06 RA41216EN10GLA1 Radio Bearer Control

8/12/2019 06 RA41216EN10GLA1 Radio Bearer Control

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Radio Bearer Control & DRX/DTX Management

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1 Nokia Siemens Networks RA41216EN10GLA1

Radio Bearer Control & DRX/DTXManagementLTE Radio Parameters RL10


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Nokia Siemens Networks Academy

Legal notice

Intellectual Property RightsAll copyrights and intellectual property rights for Nokia Siemens Networks training

documentation, product documentation and slide presentation material, all of which areforthwith known as Nokia Siemens Networks training material, are the exclusive property ofNokia Siemens Networks. Nokia Siemens Networks owns the rights to copying,modification, translation, adaptation or derivatives including any improvements ordevelopments. Nokia Siemens Networks has the sole right to copy, distribute, amend,modify, develop, license, sublicense, sell, transfer and assign the Nokia Siemens Networkstraining material. Individuals can use the Nokia Siemens Networks training material for theirown personal self-development only, those same individuals cannot subsequently pass onthat same Intellectual Property to others without the prior written agreement of NokiaSiemens Networks. The Nokia Siemens Networks training material cannot be used outsideof an agreed Nokia Siemens Networks training session for development of groups withoutthe prior written agreement of Nokia Siemens Networks.


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After completing this learning element, the participant should

be able to: State different connection / activity states of an LTE UE in

comparison to UMTS

Identify performance related aspects of the feature

Describe different transitions and relevant triggers as e.g.activity/inactivity detection

State the possible configuration choices for DRX/DTX


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1. LTE Functionalities and Overview

2. Channel Configuration3. 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


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Module Contents

UE State handling

DRX/ DTX Overview

DRX for Paging in Idle Mode

DRX/ DTX in Connected Mode (not in RL10)

Background/ Additional Slides

DRX = discontinuous reception

DTX = discontinuous transmission


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States in UTRAN, GERAN, E-UTRA

The 3 transitions supported by the RL 09/10 LTE Inter working features:

Handover

CELL_PCH

URA_PCH

CELL_DCH

UTRA_Idle

E-UTRA

RRC CONNECTED

E-UTRA

RRC IDLE

GSM_Idle/GPRS

Packet_Idle

GPRS Packet

transfer mode

GSM_Connected

Handover

Reselection Reselection

Reselection

Connection

establishment/release

Connection


Connection


CCO,

Reselection

CCO with

optional

NACC

CELL_FACH

CCO, Reselection

Supportedby feature

RL20

3G LTE GSM

SupportedRL10

Supportedby feature

RL10

Supportedby feature

RL10*CCO = Cell Change Order

NACC = Network Assisted Cell Change


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Definition of main EPS Mobility Management states

EMM-DEREGISTERED

The UE is not reachable by a MME. UE context can still be stored in the UE and MME

EMM-REGISTERED UE enters to EMM-Registered with Attach or Tracking Area Update procedure

The UE location is known with accuracy of the tracking area list

UE has at least one active PDN connection

After Detach procedure the state is changed to EMM-DEREGISTERED

UE state handling :Mobility Management States

Attach accept

DetachAttach rejectTAU Reject

All Bearer Deactivated

EMM-DEREGISTERED EMM-REGISTERED

EMM states in UE

Attach acceptTAU Accept

DetachAttach rejectTAU Reject

All Bearer Deactivated

EMM-DEREGISTERED EMM-REGISTERED

EMM states in MME


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Definition of EPS Connection Management states

ECM-IDLE UE is in ECM-IDLE state when no NAS signalling connection between UE and network exists.

In the EMM-REGISTERED and ECM-IDLE state, the UE shall perform: Tracking Area Update Periodic Tracking Area Update Service Request Answer to paging from MME with Service Request

UE and MME enter the ECM-CONNECTED state when signaling connection is established.

ECM-CONNECTED UE location is known in the MME with an accuracy of a serving eNodeB.

