmitted as follows:

l 3 slots are used for the UE with 2 ms E-DCH TTI. l 12 slots are used for the UE with 10 ms E-DCH TTI.

Figure 3-9 Frame structure of the E-HICH

The ACK and NACK mappings on the E-HICH are described in the following table. For the RLSs that do not contain the serving E-DCH cell, the NACK is transmitted discontinuously.

Table 3-4 Mapping of HARQ acknowledgement

Command HARQ Acknowledgement Indicator

ACK +1

NACK (for the RLSs not containing the serving E-DCH cell)

0

NACK (for the RLS containing the serving E-DCH cell)

1

When an ACK and an NACK are received at the same time, the UE combines them as shown in the following table.




3-13

Table 3-5 ACK/NACK combining

Transmission Data Type

ACK/NACK from Serving RLS

ACK/NACK from Non-Serving RLs

Operation of UE

All data ALL NACK ALL NACK The UE performs HARQ (re)transmissions until the maximum number of transmissions is reached.

All data At least one ACK

Either ACK or NACK

ACK

High-level data only

ALL NACK At least one ACK

ACK

Higher layer data and SI triggered by an event or timer

ALL NACK At least one ACK

The UE notifies the Scheduling Information Reporting function that the Scheduling Information is not received by the serving the RLS, flushes the packet, and includes the scheduling information with new data payload in the next packet.

SI only ALL NACK Either ACK or NACK

The UE performs HARQ (re)transmissions until an ACK from the RLS containing the serving cell is received or until the maximum number of transmissions is reached.

3.4 HSUPA Physical Channel Timing The Primary Common Control Physical Channel (P-CCPCH), on which the cell System Frame Number (SFN) is transmitted, is used as a timing reference for all the physical channels, directly for the downlink and indirectly for the uplink.

3.4.1 E-DPDCH/E-DPCCH Timing Relative to the DPCCH The timing of the E-DPCCH and all the E-DPDCHs transmitted from the UE is the same as that of the uplink DPCCH.

3.4.2 E-AGCH Timing Relative to the P-CCPCH

The E-AGCH frame offset from the P-CCPCH should be = 5120 chips.



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Figure 3-10 E-AGCH timing relative to the P-CCPCH

3.4.3 E-RGCH Timing Relative to the P-CCPCH The timing of the E-RGCH relative to the P-CCPCH is shown in the following figure.

Figure 3-11 E-RGCH timing relative to the P-CCPCH

If the E-RGCH is transmitted to the UE, and the cell transmitting the E-RGCH is in the serving E-DCH RLS, the E-RGCH frame offset should be as follows:

l If the E-DCH TTI is 10 ms, the E-RGCH frame offset from the P-CCPCH is chips.

In this case, is the DPCH frame offset from the P-CCPCH.

l If the E-DCH TTI is 2 ms, the E-RGCH frame offset from the P-CCPCH is chips.




3-15

If the E-RGCH is transmitted to the UE, and the cell transmitting the E-RGCH is not in the

serving E-DCH RLS, the E-RGCH frame offset from the P-CCPCH should be = 5120 chips.

3.4.4 E-HICH Timing Relative to the P-CCPCH The timing of the E-HICH relative to the P-CCPCH is shown in the following figure.

Figure 3-12 E-HICH timing relative to the P-CCPCH

l If the E-DCH TTI is 10 ms, the E-HICH frame offset from the P-CCPCH should

be chips.

l If the E-DCH TTI is 2 ms, the E-HICH frame offset from the P-CCPCH should be

chips.

3.4.5 Association Between Frames of Different Physical Channels 10 ms E-DCH TTI

For each cell in the E-DCH active set: The UE associates the control information received through the E-HICH frame SFNi with the data transmitted in the E-DPDCH frame SFNi-3.

The following figure shows an example of timing of the E-HICH with 10 ms TTI.



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Figure 3-13 E-HICH timing relative to the P-CCPCH

For each cell that belongs to the serving E-DCH RLS: The UE first takes into account the E-DCH control information received through the E-RGCH frame SFNi in the higher layer procedures that correspond to the E-DCH transmission in the E-DPDCH frame SFNi+1.

For each cell that does not belong to the serving E-DCH RLS: The UE first takes into account the E-DCH control information received through the E-RGCH frame SFNi in the higher layer procedures that correspond to the E-DCH transmission in the E-DPDCH frame SFNi+1+s,

Where,

For the E-AGCH frame: The UE first takes into account the E-DCH control information received through the E-AGCH frame SFNi in the higher layer procedures that correspond to the E-DCH transmission in the E-DPDCH frame SFNi+1+s,

Where,

2 ms E-DCH TTI

For each cell in the E-DCH active set: The UE associates the E-DCH control information received through subframe j of the E-HICH frame SFNi with subframe t of the E-DPDCH frame SFNi-s,

Where:

and .

For each cell that belongs to the serving E-DCH RLS: The UE first takes the E-DCH control information received through subframe j of the E-RGCH frame SFNi into account in the higher layer procedures that correspond to the E-DCH transmission in subframe j of the E-DPDCH frame SFNi+1.

For each cell that does not belong to the serving E-DCH RLS: The UE first takes the E-DCH control information received through the E-RGCH frame SFNi into account in the higher layer procedures that correspond to the E-DCH transmission in sub-frame t of the E-DPDCH frame SFNi+1+s, where




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and

For the E-AGCH frame, UE first takes the E-DCH control information received through sub-frame j of the E-AGCH frame SFNi into account in the higher layer procedures that correspond to E-DCH transmission in sub-frame t of the E-DPDCH frame SFNi+s, where

and .

