05_RAC_GC

1 © Nokia Siemens Networks RA41215EN20GLA1

Radio Admission Control (RAC)LTE Radio Parameters RL20


1. LTE Functionalities and Overview

2. Channel Configuration

3. General parameter DB structure and System Information Broadcast

4. Random Access

5. Radio Admission Control (RAC)

6. Radio Bearer Control & DRX /DTX Management

7. LTE Mobility Management

8. UL/DL Scheduler

9. MIMO Mode Control (MIMO-MC)

10.Power Control

Contents


Module Contents

• Task of Radio Admission Control

• QoS Architecture and Profiles in LTE

• Default and Dedicated Bearers

• Multiple EPS bearers

• EPS bearers for conversational voice

• ROHC

• Emergency Call Handling

• Radio Admission Control algorithms and thresholds


Radio Admission Control Introduction 1

• Scope of RAC is cell level• RAC algorithms controls establishment of

– Signaling radio bearer– Data Radio Bearer

• RAC controls number of UE in a cell– Number of established RRC connection per cell– Number of active UEs (users) per cell

• RAC controls number of DRB in a cell– Number of data radio bearers (DRB)– Number of DRB with QCI=1

• RAC controls emergency calls and emergency sessions– Special margin considered for emergency calls– Special margin considered for IMS emergency sessions (RL30)


Radio Admission Control Introduction 2

• RAC applies different criteria for call estblishment and Mobility (HO)

– offset in terms of number of rrc connections or active users used, etc

– aim is to keep the already established sessions active and support user mobility

• RAC interacts with other RRM entities– Packet Scheduler

– Mobility management

– Radio Bearer Management

– UE State Management

• RAC acts based on events like:– paging

– Handover Request

– Call establishment request


Module Contents






• ROHC




Bearer model in GTP and IETF variants

P-GWS-GW PeerEntity

UE eNB

EPS Bearer

Radio Bearer S1 Bearer

End-to-end Service

Radio S5/ S8

Internet

S1

E-UTRAN EPC

SGi

S5/S8 Bearer

P-GWS-GW PeerEntity

UE eNB

EPS Bearer

Radio Bearer S1 Bearer

End-to-end Service

Radio S5/ S8

Internet

S1

E-UTRAN EPC

SGi External Bearer

IP

Transport

IP

Transport

IP

Transport

GTP variant:

EPS bearer termination in PGW

IETF variant:

EPS bearer termination in SGW

IETF: Internet Engineering Task Force


Simplifications in QoS profile

3G EPSQCI (QoS Class

Identifier)

ARP

Max Bit Rate

Guaranteed Bit Rate

Aggregate Max Bit Rate

For GBR bearers

For non-GBR bearers

• Number of QoS parameters has been decreased• AMRB as part of rate caping feature (LTE13) is supported in RL20

Guaranteed Bitrate

Delivery Order

Max SDU Size

SDU Format Information

SDU Error Ratio

Residual Bit Error Ratio

Delivery of Erroneous SDUs

Transfer Delay

Traffic Handling Priority

ARP

Source Statistics DescriptorSignalling Indication

Max Bitrate

Traffic Class


QoS parameters in EPS

• QoS Class Identifier (QCI)– QCI is used to determine packet forwarding treatment (e.g. scheduling of packets)– QCI is used to mark packets with DSCP (Differential Service Code Point)– 3GPP has standardized 9 QCI values and mapping to resource type (GBR, non-GBR),

priority, packet delay budget and packet error loss rate

• Allocation and Retention Priority (ARP)– ARP is used to decide whether bearer establishment or modification request can be

accepted in case of resource limitations– ARP can also be used to decide which bearer(s) to drop during resource limitations– It has been agreed in 3GPP that ARP has no impact on packet forwarding treatment

• APN Aggregate Max Bit Rate (APN-AMBR) and UE Aggregate Max Bit Rate (UE-AMBR) for non-GBR EPS bearers

– APN-AMBR shared by all non-GBR EPS bearers with the same APN – downlink enforcement is done in PDN GW and uplink enforcement in UE

– UE-AMBR shared by all non-GBR EPS bearers of the UE – downlink and uplink enforcement is done in eNB

