rn31673en30gla1 ranpar combined cchs and powercontrol v1.0 ru40 mb

1 © Nokia Siemens Networks RN31673EN30GLA1

Course Content

Radio Resource Management Overview

Parameter Configuration

Common Channels & Power Control

Load Control

Admission Control

Packet Scheduling

Handover Control

Resource Manager

HSDPA RRM & parameters

HSUPA RRM & parameters

HSPA+ features & parameters


Common Channels & Power Control:Module Objectives

At the end of the module you will be able to:

• Describe the DL common channels power settings

• Name and describe the different power control loops

• Explain the open loop power control (both in UL& DL), name and describe the related RAN parameters

• Describe outer loop & closed loop power control (both in UL & DL) and the relationship between them in detail

• Explain the DL Power Balancing


Power Control

• Channel mapping

• Power Setting for DL Common Channel

• Open Loop Power Control

• Fast Closed Loop Power Control

• Outer Loop Power Control

• Optional: DL Power balancing


Channel types and location in UTRAN

Logical Channels

Transport Channels

Physical Channels

UE

Iub Frames

RNCNode B


Channel Mapping DL (Network Point of View)

P-CCPCH

PCH

BCH

CTCH

DCCH

CCCH

PCCH

BCCH

DCH

P-CPICH

P/S-SCHFACH

HS-DSCH

AICH

HS-PDSCH**

DPDCH

S-CCPCH

DTCH

PICH

LogicalChannels

TransportChannels

PhysicalChannels

DPCCH

HS-SCCH

E-HICH*

PowerControl

FixedPower

E-AGCH/E-RGCH*

* Power Control with RAN971 HSUPA DL Physical Channel Power Control

** Dynamic HS-PDSCH power allocation


Channel Mapping UL (Network Point of View)

DCCH

DCH DPDCHDTCH

LogicalChannels

TransportChannels

PhysicalChannels

RACHCCCH PRACH

DPCCH

HS-DPCCHE-DCH

E-DPDCH

E-DPCCH

OpenLoop

PowerControl

PowerControl


Example – Channel configuration during call

LogicalChannels

TransportChannels

PhysicalChannels

Data

DCCH1-4

DCH2-4

DPDCH

DTCH1 DPCCH

RRCsignalling

Speechdata

DCH1

AMR speech connection utilises multiple transport channelsRRC connection utilises multiple logical channels, signalling radio bearers

DCH5DTCH2

NRTdata

AMR speech+

NRT data


Power Control

• Channel mapping







DL Common Control Channel

• DL Common control channels must be heard over the whole cell, thus their power setting is designed for “cell edge”.

• Rel. 99 DL Common Channels do not have a power control.

• The power of the common physical channels are set relative to the CPICH

Default parameter value Power valuePtxSecSCH -3 dB 30 dBmPtxPrimaryCCPCH -5 dB 28 dBmPtxSCCPCH 1 (SF=64) 0 dB 33 dBmPtxSCCPCH 2 (SF=256) -5 dB 28 dBmPtxSCCPCH 3 (SF=128) -2 dB 31 dBmPtxPICH -8 dB 25 dBmPtxAICH -8 dB 25 dBmPtxOffsetEAGCH -5 dB 28 dBmPtxOffsetERGCH -11 dB 22 dBm


Pilot Channel Power Setting (1/2)

Adjust CPICH transmit Power

Identify Cells with poor coverage

Identify Cells with excessive coverage

Evaluate Ec/Io and RSCP performance

PtxPrimaryCPICHWCEL; -10..50; 0.1; 33 dBm

(Range; Step; Default)(20 W sector)

• The Common Pilot Channel CPICH is used by the User Equipments for• synchronization & channel estimation purposes• handover & cell reselection decisions

• The received quality of the CPICH is quantified by its Ec/Io , the field strength by the Received Signal Code Power RSCP

• Ec is the energy per chip, Io is the noise spectral density• RSCP is the CPICH power measured in the channel bandwidth• Ec/Io provides a relative measure, RSCP provides an absolute measure

• The CPICH Ec/Io & RSCP must be sufficiently high across the entire coverage area of the network• The CPICH consumes Node B transmit power which reduces DL capacity• CPICH power must be minimized to increase DL capacity while maintaining pilot coverage• By default the CPICH consumes 2 W of the Node B power (20 W PA)

• i.e. 10% of the PA power

• CPICH power used to derive the power of the other DL Common Control Channels• The CPICH should be tuned per cell


Pilot Channel Power Setting (2/2)

• In terms of coverage and capacity, the WCEL: PtxPrimaryCPICH has only a very small optimal window:

• The minimum value maximises capacity (minimises coverage). • The maximum value maximises coverage (minimises capacity).