3.5 HSUPA Key Technologies HSUPA Key Technologies describes the HSUPA key technologies: HARQ, short TTI, and fast scheduling. With these key technologies, HSUPA provides a theoretical maximum uplink MAC-e rate of 5.73 Mbit/s on the Uu interface, which increases the cell throughput.

3.5.1 HSUPA HARQ Hybrid Automatic Repeat reQuest (HARQ) is a multi-instance Stop-And-Wait (SAW) protocol. It is a combination of Forward Error Correction (FEC) and ARQ. For every HSUPA user, an HARQ entity is present on both UE and NodeB sides, each having eight HARQ processes in the case of 2 ms TTI or four HARQ processes in the case of 10 ms TTI. Several HARQ processes used together can fully use the transmission capability of the Uu interface.

HARQ Entity In the UE, the HARQ entity is located in MAC-es/MAC-e. The HARQ entity can store the MAC-e payloads and retransmit them. The RRC can configure the HARQ over MAC-controlled Service Access Point (SAP).

In the NodeB, the HARQ entity is located in MAC-e. Each process is responsible for generating ACKs or NACKs, which indicate the status of E-DCH transmissions.

The HARQ entity has the following parameters:

l E-TFC l Retransmission Sequence Number (RSN) l Power offset: used to calculate the power ratio of E-DPDCH to UL DPCCH

The E-TFC and the power offset are decided by HSUPA E-TFC Selection.

RSN (2-bit) is sent from the UE to the NodeB. If the number of transmissions is larger than three, the RSN is set to 3. The RSN can help to indicate the Redundancy Version (RV) of each HARQ transmission and to assist in the NodeB soft buffer management.



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If more than three consecutive E-DPCCH transmissions in the HARQ process cannot be decoded or the last received RSN is incompatible with the current one, the NodeB flushes the soft buffer associated with the HARQ process to ensure that the soft buffer is in a good condition.

Combining Modes of HARQ HARQ supports two coding combining modes as shown in the following table. The incremental redundancy mode is better because inconsistency between the retransmitted bit set and the former bit set leads to an increase in the redundant data and the possibility of recovery from errors on the Uu interface.

Table 3-6 Coding combining modes of HARQ

Coding Combining Mode Description

Chase combining mode In this mode, the same bit set is retransmitted.

Incremental redundancy mode In this mode, different bit sets are retransmitted.

Redundancy Version Redundancy Version (RV) defines the selection of bits that can be transmitted on the air interface resource, which is known as the rate matching pattern.

The RV can be derived by L1 from RSN and Connection Frame Number (CFN), or in the case of 2 ms TTI from the subframe number.

The E-DCH RV index specifies the used RV. The UE uses the E-DCH RV indexes as listed in the Table 3-7 .

Table 3-7 Relationship between RSN values and E-DCH RV indexes

RSN Value E-DCH RV Index (When Nsys/Ne,data,j < 1/2)

E-DCH RV Index (When Nsys/Ne,data,j 1/2)

0 0 0

1 2 3

2 0 2

3 [ mod 2 ] x 2 mod 4

Note:

is to round down a value. If configured by higher layers, only E-DCH RV index 0 can be used.

The parameters in the table are described as follows:

l Nsys is the number of system bits after channel coding.




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l Ne,data,j is the total number of bits available for the E-DCH transmission per TTI with transport format j.

l TTIN is the TTI number. For 10 ms TTI, TTIN = CFN. For 2 ms TTI, TTIN = 5 x CFN + subframe number.

In this case, the subframe number counts the five TTIs within a given CFN, starting from 0 for the first TTI to 4 for the last TTI.

l NARQ is the number of HARQ processes.

3.5.2 HSUPA Short TTI By using a short TTI on the Uu interface, HSUPA can implement faster data scheduling and data transmission with lower delay. The 10 ms TTI is mandatory for R6 UE and the 2 ms TTI is optional for R6 UE.

RAN10.0 supports both 10 ms TTI and 2 ms TTI.

3.5.3 HSUPA Fast Scheduling The MAC-e entity of the NodeB performs scheduling. The MAC-e entity uses the scheduling information contained in the enhanced uplink and the information carried by the E-DPCCH to quickly adjust the rates of UEs based on the Uu resources. Thus, the fast scheduling helps improve cell throughput.

For details about fast scheduling, see 4.2 HSUPA Fast Scheduling.

3.6 MAC-e PDU Generation MAC-e PDU Generation describes the data transmission and MAC-e PDU generation on the UE side.

3.6.1 MAC-e PDU Overview MAC-e PDU Overview describes the overview of MAC-e PDU.



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Figure 3-14 Simplified Architecture for MAC Inter-working in UE

In the figure, the left part shows the functional split, while the right part shows PDU architecture.

An RLC PDU enters MAC-d on a logical channel. The MAC-d C/T multiplexing is bypassed. In the MAC-e header, the DDI (Data Description Indicator) field (6 bits) identifies logical channel, MAC-d flow and MAC-d PDU size. A mapping table is signaled over RRC, to allow the UE to set DDI values. The N field (fixed size of 6 bits) indicates the number of consecutive MAC-d PDUs corresponding to the same DDI value. A special value of the DDI field indicates that no more data is contained in the remaining part of the MAC-e PDU. The TSN field (6 bits) provides the transmission sequence number on the E-DCH. The MAC-e PDU is forwarded to a Hybrid ARQ entity, which then forwards the MAC-e PDU to layer 1 for transmission in one TTI.

3.6.2 MAC-e PDU Generation Process On UE side, in each TTI, the UE performs Serving Grant (SG) update upon reception from the downlink control command. Based on the SG, the UE selects the E-DCH Transport Format Combination Indicator (E-TFCI) and finally creates the MAC-e PDU according to the information on different logical channels in the buffer.

