topic 03 handover control

7/29/2019 Topic 03 Handover Control

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1 Nokia Siemens Networks Presentation / Author / Date

I insert classification level

Topic : Handover Control

23 - Nov - 2009


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Soc Classification level

Course objectives

Handover Type

Intra-frequency Handover (SHO) Event1A,B,C

Event6F,G

Individual Ncell

Forbidden cell to reporting range

Neighbour list

Inter-frequency/system Handover (IFHO/ISHO)

Event1E,F

Compress Mode


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Handover Type

Intra Frequency Handover

Softer Handover

Handover between sectors of the same Node B No extra transmissions across Iub interface

Soft Handover

UE simultaneously connected to multiple cells (from different Node Bs)

Extra transmission across Iub, more channel cards are needed

Mobile Evaluated Handover (MEHO)

Hard Handover

Arises when inter-RNC is not possible (Iur not supported or Iur congestion) MEHO and RNC controlled

Causes temporary disconnection of the (RT) user

Inter Frequency Handover

Can be intra-BS, intra-RNC, inter-RNC

Network Evaluated Handover (NEHO)

Inter-System Handover

Handover between GSM and WCDMA (NEHO)


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Intra-frequency Handover

Handover control supports the following measurement reporting events:

Event 1A: adding cells to the active set

Event 1B: deleting cells from active set

Event 1C: replacing cells in the active set

Event 6F & 6G: deleting cells from the active set

Cell individual offsets for modifying measurement reporting behaviour (Disable)

Mechanism for forbidding a neighbouring cell to affect the reporting range (Disable)

Handover decision performed by RNC based on measurements and available resources

Admission control can reject the branch addition in case the maximum load is achieved in DL

(threshold + offset), valid both for RT and NRT bitrates.

Hard blocking may prevent branch addition (BTS/Transmission)


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Intra-frequency Handover (event1A)

Reporting event 1A is controlled with the following parameters:

Active Set Weighting Coefficient (ActiveSetWeightingCoefficient = 0, use the best CPICH)

Addition Time (AdditionTime = 40ms, internal value = 3)

Addition Window (AdditionWindow = 6dB, internal value = 12)

Reporting Interval (AdditionReportingInterval = 0.5s, internal value = 2)

CPICH EcNo Offset (AdjsEcNoOffcet = 0)

Maximum Active Set Size (MaxActiveSetSize = 3)

Reporting event 1A is used for adding cells in the active set. The UE sends the event 1A-triggered

measurement report when a cell enters the reporting range .





Best active set

2nd best active set

Addition Window

Addition Time Addition

Reporting

Interval

Time

EcNo


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Intra-frequency Handover (event1B)

Reporting event 1B is controlled with the following parameters:

Active Set Weighting Coefficient (ActiveSetWeightingCoefficient = 0)

Drop Time (DropTime = 2560ms, internal value = 14)

Drop Window (DropWindow = 6dB, internal value = 12)

CPICH Ec/No Offset (AdjsEcNoOffset = 0)

Reporting event 1B is used for deleting cells in the active set. The UE sends the event 1B-triggered

measurement report when a cell leaves the reporting range.


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Best active set

2nd best active set

Drop Window

Drop Time

Time

EcNo


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Intra-frequency Handover (event1C)

Reporting event 1C is controlled with the following parameters:

Maximum Active Set Size(MaxActiveSetSize= 3)

Replacement Time (Replacement Time = 100ms; internal value = 6)

Replacement Window (ReplacementWindow = 3dB, internal value = 6)

CPICH Ec/No Offset (AdjsEcNoOffset = 0)

Reporting event 1C is used for replacing cells in the active set. The UE sends the event 1C-triggered

measurement report when the number of cells in the active set is equal to the Maximum Active Set

Size (MaxActiveSetSize) parameter and a cell that is not included in the active set becomes better

than a cell in the active set.


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Best active set

2nd best active set

Replacement

Window

Replacement

Time

Replacement

Reporting

Interval

Time

EcNo

3rd best active setOne of monitor set


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Intra-frequency Handover (event6F & 6G)

UE RX-Tx time difference measurement is controlled with the following parameters:

Upper Rx-Tx Time Difference Threshold (UpperRx Tx TimeDiff) determines the upper thresholdwhich is used by the UE to trigger the reporting event 6F due to UE Rx-Tx time difference.

