antenna hopping guidelines

7/29/2019 Antenna Hopping Guidelines

http://slidepdf.com/reader/full/antenna-hopping-guidelines 1/18

PLANNING GUIDE 1 (18)

Antenna HoppingOS Performance ServicesJLedesma 11/19/04

1. SCOPE............................................................................................................................................. 2

2. FEATURE OVERVIEW.....................................................................................................................23. FEATURE BENEFITS.......................................................................................................................43.1 Better BCCH Downlink Performance..........................................................................................43.2 Better Network Performance (KPIs)...........................................................................................43.3 Non Hopping Super Layer Gain.................................................................................................43.4 Better DL Data Throughput for Static Customers.......................................................................4

4. APPLICATIONS................................................................................................................................54. DEPENDENCIES..............................................................................................................................55. IMPLEMENTATION..........................................................................................................................66. ANTENNA CONFIGURATIONS........................................................................................................77. GENERAL DEPLOYMENT AND FIELD TRIAL RESULTS...............................................................8

8.2 Cluster Level Deployment Results..............................................................................................8

8.2 Performance Trends................................................................................................................. 138. KNOWN ISSUES WITH ANTENNA HOPPING...............................................................................189. CONCLUSION and RECOMMENDATION......................................................................................18





1. SCOPE

This document is designed to explain the Antenna Hopping feature available in BSS11. It presentsthe overview, benefits, applications and dependencies of the feature and gives the reader someinformation on how the feature works and what the expectations are based on actual field trials.

2. FEATURE OVERVIEW

Antenna Hopping is a downlink performance enhancement feature designed to improve linkperformance where frequency hopping is not in use or not effective due to high correlation betweenfrequencies. In a typical sector where you have the BCCH and hopping layer, the BCCH layer has nodownlink diversity since it is only one frequency transmitting over a single antenna. This makes itmore suceptible to noise, interference and fading. The hopping layer however has the advantagethat it is “hopping” from one frequency to another creating phase diversity where it combats long termfading and frequency related interference.

This feature enables the TRXs in an RF hopping BTS to transmit with all the TX antennas in the BTSusing the existing BB (Baseband) hopping functionality in the BTS. With AH the improvement is moresubstantial on the non-hopping layer because we bring it to almost equal link performance with thehopping layer (Fig.1 and Fig 2). This translates to gain on the nonhopping layer that will improve

existing coverage and RSSI levels. This feature would also be very beneficial in interference-limitedareas.

Figure 1. Effective BCCH vs Hopping TRX coverage difference. The hopping trx would have a bigger coverage area because of the processing gain it gets. The non-hopping TRX loses coverage due to interference and fading. With antenna hopping we willbe able to bridge that gap in between the hopping and non-hopping trx.

BCCH TRX Coverage

Hopping TRX Coverage





Figure 2. Antenna Hopping creates an artificial Doppler spread resulting in increased fading rate. This translates to processinggain resulting in better performance on the non-hopping trx.

Figure 3. Simple Antenna Hopping configuration with 4 TRXs and no combiners.

Furthermore, with the Antenna Hopping feature it is possible to achieve space diversity to the regular RF hopping configuration, which means that there is a distance that separates two or moretransmitting antennas, providing uncorrelated signals. At the mobile unit a separation of half awavelength is the minimum for obtaining uncorrelated signals. At the base station frequency, theantenna height and antenna spacing makes the correlation coefficient.

Distance

Distance

Distance

Radio

Channel

RadioChannel

Averagereceivedcarrier power over burst

One antenna

Two antennas with DD

Two antennas with DD + PH, or AH

TX 1

TX 2Delay + PH

TXdata

Speech frame duration at 3 km/h:

Distance

Distance

Distance

Radio

Channel

RadioChannel

Averagereceivedcarrier power over burst

One antenna

Two antennas with DD

Two antennas with DD + PH, or AH

TX 1

TX 2Delay + PH

TXdata

Speech frame duration at 3 km/h:





3. FEATURE BENEFITS

3.1 Better BCCH Downlink Performance

• The BCCH layer is non-hopping thus it is prone to interference and fading. The deployment of

AH would improve the link performance of the BCCH layer that would translate to better HOprobability, better SDCCH Success Ratio, and better Coverage Probability.

• Intelligent Coverage Enhancement (ICE) performance improvements would also be realized

since this feature utilizes the BCCH radio.

• Coverage in the rural areas where we have slow fading would improve slightly because of the

link performance gain. This is only applicable to to the BCCH and the non-hopping TCH.

• Significant coverage improvements on GSM 1900.