HSUPA Serving Grant Update The Serving Grant (SG) update applies to every TTI boundary and takes into account the Absolute Grant (AG), serving Relative Grant (RG), and non-serving RGs that apply to every TTI.

The SG update procedure is shown in the Figure 3-15, and the AG processing procedure is shown in Figure 3-16. Related terms and definitions are as follows:




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l AG_Timer and Non_serving_RG_timer: They are equal to one HARQ RTT (40 ms in the case of 10 ms TTI, or 16 ms in the case of 2 ms TTI), as defined in 3GPP TS 25.321.

l Primary_Grant_Available: This state variable is a Boolean, indicating whether the UE SG is affected only by Primary Absolute Grants and Relative Grants (that is, not by Secondary Absolute Grants).

l Primary Absolute Grant: An AG received with the primary E-RNTI. l Secondary Absolute Grant: An AG received with the secondary E-RNTI. l Serving E-DCH RLS or Serving RLS: A set of cells that contains at least the serving

E-DCH cell and from which the UE can receive and combine one RG. The UE has only one serving E-DCH RLS.

l Identity Type: It takes the value "Primary" or "Secondary" based on whether the message is addressed to the primary or the secondary E-RNTI.

l Stored_Secondary_Grant: This state variable is used to store the last received Secondary Absolute Grant value. The possible values are "Zero_Grant" and numerical values.



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Figure 3-15 SG update procedure




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Figure 3-16 AG processing procedure

According to the two procedures shown above, the SG update is described as follows:

l If any non-serving RGs indicate DOWN for a TTI, then l The UE updates the SG and sets the Maximum_Serving_Grant to SG. l The Non_Servig_RG_Timer is started (if it is inactive) and set to one HARQ RTT, and l The AG or RG from the serving RLS at the same TTI is ignored.



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l If no non-serving RGs indicate DOWN for a TTI, the UE updates the SG according to the AG or RG (used when no AG has been received and the AG_Timer has expired) received from the serving RLS. In addition, the new SG cannot exceed the Maximum_Serving_Grant saved last time if the Non_Serving_RG_Timer has not expired.

If the HSUPA UE receives more than one RG command, then one is from the serving RLS and the others are from non-serving RLs. The RG commands from the serving RLS and non-serving RLs are listed in the following table.

For detailed information on SG update, see subclause 11.8.1.3 in 3GPP 25.321.

Table 3-8 RG commands

RG Command from Serving RLS

RG Commands from Non-Serving RLs

Final RG Command

UP All HOLD UP The new SG, however, can not exceed the Maximum _Serving_Grant if the Non_Serving_RG_Timer has not expired.

UP At least one DOWN DOWN The UE saves a new Maximum_Serving_Grant. If the Non_Serving_RG_Timer is inactive, start it.

HOLD All HOLD HOLD

HOLD At least one DOWN DOWN The UE saves a new Maximum_Serving_Grant. If the Non_Serving_RG_Timer is inactive, start it.

DOWN All HOLD DOWN

DOWN At least one DOWN DOWN The UE saves a new Maximum_Serving_Grant. If the Non_Serving_RG_Timer is not active, start it.

HSUPA E-TFC Selection At every TTI boundary, where a new transmission is required by the HARQ entity, the UE performs the E-TFC selection procedure.

The RRC configures the MAC with a HARQ profile and a multiplexing list for each MAC-d flow, as described below:

l The HARQ profile includes the power offset and the maximum number of HARQ transmissions.

l The configuration of the HARQ profile is described in E-DCH Outer-Loop Power Control.




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l The multiplexing list identifies the other MAC-d flows from which data can be multiplexed for transmission that uses the power offset included in its HARQ profile.

l The principle of configuring the multiplexing list is that the MAC-d packet of lower priority logical channel can be multiplexed into the MAC-e PDU of the higher priority logical channel, but the MAC-d packet of higher priority logical channel cannot be multiplexed into the MAC-e PDU of the lower priority logical channel.

If the Scheduling Information (SI) needs to be transmitted without any higher-layer data, the RRC configures the MAC with a special HARQ profile for "Control-only" transmissions:

l The power offset is fixed to 6dB. l The maximum number of HARQ transmissions is eight in this case.

At each TTI boundary, the UE in CELL_DCH state with an E-DCH transport channel determine the state of each E-TFC for each configured MAC-d flow based on its required transmit power and the maximum UE transmit power. Note that:

l The calculation of the required transmit power for each E-TFC is the same as that described in Power Control.

l For each configured MAC-d flow, a given E-TFC can be in Supported state or Blocked state. Only E-TFCs in Supported state are considered in E-TFC selection.

l The SG update function provides the E-TFC selection function with the maximum E-DPDCH to DPCCH power ratio that the UE is allowed to allocate for the upcoming transmission for scheduled data.

If a 10 ms TTI is configured and the TTI for the upcoming transmission overlaps with a compressed mode gap, the SG provided by the SG update function is scaled down according to the following equation:

SG' = SG x (NC/15)

Where:

l SG' represents the modified SG considered by the E-TFC selection algorithm. l NC represents the number of non DTX slots in the compressed TTI.

Nc depends on the compressed mode which can be configured by the SET TGPSCP command.

Through power offset and E-DCH Transport Format Combination (E-TFC) restriction procedure, the TB size can be obtained in the next TTI.

For the detailed procedure of E-TFC selection, refer to the 25.321 protocol.

3.6.3 MAC-e PDU Encapsulation The detailed procedure for encapsulating the MAC-e PDUs is described in Section 11.8.1.4 and Appendix C of 3GPP 25.321. According to the priority levels of logical channels and the scheduling modes, the MAC-e PDUs can be encapsulated on the basis of the following principles.

l The SI is always sent when the transmission is triggered. l Logical channels support absolute priority, that is, the UE maximizes the transmission

amount of higher-priority data. l For all logical channels:



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If the logical channel belongs to a non-scheduled MAC-d flow, the current non-scheduled grant of the user determines whether the data can be transmitted.

