GB 0604 E1 Handover and Power Control

8/8/2019 GB 0604 E1 Handover and Power Control

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ZTE University www.univ.zte.com.cnwww.univ.zte.com.cnwww.univ.zte.com.cnThe information contained in the file is solely property of ZTE corporation. Any kind of disclosing without permission is prohibited.

OBJECTIVESOBJECTIVES

To understand the procedures of GSM

Handover

To understand the procedures of Power

Control

To identify parameters needed forHandover and Power Control Operation


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HANDHAND--OVER ANDOVER ANDPOWER CONTROLPOWER CONTROL


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HAND-OVER


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HANDHAND--OVEROVER

Hand-over is a process that transfers a MS that is

in setting up or busy status to a new traffic channel.

Generally, hand-over will occur under the following

two conditions:

1. A busy MS which is moving from a cell into

another

2. An MS is making a call at overlapping area of

two cells, one of which is very busy in traffic, or

the quality or the strength of the signal

decreased.


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PURPOSES OF HANDPURPOSES OF HAND--OVEROVER

1. Save the calls in progressbad quality)

2. Cell-boundary handing over to improve

ongoing calls (weak signal)

3. Intra-cell hand-over reducing interference

within a cell (severe interference)

4. Directed Retry increase call completion

success rate5. Compelled hand-over to balance traffic

distribution of inter-cells.


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NETWORK OVERVIEWNETWORK OVERVIEW

MSCBSC

BTS

MS

BSC Evaluation and Decisionof HO

MSC: routes the call to the otherMSC during Inter-MSC HO

BTS preprocessmeasurements UL and DL

MS measures:

Signal Strength DL own celland neighboring cells, QualityDL

Signal Strength ofNeignboring Cells

BTS measures:

Signal Strength UL, QualityUL , TA


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1. Intra-cell hand-over

2. Inter-cell hand-over

3. Inter-BSC hand-over of same MSC4. Inter-MSCs hand-over

TYPES OF HANDOVERTYPES OF HANDOVER


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In this case, BSC should set up a new link with new BTS and

assign a TCH in the new cell for MS.

HANDHAND--OVER INSIDE BSCOVER INSIDE BSCBSC

H/O

BTS OLD BTS NEW


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HANDHAND--OVER INSIDE BSCOVER INSIDE BSC


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HANDHAND--OVER BETWEENDIFFERENTOVER BETWEENDIFFERENT

BSCsBSCs

BSC OLD

H/O

BSC NEW

BTS OLD BTS NEW

MSCA


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HANDHAND--OVER BETWEENDIFFERENTOVER BETWEENDIFFERENT

BSCsBSCs


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HANDOVER FLOWCHARTHANDOVER FLOWCHART

IntIntrara--CellCell HandoverHandover

MS BTS BSC MSC

Meas RepMeas Res

PhyContext Req

PhyContest Con

Chan ct

Chan ct CK

Assign Command

SABMEst Ind

UA

Assign CompleteHo Per orm

Deact SACCHRFChan Release

RF Chan Rel ACK


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InterInter--CellCell HandoverHandover

DT1HO PERF

HO CMD

CH ACT

MEAS REP

RF CH REL ACK

RF CH REL

DIHO COM

EST IND

HO DET

CH ACT ACK

MSB

TS1B

TS2B

SC MSCMEAS RES

DRHO CMD

HO ACCESS

PHY INFO

SABM

UA

HO COM


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INTERINTER--MSC HANDOVERMSC HANDOVER

OLD LINK

NEW LINK

BSC OLD

H/O BSC NEW

MSC OLD MSC NEW

BTS OLD BTS NEW5

5

5

1

5

5

7

2

3

4

4

6

3

5

7


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PROCEDURE (1)PROCEDURE (1)

1 B

SCA sends hand-over request to MSCA whendeemed necessary according to MSs measurement

report.

2 MSCA sends this request to MSCB which is

responsible for setting up links with BSCB and BTSB.