For a UE in the ECM-CONNECTED state, there exists a signalling connection between the UE andthe MME.

The S1 release procedure changes the state at both UE and MME from ECM-CONNECTED toECM-IDLE.

UE state handling :Mobility Management States

RRC Established

RRC Released

EMM-IDLE EMM-CONNECTED

EMC states in UE

S1 Established

S1 Released

EMM-IDLE EMM-CONNECTED

EMM states in MME


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Module Contents

UE State handling

DRX/ DTX Overview







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DRX/DTX General Motivation is the Challenge > BatteryCapacity Increases only Slowly Compared to Moores Law

Joseph A. Paradiso Massachusetts Institute of Technology MediaLaboratory, Thad Starner Georgia Institute of Technology, GVU

Center Energy Scavenging for Mobile and Wireless Electronics,Pervasive Computing, IEEE Volume 4, Issue 1, Jan.-March 2005Page(s):18 - 27 Digital Object Identifier 10.1109/MPRV.2005.9

CPU by Mooreslaw = double

every 18 months

Battery capacitydouble every 12

years

Battery savings

are a must and

are proportional to

active/inactive ratio


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Normal eNB initiated Transition to ECM-IDLE (e.g.due to user inactivity)

eNBUE MME S-GW

S1AP: UE Context Release Command

S1AP: UE Context Release CompleteRRC: RRC Connection Release

Release all UE relatedresources,

remove UE context

Set UE toRRC-IDLE

Set UE toECM-IDLE

Detect user inactivityor other eNB trigger

S1AP: UE Context Release Request

S11 interaction to inform S-GW

about connection release

UE inRRC-CONNECTED

L2 ACK

Main impact > UE- consumes less battery power in idle mode and there

are less active UEs which network have to handle. Fast going to inactivity

has drawback of longer connection setup time (transition idleconnected)

inactivityTimerInactivity for UL & DL

LNCEL; 10..65535s; 1s ; 300s

When both schedulers indicate inactivity on DL as well as on UL (based on DRBdata availability) the UE inactivity detection algorithm indicates UE combined activitystate inactivity to UE State Handling (UE-SH). Following this indication UE

combined activity state is reset to activity again such that as soon as the aboveconditions are met again another indication of UE inactivity to UE state handling isperformed.

Schedulers are also indicating a UE being active again to UE inactivity detectionalgorithm such that always the correct state of UL and DL activity is reflected inDRX/DTX-ALG. Once of the transmission directions becoming active again is notexplicitly reported to UE state handling.

The inactivity timer applied by the schedulers is O&M configurable T_INACTIVE

The effect of an UE inactivity indication to UE state handling is not reported back toDRX-DTX-ALG. If the UE is removed from RRC_CONNECTED state this will bevisible via release of all RBs of a UE from RAC.


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DTX/DRX Discontinuous Transmission/ Reception

Discontinuous reception/transmission means UE transceiver

is switched off for some predefined time periods. This savepower consumption on one side but might consequences inlonger call setup time and/or lower user throughputachievable.

What are DRX/DTX options?

In Idle mode for Paging this option means UE is listeningpaging messages in predefined time opportunities only andsleeping all other time. Supported in RL10.

DRX/DTX in connected mode UE is switched off forpredefined time interval. Not supported for RL10.


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Module Contents

UE State handling

DRX/ DTX Overview







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Discontinuous Reception for paging (TS 36.304)

The UE may use Discontinuous Reception (DRX) in idle mode

in order to reduce power consumption.One Paging Occasion (PO) is a subframe where there may be

P-RNTI transmitted on PDCCH addressing the pagingmessage.

One Paging Frame (PF) is one Radio Frame, which maycontain one or multiple Paging Occasion(s).

When DRX is used the UE needs only to monitor one PO perDRX cycle.


