Huawei 2008 W-CDMA (UMTS) HSDPA RRM and parameters -- how to make HSDPA work better (very good)
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Transcript of Huawei 2008 W-CDMA (UMTS) HSDPA RRM and parameters -- how to make HSDPA work better (very good)
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HSDPA RRM and
Parameters
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Page1Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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Mapping signaling and traffic
onto HSDPA! UMTS network could provide multi-services such as CS service, PS service and signaling
! In most case, CS service with high requirement of transmission quality will be mapped
onto DCH
! PS service such as PS conversational service i.e. VOIP, streaming service, BE service and
signaling ) could be mapped onto HS-DSCH
! The following figure show mapping between service and bearer
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Mapping signaling and traffic
onto HSDPA! PS conversational services may be mapped onto the DCH, HS-DSCH, or E-DCH
! If Voip channel type = DCH
" Both uplink and downlink are mapped onto DCH
! If Voip channel type = HSDPA
" Uplink is beared on DCH, downlink mapped onto HS-DSCH
! If Voip channel type = HSPA
" Uplink is beared on E-DCH, downlink mapped onto HS-DSCH
VoipChlType --- UL_DCH / DL_DCH, UL_DCH / DL_HS-PDSCH, UL_EDCH / DL_HSP-DSCH
MML: SET FRCCHLTYPEPARA
For Ps conversational service
VoIP stands for Voice over IP, a PS conversational service. It uses IP data packets
to encapsulate voice data and transports them on the IP network to
implement the conversational services.
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Mapping signaling and traffic
onto HSDPA! During the setup of an RRC connection, the single SRB can be carried on the
CCH, DCH, HS-DSCH, or E-DCH
! If the selected channel type is FACH, the SRB is carried on the CCH in both
the uplink and the downlink
! If the selected channel type is DCH, then
" In the downlink, if Srb channel type RRC effect flag is set to TRUE and Srb
channel type is set to HSDPA or HSPA, the SRB is carried on the HS-DSCH;
otherwise, on the DCH
" In the uplink, if Srb channel type RRC effect flag is set to TRUE and Srb
channel type is set to HSPA, the SRB is carried on the E-DCH; otherwise, on the
DCH
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Mapping signaling and traffic
onto HSDPA! SRB may be mapped onto the DCH, HS-DSCH, or E-DCH, RACH/FACH
!If SRB channel type = DCH
" Both uplink and downlink are mapped onto DCH
! If SRB channel type = HSDPA
" Uplink is mapped on DCH, downlink mapped onto HS-DSCH
! If SRB channel type = HSPA
" Uplink is mapped on E-DCH, downlink mapped onto HS-DSCH
Bandwidth allocation
Bearer types for SRB
SigChType --- FACH ,DCH-3.4kbps-signaling, DCH-
13.6kbps-signaling, DCH-27.2kbps-signaling
SrbChlType --- UL_DCH / DL_DCH, UL_DCH / DL_HS-
PDSCH, UL_EDCH / DL_HS-PDSCH
MML: SET FRCCHLTYPEPARA
MML: SET RRCESTCAUSE
! With SRB over HSPA, call setup delay is reduced, moreover compared with SRB
over DCH , code resource is saved
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Mapping signaling and traffic
onto HSDPA! During the setup of an RRC connection, the single SRB can be carried on the CCH, DCH,
HS-DSCH, or E-DCH
! If the selected channel type is FACH, the SRB is carried on the CCH in both the uplink and
the downlink
! If the selected channel type is DCH, then
" In the downlink, if Srb channel type RRC effect flag is set to TRUE and Srb
channel type is set to HSDPA or HSPA, the SRB is carried on the HS-DSCH; otherwise,
on the DCH
" In the uplink, if Srb channel type RRC effect flag is set to TRUE and Srb channel
type is set to HSPA, the SRB is carried on the E-DCH; otherwise, on the DCH
Bearer types for SRB SrbChlTypeRrcEffectFlag --- TURE, FALSE MML: SET FRCCHLTYPEPARA
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Mapping signaling and traffic onto
HSDPA! PS streaming services can be mapped onto the DCH, HS-DSCH, or E-DCH
" The cell supports HSDPA
" PS_STREAMING_ON_HSDPA_SWITCH is selected
" If the maximum DL service rate is higher than or equal to DL streaming traffic
threshold on HSDPA
then PS streaming service is carried on the HS-DSCH. Otherwise, it is carried on the DCH
PS_STREAMING_ON_HSDPA_SWITCH --- Enable , DisableAlgorithm switch
for streaming
over HSPA
UlStrThsOnHsupa --- 8, 16, 32, 64, 128, 144, 256, 384kbps
Bit rate threshold
for streaming
over HSPA
PS_STREAMING_ON_E_DCH_SWITCH --- Enable , Disable
DlStrThsOnHsdpa --- 8, 16, 32, 64, 128, 144, 256, 384kbps MML: SET FRCCHLTYPEPARA
MML: SET CORRMALGOSWITCH
PS streaming services can be mapped onto the DCH, HS-DSCH, or E-DCH
" If the maximum UL service rate is higher than or equal to UL streaming
traffic threshold on HSUPA
" The cell supports HSUPA
" PS_STREAMING_ON_E_DCH_SWITCH is selected
then the service is carried on the E-DCH. Otherwise, the service is carried on the DCH
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Mapping signaling and traffic
onto HSDPA! The IMS signaling can be mapped on the DCH, HS-DSCH, or E-DCH
! If IMS channel type = DCH
" Both uplink and downlink are mapped on DCH
! If IMS channel type = HSDPA
" Uplink is mapped on DCH, downlink mapped on HS-DSCH
! If IMS channel type = HSPA
" Uplink is mapped onto E-DCH, downlink mapped on HS-DSCH
Bearer types for IMS
signaling
ImsChlType --- UL_DCH / DL_DCH, UL_DCH / DL_HS-
PDSCH, UL_EDCH / DL_HS-PDSCH
MML: SET FRCCHLTYPEPARA
IMS signaling (SIP SDP) is an PS RAB to UTRAN, and only setup on DCH and use the fixed
configuration before RAN10.0
SIP / SDP characteristics based on Huawei research
- The traffic in the SIP/SDP setup phase is about 70Kbits and the setup time is generally less
than 3s, therefore, mean bit rate is 23.3Kbps
- Very low traffic exists on SIP / SDP after connection establishment
It is more suitable for HSPA to bear IMS Signaling
UTRAN PS
Domain
IMS PS
Domain
UTRAN
)
UE UTRAN PS
Domain
IMS PS
Domain
UTRAN
Session control Signaling (SIP / SDP)
Media ( RTP)
UE
Real Time Media Control (RTCP)
UE UE
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Mapping signaling and traffic
onto HSDPA! PS interactive and background services (i.e. BE service) can be mapped onto the
CCH, DCH, HS-DSCH, or E-DCH
" Low-rate PS services have relatively small amount of data. Therefore, such PS
services can be carried on the CCH to save radio resources
# If the maximum DL service rate is lower than DL BE traffic DCH decision threshold, the
maximum UL service rate is lower than UL BE traffic DCH decision threshold, and the RRC
connection is set up on the CCH, then the service is carried on the CCH.