Lower Rx-Tx Time Difference Threshold (LowerRx Tx TimeDiff) determines the lower threshold

which is used by they UE to trigger the reporting event 6G due to UE Rx-Tx time difference.

Estimation of these events:

Based on UE Rx-Tx time diference

Measurement configuration:

6F: UE Rx-Tx time differece threshold: (UpperRxTxTimeDiff = 1174chips)

6G: UE Rx-Tx time difference threshold: (LowerRxTxTimeDiff = 874chips)

Note: Some of UE not support event6


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Intra-frequency Handover (Cell Individual Offset)

Individual Ncell Offset is controlled with the following parameters:

EcNo offset (AdjsEcNoffset = 0)

Moves cell border (shrinks or enlarges cell)

Offset applied to Primary CPICH measurement before event evaluation


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Intra-frequency Handover (Cell Individual Offset)

Reporting Range

AdjsEcNoOffset

Event 1a Event 1b

Time

EcNo

1st AS

2nd AS3rd AS


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Intra-frequency Handover (Forbidding Ncell)

The primary CPICH of certain cells can be forbidden from reporting range calculation in some

instances.

Forbidding Neighbour Cell from Reporting Range:

Forbidden cell (AdjsDERR = 0; disable)


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Intra-frequency Handover (Forbidding Ncell)

Reporting Range

Time

EcNo

1st AS

2nd AS

3rd AS


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Intra-frequency Handover (Neighbour List)


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Intra-frequency Handover (Neighbour List)


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Inter-frequency/system Handover (Process Flow)


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Inter-frequency/system Handover (Triggering points)


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Inter-system Handover (event1E/1F)

Event 1F is the triggering point to compress mode for the Inter-system handover procedure if all the

active sets meet the threshold within the triggering time, and Event 1F will be cancelled from the

compress mode by the Event 1E.

Event 1E parameters:

Triggering condition: Active set cells

Threshold used frequency (HHOEcNoCancel=-10dB/HHoRSCPCancel=-102dBm)

Time to trigger (HHOEcNoCancelTime=1280ms/HHORSCPCancelTime=1280ms)

Event 1F parameters:

Triggering condition: Active set cells

Threshold used frequency (HHOEcNoThreshold=-14dB/HHoRSCPThreshold=-105dBm)

Time to trigger (HHOEcNoTimeHysteresis=640ms/HHORSCPTimeHysterisis=100ms)

I t t H d ( t1E/1F)


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HHOThreshold

CancelTime

Event 1e

Time

Threshold

Event 1f

1st AS

2nd AS

3rd AS

HHOThresholdTime

Hysterisis

Inter-system Handover (event1E/1F)

C M d


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Compress Mode

Radio path feature which enables UE to maintain the current connection on a certain frequency while

performing measurements on another frequency.

Allow the UE to monitor neighbouring cells on another frequency (FDD) or system (RAT).

Means that transmission and reception are halted for a short time (few miliseconds) to perform a

measurement on another frequency or RAT.

The alternative methods of compress mode:

Halving the spreading factor

This temporarily doubles the physical channel data rate in the radio channel. The same

amount of data can be sent in half the time it would normally take. Halving does not affect

the DCH user data rate.

Higher layer scheduling

Higher layer scheduling temporarily reduces the DCH user data rate in the radio channel by

restricting the high bit rate transport format combinations (TFCs).

C M d (M t G )


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Compress Mode (Measurement Gap)

I t t H d (RT)


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Inter-system Handover (RT)

Inter system Handover (RT)


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Inter system Handover (RT)


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Inter system Handover (NRT)


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Inter-system Handover (NRT)

Inter system Handover (NRT)


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Inter-system Handover (NRT)

Inter-system handover control parameters (FMCG & HOPG)


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Inter-system handover control parameters (FMCG & HOPG)

GSMMeasRepInterval (Gui value = 0.5s, Internal value = 2)

Interval between measurement report which being sent to BTS

GSMMinMeasInterval (Gui value = Internal value = 2s)

Minimum measurement interval for next compressed mode

GSMMeasAveWindw (Gui value = Internal value = 6)

Measurement averaging window size

GSMMaxMeasPeriod (Gui value = Internal value = 18)

Maximum measurement period which determines the maximum allowed duration of the inter-

system measurement

AdjgRxLevMinHO (Gui value = -95dBm, Internal value = 10; internal value = gui value + 110)

Minimum required GSM RSSI level before the coverage (or quality) reason handover to GSM.


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topic 03 handover control

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