2-Claro B9 Enhanced Transmission Resource Management

7/29/2019 2-Claro B9 Enhanced Transmission Resource Management

1/28

All rights reserved 2005, Alcatel

Enhanced Transmission ResourceManagement

B9 Claro Workshop - February 14th, 2006


2/28

All rights reserved 2005, AlcatelB9 Claro Workshop / February 14th 2006

Page 2

Agenda

Enhanced Transmission resource management

M-EGCH Statistical Multiplexing

Dynamic Abis Allocation

Ater Resource Management

DL Retransmission in the BTS

Related parameters & counters


3/28


Page 3

M-EGCH Statistical MultiplexingM-EGCH link (I)

An M-EGCH link (Multiplexed Enhanced GPRS CHannel) is a bi-directional link established between the MFS and the BTS.

An M-EGCH link is a set of 16k GCH channels.

An M-EGCH link is defined per TRX.

The M-EGCH link of a TRX is necessary:

To carry TBF traffic and PACCH signalling when TBFs are established on

some PDCHs of the TRX,

To carry signalling messages when MPDCHs are defined on the TRX,

To carry UL signalling messages after one-UL-block allocation (UL two-phase access),

To carry some BTS-MFS signalling.


4/28


Page 4

M-EGCH Statistical MultiplexingM-EGCH link (II)

B8: one EGCH per RTS B9: one M-EGCH link forthe whole TRX

0 1 762 3 4 5

EGC

H

0 1 762 3 4 5TRX

M-EGCH link

1 to 36 GCHs

composed of

GCH

EGC

H

EGCH

EGCH

EGCH

EGCH

EGCH

EGCH

GCH

GCH

GCH

GCH

1 to 5 GCHs dependingon the TRX class

GCH

composed of

GCH

GCH

GCH

GCH

TRX


5/28


Page 5

M-EGCH Statistical MultiplexingFilling an M-EGCH link with PDUs (I)

RLC header

MEGCH header(next segments)

MEGCH header(first segment)

SYNC pattern +Z bit indicator

Padding bits

CRC + Tail bits

MEGCH header(/NHP and addrbyte)

DummyFilling PDU

LEGEND

320 bits 320 bits 320 bits

320 bits

20 ms 20 ms 20 ms

GCH1

GCH2

GCH3

GCH4

RLC/MAC PDU 1 for DBN=x

320 bits

GCH5 Dummy Filling PDU

DummyFilling

Dummy Filling

Dummy Filling

RLC/MAC PDU 2 for DBN=x

DBN=x+1DBN=x DBN=x+2

MEGCH layer

segmentation

sub-layer

RLC/MAC layer

MEGCH

layer

framing

sub-layer


6/28


Page 6

M-EGCH Statistical MultiplexingGains brought by the feature

Reduction of the Abis and Ater consumption Resources are used in a more efficient way: Instantaneous reaction to radio variations (MCS variations).

Example:

No more TBF maximum MCS reduction is needed.

The resources not used by delayed DL TBFs, extended UL TBFs, are used by otherTBFs.

320 bits per GCH

20 ms

DBN mDBN m DBN m+ 1DBN m+ 1 DBN m+ 2DBN m+ 2

20 ms 20 ms

320 bits per GCH

20 ms

DBN mDBN m DBN m+ 1DBN m+ 1 DBN m+ 2DBN m+ 2

20 ms 20 ms

RB1 RB1 RB1

RB1 RB1 RB1RB2 RB2 RB2

RB2 RB2 RB2

RB2 RB2RB3 RB3 RB3

M- EGCH link composed of 4 GCHsM- EGCH link composed of 4 GCHs

RB3

GCH 1

GCH 2

GCH 3

GCH 4

GCH 1

GCH 2

GCH 3

GCH 4

GCH 1

GCH 2

GCH 3

GCH 4

GCH 1

GCH 2

GCH 3

GCH 4


7/28All rights reserved 2005, AlcatelB9 Claro Workshop / February 14th 2006

Page 7

M-EGCH Statistical MultiplexingTowards Dynamic Abis allocation

In B8:

The size of an EGCH link (associated to a PDCH) can be dynamically

decreased.

But the size of an EGCH link cannot be dynamically increased.