35 dBm 16 % 32 %34 dBm 13 % 26 %33 dBm 10 % 20 % (Default)32 dBm 8 % 16 % 31 dBm 6 % 12 %30 dBm 5 % 10 %

+2 dB+1 dB+0 dB-1 dB-2 dB-3 dB

% of 20W PA

% of 10W PA

CPICH power = 36 dBm is also

possible with 40W amplifiers

PtxPrimaryCPICHWCEL; -10..50; 0.1; 33 dBm

(Range; Step; Default)

(20 W sector)

• Transmitted power WCEL: PtxPrimaryCPICH should be 5%-10% of the total Tx Power for a 20W sector; Value = [-10 … 50] dBm, step 0.1 dBm

• The default value is 33dBm (2W) for 20W cell


Effects of CPICH Power modification

CPICH Transmit Power

Increased soft handover overhead

Too much

power

Too little

power

Less Power Available for traffic

CPICH coverage holes

code detection

Unreliable channel estimation

Early cell reselection /handover

Increased Eb/No requirement

Reduced system capacity


Reduced system coverage

Slow initial synchronization

Non- ideal traffic distribution

Late cell reselection /handover


CPICH Transmit Power

Increased soft handover overhead

Less Power Available for traffic

CPICH coverage holes

Unreliable scrambling code detection

Unreliable channel estimation

Early cell reselection /handout too early

Increased Eb/No requirement



Reduced system coverage

Slow initial synchronization


Late cell reselection /handout too late



SCH & P-CCPCH Power Setting

Primary Synchronisation Channel P-SCHused for DL slot (10ms/15) synchronisationP-SCH Tx power relative to CPICH.• Comments: optimal value allows decoding of the channel at the cell edge

Secondary Synchronisation Channel S-SCHused for DL Frame (10ms) synchronisationS-SCH Tx power relative to CPICH.• Comments: optimal value allows decoding of the channel at the cell edge

Primary Common Control Physical Channel P-CCPCH carries the BCH (Broadcast Channel) transport channel is a fixed rate (15 ksps, SF = 256) DL physical channel used to carry the BCHIt is a pure data channel and characterized by a fixed channelization code (Cch,256,1)It is broadcast over the entire cell and it is not transmitted during the first 256 chips of each slot, where P- SCH & S-SCH are transmittedP-CCPCH power relative to the CPICH power

PtxPrimarySCHWCEL; -35..15; 0.1; -3 dB


PtxSecSCHWCEL; -35..15; 0.1; -3 dB


PtxPrimaryCCPCHWCEL; -35..15; 0.1; -5 dB


2560 Chips256 Chips

P-CCPCH

S-SCH

P-SCH


Secondary CCPCH (1/6): Number of S-CCPCHs

• The Secondary Common Control Physical Channel S-CCPCH carries FACH & PCH transport channels

• NbrOfSCCPCHs: “Number of SCCPCHs” tells how many SCCPCHs will be configured for the cell. (1, 2 or 3)

• If only 1 SCCPCH is used in a cell, it will carry FACH-c (containing DCCH/CCCH /BCCH), FACH-u (containing DTCH) & PCH. FACH & PCH multiplexed onto the same SCCPCH.

• If 2 SCCPCHs are used in a cell, the 1st SCCPCH will carry FACH-u & FACH-c and the 2nd SCCPCH will always carry PCH only.

• If 3 SCCPCHs are used in a cell, the 3rd SCCPCH will carry FACH-s (containing CTCH) & FACH-c idle (containing CCCH & BCCH). The 3rd SCCPCH is only needed when Service Area Broadcast (SAB) is active in a cell.

NbrOfSCCPCHsWCEL; 1..3; 1; 1



Secondary CCPCH (2/6): Configuration 1

• If only 1 SCCPCH is used in a cell, it will carry FACH-c (containing DCCH/CCCH /BCCH), FACH-u (containing DTCH) and PCH. FACH and PCH multiplexed onto the same SCCPCH.

• the PCH bit rate is limited to 8 kbps

• the PCH always has priority

• the SF for SCCPCH, which is carrying FACH (with or without PCH), is 64 (60ksps)

Logical channel

Transport channel

Physical channel

DTCH DCCH CCCH BCCH PCCH

FACH-u FACH-c PCH

SCCPCH 1

SF 64

PtxSCCPCH1Transmission Power of SCCPCH1

WCEL; -35..15; 0.1; 0 dB


Secondary CCPCH (3/6): Configuration 2 a & b

• If 2 SCCPCHs are used in a cell, the first SCCPCH will carry FACH-u & FACH-c and the second SCCPCH will always carry PCH only.

