HSUPA

HSUPA RRMModule Objectives
At the end of the module you will be able to:
Explain the physical layer basics of HSUPA technology
List the key changes brought by HSUPA and their impact on the network and on the protocol model
Explain the HSUPA RRM principles and the related parameters, including packet scheduling, resource management, mobility and channel type selection
* © Nokia Siemens Networks RN3163AEN20GLA0
HSUPA Protocols & Procedures
HSUPA Physical Channels
Appendix
Node B controlled scheduling
Downward compatibility to R99, R4 & R5
HSUPA requires HSDPA
Full mobility support and urban, suburban & rural deployment
HSDPA
UEs
Iub
Uu
HSUPA
Power Control PC: Fast Power Control
on DL centralized PC
on UL individual PC
pure time multiplexing difficult
on UL fast PC still necessary (same as Rel. 99)
(UL interference UL scrambling codes)
Higher order modulation difficult for UE;
coming with Rel.7
Fast H-ARQ terminated at Node B
Fast UL Packet Scheduling controlled by Node B
Fast Link Adaptation:
- Adaptive modulation with Rel. 7
Dedicated channel DCH
used in UL or DL.
UE
Iub
Uu
Supports 2 ms TTI and 10 ms TTI
RNC
SF = 256 – 2 !
Multi-Code Operation: there may be 0, 1, 2 or 4 E-DPDCH on each radio link
up to 2x SF2 + 2x SF4 up to 5.76 Mbps
E-DPCCH:
SF = 256 fixed
Rel. 6 UL: DCH & E-DCH Configurations
E-TFCI: Enhanced Transport Format Combination Indication
RSN: Retransmission Sequence Number
HSUPA 5.8Mbps
To support an UL peak rate of 5.8 Mbps* the UE needs to send on 4 E-DCH channels in parallel (2xSF2 + 2xSF4)
UE category 6 + 7 enable transmission of 4 codes in parallel & support 5.76 Mbps at maximum with QPSK modulation
In case of 4 code E-DCH transmission 3GPP defines that no DPDCH may be allocated simultaneously
The SRB needs to be mapped on E-DCH in this case. This requires RU20 RAN 1470 “SRB's on HSUPA”, which introduces the mapping of UL SRB’s on E-DCH
SF2
SF4
SF8
Cch,2,0
Cch,2,1
Cch,4,0
Cch,4,1
Cch,4,2
Cch,4,3
E-DPDCH
RU20:
Optional Feature (ASW)
* 5.76 Mbps
WCEL; 0 (960 kbps, SF4), 1 (1.92 Mbps; 2xSF4),
2 (3.84 Mbps; 2xSF2), 3 (5.76 Mbps; 2xSF2 + 2xSF4);
“HSUPA 5.8 Mbps” active parameter value “3” allowed; else max. 2
Feature ID: RAN981
The peak bit rate on E-DCH for single user is increased up to 5.8 Mbps.
Benefits for the operator:
This feature enables operator to offer higher HSUPA bit rates to premium data subscribers and increase data service revenue.
Functional description:
HSUPA UE categories 4, 6 and 7 support higher peak bit rate than 2 Mbps. With this feature category 4, 6 and 7 UEs may transmit data with their maximum bit rate, which is achieved with an E-DCH configuration of 2ms transmission time interval (TTI). Four parallel codes are required for category 6 and 7. When four codes are transmitted in parallel, two codes are transmitted with spreading factor two (2xSF2) and two with spreading factor four (2xSF4). Also intermediate bit rates are supported with 2 ms TTI.
The maximum theoretical throughput of category 6 and 7 terminal is 5.76 Mbps. Practical throughput achievable with this feature is limited by radio reception and allowed noise rise:
Maximum theoretical throughput would require the use of coding rate close to 1. Coding rate 1 requires effectively error free reception without error correction coding. Targeting to error free reception reduces the system efficiency and capacity. In all practical conditions the throughput will be degraded if using coding rates close to 1.
Quality of radio reception depends on aspects such as received signal strength, radio channel and interference, transmitter and receiver imperfections.
* Maximum No. of bits / E-DCH transport block
Coding rate
max. #. of E-DCH Bits* / 10 ms TTI
max. # of E-DCH Bits* / 2 ms TTI
Modu- lation
modified coding
higher peak rates & spectrum efficiency !