• Guaranteed Bit Rate (GBR) and Max Bit Rate (MBR) for GBR EPS bearers


Standardized QCIs

GBR1

Resource type

Packet delay budget

Packet error loss rate Example ApplicationQCI

GBR

100 ms 1e-2 Conversation voice

2

GBR

150 ms 1e-3 Conversational video

3

GBR

50 ms 1e-3 Real-time gaming

4

Non-GBR 100 ms 1e-6 IMS signalling5

Non-GBR 300 ms 1e-6 Video, www, email, ftp6

Non-GBR7

Non-GBR8

Non-GBR9

Priority

2

4

3

1

6

7

8

9

300 ms 1e-6 Non-conversational video5

100 ms

300 ms

300 ms

1e-3

1e-6

1e-6

Interactive gaming

Video, www, email, ftp

Video, www, email, ftp

Note: Usage of operator specific QCIs in addition to standardized QCIs is possible (future).


RL20 supported QCIs

• NSN RL20 release supports the QCIs for non-GBR radio bearer services: QCI 5, 6, 7, 8 and 9

• In addtion features such as LTE10 enable QCI=1 conversational voice.

• QCI values > 9 are mapped into QCI 9.

• Parameters per QCI can be controlled on LNBTS level by qciTab.

QCIResource

Type Priority

Packet Delay

Budget

Packet Loss Rate

Default QCI Support

Default RLC Mode

RLC Profile Index

PDCP Profile Index

Further QoS

param.1 GBR 2 100 ms 1.0E-02 - - - - ...2 GBR 4 150 ms 1.0E-03 - - - - ...3 GBR 3 50 ms 1.0E-03 - - - - ...4 GBR 5 300 ms 1.0E-06 - - - - ...5 NON-GBR 1 100 ms 1.0E-06 - - - - ...6 NON-GBR 6 300 ms 1.0E-06 ENABLED RLC_AM 1 1 ...7 NON-GBR 7 100 ms 1.0E-03 ENABLED RLC_AM 1 1 ...8 NON-GBR 8 300 ms 1.0E-06 ENABLED RLC_AM 1 1 ...9 NON-GBR 9 300 ms 1.0E-06 ENABLED RLC_AM 1 1 ...

qciTabStructure {qci, resType, prio, Lcgid, qciSupp, rlcMode, rlcProfIdx, pdcpProfIdx, dscp, schedulWeight, schedulPrio, delayTarget}LNBTS;- ;9 ; -


LNBTS: qcitabx

LNBTS: qcitabx is a structured parameter with 12 parameters

dscp This parameter configures the DSCP (Differentiated Services Code Point)

Lcgid Logical Channel Group Identifier for buffer status reporting

pdcpProfIdx This parameter specifies the corresponding PDCP profile in the PDCP profile list.

prio This parameter gives the priority of the EPS bearer.

qci QoS Class Identifier.

qciSupp The given QCI is supported and enabled in this release

resType Permanent network resources allocated for GBR

rlcMode Configures the RLC mode of the radio bearer based on the corresponding QCI

rlcProfIdx This parameter specifies the corresponding RLC profile in the RLC profile list

schedulBSD Configure the Bucket Size Duration (BSD) of the UL scheduler

schedulPrio Logical Channel Priority for the UE scheduler

schedulType Specifies how the EPS bearer with this QCI is scheduled. Only for QCI=5

schedulWeight Specifies the scheduling weight for eNB schedulers

delayTarget The maximum packet delay value used by the eNB MAC scheduling algorithm. Only for QCI=1


LNBTS: qcitabx in

eNB SCF file

• qcitab1 and qcitab5 shown

Example: LNBTS: qcitabx


Module Contents






• ROHC




Default Bearers

• The initial Default EPS Bearer is created as part of the LTE Attach procedure.– UE is allocated an IP address.– QoS is based on the QCI and associated parameters.

• Additional Default EPS Bearers may be created when simultaneous access to services available via multiple Access Point Names (APN) is needed.– Trigger of an additional Default EPS Bearer is initiated by UE.– Default EPS Bearers are always non-GBR.