3.2 Better Network Performance (KPIs)

• SDCCH Success Ratio improves because of better coverage proabability. If the CSSR

formula factors the SDCCH success ratio in the Call Setup Success Rate (CSSR) KPI thenthe CSSR would improve.

•Hand Over Success Rate (HOSR) improves because the neighbor measurement reportwould show a better rssi on the target cell (due to processing gain) thus allowing the HO tooccur much sooner.

• DL RXQUAL improves because the MS will hand over to a better server without having to

stay on a serving cell with bad quality. DL FER will also improve together with this KPI.

• HO related Drop Calls would be reduced because the MS would handoff faster to a better

serving cell rather than drag the call.

3.3 Non Hopping Super Layer Gain

• BCCH Super Reuse (BSR) layer link performance improvement. BSR is a capacity featurethat allows the use of the BCCH channels at low power in a super reuse layer that wouldincrease capacity. With tight reuse you might be able to find only one BCCH channel for theBSR layer and antenna hopping would be of great help to improve the link performance.

3.4 Better DL Data Throughput for Static Customers

• GPRS territories defined on the BCCH TRX would get better C/I that can result in better

throughput. It can be used with 8PSK channels but with MCS7 to 9 there is no performancegain due to weak channel coding used by these channels (not much “overhead” added)





4. APPLICATIONS

• Rural Sites & Network Coverage Edge

o Performance gain results in improved performance on stationary and slow moving

mobiles. This also translates to better coverage (both indoor and outdoors) probability.However, this does not apply to the hopping layer. Remember that we brought the BCCHlayer performance up to par with the hopping layer.

o If the threoretical 3 dB gain is applied to the network’s coverage edge this would keep the

MS in network longer instead of going to roaming. However, this does not change thededicated mode coverage. The coverage probability would improve at the old network

coverage edge and actually move the coverage edge farther. If there is no frequencyhopping used this will definitely bring the benefits of having frequency hopping.

• Roaming Access Points (Airports and Piers)

o Roaming revenue is critical to any operators business. With the gain from AH we can

retain more customers in our network (e.g. the customer roams at the airport anddetaches on flying out. When the customer arrives at his destination the mobile will scanthe last known band used which would be the roaming network).

• Spectrum Limited Areas (3.6 MHz)

o Spectrum Limited markets would benefit from AH. The BCCH carriers are typically

reserved with the narrow bandwidth available. With AH we can go to a tighter BCCHreuse plan and free up more carriers to be allocated as TCH trxs for the hopping layer giving us more capacity with the same spectrum.

4. DEPENDENCIES

• Prerequisites

o BSS S11, OSS 3.1 & UltraSite CX4.0-3

o ULTRASITE EDGE HW

o EDGE TRX (non-EDGE TRX can be used in the same cabinet if it is in a non-hopping or

RF Hopping mode)o Minimum of 2 TRXs per BTS (or cell) where both are used for antenna hopping

o Antenna Hopping groups can include the BCCH

• Restrictions

The following features cannot be used together with Antenna Hopping:o Cannot be used with Remote Tune Combiner (RTC)

o Cannot be used with Baseband Hopping (BB) in the same BTS

o Cannot be used with IDD in the same BTS (IDD uses the same BB hopping module for

AH)

The feature is OFF in the BTS if:o TRX(s) are down

o The number of working TRXs fall below 2 TRXs/BTS





The following tests are not possible when Antenna Hopping is in use

o TRX test for Nokia UltraSiteo TRX loop test

5. IMPLEMENTATION

• Set parameter Antenna Hopping (AHOP) to Y

• AHOP is BTS level

Modification: BTS must be locked.

Range: Y/N

MML default: N

Description: With this parameter you define whether antenna hopping is used in the BTS.

Related command(s): EQE, EQO

Note: OPTIONAL (ANTENNA_HOPPING_USAGE

Activating Antenna Hopping for UltraSite BTS

1. Lock the BTSs so that the Antenna Hopping for UltraSite BTS parameter can bemodified (EQS)

ZEQS:BTS=1:L;

2. Take the Antenna Hopping in use in the BTS (EQE)

ZEQE:BTS=1:AHOP=Y;

3. Unlock the BTS (EQS)

ZEQS:BTS=1:U;





6. ANTENNA CONFIGURATIONS

These are the typical configurations at the sites in the cluster where antenna hopping was deployed.