" Otherwise, further decision need to be made as follows:
# If the maximum DL service rate is higher than or equal to DL BE traffic threshold on HSDPA,
then the service is carried on the HS-DSCH. Otherwise, the service is carried on the DCH
# If the maximum UL service rate is higher than or equal to UL BE traffic threshold on HSUPA,
then the service is carried on the E-DCH. Otherwise, the service is carried on the DCH
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Mapping signaling and traffic
onto HSDPA
DL BE traffic threshold on HSDPA --- 8, 16, 32, 64, 128,
144, 256, 384, 768, 1024, 1536, 1800, 2048, 3648, 7200,
10100, 14400kbps
UL BE traffic DCH decision threshold --- 8, 16kbps
Bit rate
threshold for BE
service over
HSPA
UL BE traffic threshold on HSUPA --- 8, 16, 32, 64, 128,
144, 256, 384, 608, 1450, 2048,2890, 5760kbps
DL BE traffic DCH decision threshold --- 8, 16kbps MML: SET FRCCHLTYPEPARA
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Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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HSDPA Code Resource Allocation
! The codes of the HS-PDSCH can be allocated in three ways:
" Static HSDPA code allocation
# In static allocation, the RNC reserves codes for the HS-PDSCH
# The DPCH, HS-SCCH, and common channels use the remaining codes
" RNC-controlled dynamic allocation
# In RNC-controlled dynamic allocation, the RNC adjusts the reserved HS-PDSCH
codes according to the real-time usage status of the codes
" NodeB-controlled dynamic allocation
# NodeB-controlled dynamic allocation allows the NodeB to use the HS-PDSCH
codes allocated by the RNC
# The NodeB can dynamically allocate the idle codes of the current cell to the HS-
PDSCH
! The channelization codes are constant resources consisting of the following three parts:
" channelization codes for HS-PDSCH
" channelization codes for Common channels and HS-SCCH
" channelization codes for DPCH
! The resources are reserved for the common channels and the HS-SCCH. The parameter of
the codes reserved for the HS-SCCH can be configured on the RNC LMT.
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HSDPA Code Resource Allocation
!Static HSDPA Code Allocation
"Static HS-PDSCH code allocation
# Spreading factor =16
# Allocate continuously
"Static HS-SCCH code allocation
# Spreading factor =128
# Allocate with common channel
PS_STREAMING_ON_HSDPA_SWITCH --- 1~15
Allocate Code Mode --- Manual, Automatic
Code Resource
Allocation Parameters
Code Number for HS-SCCH --- 1~15 MML: ADD CELLHSDPA
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HSDPA Code Resource Allocation
!RNC-controlled dynamic allocation
"In the RNC-controlled dynamic allocation, the RNC adjusts the reserved HS-
PDSCH codes according to the real-time usage status of the codes
"Min. number of codes, defined by the code min number for HS-PDSCH
parameter, are reserved for HS-PDSCH in a cell
Code Max Number for HS-PDSCH--- 1~15
MML: ADD CELLHSDPACode Min Number for HS-PDSCH --- 1~15 Code Resource
Allocation Parameters
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HSDPA Code Resource Allocation
! When R99 code consumption is reduced, RNC increases the codes reserved
for HSDPA if following conditions are met
" the shared code neighboring to the codes reserved for HS-PDSCH is idle
" At least another free code that reserved for R99 handover users. This idle code SF is
equal or less than cell LDR SF reserved threshold
* the solid dots represent the occupied codes and the circles represent the idle codes
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HSDPA Code Resource Allocation
!When the re-allocation of R99 code resource is trigger by some voice calls coming
!RNC re-allocates one shared code from HS-PDSCH to R99 if the rest idle code SF is
greater than Cell LDR SF reserved threshold
* the solid dots represent the occupied codes and the circles represent the idle codes
MML: ADD CELLLDRCell LDR SF reserved threshold --- SF8, SF16,
SF32, SF64, SF128, SF256
Code Resource
Allocation Parameters
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HSDPA Code Resource Allocation
! NodeB-controlled dynamic allocation
" NodeB-controlled dynamic allocation allows the NodeB to use the HS-PDSCH
codes that are allocated by the RNC. The NodeB can dynamically allocate the
idle codes of the current cell to the HS-PDSCH channel
" The NodeB periodically detects the SF16 codes apart from the RNC-allocated
HS-PDSCH codes every 2 ms. If the codes or sub-codes are allocated by the
RNC to the DCH or common channels, they are identified as occupied.
Otherwise, they are identified as unoccupied. Therefore, the HS-PDSCH codes
available for the HS-PDSCH channel include the codes allocated by the RNC
and those consecutive and unoccupied SF16 codes
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HSDPA Code Resource Allocation
! NodeB-controlled dynamic allocation
" For example, if the RNC allocates five codes to the NodeB, that is, No.11 to 15
SF16 codes are allocated to the HS-PDSCH. Suppose in a 2 ms TTI, No. 0 to 5
SF16 codes are allocated to the DCH and common channels. No. 0 to 5 SF16
codes are occupied. Therefore, in the current TTI, the HS-PDSCH can use No. 6
to 15 SF16 codes
" If the DCH codes allocated by the RNC are temporarily occupied by the HS-
PDSCH during the setup of radio links, the NBAP message returned to the RNC
indicates that the radio link is set up successfully. From the next 2 ms TTI, the
HS-PDSCH no longer uses these codes until they are released from the DCH
MML: SET MACHSPARADynamic codes switch--- OPEN, CLOSECode Resource Allocation
Parameters
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Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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HSDPA Power Allocation
! HS-PDSCH and HS-SCCH shared power with R99 channels
! The downlink power consists of the following parts
" Power for common channel
" Power for DPCH
" Power for DL HSDPA channel, such as HS-PDSCH, HS-SCCH
" A configurable margin is used to keep the system in stable status
Power Margin --- [0~100%]
MML: ADD CELLHSDPAThe Offset of HSPA Total Power --- [-5dB~0dB]Power Resource
Allocation Parameters
Max Power per H user --- [1%~100%]
MML: SET MACHSPARA
! The cell total transmit power is the constant resources. The DL power consists of the
following three parts:
" Power of the HSPA DL physical channel (HS-PDSCH, HS-SCCH, E-AGCH, E-RGCH and
E-HICH)
" Common channel power
" DPCH power
Time
Allowed power for HSDPA
Total Power
DPCH
Power for CCH
Higher power
utility
efficiency
Time
Power margin for DCH
power control
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HSDPA Power Control! HS-DPCCH Power Control
" Power Offset of ACK, NACK and CQI (Non SHO & SHO)
# There is no separate power control for HS-DPCCH but setting several power offsets between
HS-DPCCH and UL associated DPCCH, namely ACK, NACK, CQI
The CQI feedback in the uplink is determined by the following parameters:
! CQI_Repetition_Factor
! CQI_Power_Offset
! CQI_feedback_cycle
CQI_feedback_cycle refers to the cycle of UE providing CQI feedback. In each cycle, the CQI
is repeatedly sent within the CQI_Repetition_Factor consecutive subframes which is
equal to 1 frame
In each subframe, the CQI transmission power is equal to the associated UL DPCCH power plus
the CQI power offset
The NACK/ACK feedback in the uplink is determined by the following parameters:
! ACK-NACK_Repetition_Factor
! ACK/NACK_poweroffset
! HS-DPCCH_Preamble_Transmission_Indication
At the end of about 19,200 chips (i.e.5ms) after the UE receives HS-PDSCH subframes in the
downlink, the UE provides HARQ NACK or ACK feedback in the uplink within ACK-
NACK_Repetition_Factor consecutive HS-DPCCH subframes.