P-GWS-GWUE eNB

InternetE-UTRAN EPC

Radio S1-U S5 /S8 SGi

Default EPS Bearer

SRB2

SRB1


Dedicated EPS Bearers • Dedicated EPS Bearers (non-GBR or GBR) are created for QoS differentiation purposes.

– The IP address allocated for the default bearer is used for the dedicated EPS bearers within the same PDN connection.

– Utilization of default or dedicated EPS bearers is based on a Traffic Flow Template (TFT).

– Dedicated EPS Bearers are created by network.– RL20 supports multiple dedicated EPS bearers (not supported in RL10)– RL20 supports “conversational voice” on GBR dedicated EPS bearers (not supported

in RL10)

• The UE may have multiple dedicated EPS bearers linked to a default EPS bearer.

P-GWS-GWUE eNB

Default EPS Bearer

InternetE-UTRAN EPC


Dedicated EPS Bearer

Dedicated EPS Bearer

SRB2

SRB1


Module Contents






• ROHC




LTE7 Support of multiple EPS bearers

The Flexi Multiradio BTS supports up to four EPS bearers.

The following radio bearer combinations per UE are supported by the Flexi Multiradio BTS:– SRB1 + SRB2 + 1 x AM DRB (+ 1 x UM DRB with LTE10)

– SRB1 + SRB2 + 2 x AM DRB (+ 1 x UM DRB with LTE10)



Multiple sessions with different QoSMultiple sessions with different QoS

GBR EPS bearer

Non-GBR EPS bearer

SRB (signaling radio bearer)

Flexi Multiradio BTS S-GWUE

Note: LTE10 EPS bearers for conversational voice

actMultBearersactivates the support of multiple EPS Bearers.

LNCEL; true,false; true


LTE7 Support of multiple EPS bearers

• Multiple DRB (data radio bearers) can be either multiple default EPS bearers or a combination of default and dedicated EPS bearers.

• The radio admission is extended by additional check of the total number of DRB per cell and maximum number of DRB per UE.

• The different EPS bearers per UE can have the same or a different QCI.


• The service differentiation functionality allows to assign relative scheduling weights for each non-GBR QCI on cell level.

• The relative weight will be considered by the uplink and the downlink scheduler.

• The service differentiation functionality allows further on to define three different RLC/PDCP profiles per BTS which can be assigned to different QCIs.

• The operator can enable/disable the support of individual QCIs.

LTE9 Service differentiation for non-GBR EPS bearers

QCI based service differentiation QCI based service differentiation

actnonGbrServiceDiffactivates the Service Differentiation for non-GBR Bearers.

LNCEL; true,false; ; true


Module Contents






• ROHC




LTE10 EPS Bearers for Conversational Voice

• In RL20 voice service shall be transmitted using dedicated bearers. Voice requires two bearers:– QCI 1 for user data

– QCI 5 for IMS signaling

P-GWS-GWUE eNB

Default EPS Bearer (AM)

InternetE-UTRAN EPC


SRB2

SRB1

Dedicated EPS Bearer (UM)VoIP GBR, UM, QCI=1

VoIP GBR, UM, QCI=1

actConvVoiceActivates the support of the conversational voice bearerLNCEL; false, true; false


QCI translation table for QCI1,5-9

Parameter NameDefaults QCI1

Defaults QCI5

Defaults QCI6

Defaults QCI7

Defaults QCI8

Defaults QCI9

QCI 1 5 6 7 8 9

Resource Type 0(GBR) 1(NonGBR) 1(NonGBR) 1(NonGBR) 1(NonGBR) 1(NonGBR)

Priority 2 1 6 7 8 9

QCI Support 1 1 1 1 1 1

RLC Mode RLC_UM RLC_AM RLC_AM RLC_AM RLC_AM RLC_AM

RLC Profile Index 101 1 2 1 2 2

PDCP Profile Index 101 1 2 1 2 2

Logical Channel Group Id 1 2 3 2 3 3

Scheduling BSD 1 1 3 1 3 3

Scheduling Priority 5 9 9 10 11 12

Scheduling Type* n/a 1 n/a n/a n/a n/a

Scheduling Weight n/a 40 20 10 5 1

DelayTarget 80ms n/a n/a n/a n/a n/a

DSCP 46 34 18 20 10 0

DSCP to PHB map AF41 AF41 AF21 AF22 AF11 BE

PHB queue weight list 10000 10000 100 100 10 1

* - only for QCI5

For UL and DLFor UL and DL

Not modifiable

LTE131 Traffic prioritization on IP

layer (DiffServ)