3MSCB sends back radio channel acknowledgement to

MSCA.

4Communication links are established between MSCA

and MSCB according to Hand-over Number(HON).

5MSCA send hand-over command to MS who then

handed over to a new TCH.


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PROCEDURES (2)PROCEDURES (2)

6BSCB send to MSCB, then to MSCA the command

of hand-over completion.

7MSCA controls BSCA and BTSA to release the old

TCH.


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InterInter--MSC HandoverMSC Handover


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HANDOVER CLASSIFICATIONHANDOVER CLASSIFICATION

1. Synchronous

2. Asynchronous

3. Pseudo-synchronous


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QUEUINGAND FORCEDQUEUINGAND FORCED

DISCONNECTIONDISCONNECTION

Queuing - To increase the successful rate of hand-over,when no radio resource is available, the applicant of hand-

over may be put into queuing and wait for release of radio

resources.

Forced disconnection - when in emergency andno radio resource is available, some subscribers with

lower priority may be disconnected, or handed out forcibly

to ensure that the subscribers with higher priority couldkeep their calls continuously.


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BASE STATION PREBASE STATION PRE--PROCESSINGPROCESSING

1. Measurement reports made by MS and reported from

SACCH:

Downlink RXLEV Downlink RXQUAL(BER)

Other adjacent cells downlink RXLEVless than 6, designatedby BA list)

2. Measurement report made by BTS

Uplink RXLEV

Uplink RXQUAL

TA

Interference strip

MEA

SUREMEN

T REPORTS RECEIVED

BY BA

SETRANCEIVER STATION: (meas_rpt)


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1. RXLEV_XXXXDL or UL

For each connection, at least 32 sampling data are

retained and the average of RX level is calculated out by

BSS in each SACCH period.

2. Adjacent cells BCCH carrier receiving level

RXLEV_NCELL(n)

For each connection and each cell, the latest 32 samplingdata are stored by BSS to calculate out the adjacent cells

BCCH carrier receiving level.

PROCESSING

OF BTS MEA

SURED

DA

TA


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3. POWER BUDGET (PBGT)

For each connection and each allowable cell,

BSS calculates PBGT as follows

PROCESSING OF BTS MEASUREDDATA

PBGT(n)=(Min(MS_TXPWR_MAX,P)RXLEV_DLPWR_C_D)

(Min(MS_TXPWR_MAX(n),P)RXLEV_NCELL(n))


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3. POWER BUDGET (PBGT)

Where,

RXLEV_NCELL(n) and RXLEV_DL are got by abovedefinitions.

PWR_C_D is the difference of cell-allowed downward

maximum power with actual power

MS_TXPWR_MAX(current traffic channel)

MS_TXPWR_MAX(n) (adjacent cell n traffic channel)

P is the maximum transmission power of MS

PROCESSING OF BTS MEASUREDDATA


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4. Timing Advance

For each connection, BSS calculate the TA using

parameters Hreqt and Hreqave

5. Interference strip

BSS averages interference ( using INTAVE) on

idle time-slots and maps to five classes calledstrips.

PROCESSING

OF BTS MEA

SURED

DA

TA


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PARAMTERS IN CONNECTION WITHPARAMTERS IN CONNECTION WITH

HANDHAND--OVEROVER

PARAMETER UNCTION

U NP

U NP

D NPD NP

U NP

D NP

M D NP A H M A


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THRESHOLD COMPARISONTHRESHOLD COMPARISON

1. Hand-over will occur if at least P out of N upward levels are

lower than UpLevTh.

2. Hand-over will occur if at least P out of N downward levels

are lower than DwLevTh.3. Hand-over will occur if at least P out of N upward levels are

higher than UpQualTh.

4. Hand-over will occur if at least P out of N downward levels

are higher than DwQualTh.


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THRESHOLD COMPARISONTHRESHOLD COMPARISON

5. Hand-over will occur if the latest P out of N upward levelsare higher than UpIntfTh and condition 3 is met at the same

time.