The transmit power of the UE is equal to the associated UL DPCCH transmit power plus the
ACK_Poweroffset or NACK_Poweroffset, for NACK or ACK feedback respectively
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Several power offsets are set between the HS-DPCCH and the associated UL DPCCH. When
ACK/NACK and CQI are carried on the HS-DPCCH, their power offsets, that is, ACK,
NACK, and CQI, are set in one HS-DPCCH TTI
The transmit power of the HS-DPCCH is calculated with the following formula:
where
PUL DPCCH is the transmit power of the associated UL DPCCH
For the first slot of a TTI, HS-DPCCH means ACK when the UE responds with ACK or means
NACK when the UE responds with NACK.
For the second and third slots of a TTI, HS-DPCCH means CQI.
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HSDPA Power Control
! HS-DPCCH Power Control
" In soft handover area, the UL combining gain reduces the necessary transmission power
of UL DPCCH. While HS-DPCCH does not has the UL combining gain, to maintain the
receiving quality of the HS-DPCCH, higher power offset is needed. Thus, when UE enters or
leaves the soft handover area, the power offset for ACK/NACK and CQI may have a change
correspondingly
CQI Power Offset --- 5/15, 6/15, 8/15, 9/15, 12/15, 15/15, 19/15, 24/15, 30/15CQI Power Offset multi-RLS --- 5/15, 6/15, 8/15, 9/15, 12/15, 15/15, 19/15, 24/15, 30/15
Parameters for CQI
power offset
NACK poweroffset1 / ACK poweroffset2 / ACK poweroffset3 --- 5/15, 6/15, 8/15, 9/15, 12/15, 15/15, 19/15, 24/15, 30/15NACK poweroffset1 multi-RLS / ACK poweroffset2 multi-RLS / ACK poweroffset3 multi-RLS --- 5/15, 6/15, 8/15, 9/15, 12/15, 15/15, 19/15, 24/15, 30/15
Parameters for
NACK power offset
MML:ADD CELLHSDPCCH
ACK poweroffset1 / ACK poweroffset2 / ACK poweroffset3 --- 5/15, 6/15, 8/15, 9/15, 12/15, 15/15, 19/15, 24/15, 30/15ACK poweroffset1 multi-RLS / ACK poweroffset2 multi-RLS / ACK poweroffset3 multi-RLS --- 5/15, 6/15, 8/15, 9/15, 12/15, 15/15, 19/15, 24/15, 30/15
Parameters for
ACK power offset
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HSDPA Power Control
!HS-SCCH Power Control
"Fixed Power
# Set fixed power for each HS-SCCH by O&M
# Simple to configuration, but low utilization of the power
"Based on CQI
# If the HS-SCCH Power Control Method parameter is set to CQI, the NodeB adjust the
transmission power of HS-SCCH, depending on the following information
– CQI reported by UE
– DTX detected by NodeB
– Target frame error rate ( FER ) of HS-SCCH
HS-SCCH FER --- 1‰~999 1‰
HS-SCCH Power --- -10 dB to 10 dB
MML: SET MACHSPARAHS-SCCH Power Control Method --- FIXED, CQIHS-SCCCH power
control parameters
The process of power control adjustment within an adjustment period is as follows:
1 NodeB acquires the PHS-SCCH,init, PHS-SCCH,min and PHS-SCCH,max according to
the reported CQI
1 PHS-SCCH,init is the initial HS-SCCH transmit power, which is an offset relative to
the P-CPICH transmit power
2 PHS-SCCH,min is the minimum HS-SCCH transmit power, which is an offset relative
to the P-CPICH transmit power. PHS-SCCH,min is set to -10 dB
3 PHS-SCCH,max is the maximum HS-SCCH transmit power, which is an offset relative
to the P-CPICH transmit power
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2 NodeB calculates the HS-SCCH power for the Nth scheduling period by using the
following formula:
PHS-SCCH(n) = FUNC(PHS-SCCH(n-1), CQI(n-1), CQI(n), NDTX, Cpc, FERT, Sbase, Smax,u)
where:
Cpc is the HS-SCCH power adjustment period, indicating the number of transmitted HS-
SCCH frames. After the period, the power adjustment is performed at once. Cpc is set to
3 TTI.
Sbase is the step of power adjustment within an HS-SCCH power adjustment period. Sbase
is set to 0.02 dB.
Smax,u is the maximum allowed power step-up within a power adjustment period. Smax,u
is set to 0.5 dB.
NDTX is the number of DTXs.
FERT represents HS-SCCH FER and can be set on the NodeB LMT
3 NodeB limits the HS-SCCH power for the Nth schedule time by PHS-SCCH,min and
PHS-SCCH,min . That is, limit the HS-SCCH power in the range [PHS-SCCH,min , PHS-
SCCH,min]
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HSDPA Power Control
! HS-PDSCH Power Control
" Power is allocated in NodeB, Mac-hs allocates HS-PDSCH power for different
HSDPA users with scheduling algorithm
" When configured by static HSDPA power allocation algorithm, the total power of
HS-PDSCH and HS-SCCH shall not exceed the maximum transmission power
" When configuredby dynamic HSDPA power allocation algorithm, the maximum
transmission power is the remaining power excluding R99 power and power
margin
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HSDPA Power Control
! The initial transmit power of the downlink F-DPCH, PF-DPCH,Initial is calculated with the
following formula:
! To prevent waste of downlink power while adding a new radio link to the active set,
a power adjustment for the new radio link is used. Based on the calculation used for
calculating the initial transmit power of the F-DPCH, the power of the new radio link
is decreased by a power offset, which is 15 dB. This parameter is only available when
the branch parameter DOWNLINK_POWER_BALANCE_SWITCH is set to ON
where:
! PCPICH is the P-CPICH transmit power in a cell. It is defined by the PCPICH transmit
power parameter
! (Ec/No)CPICH is the ratio of received energy per chip to noise spectral density of CPICH
received by the UE
! is the orthogonality factor in the downlink. Orthogonal codes are employed in the
downlink to separate the physical channels, and without any multi-path propagation, the
orthogonality remains when the NodeB signal is received by the UE. If there is sufficient
delay spread in the radio channel, part of the NodeB signals will be regarded as multiple
access interference by the UE. The orthogonality of 0 corresponds to perfectly orthogonal
users. In the Huawei implementation, is set to 0.
! Ptotal is the downlink transmitted carrier power measured at the NodeB. This power is
reported to the RNC.
! (Ec/N0)F-DPCH is the Ec/No required for the TPC symbol error rate of the F-DPCH stipulated
by the protocol, that is, a symbol error rate of 4%. This Ec/No is set to -17 dB.
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HSDPA Power Control
!Downlink open loop power control on F-DPCH
"The maximum and minimum values of the transmit power range of
downlink F-DPCH is calculated with the following formulas:.