RNC
Reduced
retransmission
RNC:
functionalities
WCEL; 0..5; 1; 2
by HSUPAEnabled & EDCHQOSClasses
Maximum Number of Connections
MaxNumberEDCHCell for individual cell
Number of E-DCH allocations reserved for Soft/Softer Handover SHO:
NumberEDCHReservedSHOBranchAdditions both for individual cells & cell groups
Max. number of new E-DCH = NumberEDCHReservedSHOBranchAdditions - MaxNumberEDCHCell(LCG)
MaxNumberEDCHCell
WCEL; 1..72; 1; 20
Bit 1 = Background BG
Bit 5 = streaming
MaxNumberEDCHLCG
WBTS; 1..72; 1; 60
LCG: Local Cell Group
NSN: Maximum Bit Rate
Max. Bit Rate defined on the basis of the max. symbol rate by:
MaxTotalUplinkSymbolRate
1920 Ksps often quoted as 1.4 Mbps HSUPA
3840 Ksps often quoted as 2.0 Mbps HSUPA
Max. bit rate on E-DCH may exceed maximum bit rate defined by QoS profile by factor:
FactorEDCHMaxBitRate
if set to 0, QoS profile is ignored
if set to 1, max. E-DCH bit rate = max. bit rate defined by QoS profile
For Multi-RAB combinations own specific factors can be set
FactorEDCHMaxBitRate
RNC; 0.1..5; 0.1; 1.5
1 (1.92 Mbps; 2xSF4),
2 (3.84 Mbps; 2xSF2),
3 (5.76 Mbps; 2xSF2 + 2xSF4);
“HSUPA 5.8 Mbps” active parameter value “3” allowed; else max. 2
Modulation
QPSK
QPSK
TTI
Traffic Classes
Packet Scheduler
Appendix
HSUPA: 10 ms & 2ms (RAN 1470) TTI
3GPP Rel. 6 defines both 10 ms & 2 ms TTI for HSUPA
NSN RAS06 & RU10 support only 10 ms TTI
10 ms TTI improves cell edge performance
2 ms TTI (RAN1470) support with NSN RU20:
2 ms TTI reduces latency
2 ms supports increased peak throughputs
prerequisite for HSUPA peak rates up to 5.8 Mbps
2 ms TTI: SRB are mapped onto HSPA
(NSN implementation)
(NSN implementation)
SRB mapping onto HSUPA is mandatory for the 2×SF2 + 2×SF4 configuration because the DPDCH code is blocked by E-DPDCH codes (3GPP specification)
PriForSRBsOnHSPA: RNC; 0..15; 1; 15
defines priority SPI for SRBs on E-DCH & HS-DSCH
HSUPA2MSTTIEnabled
10 ms TTI:
Improved cell edge
CPICHRSCPThreEDCH2MS
(max. path loss)
CPICHECNOThreEDCH2MS
(min. Ec/Io)
PtxPrimaryCPICH – CableLoss* – Meas CPICH RSCP <
CPICHRSCPThreEDCH2MS + MAX(0, UETxPowerMaxRef – P_MAX)
Meas CPICH Ec/Io > CPICHECNOThreEDCH2MS
HSUPA 2 ms TTI
RAB establishment or release (TTI switching)
The 2 ms HSUPA TTI is selected if:
HSUPA 2 ms TTI is enabled by HSUPA2MSTTIEnabled
UE supports 2 ms TTI
RAB combination supports SRB on HSUPA
RNC reconfigures E-DCH 2ms TTI E-DCH 10ms TTI if
2ms TTI Coverage criteria not fulfilled
Selection starts from CELL_DCH
Selection starts from CELL_FACH
UETxPowerMaxRef
RNC; -50..33; 1; 24 dBm
Appendix
H-ARQ
ensures in sequence delivery
Multiplexing of MAC-d PDUs
HARQ
E-DCH
Short TTI = 2 (RU20) / 10 ms
Scheduling decision on basis of actual physical layer load (available in Node B)
up-to date / fast scheduling decision high UL resource efficiency
higher load target (closer to overload threshold) possible high UL resource efficiency
L1 signalling overhead
Node B (MAC-e) controlled
Stop & wait H-ARQ protocol
each process has own physical buffer
Based on synchronous DL (L1) ACK/NACK
Retransmission
1st retransmission after 40 / 16 ms (TTI = 10 / 2 ms)
Limited number of retransmissions
IR & CC
SAW: Stop and Wait
RNC; 0..3; 1; 3
RNC
Total E-DCH buffer status (TEBS)
Total amount of data available across all logical channels for which reporting has been requested by RRC
Highest priority logical channel buffer status (HLBS)
Amount of data available from the logical channel identified by HLID,