If the logical channel does not belong to a non-scheduled MAC-d flow, the current SG of the user determines whether the data can be transmitted.

The MAC-d flows are configured in non-scheduled transmission mode or scheduled transmission mode.

Non-Scheduled Transmission Mode In non-scheduled transmission mode, the UE can transmit data at the rate specified by the RNC, without a grant from the Node B. The non-scheduled transmission mode is suitable for the services with the requirements for low delay and steady source data rate.

In RAN10.0, only the streaming service, conversational service can be mapped onto the E-DCH in non-scheduled transmission mode.

If only non-scheduled MAC-d flows are configured for a UE, the NodeB does not send any AG or RG to this UE. Therefore, in non-scheduled mode, the E-DCH becomes a "fast retransmission DCH" without scheduling.

If an MAC-d flow is configured with the non-scheduled transmission mode, the MAC-d PDUs for logical channels belonging to this MAC-d flow shall not exceed the size specified by the IE "Max MAC-e PDU contents size".

The value of "Max MAC-e PDU contents size" is calculated in the RNC by the following formula:

MaxMACePDUSize = [Ceil(MBR x TTILen / RLCPDUpayload) x MACdPDUSize + 18 ] x MaxRateUpScale

Where:

l MaxMACePDUSize: Max MAC-e PDU contents size l Ceil(): to get the larger integer l MBR: maximum bit rate specified by the Iu message RAB ASSIGNMENT REQUEST l TTILen: TTI length l RLCPDUpayload: RLC PDU payload, namely RLC PDU size minus RLC PDU header l MACdPDUSize: MAC-d PDU size l 18: sum of bits for the Transmission Sequence Number (TSN), Data Description

Indicator (DDI), and N (Number of MAC-d PDUs) fields l MaxRateUpScale: used for multiplying the UL MBR in the RAB assignment to achieve

the peak bit rate for the service bearers on the E-DCH The default value of MaxRateScale is 1.01 for each RAB and 5 for each SRB.

Scheduled Transmission Mode In scheduled transmission mode, the UE receives a grant from the NodeB before sending data. For detailed information, see 4.2 HSUPA Fast Scheduling.


RAN HSUPA Description 4 HSUPA Algorithms


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4 HSUPA Algorithms HSUPA algorithms introduce the HSUPA related algorithms, and provide the detailed information on algorithms for fast scheduling, flow control, and CE scheduling.

4.1 Overview of HSUPA Related Algorithms This section describes the relation among algorithms in HSUPA.

With the introduction of HSUPA, the NodeB uses three algorithms, namely, HSUPA fast scheduling algorithm, flow control algorithm, and CE scheduling algorithm. These algorithms respectively consider the Uu resources, Iub resources, and CE resources on the NodeB.

4.1.1 Algorithm of HSUPA Fast Scheduling By sending a scheduling grant, absolute grant (AG), or relative grant (RG), the NodeB performs fast scheduling to adjust the data rates of the UE. The scheduling procedure takes into account such factors as Scheduling Priority Indicator (SPI), Guaranteed Bit Rate (GBR), Iub flow control information, and CE resources for the UE, and uses the corresponding algorithms to perform the following functions:

l Efficient use of uplink resources: The algorithm maximizes the uplink throughput of a cell under the condition that the QoS requirements of all the UEs are met.

l Fairness of services: If some UEs have the same Scheduling Priority Indicator (SPI), the algorithm allocates the same uplink resources to these UEs.

l Differentiated services: If a user has a higher SPI, it can obtain more uplink resources compared with a user with a lower SPI.

4.1.2 Algorithm of Flow Control Flow control is implemented to reduce delay and packet loss rate, to maximize uplink throughput, and to achieve better utilization of the Iub bandwidth.

Flow control algorithm dynamically adjusts the available bandwidth of HSUPA UE based on the congestion state of the transport network, the buffer usage, and variation trend of the Iub port. This algorithm can also affect the way the fast scheduling algorithm grants the UE, thus matching the Uu rate with the Iub transport capability.

4.1.3 Algorithm of CE Allocation After HSUPA is introduced, more CEs are required. As the number of HSUPA UEs increases, the consumption of CEs also increases, and the CE resource may become a bottleneck.


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The CE scheduling algorithm dynamically adjusts the CE resources allocated to the UEs according to their data rates and preferentially serves the E-DCH RLS UE. It aims to reduce the probability of demodulation failure caused by CE resources, thus fully using the CE resources.

4.1.4 Relation Among HSUPA Algorithms Flow control and CE scheduling cannot directly control the transmit data rate of the UE, the results of both flow control and CE scheduling shall be reported to the MAC-e entity. That is, the MAC-e scheduling controls the UE maximum data rate.

Figure 4-1 Overview of HSUPA algorithms relation

The figure shows the relation among the three HSUPA algorithms on the NodeB side. The HSUPA CE scheduler provides the MAC-e scheduler with the number of CEs allocated to the UE and the maximum SG. The HSUPA flow control entity sends the available bandwidth of HSUPA UE and the grant indicator to the MAC-e scheduler. In addition to the Uu resources, the MAC-e scheduling also considers the impact of flow control and CE scheduling results when giving the scheduling grants.

4.2 HSUPA Fast Scheduling 4.2.1 Overview of HSUPA Scheduling

In scheduled transmission mode, the NodeB can control uplink interference. In this mode, the UE sends resource requests with the Scheduling Information (SI) on the E-DPDCH and the Happy Bit on the E-DPCCH, and the NodeB assigns a granted power ratio to the UE to determine the UE rate.