# Maximum transmit power value = PCPICH + FDPCH maximum reference power +
F-DPCH Power Offset
# Minimum transmit power value = PCPICH + FDPCH minimum reference power +
F-DPCH Power Offset
Soft handover initial power offset --- 0dB ~ 25dB
FDPCH minimum reference power --- -35dB ~ 15dB
MML: SET FDPCHRLPWRFDPCH maximum reference power --- -35dB ~ 15dB F-DPCH initial
transmission power
parameters
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Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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HSDPA Mobility Management
! HSDPA connection
" One HSDPA user has up to one HSDPA connection with network at the
same time
" HSDPA connection HO means HO caused by moving
! DPCH connection
" DPCH connection has same function as R99 HO, Containing SHO, HHO
and inter-RAT HO
! Both HSDPA connection and DPCH connection HO are based on UE
measurement report and other information, and they are controlled by
UTRAN side
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Intra-frequency Handover of HSDPA
before handover after handover
Cell 2(HSDPA)Cell 1(HSDPA) Cell 2(HSDPA)Cell 1(HSDPA)
The 1D event is triggered by
cell 2
Cell 2(R99)Cell 1(HSDPA) Cell 2(R99)Cell 1(HSDPA)
before handover after handover
Cell 2(R99)Cell 1(HSDPA) Cell 2(R99)Cell 1(HSDPA)
before handover after handover
Soft handover
The 1B (remove) is triggered
by HSDPA cell
Soft handover
HSDPA cell is added into active set
The 1D event is triggered by HSDPA
cell
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Intra-frequency Handover of HSDPA
MML: SET HOCOMMThe timer length of D2H Intra-handover --- 0s ~ 999s Parameter
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! If all the cells in the active set support the F-DPCH after the active set is updated and the
SRB is carried on the DCH, the SRBD2HHoTimer starts. After this timer expires, the RNC
decides whether to switch the SRB to the HS-DSCH
! After the UE is handed over to an HSDPA cell from an R99 cell, the D2HRetryTimer
starts. After this timer expires, the RNC decides whether to switch the SRB to the HS-DSCH
and whether to set up the F-DPCH. D2HRetryTimer is set through The timer length of
D2H Inter-freq handover and The timer length of D2H Intra-freq handover
Handover Between a Cell Supporting the
F-DPCH and a Cell Not Supporting the F-DPCH
MML: SET HOCOMMThe timer length of Srb Over Hspa Retry Delay[100ms] --- 0s ~ 60s
Parameter
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Inter-frequency Handover of HSDPA
! Inter-frequency handover can be triggered on the basis of coverage, load, and
Hierarchical Cell Structure (HCS).
!The introduction of HSDPA does not affect the triggering conditions and
decisions of these types of inter-frequency handover
Inter-Frequency Handover Between HSDPA Cells The UE moves from one HSDPA cell to another HSDPA cell.Event 2B is triggered
Scenario 3
Inter-Frequency Handover from an R99 Cell to an HSDPA CellThe UE moves from a non-HSDPA cell to an HSDPA cell.Event 2B is triggered
Scenario 2
Inter-Frequency Handover from an HSDPA Cell to an R99 Cell The UE moves from an HSDPA cell to a non-HSDPA cell.Event 2B is triggered
Scenario 1
DescriptionScenario
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Inter-frequency Handover of HSDPA
before handover after handover
Cell 2(HSDPA)Cell 1(HSDPA) Cell 2(HSDPA)Cell 1(HSDPA)
Inter-frequency handover
2B is triggered by HSDPA
cell (cell2)
Cell 2(R99)Cell 1(HSDPA) Cell 2(R99)Cell 1(HSDPA)
before handover after handover
Inter-frequency handover
2B is triggered by R99 cell Inter-frequency handover
The 2B event is triggered by
HSDPA cell
Cell 2(R99)Cell 1(HSDPA) Cell 2(R99)Cell 1(HSDPA)
before handover after handover
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Inter-frequency Handover of HSDPA
The timer length of D2H Inter-handover--- 0s ~ 999s MML: SET HOCOMMParameter
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Inter-RAT Handover of HSDPA
! The introduction of HSDPA does not affect the inter-RAT handover algorithms.
! The switch CM permission ind on HSDPA decides whether the Compressed
Mode (CM) can be used on HSDPA. For detailed information about the switch, see
Inter-Frequency Handover of HSDPA
! When the UE handover to a cell supporting the F-DPCH from another system and
a UL or DL event 4A is reported, the RNC decides whether to change the bearing
mode of TRB and SRB.
! If the TPC command is carried on the F-DPCH between the UE and the UTRAN, the
SRB and the TRB are carried on the HS-DSCH. If a cell not supporting the F-DPCH
is added to the active set, all the F-DPCHs are deleted. In addition, new DPCHs
between the UE and all the cells in the active set are set up to carry the SRB and
TPC commands. In this case, the TRB is still carried on the HS-DSCH.
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Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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HSDPA Channel Switching
!With introducing HSDPA technology, the UE has one more RRC state
CELL_DCH (with HS-DSCH)
CELL_PCH CELL_FACH
CELL_DCH
CELL_DCH(with HS-DSCH)
HS-DSCH FACHCell-DCH ( with HS-DSCH ) Cell-FACH
HS-DSCH DCHCell-DCH ( with HS-DSCH ) Cell-DCH
Channel SwitchingUE State Transition
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HSDPA Channel Switching
" Channel Switching between HS-DSCH and DCH
# Channel Switch from HS-DSCH to DCH
– Mobility
# Channel Switch from DCH to HS-DSCH
– Mobility
– Timer (H Retry Timer)
– Traffic Volume
~ The UE is rejected by the admission control algorithm when it attempts to access
an HSDPA cell. If the activity of the UE that performs data services increases and
the RNC receives an event 4A report, the RAN tries to hand over the UE from the
DCH to the HS-DSCH
– Channel switching from DCH to HS-DSCH needs to implement the process of
HSDPA directed retry
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HSDPA Channel Switching
MML:SET COIFTIMER H Retry Timer Length --- 0 ( disable ), 1 180s
MML: SET CORRMALGOSWITCH
PS _Non_ BE _ State_ Trans _Switch --- Enable , Disable
PS _ BE _ State_ Trans _Switch --- Enable , Disable
HSDPA_ State_ Trans _Switch --- Enable , DisableParameters
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HSDPA Channel Switching
! Channel Switching between HS-DSCH and FACH
" Since the HSDPA UE occupies the DPCH, the RAN will switch the transport
channel from HS-DSCH to FACH to reduce occupation of the DPCH when
the following conditions are met
# The HS-DSCH carries the BE service for the UE
# There is a few data flow of any of the services for a certain length of time
" By contrary, if data service activity increased, for example, when the RNC
receives a 4A event measuring report ,state transfer is triggered for Cell-
FACH to Cell-DCH ( with HS-DSCH )
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HSDPA Channel Switching
Realtime Traff DCH Or HSPA To FACH Transition Timer --- 1s~65535s
BE HS-DSCH To FACH 4b Pending Time After Trigger --- 250, 500, 1000, 2000, 4000, 8000, 16000ms
BE HS-DSCH To FACH 4b Time To Trigger --- 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000ms
BE HS-DSCH to FACH 4B threshold --- 8 16 32 64128 256 512 1024 2k 3k 4k 6k 8k 12k16k 24k 32k 48k 64k 96k 128k 192k
256k 384k 512k 768kbytes
MML:SET UESTATETRANSBE HS-DSCH to FACH Transition Timer --- 1s~65535s
Realtime Traff DCH Or HSPA To FACH 4b Pending Time --- 250, 500, 1000, 2000, 4000, 8000, 16000 ms
Realtime Traff DCH Or HSPA To FACH 4b Time To trigger --- 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000ms
Realtime Traff DCH Or HSPA To FACH 4b Threshold ---8 16 32 64 128 256 512 1024 2k 3k 4k
6k 8k 12k 16k 24k 32k 48k 64k 96k128k 192k 256k 384k 512k 768kbytes
Parameters
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Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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HSDPA Qos Management
! QoS Requirements of Different Services
" IMS / SRB
" Voice over IP (Conversational Service)
" Streaming Service
" BE Service
! QoS Parameters Mapped onto the MAC-hs Layer of the NodeB
" MAC-hs Discard timer
" Scheduling Priority Indicator (SPI)
" Guaranteed Bit Rate (GBR)
IMS/SRB: Signaling has a high requirement for transmission delay. If the requirement cannot be
met, the service may be affected. For example, an SRB delay may lead to a handover delay.