Figure 4. Dual Stage 4 way combining

Figure 5. Single Stage 2 way combining

TRXCOMB

2way

TRX

TRX

TRX

COMB

2way

DDU

(Filter)

Port 1

Port 2 Antenna

Antenna

TRX

TRX

TRX

TRX

TRX

TRX

TRX

TRX

COMB

2way

COMB2way

COMB

2way

COMB

2way

COMB

2way

COMB

2way

DDU

(Filter)

Port 1

Port 2

Antenna

Antenna





7. GENERAL DEPLOYMENT AND FIELD TRIAL RESULTS

8.2 Cluster Level Deployment Results

Antenna Hopping is better deployed in a cluster level. With cluster level deployment we can see theoverall benefits of the processing gain that we can get. Below are the KPIs of a cluster with AntennaHopping deployed. The green line in the graphs marks the start date of AH.

DCR_8C 1700H

0

0.5

1

1.5

2

2.5

3

0 9 - 0 1 - 2 0 0 4 : 1

7

0 9 - 0 4 - 2 0 0 4 : 1

7

0 9 - 0 7 - 2 0 0 4 : 1

7

0 9 - 1 0 - 2 0 0 4 : 1

7

0 9 - 1 3 - 2 0 0 4 : 1

7

0 9 - 1 6 - 2 0 0 4 : 1

7

0 9 - 1 9 - 2 0 0 4 : 1

7

0 9 - 2 2 - 2 0 0 4 : 1

7

0 9 - 2 5 - 2 0 0 4 : 1

7

0 9 - 2 8 - 2 0 0 4 : 1

7

1 0 - 0 1 - 2 0 0 4 : 1

7

1 0 - 0 4 - 2 0 0 4 : 1

7

1 0 - 0 7 - 2 0 0 4 : 1

7

1 0 - 1 0 - 2 0 0 4 : 1

7

1 0 - 1 3 - 2 0 0 4 : 1

7

1 0 - 1 6 - 2 0 0 4 : 1

7

1 0 - 1 9 - 2 0 0 4 : 1

7

1 0 - 2 2 - 2 0 0 4 : 1

7

1 0 - 2 5 - 2 0 0 4 : 1

7

1 0 - 2 8 - 2 0 0 4 : 1

7

1 0 - 3 1 - 2 0 0 4 : 1

7

%

DCR_8c threshold1 threshold2

1700 Busy Hour provides agood variety of mobiletraffic in the network. The

DCR has improved greatlyafter antenna hopping wasactivated.

The DCR causes alsoindicate that the TCHRADIO FAIL percentageand the TCH RF OLD HOpercentages haveimproved.