In B9:

The size of an M-EGCH link (associated to a TRX) can be dynamically

decreased or increased.

The algorithms to dynamically decrease or increase the size of an M-EGCH

link correspond to the Dynamic Abis allocation.


8/28All rights reserved 2005, AlcatelB9 Claro Workshop / February 14th 2006

Page 8

Agenda








9/28


Page 9

Dynamic Abis AllocationStatic versus Dynamic Abis allocation

B8: static Abis allocation B9: dynamic Abis allocation

0 1 762 3 4 5

EGCH

0 1 762 3 4 5TRX

M-EGCH link

1 to 36 GCHs (mixture of GCHs usingbasic, extra and bonus Abis nibbles)

composed of

1 to 5 GCHs depending on theTRX class (and only one GCHcan use a basic Abis nibble)

GCHB

a

sic

composed of

EGCH

EGCH

EGCH

EGCH

EGCH

EGCH

EGCH

GCHE

x

tra

Basic Abis nibblesand

Extra Abis nibblesare statically

mapped to a RTS.

They can only beused in the EGCH

of this RTS.GCHE

xtra

GCHE

x

tra

GCHE

xtra

GCHB

asic

GCHE

xtra

GCHB

asic

GCHE

xtra

No moreconstraints

in B9!

GCHB

asic

TRX


10/28


Page 10

Dynamic Abis AllocationAbis nibbles wasted in B8

In B8, the following Abis nibbles were wasted:

X X X X X XExtra Abis nibbles

(number of nibbles per RTS = TRX class-1)

X X Basic Abis nibbles

B S M M P P T T TRX configuration on the air interface

Legend:

B: BCCH, S: static SDCCH, M: MPDCH, P: PDCH, T: TCH, X : Abis nibblewasted

in B8, : Abis nibble usedin B8


11/28


Page 11

Dynamic Abis AllocationAbis nibbles usable for PS traffic (I)

In B9, the following Abis nibbles are usable for PS traffic: The basic Abis nibbles mapped to a RTS currently available for

PS traffic(see Autonomous Packet Resource Allocation" feature toknow the list of those RTSs) or mapped to a RTS used as MPDCH.

Example:

P P P P M C C C RTSs in a 2-TRX cell

Legend:- C: RTS currently used for CS traffic (CS call),- P: RTS currently used for PS traffic (TBF or MPDCH traffic).

RTS available for PS traffic

RTS reserved for CS traffic

The basic Abis nibbles of those RTS can beused to establish some GCHs


12/28


Page 12

Dynamic Abis AllocationAbis nibbles usable for PS traffic (II)

The bonus basic Abis nibbles currently used for BCCH or

static SDCCH channels:

The list of bonus Abis nibbles depends on the cell configuration.

All the extra Abis nibbles of the BTS:

A number of 64k extra Abis TSs is defined for each BTS by O&M

(N_EXTRA_ABIS_TS).

The list of extra Abis TSs of a BTS is provided by the BSC to the MFS.


13/28


Page 13

ynam c s oca onLevel of sharing of the Abis nibbles usable for PStraffic

The basic Abis nibbles mapped on a RTS allocated to MFS can

be used in the M-EGCH link of any TRX of the CELL.

The extra Abis nibbles can be used in the M-EGCH link of any TRX

of the BTS.

The bonus Abis nibbles can be used in the M-EGCH link of any

TRX of the BTS.


14/28


Page 14

Dynamic Abis AllocationImpacts on existing scenarios and new scenarios

Due to Dynamic Abis allocation, new messages have to be sent to the BTS to

notify each TRE which Abis nibbles are associated..

Those messages are sent via GSL and RSL interfaces.

The following scenarios are therefore modified: GCH establishment.

GCH release.

New scenario appear to distribute GCH resources : Intra-cell GCH pre-emption : between TRXs of a cell

Inter-cell GCH pre-emption : between cells of a BTS


15/28


Page 15

Agenda







A R M


16/28


Page 16

Ater Resource ManagementPrinciples

The Ater Resource Management in a given GPU is based

on two complementary mechanisms:

GPU Ater TS margin,

High Ater usage handling.