• PCH bit rate limited to 8 kbps (RU10 & earlier) or can be extended

to 24 kbps (RU20 feature RAN 1202: 24 kbps Paging Channel)

• if PCH24kbps enabled, NbrOfSCCPCHs must be set to “2” or “3”

• if SAB Support with 2 SCCPCH enabled, SAB can be used with NbrOfSCCPCHs = “2”

Logicalchannel

Transportchannel

Physicalchannel

DTCH DCCH CCCH BCCH PCCH

FACH-u FACH-c/s PCH

SCCPCH 1 SCCPCH 2

SF 64 SF 256

PCH24kbpsEnabledWCEL; 0 (Disabled), 1 (Enabled);

default: 0 (Disabled)

SF 128or

PtxSCCPCH2used for 8 kbps paging

WCEL; -35..15; 0.1; -5 dB

PtxSCCPCH2SF128used for 24 kbps paging

WCEL; -35..15; 0.1; -2 dB

CTCH

For SABFor SAB


Logical channel

Transport channel

Physical channel

DTCH DCCH CCCH BCCH CTCH

FACH-u PCHFACH-s

SCCPCH connected

SCCPCH idle

PCCH

FACH-c FACH-c

SCCPCH page

For SABFor SAB

Secondary CCPCH (4/6): Configuration 3a & b• If 3 SCCPCHs are used in a cell, the 3rd SCCPCH will carry FACH-s (containing CTCH) & FACH-c

idle (containing CCCH & BCCH). The 3rd SCCPCH is only needed when Service Area Broadcast (SAB) is active in a cell.

SF 64 SF 128 SF 256

SF 128orPtxSCCPCH3

WCEL; -35..15; 0.1; -2 dB


Secondary CCPCH (5/6): Summary Power Setting • The power of SCCPCHs are set relative to CPICH transmission power, but it is based on the bitrate.

• The SF for SCCPCH, which is carrying FACH (with or without PCH), is 64 (60ksps)

• The SF for SCCPCH, which is carrying PCH only is 256 (15ksps) or 128 (30ksps)

• The SF for SCCPCH, which is carrying FACH-s/FACH-c idle for SAB, is 128 (30ksps)

• Recommended value of the SCCPCH Tx power is depended on the number of SCCPCHs:

• WCEL: PtxSCCPCH1 (SF=64) for PCH/FACH or standalone FACH

• WCEL: PtxSCCPCH2 (SF=256) for Standalone PCH (8 kbps paging)

• WCEL: PtxSCCPCH2SF128 (SF=128) for Standalone PCH (24 kbps paging)

• WCEL: PtxSCCPCH3 (SF=128) for SAB

PtxSCCPCH1WCEL; -35..15; 0.1; 0 dB


PtxSCCPCH3WCEL; -35..15; 0.1; -2 dB

SF: Spreading Factor

PtxSCCPCH2used for 8 kbps paging

WCEL; -35..15; 0.1; -5 dB

PtxSCCPCH2SF128used for 24 kbps paging

WCEL; -35..15; 0.1; -2 dB


Secondary CCPCH (6/6): Power offset for TFCI

• At setup or reconfiguration, the BS is given the SCCPCH power offset information (PO1 for TFCI bits). The TFCI bits are transmitted irrespective of whether or not there is data transmitted.

WCEL: PowerOffsetSCCPCHTFCI (child parameters: PO1_15, PO1_30, PO1_60)

this parameter defines the power offset of the TFCI bits relative to the power of the data field; the power offset shall vary in time according to the bit rate of the SCCPCHRange: [0…6] dB step 0.25 dB

Default:PO1_15 2 dB for the 15ksps (SF=256)

PO1_30 3 dB for the 30ksps (SF=128)

PO1_60 4 dB for the 60ksps (SF=64)

PO1 is power offsetof TFCI relative for the

power of data field.T slot = 2560 chips

Data

PO1

DL transmission

Power

TFCI

The higher the SCCPCH data rates, the more important it is to correctly read TFCI


PICH power setting• The PICH is transmitted constantly and it carries the Paging Indicators (PI) which the UE reads to find out

whether there is paging in the paging group which it belongs to.

• The number of paging indicators (paging groups) in PICH is a parameter. Smaller number means that there is more repetition in the paging symbols => less DL transmit power is needed BUT UE has to decode the paging message more often (higher battery consumption)

• Parameters to be optimised:

• WCEL: PtxPICH: Power of the PICH relative to the CPICH power• [-10 … 5] dB, step 1 dB, default depends on PI_Amount:

-10 dB for 18 and 36 PI/frame-8 dB for 72 PI/frame-5 dB for 144 PI/frame

• Related parameters:• WCEL: Pi_amount: Number of paging indicators in a frame, 18, 36, 72 or 144

(the repetition of PICH bits is 16, 8, 4 and 2 correspondingly)

• WCEL: UTRAN_DRX_length: [80; 160; 320; 640; 1280; 2560; 5120] ms. The DRX cycle length used by UTRAN to count paging occasions for discontinuous reception.

• IuCS & IuPS: CNDRXLength; CN domain specific DRX cycle length [640; 1280; 2560; 5120] ms. The DRX cycle length used by UTRAN to count paging occasions for discontinuous reception.