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Paging Related DRX/DTX Parameters in RL10

defaultPagingCycle The Default Paging Cycle defines the cell specific paging DRX cycle duration. It

also determines the maximum paging DRX duration applicable in the cell.Referred to as ' T ' in TS 36.304. Value 32rf corresponds to 32 radio frames,64rf corresponds to 64 radio frames and so on (possible vales to set are 32rf(0), 64rf (1), 128rf (2), 256rf (3), default 128rf).

One rf means radio frame = 10ms in time Increasing parameter value save battery capacity in idle mode as listening to

paging is less frequent, but mean call setup time is getting longer due to longeraverage paging time.

pagingNb Paging nB defines the number of possible paging occasions per radio frame,

i.e. the density of paging occasions. This parameter is used to calculate thenumber of paging occasions within one paging DRX duration, which in turn isused to calculate the paging occasion. (possible values to set are RL09 areoneT (2), halfT (3), quarterT (4), oneEighthT (5), oneSixteenthT (6),

oneThirtySecondT (means 1/32 as per TR36.304) (7), default is quarterT). Side values existing in RL10 3GPP defines also possible values fourT and twoTwhich are not implemented in RL10. Reason more than 1 paging occasion perradio frame seems unrealistic.


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Occasion of Paging Messages

The cell specific DRX cycle length Tsib is broadcasted by SystemInformation (PCCH-Config parameter defaultPagingCycle (in number of

radio frames) - defined by O&M).

The UE specific DRX cycle length Tue might be received from corenetwork from S1AP Paging Message as Optional IE.

The used paging DRX Cycle T (in number of radio frames) is setto:T=MIN(Tue,Tsib). (Referred to as ' T ' in 3GPP TS 36.304)

The relationship paging occasions - radio frame is given by theparameter pagingNb provided in System Information (PCCH-Configparameter pagingNb). nB shall be interpreted as a calculation formula(how to derive paging occasions from T). For better understanding, theresult of the calculation formula nB will be written as nB(T) in this section.Example: quarterT denotes nB(T)= 1/4*T (there is one paging occasion inevery 4th radio frame).


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Occasion of Paging Messages Explain ofVariables as per SFS (UE Behavior)

Paging capacity is not a limiting factor as the Paging Channel (PCH) ismapped dynamically on the PDSCH.

The factor (T div N) gives the distance of radio frames with pagingoccasions. The calculation of the factor (T div N) is 2(i-k).

The factor (UE_ID mod N) gives a relative index of a radio frame withpaging occasions inside a Paging DRX cycle. The calculation of factor(UE_ID mod N) is a simple mask operation for the last k bits.

The product (T div N)*(UE_ID mod N) gives the relative position of a radioframe with paging occasions relative to the start of a Paging_DRX cycle.

(SFN mod T) provides a SFN numbering relative to the start of a Paging-DRX cycle. The calculation of factor (SFN mod T) is a simple mask

operation for the last i bits. Example of paging with impact of mean paging time:

Microsoft Excel

Worksheet

*SFS = System Feature Sheet


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Example (as per UE Behaviour SFS, simplified, note theTue is smaller than allowed by 3GPP):

Assumptions:

Cell paging DRX Tsib = 32(frames),

nB(T)=halfT,UE paging DRX Tue = 8 (frames)

Calculation:

T = MIN(Tue,Tsib) = MIN(8,32) = 8 frames -> DRX cycle length

nB(T) = half(8) = 4 -> paging occasions per DRX cycle

N = MIN(T,nB(T)) = MIN(8,4) = 4 paging groups

Ns = MAX(1, nB(T)/T) = MAX(1, 4 / 8) = MAX(1,0)= 1 subframe used for paging

UE_ID = 3, assumption for this example (it could be any number)

T div N = 8 div 4 = 2 -> distance between 2 radio frames with paging occasions

UE_ID mod N = 3 mod 4 = 3 -> relative index of a frame with PO inside DRX

(T div N)*(UE_ID mod 4) = 2*3 = 6 -> relative position of the PO inside DRX

Let next reachable be SFN = 501; therefore (SFN mod T) = 5; therefore SFN forpaging is 501+(6-5)=502.