A strong requirement is to ensure GPRS access in all thecells of the GPU (no cell shall be blocked due to an Atercongestion).


17/28


Page 17

Ater Resource ManagementGPU Ater TS Margin

GPU 64k Ater TS margin:

Aim:

Ensures that GPRS access can never be blocked in a cell due to lack ofAter resources in the GPU.

Handled in each GPU to serve some priority requests at any moment and inany cell managed by the GPU.

Priority request is the GCH establishment request for the first PS traffic ina cell (first TBF to establish in a cell).

Management:

Release of some GCHs when the remaining number of free 64k Ater TSs in

the GPU becomes too low (O&M parameter N_ATER_TS_MARGIN_GPU). For a given TRX, when releasing GCHs, it is ensured that:

Established_Nb_GCH remains higher than Min_Nb_GCH.

At R M t


18/28


Page 18

Ater Resource ManagementHigh Ater usage handling (I)

High Ater usage handling:

Definition of the Ater usage of a GPU:

Represents the consumption of Ater nibbles (by GCH channels)

among the PCM links connected to the GPU,

Ater usage can be either normal or high.

Decision based on the comparison of the Ater nibble consumption

with a threshold (Ater_Usage_Threshold O&M parameter).

At R M t


19/28


Page 19

Ater Resource ManagementHigh Ater usage handling (II)

Behaviour if Ater usage is high:

Target_Nb_GCH values associated to TRXs of the GPU supportingsome PS traffic will be reduced:

GCH_RED_FACTOR_HIGH_ATER_USAGE O&M

parameter. The reduction factor is only applied on PDCHs newly open.

newly open PDCH means that no radio resources werepreviously allocated on this PDCH.

When evaluating Target_Nb_GCH on a given TRX:

If PDCH already open, no reduction is applied, If PDCH is newly open, reduction is applied.

At R M t


20/28


Page 20

Ater Resource ManagementHigh Ater usage handling (III)

Example:

Max_EGPRS_MCS = MCS-9,

GCH_RED_FACTOR_HIGH_ATER_USAGE = 0,5

1)Ater usage = normal

2) Establishment of an EGPRS DL TBF on RTS0-3 Target_Nb_GCH = 4 * Nb_GCH(Max_EGPRS_MCS) = 4 * 4,49 = 18

3)Ater usage = high

4) Establishment of an EGPRS DL TBF on RST4-7

Target_Nb_GCH = 4 * Nb_GCH(Max_EGPRS_MCS) + 0,5 * 4 *

Nb_GCH(Max_EGPRS_MCS) = 4 * 4,49 + 4 * 0,5 * 4,49 = 27 (< 36)


21/28


Page 21

Agenda







DL t i i i th BTS


22/28


Page 22

DL retransmission in the BTSPrinciples

Goal:

Avoid consuming transmission resources (Abis + Ater) in case of DL

RLC data block retransmissions.

Principles:

Store for a certain time, in the memory of the TRE involved in the

packet transfer mode with an MS, the DL RLC data blocks received

from the RLC/MAC layer for this MS.

Then, the RLC/MAC layer (in the MFS) can ask the TRE (in the

BTS) to retransmit some data blocks.Data received from the MFS are stored in a buffer.

DL t i i i th BTS


23/28


Page 23

DL retransmission in the BTSPrinciples

This mechanism is enabled / disabled at TRX/TRE level:

Gains:

Higher available transmission bandwidth.

M-EGCH link dimensioning is eased.

EN_DL_RETRANS_BTS

Round_Trip_Delay

HW generation of the TRE

CS-2

(DRFU)

CS-4

(G3 or M4M)

CS-4+MCS-9

(G4 or M5M)

Enabled < 500 ms Disabled Disabled Enabled

Enabled 500 ms Disabled Disabled Disabled

disabled - Disabled Disabled Disabled


24/28


Page 24

Agenda









25/28


Page 25

HMI name Definition Sub-system

Instance

OMC-Raccess

Type Defvalue

Range Unit

NEW :N_EXTRA_ABIS_TS

Number of extra Abis (64k) timeslots configured for aBTS.