The average rate of signaling is lower than 20 kbit/s.
VoIP: The VoIP service is highly delay sensitive. The end-to-end delay of a voice frame should
be shorter than 250 ms. The tolerant frame error rate is about 1%. The average rate of the
VoIP service with the header compressed is about 20 kbit/s.
Streaming: The streams at the receiver end should be continuous. Compared with VoIP, the
streaming service has a relatively low delay sensitivity, because a buffer that can avoid jitter
for several seconds is configured at the receiver end. When the rate of the streaming service
is equal to or higher than the GBR, the QoS can be guaranteed.
BE (background and interactive): The data rate at the service source end can reach a high value,
for example, several Mbit/s during a burst. The BE service has a low requirement for
transmission delay but has a high requirement for reliable transmission.
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MAC-hs Discard timer: An MAC-d PDU in an MAC-hs queue is discarded if the waiting time
exceeds the length of this discard timer. This timer is set on the RNC side. It is an optional IE
on the Iub interface. For the VoIP service, the timer is set to 100 ms. For the BE and
streaming services, the timer may not be set. For an MAC-hs queue configured with the
discard timer, the scheduler should send out the MAC-d PDUs before expiry of the timer.
Scheduling Priority Indicator (SPI): This parameter specifies the scheduling priority of an
MAC-hs queue. The priority is derived from the Traffic Class, Traffic Handling Priority,
and User Priority that are mapped onto this queue.
Guaranteed Bit Rate (GBR): It is configured on an MAC-hs queue basis. For the streaming
service, the GBR specifies the rate that can meet the requirement of the user for viewing
and the GBR of a queue is determined by the NAS. For the BE service, the GBR specifies the
required minimum rate for the service of the users in the RAN. The GBR of a BE service user
is set through the SET USERGBR command on the RNC side. The setting is based on the
user priority, namely, gold user, silver user, or copper user.
Services with different QoS requirements require different QoS guarantee policies. For example,
the VoIP service has a high requirement for delay. To limit the delay caused by flow control
or scheduling within a proper range, the algorithm grants the VoIP queue a priority to
occupy resources first. The streaming service has a high requirement for GBR. Therefore,
the scheduling and flow control algorithms guarantee that the average rate of the service is
not lower than the GBR during Iub traffic distribution and Uu resources allocation. The BE
service has a high requirement for reliability, which can be achieved through more
retransmissions on the Uu interface.
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HSDPA Qos Management
! Scheduling Priority Indicator (SPI) is the relative priority of the HS-DSCH FP
data frame and the SDUs included
! The SPI is set according to the following factors
" Traffic Class (TC)
" Traffic Handling Priority (THP) of the interactive service
" User Priority
! The SPI is set on the RNC LMT and sent to the NodeB through NBAP signaling
User priority
The case for mapping of traffic class, user priority, and THP to SPI
333332222211111ErrorUser
priority
15141
31211109876543210ARP
11None3
11None2
12None1Streaming
13None3
13None2
13None1Conversationa
l (VoIP)
14NoneNo ARPIMS signaling
15NoneNo ARPSRB signaling
SPITHPUser PriorityTraffic Class
2None3
5None2
8None1Background
23 to 153
323
413
53 to 152
622
712
83 to 151
921
1011Interactive
SPITHPUser PriorityTraffic Class
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The case for algorithm configuration based on SPI
80%FLOW_CONTRL_DYNAMICTS_SCHEDULE42
80%FLOW_CONTRL_DYNAMICTS_SCHEDULE43
80%FLOW_CONTRL_DYNAMICTS_SCHEDULE44
90%FLOW_CONTRL_DYNAMICTS_SCHEDULE45
90%FLOW_CONTRL_DYNAMICTS_SCHEDULE46
90%FLOW_CONTRL_DYNAMICTS_SCHEDULE47
100%FLOW_CONTRL_DYNAMICTS_SCHEDULE48
100%FLOW_CONTRL_DYNAMICTS_SCHEDULE49
100%FLOW_CONTRL_DYNAMICTS_SCHEDULE410
90%FLOW_CONTRL_DYNAMICTS_SCHEDULE411
100%FLOW_CONTRL_DYNAMICTS_SCHEDULE412
100%FLOW_CONTRL_FREEDS_URGENT_SCHEDULE213
100%FLOW_CONTRL_FREEDS_PQ_SCHEDULE414
100%FLOW_CONTRL_FREEDS_PQ_SCHEDULE415
Weight of
SPI
Flow Control
Algorithm Switch
EPF Schedule
Algorithm Switch
Max
Retrans
mission CountSPI
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HSDPA Qos Management
MML: ADD TYPRABHSPAMAC-hs Discard timer [ ms ]--- 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 250, 300, 400, 500, 750,
1000, 1250, 1500, 1750, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 7500 ms
Parameters
MML: SET SCHEDULEPRIOMAPScheduling Priority Indicator (SPI) --- 0~15
Traffic Class --- CONVERSATIONAL, STREAMING, INTERACTIVE, BACKGROUND, IMS, SRB
User Priority --- Gold, Silver, Copper
Traffic Handling Priority (THP) --- 1~15
MML: SET MACHSSPIPARAWeight of SPI (%) --- 1% ~ 100%
MAC-hs Discard timer specifies the maximum waiting time for sending a MAC-d PDU after it
is put in the MAC-hs queue. The MAC-d PDU is discarded when the timer expires.
SPI indicates the scheduling priority of the service of the user. The value 15 indicates the
highest priority and the value 0 indicates the lowest priority.
User priority is set according to the ARP
THP is valid only when the traffic class is interactive. The value 1 indicates the highest priority,
14 indicates the lowest priority, and 15 indicates no priority
Weight of SPI is used in the scheduling algorithm to select a queue to send data. To
implement differentiated services, it can adjust the proportions of the rates obtained by the
users with different SPIs in the same channel conditions. When Scheduling Method is set
to EPF, this parameter is valid in the scheduling algorithm. When Flow Control Switch is
set to SIMPLE_FLOW_CTRL or AUTO_ADJUST_FLOW_CTRL, this parameter is valid in the
flow control algorithm.