Relative to highest value of buffer size range reported by TEBS when reported TEBS index is not 31
Relative to 50000 bits when reported TEBS index is 31
Highest priority logical channel identity (HLID)
Highest priority logical channel with available data
If multiple logical channels exist with same highest priority, that one corresponding to highest buffer occupancy will be reported
PeriodicityForSI
PowerOffsetForSI
Appendix
E-RGCH
E-DPCCH
L1 control: E-TFCI, RSN, happy bit
E-DPDCH
User data & CRC
ACK/NACK
RSN: Re-transmission sequence number
Max. configuration according 3GPP: 2 * SF2 + 2 * SF4
Max. configuration according RU10: 2 * SF2
SF = 256 – 2 (BPSK-like)
Pure user data & CRC (1 CRC per TTI, size 24 bit)
TTI = 2 / 10 ms (at cell edge 10 ms required for sufficient performance)
UE receives resource allocation via grant channels
managed by MAC-e/-es
Soft / softer handover support
E-DPCCH
E-TFCI (7 bit): E-DCH Transport Block Size i.e. Coding at given TTI
RSN: Retransmission Sequence Number RSN (2 bit)
Value = 0 / 1 / 2 / 3 for initial transmission, 1st / 2nd / further retransmission
Happy bit (1 bit): indicats if UE needs more resources or not: = 1, = 0
These 10 bits are channel coded to generate 30 bits per 2 ms sub-frame
2 ms TTI => the 30 bits are transmitted once during the 2 ms
10 ms TTI => the 30 bits are repeated 5 times during the 10 ms
Happy bit
Included as part of E-DPCCH
Happy bit delay condition
Defines time over which to evaluate the current serving grant relative to total buffer status
Happy bit set to ‘unhappy’ if all 3 following conditions true:
UE transmitting as much scheduled data as allowed by current Serving Grant
UE has sufficient power to transmit at higher data rate
with current Serving Grant, UE would need at least the following time to transmit the total amount of data in its buffer: HappyBitDelayConditionEDCH
HappyBitDelayConditionEDCH
Happy bit delay condition for E-DCH
RNC; 2, 10, 20, 50, 100, 200, 500, 1000 ms; 50 ms
Transfers a total of 6 bits per 2 ms sub-frame
Absolute Grant value (5 bits)
signals transmit power allowed for E-DPDCH relative to DPCCH
Absolute Grant scope (1 bit) - only applicable to 2 ms TTI
indicates whether grant applies to single HARQ process or to all HARQ processes
Transfers E-RNTI (16 bit)
SF 256 used
2 ms TTI 60 coded bits occupy TTI
10 ms TTI 60 coded bits repeated 5 times to occupy TTI
PtxOffsetEAGCH
WCEL; -32..31.75; 0.25; -5 dB
command Up, Down & Hold
SF 128 used
E-RGCH can occupy
2 ms TTI and serving radio link set occupies 2 ms
Non serving radio link set occupies 10 ms
Channelization code
For specific UE, channelization code used for E-RGCH & E-HICH shall be the same
40 orthogonal signatures defined to allow multiple UEs to share same channelization code
PtxOffsetERGCH
WCEL; -32..31.75; 0.25; -11 dB
Command
UP
+1
Allowed HOLD, DOWN
DOWN = overload indication
Iub
Iub
Iu
Serving E-DCH RLS cells
(under same Node B)
Allowed UP, HOLD, DOWN
transmitted by all Active Set cells
UE continues to re-transmit until ACK received from at least one cell (or until re-transmission time out)
SF 128 used
E-HICH can occupy
Channelization code
For specific UE, same channelization code used as for E-RGCH
40 orthogonal signatures defined to allow multiple UEs to share same channelization code
E-HICH
PtxMaxEHICH
WCEL; -32..31.75; 0.25; -11 dB
NACK*: RLS not containing the Serving E-DCH cell