288 bit/frame

PtxPICHWCEL; -10..5; 1; -8 dB



PICH power optimisation

The larger the value of Pi_amount, the

• more paging groups are created per frame (the fewer the number of mobiles per group)

• less PIs are repeated per paging group and frame

• less often the UE is paged and it has to listen the SCCPCH (PCH) (leading to lower mobile power consumption but longer call setup time)

• less bits used for one paging indicator the more power for the PtxPICH

Morepower

for PICH

Morepower

for PICH

MoreUsersPer PI

MoreUsersPer PI

Pi_amount = 18 => 16 bits in PICH are used to indicate one PI is "active" , 18*16 = 288Pi_amount = 36 => 8 bits in PICH are used to indicate one PI is "active" , 36*8 = 288Pi_amount = 72 => 4 bits in PICH are used to indicate one PI is "active" , 72*4 = 288Pi_amount = 144 => 2 bits in PICH are used to indicate one PI is "active" , 144*2 = 288


AICH power setting

• AICH is carrying the Acquisition Indicators (AI) to reply to RACH pre-ambles. All together 16 AI can be multiplexed on one access slot in AICH.

• The parameter to be optimized:

WCEL: PtxAICH, the AICH Tx power is relative to CPICH.

Range: [-22 … 5] dB, step 1dB, default -8 dB

• Related parameters: PRACH parameters including PRACH_preamble_retrans, if AI power is too low for UE to decode, it keeps sending preambles until the PRACH_preamble_retrans is exceeded (see Open Loop Power Control).

PtxAICHWCEL; -22..5; 1; -8 dB



Total DL Common Channel Power without HSPA

Service Type

DefaultPower

MinimumActivity

Minimum Average

Power

Maximum Activity

Maximum Average

Power

CPICH 33 dBm 100 % 33 dBm 100 % 33 dBm

P-SCH 30 dBm 10 % 20 dBm 10 % 20 dBm

S-SCH 30 dBm 10 % 20 dBm 10 % 20 dBm

P-CCPCH 28 dBm 90 % 27.5 dBm 90 % 27.5 dBm

S-CCPCH 33 dBm 25 % 27 dBm 115 %* 33.6 dBm

PICH 25 dBm 96 % 24.8 dBm 96 % 24.8 dBm

AICH 25 dBm 0 % - 80 % 24 dBm

Total - - 35.5 dBm3.5 W

- 37.5 dBm5.6 W

* S-CCPCH control (TFCI) bits transmitted with higher power than data bits


Power Control

• Channel Mapping







UL Outer LoopPower Control

Open Loop Power Control(Initial Access)

(Fast) Closed Loop Power Control

RNCBS

MS

DL Outer LoopPower Control

Power Control types

BLER target


Power control during the call setup

Ptx

Time

UL: First RACH Preamble

power

UL: Power ramp-up

0PmpP

DL: Ack on AICH

UL: RACH data

Initial power of DPCH

CL & OL PC

DL: FACH

PRACH OpenLoop PC DPCH Open

Loop PCCL: Closed LoopOL: Outer Loop


CPICH Power setting / Effect of MHA & CableLoss parameters

WBTS

MHA

Relevant DL pathloss

Relevant UL pathloss

Feeder loss

• UL & DL path losses differ by feeder loss• UE needs UL path loss for proper setting of initial PRACH

power, but measures DL path loss as:

Broadcasted CPICH TX power – CPICH RX power• CableLoss parameter reduces the broadcasted value of

CPICH TX power, thus UE path loss estimation is correct for UL

CableLossWCEL: 0..100; 0.1; 3 dB

MHAMast Head Amplifier used; WCEL;

Offset not used (0), Offset used (1)(Range & Default)

If MHA = “Offset not used” ⇒ Primary CPICH TX power = PtxPrimaryCPICH

If MHA = “Offset used” ⇒ Primary CPICH TX power = MAX(PtxPrimaryCPICH – CableLoss, CPICHMin)

• It is possible to change the SIB5 IE P-CPICH Tx power through parameters MHA & CableLoss as below:

CPICHMin: min. value allowed for IE Primary CPICH TX


PRACH Open Loop PC• Purpose: To set the initial transmitted power of PRACH UL.

• UE determines the UL preamble power of PRACH

• UE PRACH First Preamble Power =

• Open loop PC is a part of the random access procedure for PRACH channel• For the accuracy of the UE Open Loop measurement, it is safest to start from a low power and increase it gradually

until the acquisition is received.

Path loss calculatio

ns

Path loss calculatio

ns

Minimum received power at

BTS

Minimum received power at

BTS

Transmission power of CPICH (Broadcast on BCH, SIB 5)) -

DL RSCP measurement from active cell on CPICH (Measured by UE) +

Total received wideband interference power at WCDMA BTS (Broadcast on BCH, SIB 7) +

PRACH Required Received C/I at the WCDMA BTS (Broadcast on BCH, SIB 5)

PRACHRequiredReceivedCI WCEL: -35..-10; 1; -25 dB

(Range, Steps; Default)

PRACHRequiredReceivedCI: • WCEL: range: -35..-10 dB; steps: 1.0 dB; default: -25 dB• This UL required received C/I value is used by the UE to calculate the initial output power on PRACH according to the Open Loop Power Control procedure.• If the value is too low then the RACH preamble ramping up takes a too long time. If it is too high, then it may cause blocking or high noise rise at BTS since the UE measurement on RSCP code power has a poor accuracy. • This parameter can impact on the RACH coverage.