BSC BTS Changeable

Number

0 [0,60] None

NEW :N_GCH_FAST_PS_ACCESS

Two definitions are possible :

- If EN_FAST_INITIAL_GPRS_ACCESS = enabled :number of GCHs required to be established due to theFast Initial PS Access feature,

- If EN_FAST_INITIAL_GPRS_ACCESS = "disabled :

number of GCHs to keep established when there is nomore (E)GPRS traffic in a cell (while theT_GCH_INACTIVITY_LAST timer is running).

MFS MFS None(DLS)

Number

1 [1,5] None

NEW : T_GCH_Inactivity - For Non Evolium BTS : Timer to postpone the releaseof one slave PDCH, when it does not support any(E)GPRS traffic.

- For Evolium BTS : Timer to postpone the release ofthe "unused" GCHs of the M-EGCH link of a TRX (thecondition for some GCHs of the M-EGCH link of a TRXto become "unused" is that some TBFs

MFS BSS Changeable

Timer 3 [1,100] sec

NEW :T_GCH_Inactivity_Last

- For Non Evolium BTS : Timer to postpone the releaseof the last established slave PDCH of a cell, when itdoes not support GPRS traffic anymore.

-For Evolium BTS : Timer to postpone the release ofthe last N_GCH_FAST_PS_ACCESS GCHsestablished in a cell, when the last TBF has beenreleased in the cell. -

MFS BSS Changeable

Timer 20 [1,200] sec

Related parameters & countersParameters



26/28


Page 26

Removed parameters :

NB_EXTRA_ABIS_TS

T_PDCH_Inactivity

T_PDCH_Inactivity_Last

MAX_PDCH_PER_TBF_High_Ater_Usage

HMI name Definition Sub-system

Instance

OMC-Raccess

Type Defvalue

Range Unit

NEW :N_ATER_TS_MARGIN_GPU

Number of free 64k Ater TSs that are kept in reservein order to be able to serve some prioritary requests incells managed by the GPU. The prioritary requests arethe GCH establishment requests launched when thefirst TBF has to be established in a cell.

Note : In case of non-Evolium BTS, those are PDCHsthat will be established instead of GCHs.

MFS BSS Changeable

Number

2 [0,10] none

NEW :GCH_RED_FACTOR_HI

GH_ATER_USAGE

Reduction factor of the number of GCHs targeted perPDCH, when the Ater usage is high.

MFS cell Changeable

Number

0.75 [0,1] none

NEW :

EN_DL_RETRANS_BTS

This flag enables / disables downlink retransmission inthe BTS.

MFS MFS None(DLS)

Flag 1 [0,1] None

Related parameters & countersParameters



27/28


Page 27

Counternumber

Name Definition

P100c CUMULATED_TIME_BUSY_GCH_CELL The counter cumulates over the reporting period the timeduring which a GCH is busy in the cell.

P100d MAX_NB_BUSY_GCH_CELL Maximum number of busy GCH (16k channel) in the cell.

P105 i / j NB_DL/UL_TBF_EST_FAIL_CONG_ABIS Number of DL/UL TBF establishment failures due to a lackof Abis resources.

P469 MAX_NB_DEFICIT_GCH Maximum number of GCH in deficit reached in the cell.

P470 CUMULATED_TIME_DEFICIT_GCH Cumulative time (in seconds), per cell , during which thereis a deficit of GCH resources (16k channel).

P471 CUMULATED_TIME_EXCESS_GCH Cumulative time (in seconds), per cell ,during which thereis a excess of GCH resources (16k channel).

P472 CUMULATED_TIME_FREE_EXTRA_BONUS_ABIS_NIBBLES

Cumulative time (in seconds), per BTS ,during which thereare free extra and bonus Abis nibbles available.

P474 CUMULATED_TIME_FREE_ATER_NIBBLES Cumulated time during which a PDCH is used by at leastone DL TBF (in GPRS or EGPRS mode), cumulated overall the PDCHs of the cell.

P484 MIN_NB_FREE_EXTRA_BONUS_ABIS_NIBBLE

Minimum number of free extra and bonus Abis nibbles.

P486 MIN_NB_FREE_ATER_NIBBLE Minimum number of free Ater nibbles.

Related parameters & countersCounters

Documents

2-Claro B9 Enhanced Transmission Resource Management