NACK#: RLS containing the Serving E-DCH cell
Command
for Voice & SRB if CS Voice over HSPA not used
3.4 kbps SRB uses SF128
DPCCH
if CPC not enabled
WCEL; -32..31.75; 0.25; -5 dB
PtxOffsetERGCH
WCEL; -32..31.75; 0.25; -11 dB
PtxMaxEHICH
WCEL; -32..31.75; 0.25; -11 dB
UE
E-AGCH
E-DPDCH
HS-DPCCH
Appendix
depending on:
UE Capability
Transmission power
Service grant
TB size derived from TB index with help of TBS size table
1 TBS size table for each TTI (2 ms & 10 ms)
TBS size tables optimised for MAC-d PDU sizes of 336 and 656 bits
E-TFC Selection (1/3)
TS 25.321 MAC
Excluded: UE without sufficient transmit power (blocked state)
0 – 2 Excluded: Transport Block size too small for 336 bit MAC-d PDU
minimum E-TFCI set
maximum E-TFC which cannot be blocked due to lack of UE power
Can be used if
absolute service grant given
no DCH transmission present
Excluded E-TFC: based upon Serving Grant
UE can select e.g. this E-TFC because if it has less data to send
Step 2
Identify E-TFC allowed by serving grant (maximum E-DPDCH / DPCCH power ratio)
Select E-TFC based upon quantity of data to be send
Appendix
RNC limits E-TFC based upon UE capability and QoS profile
Node B limits E-TFC based upon packet scheduling principles
UE limits E-TFC based upon transmit power capability
UE selects E-TFC based upon data to be transferred
1.
RNC
BTS
2.
UE
3.
4.
Absolute & relative grants
Iub resources
Throughput & load based scheduling
PrxMaxTargetBTS
Throughput based
Throughput based scheduling
Node B calculates own cell load
If own cell load < Lmin_cell then throughput based scheduling can be applied to increase own cell load up to Lmin_cell
PrxMaxTargetBTS
Lmin_cell
Actual own cell load
LminCell 37%
PrxLoadMarginEDCH
Interference margin for minimum E-DCH load; WCEL; 0..30; 0.1; 2 dB 1.585
Corresponding load factor LminCell =
1 - 1/100.2 = 0.37 (37 %)
Load based scheduling
if calculated own cell load > Lmincell power based scheduling is applied to increase total cell load up to maximum cell load
Node B measures actual RTWP & calculates actual total load
Lmin_cell
Schedulable resource
Actual own cell load
LmaxCell = 75%
LminCell 37%
PrxMaxTargetBTS
WCEL; 0..30; 0.1; 6 dB = 2.0
Corresponding load factor LmaxCell =
RTWP < maximum target more HSUPA service can be offered
Otherwise
more HSUPA service can not be offered any more; HSUPA service has to be down-graded if too much RWP from non served UEs in comparison to E-DCH RWP
Absolute grant
service grant value
Mapping between power ratios & E-TFCs hardcoded
Initial power ratio = (21/15)2 independent on service profile and
UL load (corresponds to 32 kbps)
E-TFC
TB-Index (= E-TFC)
Amplitude Ratio
Relative grant
DPCCH power ratio
value increases by 1
grant value decreases by 1
UP e.g. from 23 to 24
DOWN e.g. from 19 to 18
Single Modifiable ‘unhappy’ UE?
fast Ramp-Up Procedure
Increase the bit rate of the modifiable ‘unhappy’ UEs using the E-RGCH
Load increase estimation
Hardware resources available?
Handling load increase (upgrade queue)
Node B maintains upgrade queue for each HSUPA UE whose serving RL belongs to that Node B
Node B sorts UEs according to their current max. allocated E-TFCI
UE with lowest allocated E-TFCI is allocated highest priority
If 2 UE have same allocated E-TFCI UE with highest utilisation is assigned the highest priority
UEs with low utilisation shall not be considered when allocating upgrades
using the E-RGCH
Active E-DCH Exists?