6. Hand-over will occur if the latest P out of N downward levels

are higher than DwIntfTh and condition 4 is met at the

same time.

7. Hand-over will occur if the latest P out of N TAs are higher

than MsDistTh.

8. Hand-over will occur if PBGT of some adjacent cell is higher

than its corresponding HoMargin.


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HANDOVER ALGORITHMHANDOVER ALGORITHM

The hand-over algorithmB

SC adopts is based on thefollowing equation:

1) RXLEV_NCELL(n) > RXLEV_MIN(n) + Max (0, Pa)

where: Pa = (MS_TXPWR_MAX(n)P)

2) PBGT (n) - HO_MARGIN(n) > 0

BSS selects from all adjacent cells that both meets equation

(1) and (2) and queue them from large PBGT to small

ones and serves as candidate adjacent cells.


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POWER CONTROLPOWER CONTROL


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PURPOSE OF POWER CONTROLPURPOSE OF POWER CONTROL

Lower interference within a cell

Save power

Consideration: Call quality or data

transmission quality be guaranteed


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POWER CONTROL PROCEDURESPOWER CONTROL PROCEDURES

MEASURED DATA

AVERAGE MEASURED DATA

POWER CONTROL DECISION

SEND POWER CONTROL

COMMAND

MEASURED DATA

CORRECTION


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RELATION OF LEVEL WITH POWERRELATION OF LEVEL WITH POWER

CONTROLCONTROL

63

0

Upper limit

Lower limit

Fast power control

zone

Fast power control zone

High

Low

Normal


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RELATION OF BER WITH POWERRELATION OF BER WITH POWER

CONTROLCONTROL

0

7

Upper limit

Lower

limit

Fast power control

zone

Fast power control zone

Low

High

Normal


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Corresponding Relation between

RXQUAL and BER

RXQUAL BER (%) Typical(%)

0 BER


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BTS POWER CONTROLBTS POWER CONTROL

STRATEGYSTRATEGY

Keep current transmission power when received levelis normal.

Lower the transmission power when received level is

high.

Increase the transmission power when received level

is low.

Keep current transmission power when BER is

normal.

Increase the transmission power when BER is high.

Lower the transmission power when BER is low.


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MS POWER CONTROL STRATEGYMS POWER CONTROL STRATEGY

Normal Level LEVELCAUSE = 0Low Level LEVELCAUSE = 1

High Level LEVELCAUSE = 2

Normal BERQUALCAUSE = 0

Low BER QUALCAUSE = 1

High BER QUALCAUSE = 2

L L AQU

AL AUSE

OUTPUT

0 2 INCREASE

1 0 STAY

1 1 STAY

1 2 INCREASE

2 0 DECREASE

2 1 DECREASE

2 2 INCREASE


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RANGE OF POWER CONTROLRANGE OF POWER CONTROL

1BTS Power Control

BTS has 6 classes of static power configured by network, each classhas 15 levels of dynamic power which can be configured bynetwork.

2MS Power Control

GSM900 class A MS power capability 43dbm20W

GSM900 class B MS power control 39dbm8WGSM900 class C MS power capability 37dbm5W

GSM900 class D MS power capability 33dbm2W

GSM900 class E MS power capability 29dbm0.8W

GSM900 power control range of MS is 43dbm ~ 5dbm at least

2dbm one stepDCS1800 class A MS power control capability 30dbm1W

DCS1800 class B MS power control capability 24dbm0.25W

DCS1800 class C MS power control capability 36dbm4WDCS1800 power control range 36dbm ~ 0dbm2dbm one step


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ZTE University www.univ.zte.com.cnwww.univ.zte.com.cnwww.univ.zte.com.cnThe information contained in the file is solely property of ZTE corporation Any kind of disclosing without permission is prohibited

GB 0604 E1 Handover and Power Control

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Transcript of GB 0604 E1 Handover and Power Control