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HSDPA Scheduling Algorithm
! Huawei RAN10 product supports 4 scheduling algorithms:
" Max C/I
" RR (Round Robin)
" PF (Proportional Fair)
" EPF (Enhanced Proportional Fair)
When the HS-DSCH carries only the BE service, the PF scheduling algorithm can make a
tradeoff between user equity and cell throughput. When the HS-DSCH carries more types
of services, such as VoIP, streaming, SRB, and IMS, the HSDPA scheduling algorithm needs
to guarantee the QoS. The reason is that such services have high requirements for delay or
GBR. Based on the PF, the EPF algorithm is designed to guarantee the QoS of these services
as follows.
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HSDPA Scheduling Algorithm
$DS_PQ_SCHEDULE: SRB/IMS scheduling policy. The SRB and IMS queues are scheduled
before the VoIP, streaming and BE queues. DS means delay sensitive. PQ means priority queue.
$DS_URGENT_SCHEDULE: VoIP scheduling policy. The VoIP queues are scheduled before the
streaming and BE queues but after the SRB and IMS queues.
$TS_SCHEDULE: streaming/BE scheduling policy. The streaming and BE queues are scheduled
after the SRB, IMS, and VoIP queues. Among the streaming and BE queues, the resources for
GBR are allocated first. The remaining resources are allocated as required by golden, silver, and
copper users. TS means throughput sensitive
Queue types i.e. QOS
requirement of different
services
EPF
$To select users according to the value of R/r in descending order, where R is the maximum
data rate corresponding to the CQI, and r is the average data rate of the MAC-hs priority queue.
$The PF scheduler uses the variation in the radio channel qualities of individual users (for
example, multi-user diversity) and provides the user with an average throughput proportional to
its average CQI. This algorithm is a tradeoff between cell capacity and fairness among users.
CQI,
Average data rate of the
MAC-hs priority queue
PF
$To select users according to the waiting time of data buffered in the MAC-hs priority queue in
descending order. The waiting time is the only factor considered in this algorithm and therefore
the fairness among users can be guaranteed but the cell capacity degrades because the channel
quality is not taken into account.
Waiting time of data
buffered in the MAC-hs
priority queue
RR
$To select users according to the CQI value in descending order. The radio channel quality is the
only factor considered in this algorithm and therefore the fairness among users cannot be
guaranteed.
CQIMAX C/I
Scheduling PrincipleFactor considered in
algorithm
Scheduling
Algorithm
When the HS-DSCH carries only the BE service, the PF scheduling algorithm can make a
tradeoff between user equity and cell throughput. When the HS-DSCH carries more types
of services, such as VoIP, streaming, SRB, and IMS, the HSDPA scheduling algorithm needs
to guarantee the QoS. The reason is that such services have high requirements for delay or
GBR. Based on the PF, the EPF algorithm is designed to guarantee the QoS of the multiple
services
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HSDPA Scheduling Algorithm
! EPF ( Enhanced Proportional Fair )
" The types of queues are considered
" Qos guarantee for delay-sensitive service (delay) and throughput-sensitive
service (GBR)
" Configurable for SPI
$DS_PQ_SCHEDULE: SRB/IMS scheduling policy. The SRB and IMS
queues are scheduled before the VoIP, streaming and BE queues. DS means delay sensitive. PQ means priority queue.$DS_URGENT_SCHEDULE: VoIP scheduling policy. The VoIP queues are scheduled before the streaming and BE queues but after the SRB and IMS queues. $TS_SCHEDULE: streaming/BE scheduling policy. The streaming and BE queues are scheduled after the SRB, IMS, and VoIP queues. Among the streaming and BE queues, the resources for GBR are allocated first. The remaining resources are allocated as required by golden, silver, and copper users. TS means throughput sensitive
Queue types i.e.
QOS requirement of different services
EPF
Scheduling PrincipleFactor
considered in algorithm
Scheduling Algorithm
When the HS-DSCH carries more types of services, such as VoIP, streaming, SRB, and IMS
signaling, the HSDPA scheduling algorithm needs to guarantee the QoS. The reason is that
such services have high requirements for delay or GBR. Based on the PF, the EPF algorithm
is designed to guarantee the QoS of the following services:
! SRB and IMS have high requirements for service connection delay and handover delay. In
addition, the average traffic volume and the consumption of the Uu interface are low.
Therefore, the algorithm always selects the MAC-hs queues of SRB and IMS first.
! The VoIP service is highly delay sensitive. The maximum delay of MAC-d PDUs in a queue is
specified by the discard timer of the MAC-hs queue. The scheduler needs to send out the
MAC-d PDUs before the discard timer expires. The discard timer is usually shorter than 100
ms. Therefore, the scheduler has little chance of considering the channel quality. The
scheduler always selects VoIP services after scheduling SRB and IMS services. Among MAC-
hs queues of VoIP, the selection is based on both delay and channel quality.
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! The streaming service is usually the CBR (Constant Bit Rate) streaming service. If the rate of
this service is not lower than the GBR, the user can obtain good experience. Therefore, the
scheduler needs to guarantee the GBR. When the average rate of the streaming service is
lower than the GBR, the queues of the streaming service are selected first after SRB, IMS,
and VoIP. Among the MAC-hs queues of the streaming service, the selection is based on PF.
! The BE service is allocated with the remaining resource after the resource requirements of
the SRB, IMS, VoIP, and streaming services are met. Among the MAC-hs queues of the BE
service, the selection is based on PF. In addition, the resource allocation complies with the
following rules.
" Firstly, the GBR should be guaranteed first.
" Secondly, the algorithm considers the requirement for user differentiation. For all the
users in the cell, the scheduler intends to allocate the radio resource in proportion to
their Weight of SPI, which is based on user priorities, eg. gold, silver and copper.
# For example, assuming that radio resource is the bottleneck, gold , silver and
copper users of same channel quality are using FTP service simultaneously,
then the Uu throughputs of gold, silver and copper users are in proportion to
the ratio of their SPI weights.
# For another example, assuming that the silver user is using HTTP service, the
gold and copper user are using FTP service, and the silver user are reading the
HTTP page, then the gold and copper users share the radio resource, and the
Uu throughput of the gold and copper users are in proportion to the ratio of their SPI weight.