Principle of the Scheduling Algorithm

The scheduling algorithm considers the UL load factor, available uplink Iub bandwidth, and CE resource. It uses the DL control channel (E-AGCH or E-RGCH) to affect the E-TFCIs used by the UEs. Thus, the algorithm can control the UL interference on the Uu interface and avoid congestion on the Iub interface.

The scheduling algorithm mainly performs the following operations:

l Assigning the AG based on the SI and Happy Bit sent by the UE to control the maximum rate that can be used by the UE.

l Assigning the RG according to the Happy Bit.




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l If the user is configured with the GBR by the RNC, and the GBR Schedule Switch parameter is set to TRUE (OPEN), the algorithm guarantees the GBR.

For an unhappy user,

l If the conditions for sending AG UP are met, the algorithm assigns AG to the user. l Else if the conditions for sending RG UP are met, the algorithm assigns RG to the user.

Process of the Scheduling Algorithm When the scheduling period (equal to one TTI) arrives, the scheduling algorithm functions are as follows:

1. Calculating the uplink Uu load resource of each cell and the uplink Iub bandwidth for NodeB Uplink Uu load resource of a cell = Maximum Target Uplink Load Factor - actual load Uplink Iub bandwidth of a NodeB = bandwidth available for HSUPA users within the NodeB range - total throughput of the users

2. Limiting the UE rates according to the CE resource Based on SGmax and CE preemption, the algorithm sends AG DOWN. For detailed information on CE preemption and SGmax, see 4.4 Dynamic CE Resource Management

3. Limiting the UE rates according to the MBR The algorithm directly sends RG DOWN to the UEs whose rates need to be downsized by MBR limitation and updates the UL load based on the current UL load. For detailed information, see 4.2.6 MBR Processing in the Scheduling Algorithm.

4. Limiting the UE rates according to the buffer congestion state The algorithm sends RG DOWN to the user on the Iub port whose buffer is in a congested state. For details about how to judge the buffer status, see 4.3.4 Handling Iub Buffer Congestion.

5. Queuing users The algorithm arranges all the users that are not granted within the NodeB based on Happy Bit, thus obtaining a sequence of happy queues and a sequence of unhappy queues. The factors to be considered include the scheduling information, scheduling priority indicator, GBR, and effective data rate.

6. Updating the remaining resources The algorithm calculates the maximum resources that can be released by the happy users for the unhappy users, rather than sends RG DOWN to the happy users.

7. Scheduling the unhappy queues in a reverse order

a. If the conditions for sending AG UP are met, the algorithm assigns AG to the user based on the available load resource of the cell where the UE camps or the available bandwidth of the Iub port where the UE is carried, and updates the remaining resources. For details, see 4.2.3 AG UP Processing in the Scheduling Algorithm.

b. If the conditions for sending RG UP are met, the algorithm assigns RG to the user based on the available load resource of the cell where the UE camps or the available bandwidth of the Iub port where the UE is carried, and updates the remaining resources. For details, see 4.2.4 RG UP Processing in the Scheduling Algorithm.

8. Scheduling the happy queues and the unhappy queues in turn



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If the available load resource of the cell where the UE camps or the available bandwidth of the Iub port where the UE is carried is smaller than zero, the algorithm sends RG DOWN to the UE and updates the remaining resources.

In the process, if the GBR Schedule Switch is ON and the value of Reff of an unhappy user is smaller than the GBR, the algorithm performs 4.2.5 GBR Processing in the Scheduling Algorithm.

The update is necessary to the remaining UL load source and remaining UL Iub bandwidth after sending the AG and RG to the UEs.

The NodeB does not send the non-serving RL RG DOWN command unless both of the following criteria are met:

l Experienced RTWP of the NodeB > target RTWP sent from the CRNC l Non-serving E-DCH to total E-DCH power ratio > Target Non-serving E-DCH to

Total E-DCH Power ratio sent from the CRNC

Target Non-serving E-DCH to Total E-DCH Power ratio can be set on the RNC LMT.

4.2.2 User Queuing in the Scheduling Algorithm Regardless of whether AG or RG is assigned, the users must be queued first. When the scheduling period arrives, and the NodeB receives the data or SI correctly, the scheduling algorithm puts the users who can correctly receive data or SI into a happy sequence or an unhappy sequence according to the happy bit carried on the E-DPCCH. During the queuing, the algorithm also considers the SPI, GBR, and current effective data rate of each user.

Queuing Happy Users Regardless of whether the requirements of the users for the GBRs are met, the algorithm queues all the happy users in descending order by Priorityn.

Priorityn = Reff/SPI

Where,

l Priorityn is the priority value of user n l SPI is assigned by the RNC, which is used to provide different scheduling opportunities

according to the scheduling priority. SPI and SPI (SPI weight) are the same as those used for HSDPA. For details, see QoS Management of Services Mapped on HSDPA. The smaller the SPI, the greater the value of Priorityn. During the scheduling, the rate of such a user is decreased before that of a user with a smaller Priorityn.

l Reff is calculated according to the formula described in Calculating the Effective Data Rate.

Queuing Unhappy Users When queuing unhappy users, the algorithm considers the effective data rate, SPI, and GBR satisfaction degree.

Firstly, for zero_grant users,

The algorithm arranges zero_grant users in descending order by Priorityn and puts them to the end of the unhappy sequence. Priorityn is calculated by using the following formula:




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Priorityn = 1/(SPI x Rreq)

Where,

l Priorityn is the priority value of user n. l SPI is assigned by the RNC, which is used to provide different scheduling opportunities

according to the scheduling priority. l Rreq is calculated according to the formula described in Calculating the Requested Data

Rate (Rreq).