Random Access Procedure

p-m

p-p

Message part

PRACHaccessslots TX atUE

1 access slot

p-a

Acq.Ind.

AICHaccessslots RX atUE

P0

Pp-m

Pre-amblePre-

amble

DL

UL

TS 25.211:

Preamble-to-Preamble distance p-p p-p,min = 6 / 8 Slots

Preamble-to-AI distance p-a = 3 / 4 Slots

Preamble-to-Message distance p-m = 6 / 8 Slots

Broadcasted by P-CCPCH; NSN (WCEL):

AICHTraTime = 0, 1; 0



Downlink / BSDownlink / BS

Preamble 1 Message part

…. ….

Preamble n

PRACH_preamble_retrans: The maximum number of preambles allowed in 1 preamble ramping cycle

RACH_tx_Max: # of preamble power ramping cycles that can be done

before RACH transmission failure is reported,

UEtxPowerMaxPRACH WCEL: -50..33; 1; 21 dBm

PRACH_preamble_retrans WCEL: 1..64; 1; 8

PowerRampStepPRACHpreamble

WCEL: 1..8; 1; 2 dB

Uplink / UEUplink / UE

PowerOffsetLastPreamble

PRACHmessageWCEL:

-5..10; 1; 2 dB

RACH_tx_Max WCEL: 1..32; 1; 8




• The power ramp-up process will continue until 1) A positive AI is received from the network Send RACH message2) A negative AI is received from the network Exit RACH procedure

3) PRACH_preamble_retrans value is exhausted ((WCEL)(1…64)( = 1)(8))

4) TX power exceed UEtxPowerMaxPRACH value by > 6dB Exit RACH procedure(WCEL)(-50dBm…33dBm)( = 1dBm)(21dBm)

• When the PRACH_preamble_retrans value is exhausted, PRACH preamble power will be re-set to the initial value of the cycle and a new power ramp-up cycle initiated. The preamble power ramp-up cycle will be repeated RACH_tx_Max times. At this stage the UE will send a RACH failure message to the UE MAC layer.

• The maximum allowed UE transmit power for the PRACH procedure is defined by UEtxPowerMaxPRACH. Layer 1 of the UE controls the UE transmit power during the PRACH procedure using the ‘commanded transmit power’. If the commanded transmit power exceeds the maximum allowed transmit power then the UE transmits the maximum allowed transmit power.

• If the commanded transmit power exceeds the maximum allowed transmit power by 6 dB then layer 1 of the UE is able to inform higher layers and exit the PRACH procedure. If the step size is 1 dB then this corresponds to transmitting 6 preambles at maximum power.

• As RU10 supports SIB4, UEtxPowerMaxPRACHConn applies in Connected Mode


PRACH Open Loop PC Parameters

Algorithm Parameters Group Default

Open Loop Power Control

PRACHRequiredReceivedCI WCEL -25 dB

PowerOffsetLastPreamblePRACHmessage WCEL 2 dB

PowerRampStepPRACHpreamble WCEL 2 dB

PRACH_preamble_retrans WCEL 8

RACH_tx_Max WCEL 8

UEtxPowerMaxPRACHConn WCEL 21 dBm


Power Control

• Channel Mapping







Uplink power control target

• Minimise required UL received power minimised UL transmit power and interference

UE1 UE2

Ptx1

Ptx1

- solve Near-Far Problem !- reduce Interference- stabilize transmission/ reduce required Eb/No optimize Capacity


• The closed loop power control scheme is fast enough to follow multipath fading for a wide range of mobile speeds

• Received Eb/No can be kept stable but on the other hand transmitted power is peaky

• => Received Eb/No can be kept low in spite of multipath fading, but fading margin must be added to transmitted powers

0 200 400 600 800-20

-15

-10

-5

0

5

10

15

20

Time (ms)

Rel

ati

ve

po

wer

(d

B)

Channel Transmitted powerReceived power

Fast closed loop power control


MS sets the power on UL DPCCHand UL DPDCH on following way:

TPC = '1' --> increase power by 1 dBTPC = '0' --> decrease power by 1 dB

UL DPCCH

MS

Measure received SIR on UL DPCCH Pilot

Compare measured SIR withSIR target value received from

UL outer loop PC

Measured SIR < SIR target --> TPC bit = '1'Measured SIR => SIR target --> TPC bit = '0'

BS

Send TPC bit on DL DPCCH

Changed power on UL DPCCH

UL Closed loop power control

• UL fast closed loop PC shall be active as soon as the frame synchronization has been established in the dedicated physical channels.

• PC frequency 1500 Hz

• PC step 1dB

• PC delay approx. one slot

• In Soft(er) HO power is increased only, if all (reliable) TPC bits are 1


UL PC Algorithm

• UE adjusts the DPCCH power by DPCCH = TPC TPC_cmd.

• Power control step size TPC is fixed to 1 dB in NSN RAN

• When a UE is not in soft(er) handover, only 1 TPC command will be received in each slot.