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HSDPA Scheduling Algorithm
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HSDPA Scheduling Algorithm
MML: SET MACHSPARAScheduling Method --- EPF (Enhanced PF), PF (PF), RR (Round Robin), MAXCI (Max C/I )
Parameters
MML: SET MACHSSPIPARAEPF Schedule Algorithm Switch --- DS_PQ_SCHEDULE, DS_URGENT_SCHEDULE, TS_SCHEDULE
EPF Schedule Algorithm Switch is valid only when Scheduling Method is set to EPF
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Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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HSDPA TFRC Selection
! Transport Format Resource Combination (TFRC) selection determines the
transport block size, modulation type, HS-PDSCH codes, and HS-PDSCH
transmission power
! The UEs estimate and send CQI to the UTRAN to aid the TFRC selection
! The CQI indicates the number of bits that can be transmitted to the UE
through certain HS-PDSCH power, a certain modulation method (QPSK or
16QAM), and a certain number of HS-PDSCH codes with an initial
transmission BLER of 10%
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HSDPA TFRC Selection
! TFRC selection is performed according to the following factors
" Available power of the HS-PDSCH
" Available codes of the HS-PDSCH
" CQI from the UE
" UE capability
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HSDPA TFRC Selection
! If there is sufficient amount of data cached in the MAC-hs queue (TBSmax <
Queue length), the data is scheduled for the UE as much as possible in the
maximum format of TFRC, that is, TBS = TBSmax
! If there is insufficient amount of data cached in the queue (TBSmax > Queue
length), the Uu resources necessary for the UE are allocated on the basis of
the amount of data in the queue
" Select the TFRC (power, code, and modulation mode) by searching the CQI-Max
TBS mapping table and taking the amount of data cached in the queue into
consideration
" The search is based on the priority defined by the Resource Allocate Method
parameter, that is, code preferable or power preferable
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HSDPA TFRC Selection
! TFRC Selection Process
Macro cells usually have a
poor radio environment
with limited power
resource. The downlink
power resource of a cell is
used up when the downlink
code resource is enough
Indoor pico cells usually
have a good radio
environment with
limited code resource.
The downlink code
resource of a cell is
used up when the power
resource is enough
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HSDPA TFRC Selection
! Example of TFRC selection process
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HSDPA TFRC Selection
! After TFRC is determined, the matched CQI of TBS in the CQI-
MaxTBS mapping table is determined. This CQI is expressed as
CQIused. Then, the transmit power of the HS-PDSCHs is calculated as
follows:
POWERHS-PDSCH = PCPICH + – (CQIadjusted - CQIused)
MML: SET MACHSPARAResource Allocate Method --- code priority, power priority
Parameters
MAX POWER PER HS-USER --- 1% to 100%
Within one TTI, the HS-PDSCH power and HS-SCCH power allocated to one UE cannot exceed
the value of the MAX POWER PER HS-USER parameter.
The HSDPA cell load is limited by the The Offset of HSPA Total Power parameter.
! = Max(-6, Min(13, PCellMAX - PCPICH - MPOconstant))
" PCell-MAX - PCPICH = maximum transmit power of the cell - CPICH transmit power
" MPOconstant represents HS-PDSCH MPO Constant and can be set on the RNC LMT
(MML: ADD CELLHSDPA)
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Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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Overview of NodeB HSDPA Flow
Control! HSDPA Flow control is a process used to control HSDPA data flow from RNC MAC-d to
NodeB MAC-hs according to Iub bandwidth and air interface bandwidth
! After HSDPA is introduced, users’ rate on air and on Iub is not consistent. It is necessary
to adjust rate on Iub according to its rate on air
! The signaling of HSDPA flow control process is implemented through the capacity
request and capacity allocation. The NodeB allocates the capacity for each MAC-hs
queue, and the RNC limits the downlink rate of each MAC-hs queue according to the
allocated capacity
! capacity means how much data RNC can send to NodeB in an interval
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Signaling of HSDPA Flow Control
! Capacity Request includes following IEs
" CmCH-PI : Scheduling priority Indicator ( SPI ) of the queue
" Uesr buffer size: Occupancy status of RLC buffer
The RNC sends Capacity Request to the NodeB, when some RLC PDUs are
accumulated in RLC buffer or CREDITS (i.e. some control messages in the latest
Capacity Allocation) are expired
The RNC also sends Capacity Request if No RLC PDU but allocated capacity is greater
than zero, indicating the NodeB can stop Capacity Allocation
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Signaling of HSDPA Flow Control
! The NodeB sends the HS-DSCH Capacity Allocation message to the RNC in
response to a HS-DSCH Capacity Request
! Capacity Allocation includes following IEs
" Maximum MAC-d PDU Length: maximum PDU size among the MAC-d PDU sizes
configured in the NBAP messages
" HS-DSCH Credits : total quantity of Mac-d PDU that CRNC can send during HS-
DSCH interval
" HS-DSCH interval : time interval during which the HS-DSCH credits granted in
Capacity Allocation can be used
" HS-DSCH Repetition : number of subsequent intervals during which the HS-DSCH
Credits IE granted in the HS-DSCH CAPACITY ALLOCATION control frame can be
used and the value 0 means that there is no limit to the repetition period
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Capacity Allocation Policy
! Generally, the NodeB allocating the capacity to a MAC-hs queue considers the
data rate on the Uu interface and Iub available bandwidth
! For different service (i.e. QoS requirements), the NodeB uses different flow
control policies
" Flow control free policy for SRB, IMS signaling or VOIP
" Dynamic flow control policy (for streaming service or BE service)
! Flow control free Policy
" After the HS-DSCH bearer is set up, the NodeB sends a capacity allocation message
to the RNC, indicating that the DL traffic of the new MAC-hs queue is not limited
and the RNC MAC-d can send data as much as required
" The allocation keeps unchanged for the service
" The policy of no flow control policy is applied only to VoIP, IMS, and SRB, for these
services are delay sensitive and have a relative low rate
For VOIP, the flow control free Policy is applied to the Mac-hs queue due to
It is highly delay sensitive. Therefore VOIP service is mapped onto bearers with high
priorities to guarantee the high requirement for delay. The bearer priority of VOIP on
the Iub interface is higher than that of non-real-time service. The scheduling priority of
VOIP queue on Uu interface is also higher than that of non-real-time service queue.
Average rate of VOIP is low. The rate is about 20kbps. The probability of congestion
incurred by VOIP on the Uu interface and Iub interface is low
The IMS signaling / SRB has a low average rate. It is also highly delay sensitive. So flow
control free is also applied to them.
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Capacity Allocation Policy
! Dynamic flow control
" Dynamic flow control is mainly applied to MAC-hs queues of BE
service, for theses services are not delay sensitive, the rate varies in
a wide range, and will reach a high rate during a burst
" Dynamic flow control is also applied to MAC-hs queues of
streaming service, for streaming service has a relative high rate
and may result in congestion on Uu
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Capacity Allocation Policy
!Dynamic flow control
"Dynamic flow control process with adaptive Iub bandwidth is as follows:
# The congestion status of the transport network is reflected to NodeB through DRT
and FSN. The NodeB adaptively adjusts the Iub bandwidth available for HSDPA
based on the congestion detection
# Depending on the available bandwidth and rate on air interface, the NodeB
allocates bandwidth to HSDPA users and performs traffic shaping (Iub shaping) to
avoid congestion and packet loss over the Iub interface
# The RNC limits the flow of HS-DSCH data frames for each MAC-hs queue
according to the HS-DSCH capacity allocation
MML: SET MACHSSPIPARAFlow Control Algorithm Switch ---FLOW_CONTRL_FREE, FLOW_CONTRL_DYNAMIC
Parameters
We can configure the Flow Control Algorithm according to SPI.