Not modifiable

Not modifiable

RRM configuration related parameters

Not modifiable

Has to be set to 0 (signaling) when using

LTE10

If actnonGbrServiceDiff “disabled” QCI9 must be

“enabled”

QOS/dscpMap

QOS/perHopBehaviourW

eightList


Module Contents






• ROHC




Motivation for ROHC (LTE11)

• IP/UDP/RTP headers size can be either 40 bytes (52% of a packet) for IPv4 or even 60 bytes (63%) for IPv6

This means enormous waste of energy for transmitting headers instead of speech data

• In order to prevent that waste, in RL20, in parallel to LTE10 Conversational Voice, there is also LTE11 feature which provides the functionality of Robust Header Compression

• For example, with ROHC, a 10 minutes of 12.2 kbps AMR coded VoIP call with talk spurt/silent period alternating every 1 second (SID packets excluded), the transmission overhead is reduced by 91.5%

actPdcpRohcactivates the usage of PDCP Robust Header CompressionLNCEL; false, true; false


Idea of compression

IP/UDP/RTP header consisting of predictable and unpredictable fields - subjected to compression

Field predictable in the course of transmission -

„Destination IP”

MAC header, RLC header, VoIP payload, CRC

checksum - not subjected to compression

10.0.0.10

10.0.0.10

10.0.0.10

10.0.0.10

10.0.0.10

10.0.0.10

6

3

7

0

1

8

„from now on assume Destination IP is 10.0.0.10”

10.0.0.10 6

3

7

0

1

8

x

Uncompressed transmission

Compressed transmission

Unpredictable field

Initial transmission, „context” is initialized so that next

transmissions can be compressed

Context - information about all fields that are predictable and their change patterns sent in the beginning of transmission to allow header compression

In the course of transmission header fields initialized in context do not have to be

transmitted

rohcMaxCidconfigures the maximum number of ROHC contexts used for a data radio bearer in one directionLNCEL; 1,…,16;1; 4


Module Contents






• ROHC




Emergency Call Handling (LTE22)

• Introduces CS Fallback functionality applicable to emergency calls only

• There are two cases:Case 1: UE is idle mode, eNB checks RRC Connection Request for call

establishment cause and in case it is 'Emergency', then a separate admission threshold is used and calls will not be rejected due to capacity license limitations

RRCConnectionEstablishmentRequest, Cause: Emergency

CS Fallback Redirect to UTRAN or GSM

Admission control: AdmittedUE initials an emergency call

actEmerCallRediractivates the feature 'Emergency Call Via Redirection'.LNBTS; Disabled (0), Enabled (1);- ; Disabled (0)


Emergency Call Handling (LTE22)

Case2: MME is sending CS Fallback Indicator IE with value 'CS Fallback High Priority'

MME

CS Fallback High Priority

MME initials an emergency call

CS Fallback Redirect to UTRAN or GSM


Module Contents






• ROHC




Radio Admission Control

• RL20 RAC checks against operator configurable thresholds– on call establishment:

max_number_of_rrc_connection max_number_of_rrc_connection_emergency_calls (LTE22 supported) max_number_of_active_users max_number_of_active_DRB (LTE7 supported) max_number_of_QCI1_DRB (LTE10 supported)

– on intra-frequency (incoming) handover:

additional offsets can be defined for • time critical handover (event A5)

• handover desired for radio reasons (event A3)

„all or nothing“ – SRB && DRB must be admitted in target cell


RL20 Admission of SRB1

• RAC compares the number of currently allocated RRC connections in the cell

against following parameter:

• Admission Control criteria for Signalling Bearer:

maxNumRrc

(LNCEL)

Name Range Description

0...840, step 1

Default

240

(420)*

Maximum number of UEs in the cell with an established RRC connection.