Then, for non-zero_grant users,

l If the GBR Schedule Switch is set to ON, the algorithm queues the users according to the following principles: For the users whose requirements for the GBRs are not met, the algorithm arranges

them in descending order by Priorityn and puts them before the zero_grant users. Priorityn is calculated by using the following formula: Priorityn = Reff/(SPI x RGBR) RGBR is the GBR of the user.

For the users whose requirements for the GBRs are met, the algorithm arranges them in descending order by Priorityn and puts them before the users whose requirements for the GBRs are not met. Priorityn is calculated by using the following formula: Priorityn = Reff/SPI.

The rate of a user is decreased before that of a following user but increased after that of the following user.

l If the GBR Schedule Switch is OFF, the users are queued according to the following principles: For non-zero_grant users, the algorithm arranges them in descending order by Priorityn: Priorityn = Reff/SPI The rate of a user is decreased before that of a following user but increased after that of a following user.

Calculating the Effective Data Rate (Reff) Reff is the effective data rate, which is a filtered value of the successfully received data rate with a -filter:

Reff(n,k) = (1 - eff) x Reff(n, k - 1) + eff x R(n, k)

l (n, k) means user n and TTI k. l If the data is received correctly, R(n, k) is equal to the total size of all the MAC-es PDUs

(which are from the same MAC-e PDU) divided by the TTI length. l Otherwise, R(n, k) is equal to zero. Reff(n, 1) is an initial value and is zero. l eff is an effective rate smooth factor and is fixed to 0.6%.

Calculating the Requested Data Rate (Rreq) The NodeB must determine the requested data rate (Rreq) based on the available data amount obtained from TEBS in the UE buffer. The Rreq can not exceed the maximum data rate configured by the RNC and the power can not exceed the available power obtained from UE Power Headroom (UPH).



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The formula for calculating Rreq is as follows:

Rreq(n,k) = min(Rmax(UPH), argmax{R|Q(k) R x TTI}, Rsupport), where (n,k) means user n and TTI k.

1. Calculate Rmax(UPH).

a. Calculate (ed/c)2UPH according to UPH.

Assume that UPH = (ed/c)2UPH + (ec/c)2 + 1, where 1 stands for (c/c)2, the power of DPCCH. Because (ec/c)2 is known, (ed/c)2UPH can be obtained from the equation.

b. Calculate all (ed/c)2 for all E-TFCIs according to 3GPP.

1-1 Get the TB size for jth E-TFCI based on the TB table configured by the RNC. 1-2 Calculate the quantized ed,j for jth E-TFCI using the method presented in HSUPA Power Control. Here, harq is the HARQ power offset of the MAC-d flow carrying the logical channel with the ID of HLID. 1-3 j ++ ; If the value exceeds the range of the TB table, the process stops. Otherwise, return to 1-2.

c. Select Rmax(UPH).

The maximum (ed/c)2 is (ed/c)2UPH. From the TB table, select one E-TFCI whose (ed/c)2 is the most similar to but smaller than (ed/c)2UPH. Then, the TB size can be obtained. With the TTI attribute of the UE, the Rmax(UPH) is easy to obtain.

2. Calculate R, which acts as the TB size divided by the TTI length for each E-TFC. Argmax{R|Q(K) R x TTI} means finding a value R that is the maximum one and

meets the condition Q(k) R x TTI. Q(k) is the buffer size. According to the buffer size and the TTI attribute of the UE, the R restricted by Q(k) is obtained.

3. Calculate Rsupport. Rsupport = min{R (Maximum set of E-DPDCHs), R(E-DCH MBR)}

4.2.3 AG UP Processing in the Scheduling Algorithm After the serving E-DCH cell of the UE receives the SI of the UE, the NodeB calculates the requested rate. For a user in the unhappy sequence, the algorithm determines whether to assign AG UP to the user based on whether a request for the SI is received from the UE, whether the AGCH code is idle, and whether the Iub bandwidth and CE resource are available. If the conditions for sending AG UP are met, the algorithm calculates the grant that can be assigned to the user based on the requested rate, Iub bandwidth, and Uu bandwidth.

Conditions for Sending AG UP When the user meets all of the following conditions, the NodeB schedules this user through AG:

l The user is unhappy and the SI sent from the user is received. l The AGCH code allocated to the user is idle and not used by other users. l The user meets the requirement: SGIndexreq - SGIndexcur > AG Threshold.

SGIndexreq and SGIndexcur are obtained from Rreq and Rcur.




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Rcur is the current bit rate of the UE, which is calculated on the basis of the E-TFCI carried on the E-DPCCH. Rcur is equal to the MAC-e PDU size divided by the TTI length. The MAC-e PDU size can be obtained according to the E-TFCI.

Rreq is calculated according to the formula described in 4.2.2 User Queuing in the Scheduling Algorithm.

The AG threshold is adjusted dynamically according to the traffic volume at the service source. For details, see Dynamically Setting the AG Threshold.

l The rate of the user is not decreased because of MBR processing, Iub bandwidth limitation, and CE resource limitation.

l The user demodulates the data on the E-DPDCH correctly.

If the user meets all these conditions, the scheduling algorithm calculates the AG to be assigned to the user based on the Uu bandwidth and Iub bandwidth.

Dynamically Setting the AG Threshold When a non-zero_grant user sends an SI request, the NodeB can schedule the user through AG if SGIndexreq - SGIndexcur > AG Threshold.

Compared with RG, which increases or reduces the UE scheduling grant step by step, AG can perform a faster data rate. But if the AG threshold is too low, AG causes larger fluctuation of uplink load due to a large UE data rate change.