In this case, the value of TPC_cmd shall be derived as follows:

- If the received TPC command is equal to 0, then TPC_cmd for that slot is –1.

- If the received TPC command is equal to 1, then TPC_cmd for that slot is 1.

Every TS 1 dB up or down

• If the UE is in Soft(er) handover:• UE measures SIR for all the cells in the active set

• if SIR is sufficiently large, the TPC is considered reliable

• if only one of the reliable TPC bits is 0, the UE transmission power is decreased

• only if all reliable TPC are 1 the power in increased


DL Fast Closed Loop PC: UTRAN behaviour

UE

Measured SIR < SIR target --> TPC command is "1"

Measured SIR => SIR target --> TPC command is "0"

Compare measured SIR with SIR target

value received from DL outer loop PC

Measure received SIR on DL DPCCH

WCDMA BTS

BS sets the power on DL DPCCH andDL DPDCH following way:

TPC command = "1" --> increase power by 1 dBTPC command = "0" --> decrease power by 1 dB

DL DPCCH + DPDCHs

Send TPC command on UL DPCCH

Changed power on DL DPCCH + DPDCHs

• Upon receiving the TPC commands BS adjusts its DL DPCCH/DPDCH power accordingly.

• UTRAN shall estimate the transmitted TPC command TPCest to be 0 or 1, and shall update the power every slot.

• After estimating the k:th TPC command, UTRAN shall adjust the current DL power P(k-1) [dB] to a new power P(k) [dB] according to the following formula:

P(k) = P(k - 1) + PTPC(k) + Pbal(k)

where PTPC(k) is the k:th power adjustment due to the inner loop power controlPbal(k) is the k:th power correction due to Power balancing procedure

DownlinkInnerLoopPCStepSize

DownlinkInnerLoop PCStepSize

RNAC: 0.5..2; 0.5; 1 dB(Range, Steps; Default)


Gain of Fast Power Control PC

• Speech performance FER= 1% (8kbps 10ms interleaving) with 2 branch receiver antenna diversity in UL

• Slow PC = no PC in simulations = correct average power

Slow power control Fast 1.5kHz power control

Gain from fast power control

ITU Pedestrian A 3 km/h 11.3dBm 7.7dBm 3.6dB

ITU Vehicular A 3 km/h 8.5dBm 7.5dBm 1.0dB

ITU Vehicular A 50 km/h 6.8dBm 7.6dBm -0.8dB

• The gain from the fast PC is larger for low mobile speeds than for high mobile speeds in received powers than in transmitted powers if only little multipath diversity is available

• the less diversity there are, the higher is the average Tx power.

• Fast PC allows to reduce Eb/No values by reducing fading effects

• The drawback of the fast PC algorithm is a rise of average TX power

Transmittedpower


Power Control

• Channel Mapping







BS RNC

UL Outer Loop Power Control

• Outer PC loop is performed to adjust the TARGET SIR in BS/UE, according to the needs of individual radio link. Required SIR depends on

• UE speed• Changes in the propagation conditions• Available multipath diversity• UE power control dynamics (close to peak power)• SHO branches (Macro Diversity Combining)

• SIR is constantly adjusted in order to maintain a constant QUALITY, usually defined as a certain BLER target of the transport channel

• BLER is measured for each transport channel separately

DL Outer LoopPower Control

Outer Loop Power Control


UL OLPC

UL OuterLoop PCEntity #N

UL OuterLoop PCEntity #1

UL Outer Loop PCController

RNC

BTS 1UL Fast Closed

Loop PC

BTS 2UL Fast Closed

Loop PC

UL Outer Loop PC• In the RNC the functionality of the UL outer loop PC

is divided into two parts:

- UL outer loop PC Controller, one for each RRC

connection

- UL outer loop PC Entities, one for each

transport channel multiplexed in the same RL


UL OLPC Entities & Controller

• There is one UL outer loop PC Entity for each transport channel in the RNC.

• This UL OLPC Entity calculates the required change in SIR Target according to UL quality estimates (CRC).

• One of UL OLPC Entities under the same radio link is selected to transmit the New SIR Target to the WCDMA BTS.

• An UL Outer Loop PC Controller controls all UL OLPC Entities under the same RRC connection.

• The UL OLPC Controller sets the parameters for each UL OL PC Entities at the RAB Setup/Modification.

• The UL OLPC Controller also combines SIR Target changes from the UL OLPC Entities and sends the result to the UL OLPC Entity, which is selected to transmit it to the WCDMA BTS.