Simplified case (*to be shown in the picture) as the Tue is smaller than allowed by3GPP.

SFN

T div N

T (Paging DRX)PagingOccasionPO

[SFN=x*T] [SFN=(x+1)*T]

(T div N)*(UE_ID mod N)

*SFS = System Feature Sheet


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Module Contents

UE State handling

DRX/ DTX Overview







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DRX Principles (not in RL 10, planned for RL20)

DRX Cycle (DRXPeriod):

Specifies theperiodic repetitionof the On- Durationfollowed by apossible period ofinactivity.

On Duration Timer: Specifies the number of consecutive TTIs during which the UE shall monitor the PDCCH

for possible allocations. The On Duration Timer is a part of a DRX Cycle.

DRX Inactivity Timer: Specifies the number of consecutive TTIs during which the UE shall monitor the PDCCH

after successfully decoding a PDCCH indicating an initial UL or DL user data transmissionfor this UE.

Active Time:

Time that the UE is awake. When DRX is configured by higher layer, this includes the OnDuration, the time UE is continuously monitoring the PDCCH while the DRX InactivityTimer has not expired and the time UE is continuously monitoring the PDCCH while theDRX Retransmission Timer has not expired.

Referen ce: 36.321

In RL10 the DRX/DTX control functionality is not supported as with the underlyingscenarios the DRX/DTX control mainly limits throughput and increases latency forthe benefit of an increased battery life time of UEs, which is not that relevant for datacards being used together with a mobile computer.

In RL20 the DRX/DTX control functionality shall be enhanced by supporting DRX inRRC Connected Mode. DRX is applied only for UEs with the according capabilities. Itis switched off when gap assisted measurements are activated.

During a DRX cycle the UE monitors the PDCCH only for a limited number ofconsecutive sub-frames; initial data transmission to and from the UE is therefore onlypossible during a limited time frame being part of a DRX cycle.

The DRX feature therefore is mainly a means to save on battery power on UE side,but may be utilized in the eNodeB also to reduce the number of UEs having to beconsidered actively in scheduling all the time (limited to certain points in time then).However, this comes at the expense of an increased complexity for configuring andcontrolling the DRX feature. In addition it is expected, that DRX will impact not onlyRRM, but also U-plane. Detailed algorithms and benefits are still for further studies.

The DRX feature should operate on a smaller time scale than the UE inactivitydetection. The feature requires interoperation to U-plane/C-plane functionalities toget UE-specific information about activation of the feature, timers controlling theactive/idle patterns, etc.


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Module Contents

UE State handling

DRX/ DTX Overview







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Occasion of Paging Messages

For each case when specific UE shall be paged in, the next appropriateradio frame and sub-frame for sending the corresponding RRC PAGING

message can be derived from:

The UE Identity Index Value IE (UE_ID) is provided in the S1AP: PAGINGmessage. The Paging Group Count on radio frame level (N) that iscalculated from T and nB(T):

..

As the nB values fourT and twoT are not supported N is always nB(T).

The number of sub-frames used for paging per radio frame (Ns) (only forthose radio frames used for paging). As the nB values fourT and twoT arenot supported in RL09, Ns =1 is valid for all cases. Generally:

.

( )),( TnBTMINN =

( ) )/,1( TTnBMAXNs =

( ) )/,1( TTnBMAXNs =


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Occasion of Paging Messages Cont.

The SFN of the radio frame for paging shall be calculated based on thefollowing formula give by [3GPP 36.304]:

The sub frame number is given by chapter 7.2 of [3GPP 36.304]. SinceNs==1 is valid for all cases in the current release, the sub frame numbershall always be set to 9 for FDD.

)mod_(*)div(mod NIDUENTTSFN ==

06 RA41216EN10GLA1 Radio Bearer Control

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