LmaxCell = 75%
Basics of HSUPA Mobility
HSUPA Channel Type Selection
Static & dynamic load target
R99 static load target
Fixed load target PrxTarget (relative to PrxNoise)
Fixed overload threshold PrxOffset (relative to PrxTarget)
HSUPA dynamic load target
for cells with active HSUPA service similar concept as for HSDPA dynamic power allocation
for non-controllable traffic same fixed load target PrxTarget as in static case
for NRT traffic adjustable load target PrxTargetPS
PrxTargetPSMin (minimum value)
PrxTargetPSMax (maximum value, also initial value)
same PrxOffset value used as in static case to decide about overload actions, but now relative to PrxTargetPS
WCEL; 0.1..30; 0.1; 4 dB
PrxTargetPSMax
WCEL; 0.1..30; 0.1; 4 dB
HSUPA active
i.e. fixed
LmaxCell = 75%
Appendix
But specific FMCS parameter set available for
User both with HSDPA + HSUPA
User both with HSDPA + HSUPA and AMR
HSDPA serving cell change not affected by HSUPA SHO
HSPAFmcsIdentifier
WCEL; 1..100; 1; -
E-DCH AS: subset of DCH AS
Cells can be left out from E-DCH AS but included within DCH AS due to
HSUPA not enabled for DCH active cell
Max. number of E-DCH users reached for that cell or cell group to which it belongs
No free E-DCH resources within cell group to which it belongs
Softer HO E-DCH & DCH AS have to be identical
Soft HO E-DCH & DCH AS can be different
Cell shall be added to E-DCH AS later if possible (by using internal retry timer)
HSDPA cell is also HSUPA serving cell
E-DCH
E-DCH
DCH
If SHO failure for E-DCH
Channel type switch to DCH, if non active cell becomes too strong in comparison to best active cell
In case of Softer HO for DCH no AS update either (RRC connection release due to DCH SHO failure possible as usual)
same FMCI parameter set used as for HSDPA
same HOPI parameter set used as for R99
Inter-System HHO
E-DCH Establishment
E-DCH Release
PDP Context Activation
Measurement Report 4a
Same high level procedures as for NRT DCH
After PDP context activation RNC starts by allocating DCH 0/0 kbps connection
Selection between DCH and E-DCH completed when RNC receives UL capacity request
HSUPA can be allocated from CELL_FACH as well
Uplink NRT RB mapped to DCH > 0 kbps
UE capability supports E-DCH
Traffic class and THP allowed on E-DCH
HSDPA mobility enabled and HS-DSCH available
and no IFHO/ISHO measurements
Preliminary E-DCH active set is acceptable
HS-DSCH possible to select in the downlink
Number of E-DCH allocations is below the maximum
Yes
No
No
No
No
No
No
No
No
No
UE specific PS
Minimum E-DCH active set selected
E-DCH Establishment (2/3)
2) RAB combinations allowed for HSUPA
up to 3 NRT RAB (any combination E-DCH RABs / DCH RABs) with or without AMR
3) Preliminary active set = all active cells with HSUPA enabled
4) Minimum AS = all HSUPA enabled active cells with sufficient quality
2
3
4
EC/I0 of E-DCH cell < EC/I0 of serving E-DCH cell + EDCHAddEcNoOffset
E-DCH Establishment (3/3)
HSUPA enabled
HSUPA disabled
HSUPA enabled
HSUPA enabled
HSUPA enabled
CPICH Ec/Io = -5 dB
CPICH Ec/Io = -7 dB
FMCS; -10 .. 6; 0.5; 0 dB
HspaMultiNrtRabSupport
HSPA multi NRT RAB Support; up to 3 NRT RAB
WCEL; 0 or 1; 0 = disabled; 1 = enabled
AMRwithEDCH
* AMR codec selection not affected by HSUPA
Multi-RAB
EDCHMACdFlowThroughputAveWin
sliding window moved every TTI
Release Trigger: low throughput indication
After E-DCH allocation no MAC-d flow detected for
EDCHMACdFlowThroughputAveWin + 2 s
Low throughput ≤ EDCHMACdFlowThroughputRelThr
returns above threshold then normal throughput indication
is triggered immediately
RNC; 0.5..10; 0.5; 3 s
TTI
EDCHMACdFlowThroughputAveWin
EDCHMACdFlowThroughputRelThr
EDCHMACdFlowThroughputTimetoTrigger
low throughput time to trigger of the E-DCH MAC-d flow
RNC; 0..300; 0.2 s; 5 s
EDCHMACdFlowThroughputRelThr
RNC; 0..64000; 256; 256 bps
Benedikt Aschermann
Benedikt Aschermann

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HSUPA