Dynamically setting AG threshold can avoid the disadvantage described above.

l When the traffic volume of a service source is small, the AG threshold is set to 3 so that the user can get enough resource to send data out as soon as possible. It helps to improve user experience with smaller latency.

l When the traffic volume of a service source is large, the AG threshold is set to 37 to avoid usage of AG, and instead RG can be used to provide a steady cell uplink load and a steady throughput for each user.

When an SI is received by NodeB, the scheduler checks a Flag to decide the AG threshold:

l If the Flag is TRUE, the AG threshold is 3, the scheduler assigns AG to this UE when SGIndexreq - SGIndexcur > AG Threshold.

l If the Flag is FALSE, AG threshold is 37 and only the RG can be used.

The scheduler in NodeB maintains the Flag for each user periodically. The Flag can be decided in the following ways:

l The initial value of the Flag is TRUE. The period is set to 500ms. l In the period, the Flag is set to FALSE when one of the following requirements is met:

If the total received data bit number is greater than 2 k bytes or the data rate is greater than 4 k byte/sec, AG will not be used except at the beginning of transmission.

If any TEBS in SI received in this period is greater than 20, which means 1658byte < TEBS 2202byte.

SI Transmission The SI is attached to the end of the MAC-e PDU and is used to notify the serving NodeB of the amount of system resources required by the UE.



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The SI is sent by the UE to the NodeB, as shown in the following figures.

Figure 4-2 SI transmission

Figure 4-3 SI structure

Where,

l UPH: UE Power Headroom, which indicates the ratio of the maximum UE transmission power to the corresponding DPCCH code power.

l TEBS: Total E-DCH Buffer Status, which identifies the total amount of data available across all logical channels (for which the reporting has been requested by the RRC) and indicates the amount of data in bytes available for transmission and retransmission at the RLC layer.

l HLBS: Highest priority Logical channel Buffer Status, which indicates the amount of data available from the logical channel identified by the HLID.

l HLID: Highest priority Logical channel ID, which identifies the highest-priority logical channel with available data.

The transmission of SI is initiated by the quantization of the transport block sizes that can be supported, or by the triggering conditions. For details, see 3GPP25.321.

The reporting of SI is triggered according to the SG after SG is updated. The triggering of a report is indicated to the E-TFC selection function at the first new transmission. This process may be delayed if the HARQ processes are occupied by retransmissions.

When the TEBS is not zero, the SI transmission can be triggered by the following conditions:

l Triggered by events At each TTI boundary, the UE checks the SG and the buffer status. If the SG has the value Zero_Grant or all processes are deactivated and the TEBS becomes greater than zero, then the SI transmission is triggered. If the serving E-DCH cell changes, the SI transmission is triggered. The change occurs, for example, when the RNC sends a reconfiguration message in response to a 1D event measurement report. In this case, a new serving E-DCH cell is indicated in the message and the new serving E-DCH cell is not in the previous serving E-DCH RLS.




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l Triggered periodically Triggered by the timer T_SIG (Timer Scheduling Information - not "Zero_Grant"), which can be configured on the RNC LMT through the parameter HSUPA schedule period with grant. Triggered by the timer T_SING (Timer Scheduling Information - "Zero_Grant"), which can be configured on the RNC LMT through the parameter HSUPA schedule period without grant.

If the HARQ process fails to deliver an MAC-e PDU that contains a triggered SI to the RLS that contains the serving cell, and the SI is transmitted together with higher-layer data multiplexed into the same MAC-e PDU, the transmission of a new SI is triggered.

If the SI transmission is not triggered under the previous condition, but the size of the data plus the header is smaller than or equal to the TB size of the UE-selected E-TFC minus 18 bits, the SI is concatenated into this MAC-e PDU. In this case, however, no new SI is triggered if the HARQ process fails to deliver the MAC-e PDU.

For details of SI triggering, see 3GPP 25.321.

4.2.4 RG UP Processing in the Scheduling Algorithm This part describes the conditions necessary for the algorithm to send the RG UP to the users.

l The user is unhappy. l The user does not meet the conditions for sending AG UP. l The rate of the user is not decreased because of MBR processing, Iub bandwidth

limitation, and CE resource limitation. l The user demodulates the data on the E-DPDCH correctly.

If all these conditions are met and both the Uu bandwidth and the Iub bandwidth allow an increase in the user rate, the algorithm sends RG UP to the user.

4.2.5 GBR Processing in the Scheduling Algorithm If a UE is configured with the GBR by the RNC and the GBR Schedule Switch parameter is set to TRUE (OPEN), the scheduling algorithm should compare the effective data rate with the GBR and decide whether the GBR is met.

GBR is transmitted from RNC to NodeB:

l If the RAB ASSIGNMENT REQUEST message from the CN carries the GBR when the RAB is set up, the GBR is sent to the NodeB.

l Otherwise, the GBR configured on the RNC LMT is sent to the NodeB when the RAB is carried on HSUPA. The GBR can be configured for each user priority (gold, silver, or copper) through the SET USERGBR command on the RNC LMT.

GBR processing is as follows:

l If the load on the Uu interface exceeds the value of Maximum Target Uplink Load Factor, the algorithm does not send AG UP or RG UP to those users whose requirements for the GBRs are already met.

l If the load on the Uu interface exceeds the value of Maximum Target Uplink Load Factor but does not exceed the load congestion threshold, the algorithm meets the requirements of the users for the GBRs.



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l If the load on the Uu interface exceeds the load congestion threshold, the algorithm does not meet the requirements of the users for the GBRs.

When the user meets the conditions for sending AG UP,

l If Rreq is smaller than the GBR, only Rreq needs to be assigned to the user. l If Rreq is larger than the GBR,

If the estimated load does not exceed the load congestion threshold after the GBR is reached, at least the GBR is assigned to the user.