Default configuration for Flow Control Algorithm
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HSDPA Flow Control
! Dynamic flow control consists of the following modules:
" Adaptive capacity allocation
# NodeB adaptively allocates capacity to an MAC-hs queue based on its rate on air interface
# Capacity means how much data RNC can send to NodeB in an interval
" Congestion control on Iub
# The total flow of all the MAC-hs queues should not exceed the available Iub bandwidth to
avoid congestion on Iub
# NodeB provides the following functions to avoid Iub congestion:
– Adaptive adjustment of Iub bandwidth
~ NodeB periodically detects Iub congestion and adaptively adjusts the available Iub bandwidth
according to the Iub state
– Iub shaping
~ Iub shaping is used to allocate Iub bandwidth to every MAC-hs queue based on the available
Iub bandwidth and ensure the total flow of the queues does not exceed the available Iub
bandwidth. Thus, congestion control is achieved on the Iub interface, which increases the
bandwidth usage and avoids overload
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HSDPA Dynamic Flow Control
! Dynamic flow control policy is configured through the Flow control switch.
!If the switch is set to AUTO_ADJUST_FLOW_CTRL, the NodeB performs adaptive
capacity allocation, Iub shaping and adaptive adjustment of Iub bandwidth
" When the Iub resource is the bottleneck, the algorithm performs capacity
allocation based on the bit rate on the Uu interface and the Iub shaping of
dynamic flow control queues.
" When the congestion on the Iub interface is invisible for the NodeB, the
algorithm performs capacity allocation based on the bit rate on the Uu interface
MML: SET HSDPAFLOWCTRLPARA Flow Control Switch--- SIMPLE_FLOW_CTRL, AUTO_ADJUST_FLOW_CTRL, NO_FLOW_CONTROL
Parameters
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HSDPA Dynamic Flow Control
! If the switch is set to NO_FLOW_CONTROL, the NodeB performs
adaptive capacity allocation, and does not perform Iub shaping and
adaptive adjustment of Iub bandwidth
! If the switch is set to SIMPLE_FLOW_CTRL, the NodeB performs
adaptive capacity allocation and Iub shaping, and does not perform
adaptive adjustment of Iub bandwidth
" Some Iub bandwidth should be reserved for HSDPA users. This setting is
used mainly for testing the algorithm during the design phase
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HSDPA Flow Control
! MAC-hs / MAC-d flow control
" The flow control keeps the queue occupancy in a reasonable level
in order to reduce data transmission delay, L2 layer signal delay,
and discarding as the result of priority queue congestion or reset
during handover
" In this sense, the functionality is called capacity allocation adaptive
to Uu interface bit rate, where capacity allocation for each priority
queue is based on the Uu interface bit rate and the buffer
occupancy level
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HSDPA Flow Control
! MAC-hs / MAC-d flow control when Iub interface resource is
not congested
" If there is not enough data in the queue, large bandwidth is
allocated
" If there is enough data in the queue, the bandwidth that is close
to the rate on the Uu interface is allocated
" If there is too much data in the queue, small bandwidth or no
bandwidth is allocated
If the resource on the Uu interface is the bottleneck, or the total traffic volume within the
NodeB (i.e. Mac-hs queue) is low, or the congestion on the Iub interface is managed
by the RNC back pressure algorithm, then the algorithm allocates the capacity based
only on the rate of each queue on the Uu interface. The MAC-hs performs flow control
for each priority queue periodically.
Whether there is enough data in the queue is judged by the time length of the priority
queue. Time length is defined as the ratio of the length of the queue to the air interface
bit rate of the queue. In this way, the average delay of MAC-d PDU at the MAC-hs
layer is limited within a hundred milliseconds.
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HSDPA Flow Control
! Adaptive adjustment of Iub bandwidth available for HSDPA
" Adaptive adjustment of Iub bandwidth available for HSDPA is a
part of the mechanism to control the congestion on Iub.
" Adaptive adjustment of Iub bandwidth available for HSDPA
comprises the following process
# detection of Iub congestion
# adjustment of Iub bandwidth available
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HSDPA Flow Control
! Detection of Iub congestion
" This Iub congestion detection algorithm periodically
measures the transmission delay and frame loss
" Assuming that for each MAC-d flow the HS-DSCH
data frame must be delivered to the MAC-hs layer in
FSN sequence, Iub frame loss is counted and the
frame loss ratio at the Iub level in a specific time
window is calculated
" The HS-DSCH data frame transmission delay is the
interval from the time when HS-DSCH data frame
generated in the RNC (identified as DRT) to the time
when the frame arrives at the NodeB MAC-hs layer
Frame Sequence Number: used to detect frame loss over the Iub interface.
DRT: Delay Reference Time, used to detect transmission delay over the Iub interface
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HSDPA Flow Control
! Detection of Iub congestion
" Periodically the Iub congestion status is differentiated into three levels:
# Congestion due to delay means that the delay buildup is larger than the Time
Delay Threshold
# Congestion due to frame loss that means the frame loss ratio is larger than the
Discard Rate Threshold. Otherwise frame loss may be caused by an Iub bit error
# Congestion released means that there is no congestion due to delay and no
congestion due to frame loss
MML: SET HSDPAFLOWCTRLPARADiscard Rate Threshold --- 0~100%Parameters
Time Delay Threshold --- 0~500ms
The other two thresholds related to Iub congestion detection are described as follows:
Discard Rate Threshold: is used to determine whether the Iub interface is congested
because of frame loss. Generally, frame losses due to bit error are less than those due
to congestion. By default, the threshold is set to 5%. It can be adjusted on the basis of
transport network quality. The HS-DSCH frame error rate on the Iub interface within
300 ms can be a reference. If the threshold is too high, the congestion on the Iub
interface cannot be relieved in time. If the threshold is too low, the Iub interface will be
regarded as congested in the case of frame loss due to bit error. Thus, the Iub
bandwidth cannot be fully utilized.
Time Delay Threshold: is used to determine whether the Iub interface is congested
because of delay buildup. By default, this threshold is set to 20 ms. It can be adjusted
on the basis of the delay jitter allowed on the transport network. Generally, the
threshold is set to the allowed delay jitter plus several ms. If the threshold is too high,
the transmission on the Iub interface will be much delayed when the Iub interface is the
bottleneck. If the threshold is too low, the Iub interface will be regarded as congested
by mistake. Thus, the transmission resource cannot be fully utilized.
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HSDPA Flow Control
! Adjustment of Iub bandwidth available
" The algorithm actively adjusts the Iub bandwidth based on the congestion
detection
# If the Iub is in the congestion due to delay, the Iub bandwidth available for HSDPA is
decreased by a step in direct proportion to the delay buildup
# If the Iub is in the due to frame loss, the Iub bandwidth available for HSDPA is decreased by a
big step regardless of the delay buildup
# If the Iub is in the congestion released, the Iub bandwidth available for HSDPA is increased by
a smaller step, applying the Policy of increasing slowly, yet decreasing fast
" In a time window of tens of seconds, if consecutive "congestion released" is
detected, the Iub resource is identified as not the bottleneck. In this case, the
MAC-hs/MAC-d flow control does not take the Iub bandwidth available for HSDPA
as the limitation of capacity allocation
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Contents
1. HSDPA Channel Type Mapping
2. HSDPA Code Resource Management
3. HSDPA Power Management
4. HSDPA Mobility Management
5. HSDPA Channel Switching
6. HSDPA Mac-hs Scheduling Algorithm
7. HSDPA TFRC Selection
8. HSDPA Flow control
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