Note*: min(ulChBw,dlChBW) is set to value '20 MHz'

Number of currently established RRC connections < maxNumRrc


Admission of signaling radio bearer SRB1

if min(ulChBw,dlChBw) has value ' 5MHz' and '10 MHz'- maxNumRrc value range is restricted to 0...480 (default value 240)- maxNumRrc+max(addAUeRrHo, addAUeTcHo) <= 480

if min(ulChBw,dlChBw) has value '15 MHz ' and '20 MHz'- maxNumRrc value range is restricted to 0...840 (default value 420)- maxNumRrc+max(addAUeRrHo, addAUeTcHo) <= 840

addAUeRrHoAdditional # of active UEs, which are allowed to access a cell via handover with HO cause: "HO desirable for radio reasons", when RRC connection (maxNumRrc) or active UE (maxNumActUE) limit already reached.LNCEL; 0...840;1; 15

addAUeTcHoAdditional # of active UEs, which are allowed to access a cell via handover with HO cause: "Time critical handover", when RRC connection (maxNumRrc) or active UE (maxNumActUE) limit already reachedLNCEL; 0...840;1; 20

„0“ implies that no admission priority is granted for UEs accessing the cell via HO


RL20 Admission of SRB1 for Emergency Call

• RAC compares the number of currently allocated RRC connections in the cell

against following parameter:

• Admission Control criteria for Signalling Bearer:

Note: maxNumRrcEmergency should be greater than the actual configured threshold maxNumRrc

maxNumRrcEmergency

(LNCEL)


0...840, step 1

Default

440

(800)*

Maximum number of UEs in the cell which may establish a RRC connection for an emergency call.

Note*: min(ulChBw,dlChBW) is set to value ‚15 MHz‚ or '20 MHz'

Number of currently established RRC connections < maxNumRrcEmergency


RL20 Admission of Single non-GBR radio bearer

• As par of the S1AP initial context setup, the bearer management function requests RAC to admit the single non-GBR data radio bearer setup request for UEs for which the SRB1 and SRB2 have been successfully established.

• RAC compares the number of currently UEs with established DRB in the cell against following parameter:

• Admission Control criteria for non-GBR radio bearer:

maxNumActUE

(LNCEL)


0...840, step 1

Default

120

(240)

Maximum number of UEs in the cell with established DRB.

Note: default 240 for 20MHz

number of currently active UEs < maxNumActUE


if min(ulChBw,dlChBw) has value '10 MHz'- maxNumActUE value range is restricted to 0...480 (default value 120)- maxNumActUE +max(addAUeRrHo, addAUeTcHo) <= 480

if min(ulChBw,dlChBw) has value '20 MHz'- maxNumActUE value range is restricted to 0...840 (default value 240)- maxNumActUE +max(addAUeRrHo, addAUeTcHo) <= 840

Admission of single non-GBR radio bearer

addAUeRrHoAdditional # of active UEs, which are allowed to access a cell via handover with HO cause: "HO desirable for radio reasons", when RRC connection (maxNumRrc) or active UE (maxNumActUE) limit already reached.LNCEL; 0...840;1; 15

addAUeTcHoAdditional # of active UEs, which are allowed to access a cell via handover with HO cause: "Time critical handover", when RRC connection (maxNumRrc) or active UE (maxNumActUE) limit already reachedLNCEL; 0...840;1; 20


RL20 Admission of Multiple EPS bearers

• The bearer management function requests RAC to admit the data radio bearer setup request for UEs for which the SRB1 and SRB2 have been successfully established.

• RAC compares the number of currently established DRB in the cell against following parameter:

• Admission Control criteria for Multiple EPS bearers:

maxNumActDrb

(LNCEL)


0...4200, step 1

Default

360

(720)

maximum number of established DRBs in the cell.