Otherwise, the algorithm calculates the maximum grant that can be assigned to the user according to the load congestion threshold.

When the user does not meet the conditions for sending AG UP but meets the conditions for sending RG UP,

l If the estimated load does not exceed the load congestion threshold after RG UP is sent, RG UP is sent to the user.

l Otherwise, RG UP is not sent to the user.

The load congestion threshold is 0.95. If the estimated load does not exceed the load congestion threshold, neither the serving RLS nor the non-serving RL will send RG DOWN to those users whose Reff is smaller than the GBR.

In addition, no matter whether the requirement for the GBR can be met, the grant assigned to the user can not cause the throughput of the user to exceed the bandwidth available for the HSUPA users in the NodeB.

4.2.6 MBR Processing in the Scheduling Algorithm At each TTI, if both Rcur and Ravg of a user are greater than the E-DCH MBR, RG DOWN is sent to this user.

The E-DCH MBR is transmitted by RNC to NodeB through the signaling. For detailed information, see 3GPP 25.433 9.2.2.13T.

Ravg is the average data rate of the UE, which is a smoothed value of Rcur with an filter.

Ravg(n, k) = (1 - avg) x Ravg(n, k - 1) + avg x Rcur(n, k)

l (n, k) indicates user n and TTI k. l avg is an Average Rate Smooth Factor, which is an coefficient. l Ravg(n,1) is an Average Rate Initial Value, which is used at the beginning. l Rcur(n, k) is the current bit rate of the UE, which is calculated on the basis of the E-TFCI

carried on the E-DPCCH.

Rcur is equal to the MAC-e PDU size divided by the TTI length. The MAC-e PDU size can be obtained according to the E-TFCI.

Average Rate Initial Value is set to 0 kbit/s and avg is set to 0.6%. Thus, the smoothing time is 1.6s, about 10 times the period of fast fading that occurs during 3 km/h movement. The purpose is to reflect the impact of the channel fading and to smooth it.




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4.3 HSUPA Flow Control 4.3.1 Overview of HSUPA Flow Control

Flow control is implemented to reduce delay and packet loss rate, to maximize uplink throughput, and to achieve better use of the Iub bandwidth.

l The uplink throughput of a UE on the Uu interface may vary in a wide range. HSUPA UEs would share Iub resources in a more flexible way than R99 UEs.

l If the uplink throughput on the Uu interface is continuously wider than the Iub bandwidth, the data stored in the Iub buffer will be continuously increased. Without flow control, a higher delay or packet loss rate may be incurred.

l When the Iub bandwidth becomes the bottleneck of uplink data transmission, the delay must be kept within the given range and packet loss must be minimized, thus maximizing the uplink throughput and achieving better use of the Iub bandwidth.

Principles of Flow Control The data rate on the Uu interface is restricted only by the UE capability and the grant given by the MAC-e scheduler. Meanwhile, the flow control algorithm needs to maintain the throughput from the Uu interface, which is the input throughput of the Iub interface under the maximum rate allowed by the Iub bandwidth. Therefore, the flow control algorithm restricts the throughput on the Uu interface only by affecting the grant given by the scheduler.

Figure 4-4 Principles of flow control

To control the packet loss and the delay on the Iub interface, the flow control algorithm performs the following functions:

l Adjusts the maximum available bandwidth of Iub port according to the congestion state of the transport network. This prevents large amounts of data from being discarded when data convergence causes congestion in the transport network.

l Adjusts the available bandwidth of HSUPA according to the change trend of the Iub buffer, and informs the scheduler of controlling the total traffic volume of HSUPA UEs according to their available bandwidth.

l Controls the Iub buffer usage to ensure that the buffer-caused delay is within the allowed range without any packet loss.

The functional modules of the flow control algorithm are shown in the following figure.



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Figure 4-5 Functional Modules of Flow Control Algorithm

l Scheduling Module: allocates grants to the UEs according to the Uu load resources and the available bandwidth of the HSUPA users.

l Flow Control Module: adjusts the available bandwidth of every HSUPA user according to the reported change trend of the buffer usage and the maximum available bandwidth, and provides the buffer congestion state of Iub port according to the buffer use.

l Transport Network Congestion Control Module: detects the congestion state of the transport network and adjusts the maximum available bandwidth of Iub port accordingly.

l Buffer Usage Reporting Module: reports the buffer use of Iub port.

The detailed functions of each module are described in the following sections.

l 4.3.2 Adjusting the Maximum Available Bandwidth of the Iub Port l 4.3.3 Adjusting the Available Bandwidth of HSUPA l 4.3.4 Handling Iub Buffer Congestion

4.3.2 Adjusting the Maximum Available Bandwidth of the Iub Port

In the case of network convergence or hub NodeB, the bandwidth configured for the NodeB can be greatly wider than the resource available in the transport network. The HSUPA flow control algorithm automatically adjusts the maximum available bandwidth of the Iub port based on the congestion state of the transport network. ATM transport is different from IP transport; therefore, two different algorithms are provided.

Algorithm for ATM Transport The RNC side detects the delay and loss of the FP frame in each MAC-d flow by using the FSN and CFN in the FP frame. Then, the RNC side sends a congestion indication to notify the NodeB of the congestion state when the MAC-d flow is transmitted on the Iub interface, as shown in the following figure.




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Figure 4-6 Procedure of TNL congestion indication

Where the Congestion Status indicates whether there is transport network congestion. Its value range is described as follows:

l 0: no TNL congestion l 1: reserved for future use l 2: TNL Congestion detected by delay build-up l 3: TNL Congestion detected by frame loss

When the period for adjusting the maximum available bandwidt

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