UL OuterLoop PCEntity #N

UL OuterLoop PCEntity #1

UL Outer Loop PCController

RNC

BTS 1UL Fast Closed

Loop PC

BTS 2UL Fast Closed

Loop PC

UL Outer Loop PC


Uplink OLPC Algorithm

1. RAB Setup:Initial SIR Target

UL Outer Loop PC Entity #n

UL Outer Loop PC Controller

2. - PC Parameters - Initial SIR target

8. Collection of the SIR target changes and calculation of new SIR Target

3. Setting of the UL Outer Loop PC Entities

2. PC Parameters at RAB setup

9. New SIR Target, active PC Entity

BTS1. SIR Target

1. UL fast closed loop PC

Admission Control

- Entity selected to carry the “active” flag

- Activity reporting period

4. - PC parameters

6. Calculation of SIR Target change

4. Parameters 7. SIR Target modification command

5. Quality info: BER, BLER

5. L1 FP: UL quality info

10. New SIR Target

10. L1 FP: SIR Target

10. Transmission of new SIR Target value to MDC

MDC


UL OLPC SIR target change• The algorithm for calculating the change of SIR Target is based on BLER estimation

Where:

And:

dB nTarget SIRnTarget SIR )()1( dB nTarget SIRnTarget SIR )()1(

)_(*_ tBLER_targeestimationBLERsizestep )_(*_ tBLER_targeestimationBLERsizestep

n_of_TBlstotal

RCsn_of_nok_CationBLER_estim

_

n_of_TBlstotal

RCsn_of_nok_CationBLER_estim

_

• This calculation is completed every TTI. This limits the resolution of the BLER estimation. For example, the speech service includes a single CRC per TTI and so the BLER estimate is either 0 % or 100 %.

• If the BLER target is 1 % then the SIRTarget is increased by the step size * 0.99 or decreased by the step size * 0.01, i.e. the SIR target tends to increase more rapidly than it decreases

• Data services have multiple CRC per TTI and can achieve a greater BLER estimate resolution• step_size is given by RNC: StepSizeForDCHBLER ((0.1…1dB)(0.1dB)(0.3dB)• RAN2886 Faster OLPC introduces new parameters for OLPC SIR Target change algorithm:

• Faster OLPC step size of SIR target changes RNAC: FOLPCStepSizSIRTgt ((0.1…1dB)(0.1dB)(0.1dB) defines minimum Δ[dB] that UL NRT return channel can request

• Faster OLPC SIR target modification interval RNAC: FOLPCSIRTgtModInt ((100..700 ms)(100ms)(200ms)defines the minimum interval between two SIR target modification commands sent by OLPC entity of UL NRT return channel

StepSizeForDCHBLERRNAC: 0.1..1; 0.1; 0.3 dB


FOLPCStepSizSIRTgtused for Faster OLPC

RNAC: 0.1..1; 0.1; 0.1 dB(Range, Steps; Default)

FOLPCSIRTgtModInt used for Faster OLPC

RNAC: 100..700ms; 100ms; 200ms(Range, Steps; Default)


PC parameters at RAB setup

At the RAB setup the UL outer loop PC Controller gets the following bearer and radio link specific parameters from the Admission Control :

Radio link specific parameters Initial SIR Target Minimum value of the SIR Target Maximum value of the SIR Target

Bearer specific parameters for each DCH Initial planned Eb/No target Target BLER (Block Error Ratio) Interleaving time


UL Quality deterioration• If the UL SIR target has reached the maximum and the UL SIR Target modification

commands, received by the outer loop PC controller from the current active PC Entity during ULQualDetRepThreshold seconds are all greater than zero, then the UL outer loop PC controller shall send the quality deterioration report to HC.

time

Target SIR

Max SIR target

Min SIR target

Actual SIR target

Quality deterioration report to HC

Quality deterioration report (if the condition is still satisfied

the message is periodically repeated)

ULQualDetRepThreshold

EnableULQualDetRepQuality deterioration report from

UL OLPC controller

RNMOBI: 0 (No) / 1 (Yes)(Steps; Default)

ULQualDetRepThresholdUL quality deterioration reporting threshold

RNMOBI : 0.5..5 s; 0.5s; 0.5s(Range; Steps; Default)


DL Outer Loop PC

• This function is implemented in the UE in order to set the SIR target on each CCTrCH used for the DL closed loop PC.

• This SIR value is adjusted according to an autonomous function of the UE in order to achieve the same measured quality as the quality target set by the RNC.

• In order to control the DL outer loop PC quality target in UE, Admission Control (AC) determines the value of the DL BLER target for each DCH mapped on a DPCH.

• After AC functionality has determined the DL BLER target for each transport channel, the RNC sends these values to the UE.

• DL outer loop PC during the compressed mode (CM)• Different SIR targets are used during & after compressed frames

• CM parameters provided by admission control are communicated to UE by RNC


Power Control






DL power control during SHO

• The transmit power of the added radio link is set at a calculated initial power

• based on CPICH Ec/No of the new RL from UE

• Power imbalance exists already at the beginning of the SHO

• theoretically equal to the Addition window after Event 1A

Initial Imbalance

• During SHO the DL power of the AS radio links should be at equal level (balanced) to achieve optimum interference performance

• Practical limitations cause imbalance between the RL powers• Initial imbalance• Power drifting

• Power balancing algorithm compensates the imbalance


Power drifting

• In case of the SHO, the single power control command from the UE is detected by each WCDMA BTS independently