Note: default 720 for 20MHz

number of currently established DRBs < maxNumActDrb


If dlChBw is set to '5 MHz' or '10 MHz'

- maxNumActDrb + max(addNumDrbRadioReasHo, addNumDrbTimeCriticalHo) <= 2400

If dlChBw is set to '15 MHz' or '20 MHz'

- maxNumActDrb + max(addNumDrbRadioReasHo, addNumDrbTimeCriticalHo) <= 4200

Admission of Multiple EPS bearers

addNumDrbRadioReasHoAdditional margin for the maximum number of active DRBs in the cell accessing the cell via HO with HO-cause: "HO desirable for radio reasons“.LNCEL; 0...4200;1; 35

addNumDrbTimeCriticalHo Additional margin for the maximum number of active DRBs in the cell accessing the cell via HO with HO-cause: "Time Critical HO".LNCEL; 0...4200;1; 60


RL20 Admission of QCI1 Conversational bearers

• The bearer management function requests RAC to admit the data radio bearer setup request for UEs‘ conversational voice

• RAC compares the number of currently established QCI=1 DRB in the cell against following parameter:

• Admission Control criteria for QCI=1 Conversational EPS bearers:

maxNumQci1Drb

(LNCEL)


0...200, step 1

Default

100 Max Number QCI1 DRBs (GBRs)

number of currently established QCI=1 DRBs < maxNumQci1Drb


If dlChBw is set to '5 MHz'

- maxNumQci1Drb + max( addNumQci1DrbRadioReasHo, addNumQci1DrbTimeCriticalHo) <= 150,

If dlChBw is set different to '5 MHz'

- maxNumQci1Drb + max( addNumQci1DrbRadioReasHo, addNumQci1DrbTimeCriticalHo) <= 200

Admission of QCI1 Conversational bearers

addNumQci1DrbRadioReasHo Additional margin for the maximum number of active DRBs in the cell accessing the cell via HO with HO-cause: "HO desirable for radio reasons“.LNCEL; 0...200;1; 15

addNumQci1DrbTimeCriticalHo Additional margin for the maximum number of active DRBs in the cell accessing the cell via HO with HO-cause: "Time Critical HO".LNCEL; 0...200;1; 20


Radio Bearer Management

• Main feature of RL20 is retrieval and utilisation of UE capabilities in RRM– A Layer 3 RRC signaling procedure

– 3GPP TS 36.306 defines UE capabilities

RRC: UECapabilityEnquiry

eNBUE

RRC: UECapabilityInformation

Ue-RadioAccessCapRequest (eutra)

{(eutra, ueCapabilitesRAT-Container (UE-EUTRA-Capability)), optional UE capabilitities for other RAT types}


Radio Bearer Management

• Radio Admission Control may select UL/DL maximum bitrates for a UE:– based on UE capability information received from UE (mbrSelector=0)

– based on O&M parameters maxBitRateUl and maxBitRateDl (mbrSelector =1)

• The maximum Bitrate for a UE in UL and DL for all radio

bearers incl. SRBs are limited to O&M parameter setting:

mbrSelectorLNCEL; 0 (ueCapability), 1 (OaM) ; 0

maxBitRateDlLNCEL; 50…300000kbps;50 ; 170000 Kbps

maxBitRateUlLNCEL; 50…75000kbps;50 ; 50000 Kbps


Radio Admission Control for intra-frequency HO

• For LTE intra-frequency handover there can be separate admission control

thresholds defined depending on HO trigger cause:

– Time Critical Handover – flag is set when HO trigger is event A5 (urgency is „high“ for coverage handover (event A5))

– Handover Desirable for Radio Reasons – flag is set when HO trigger is event A3 (urgency is „low“ for power budget handover (event A3))

• Better to support the call with Handover rather than rejecting and/or dropping


Radio Admission Control for intra-frequency HO

Definition of new admission control threshold for time critical HO:

• HoThreshRrc = maxNumRrc + max(addAUeTcHo, addAUeRrHo)• HoThreshUe = maxNumActUe + max(addAUeTcHo, addAUeRrHo) • HoThreshDrb = maxNumActDrb + max(addNumDrbRadioReasHo, addNumDrbTimeCriticalHo) • HoThreshGbr = maxNumQci1Drb + max( addNumQci1DrbRadioReasHo, addNumQci1DrbTimeCriticalHo)

If NumRRC < HoThreshRrc AND NumActUE < HoThreshUe AND NumActDrb < HoThreshDrb AND NumQci1Drb < HoThreshGbr then

admit HO request in target cell

Otherwise reject HO request for target cell

05_RAC_GC

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