• Due to detection errors the PC commands are decoded differently at different WCDMA BTS• DL transmission powers of radio link on the different WCDMA BTS start drifting apart i.e. the

powers are unbalanced

UE

PC command

PC command

Detection ofPCcommand

Adjustment of DL power

Detection ofPCcommand

Adjustment of DL power

4

BTS 1BTS 2

Cell2

Actual Power P(k) Diff Power

Power

Time

Cell1

M isinterpretion Cell1 power goes – 1dB wrong

Power drifting


Power Balancing• Power imbalance causes inefficient DL

power usage and capacity loss

• Power imbalance is eliminated by Power Balancing

• Power balancing algorithm is controlled by RNC

• BTS calculates power corrections used in DL fast closed loop power control

• Power Balancing can be activated with PowerBalancing; it is always used for SHO links

• Power Balancing ends automatically when• The SHO state ends• The dedicated measurement report does not

arrive from a SHO branch before timeout• Timeout is defined to be 10 times the largest

Reporting Period of all involved radio links

I ub

SRNC

BS #2

I ub

DRNC

BS #3

I ur

from BS's to RNC: Averaged DL power from RNC to BS's: Initial parameters, reference transmission power

L3

L3

L3

BS #1

DL fast closed loop PC / PB algorithm



HC/PBInit parameters+ Pref update

PowerBalancing RNFC; not in use (0), in use (1)

• The dedicated measurement fails for any active set branch• When the last RL of the serving RNC is deleted in anchoring situation

• Power balancing is not supported in anchoring, so it is deactivated • Power Balancing can be activated again if the anchoring situation ends


Power Balancing – RNC

• RNC calculates DL RL power reference value & send it to all BTSs involved in SHO• Reference power is sent in NBAP: DL POWER CONTROL REQUEST message

• Reference power only if change in value than value of parameter MinPrefChange

• 1st algorithm gives initial reference power, when Power Balancing is started up• The initial DL transmission powers of all radio links participating in the SHO are calculated and

the largest value is selected as Phighest

Initial reference power: Pref_ini = Phighest – PrefSubtract

• 2nd algorithm gives the updated reference power, when Power Balancing & related measurements already running

• RNC calculates reference value based on received DL RL power measurements PDLaverage

• Reference power can be updated after receiving the NBAP: DEDICATED MEASUREMENT REPORT from each SHO branch

• Highest AS BTS measurement value PDLaverage(s) is used for reference power calculation

Updated reference power: Pref = PDLaverage(s) – PP-CPICH(s) – PrefSubtract

PrefSubtractRNAC; 0..10; 1; 2 dB

MinPrefChange new Ref. Power to WBTS

only if change RNAC; 1..6; 1; 3 dB


Power Balancing – BTS

• Power balancing algorithm works in the WCDMA BTS together with the DL fast closed loop PC when the SHO is on

• The DL power at time instant k: P(k) = P(k-1) + PTPC(k) + Pbal(k)

AdjustmentPeriod

Cell2

Actual Power Imbalance

Power

Time

Reference power calculated by RNC Adjustment period starts

Cell1

AdjustmentPeriod

Power correctionsAdjustmentPeriod

RNAC; 1..256; 1; 2 framesperiod until DL Tx pwr has to be

corrected to Ref pwr

MaxAdjustmentStep RNAC; 1..10; 1; 8 slots

max. adjustment = 1 dB


• Power correction is calculated in the BTS so that the total change over the adjustment period AdjustmentPeriod equals

Pbal = (1 – r)(Pref + PP-CPICH(s) – Pinit)

Where

• Pinit is the code power of the last slot of the previous adjustment period

• r is the AdjustmentRatio

• Maximum adjustment is limited to 1 dB within MaxAdjustmentStep (time slots)

• During which the accumulated power adjustment will be no more than 1dB

Initial in-balance at the beginning of the adjustment period

AdjustmentPeriod RNAC; 1..256; 1; 2 frames

r = AdjustmentRatio RNAC; 1..100%; 1%; 0%

Power corrected to DL reference power

MaxAdjustmentStep RNAC; 1..10; 1; 8 slots

max. adjustment = 1 dB

Power Balancing – BTS


Power Balancing – Example

RNC

BTS1 BTS2

20 dBm 25 dBm

RNC

BTS1 BTS2

Pref = 25 dBm – 33 dBm – 2 dB = -10 dB

RNC

BTS1 BTS2

-10 dB -10 dB

RNC

BTS1 BTS2

23 dBm* 23 dBm*

1 2

3 4

Initial imbalance = -2 dBInitial imbalance = 3 dB

AdjustmentPeriod

* UE closer to BTS1 , power drivenby fast closed loop PC

Pref = PDLaverage(s) – PP-CPICH(s) – PrefSubstract

Pref = 25 dBm – 33 dBm - 2 dB = -10 dB

Pbal = (1-r) (Pref + PP-CPICH(s) – Pinit)

= (1 – 0) (-10 + 33 – 20) = 3 dB

Pbal = (1 – 0) (-10 + 33 – 25) = -2 dB

rn31673en30gla1 ranpar combined cchs and powercontrol v1.0 ru40 mb

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