DCR Causes 1700H

0

0.5

1

1.5

2

2.5

3

3.5

4

0 9 - 0 1 - 2 0 0 4 : 1 7

0 9 - 0 4 - 2 0 0 4 : 1 7

0 9 - 0 7 - 2 0 0 4 : 1 7

0 9 - 1 0 - 2 0 0 4 : 1 7

0 9 - 1 3 - 2 0 0 4 : 1 7

0 9 - 1 6 - 2 0 0 4 : 1 7

0 9 - 1 9 - 2 0 0 4 : 1 7

0 9 - 2 2 - 2 0 0 4 : 1 7

0 9 - 2 5 - 2 0 0 4 : 1 7

0 9 - 2 8 - 2 0 0 4 : 1 7

1 0 - 0 1 - 2 0 0 4 : 1 7

1 0 - 0 4 - 2 0 0 4 : 1 7

1 0 - 0 7 - 2 0 0 4 : 1 7

1 0 - 1 0 - 2 0 0 4 : 1 7

1 0 - 1 3 - 2 0 0 4 : 1 7

1 0 - 1 6 - 2 0 0 4 : 1 7

1 0 - 1 9 - 2 0 0 4 : 1 7

1 0 - 2 2 - 2 0 0 4 : 1 7

1 0 - 2 5 - 2 0 0 4 : 1 7

1 0 - 2 8 - 2 0 0 4 : 1 7

1 0 - 3 1 - 2 0 0 4 : 1 7

tch_act_fail_call

tch_lapd_fail

tch_netw_act

tch_user_act

tch_bts_fail

tch_bcsu_reset

tch_a_if_fail_old

tch_a_if_fail_call

tch_tr_fail_old

tch_tr_fail

tch_abis_fail_old

tch_abis_fail

tch_rf_old_ho

tch_radio_fail





HO Failure Rate 1700H

0

5

10

15

20

25

30

35

40

45

0 9 - 0 1 - 2 0 0 4 : 1 7

0 9 - 0 4 - 2 0 0 4 : 1 7

0 9 - 0 7 - 2 0 0 4 : 1 7

0 9 - 1 0 - 2 0 0 4 : 1 7

0 9 - 1 3 - 2 0 0 4 : 1 7

0 9 - 1 6 - 2 0 0 4 : 1 7

0 9 - 1 9 - 2 0 0 4 : 1 7

0 9 - 2 2 - 2 0 0 4 : 1 7

0 9 - 2 5 - 2 0 0 4 : 1 7

0 9 - 2 8 - 2 0 0 4 : 1 7

1 0 - 0 1 - 2 0 0 4 : 1 7

1 0 - 0 4 - 2 0 0 4 : 1 7

1 0 - 0 7 - 2 0 0 4 : 1 7

1 0 - 1 0 - 2 0 0 4 : 1 7

1 0 - 1 3 - 2 0 0 4 : 1 7

1 0 - 1 6 - 2 0 0 4 : 1 7

1 0 - 1 9 - 2 0 0 4 : 1 7

1 0 - 2 2 - 2 0 0 4 : 1 7

1 0 - 2 5 - 2 0 0 4 : 1 7

1 0 - 2 8 - 2 0 0 4 : 1 7

1 0 - 3 1 - 2 0 0 4 : 1 7

%

ho_fail_inter ho_fail_intra ho_fail threshold1 threshold2

EFL 1700H

0

2

4

6

8

10

12

14

0 9 - 0 1 - 2 0 0 4 : 1 7

0 9 - 0 4 - 2 0 0 4 : 1 7

0 9 - 0 7 - 2 0 0 4 : 1 7

0 9 - 1 0 - 2 0 0 4 : 1 7

0 9 - 1 3 - 2 0 0 4 : 1 7

0 9 - 1 6 - 2 0 0 4 : 1 7

0 9 - 1 9 - 2 0 0 4 : 1 7

0 9 - 2 2 - 2 0 0 4 : 1 7

0 9 - 2 5 - 2 0 0 4 : 1 7

0 9 - 2 8 - 2 0 0 4 : 1 7

1 0 - 0 1 - 2 0 0 4 : 1 7

1 0 - 0 4 - 2 0 0 4 : 1 7

1 0 - 0 7 - 2 0 0 4 : 1 7

1 0 - 1 0 - 2 0 0 4 : 1 7

1 0 - 1 3 - 2 0 0 4 : 1 7

1 0 - 1 6 - 2 0 0 4 : 1 7

1 0 - 1 9 - 2 0 0 4 : 1 7

1 0 - 2 2 - 2 0 0 4 : 1 7

1 0 - 2 5 - 2 0 0 4 : 1 7

1 0 - 2 8 - 2 0 0 4 : 1 7

1 0 - 3 1 - 2 0 0 4 : 1 7

%

HoppingEFL/Cell

HO Failure rate hasimproved slightly.

EFL has remainedconsistent and evenincreased on the 1-November but the DCRimprovement is stillretained.





DCR_8C 2100H

0

0.5

1

1.5

2

2.5

3

3.5

0 9 - 0 1 - 2 0 0 4 : 2 1

0 9 - 0 4 - 2 0 0 4 : 2 1

0 9 - 0 7 - 2 0 0 4 : 2 1

0 9 - 1 0 - 2 0 0 4 : 2 1

0 9 - 1 3 - 2 0 0 4 : 2 1

0 9 - 1 6 - 2 0 0 4 : 2 1

0 9 - 1 9 - 2 0 0 4 : 2 1

0 9 - 2 2 - 2 0 0 4 : 2 1

0 9 - 2 5 - 2 0 0 4 : 2 1

0 9 - 2 8 - 2 0 0 4 : 2 1

1 0 - 0 1 - 2 0 0 4 : 2 1

1 0 - 0 4 - 2 0 0 4 : 2 1

1 0 - 0 7 - 2 0 0 4 : 2 1

1 0 - 1 0 - 2 0 0 4 : 2 1

1 0 - 1 3 - 2 0 0 4 : 2 1

1 0 - 1 6 - 2 0 0 4 : 2 1

1 0 - 1 9 - 2 0 0 4 : 2 1

1 0 - 2 2 - 2 0 0 4 : 2 1

1 0 - 2 5 - 2 0 0 4 : 2 1

1 0 - 2 8 - 2 0 0 4 : 2 1

1 0 - 3 1 - 2 0 0 4 : 2 1

%

DCR_8c threshold1 threshold2

2100 Busy Hour traffic ismostly static customersand majority of the calls areindoors. The improvementin DCR is even moresignificant – more than0.5%.

The DCR causes alsofollow the trend where the

TCH RADIO FAIL and TCHRF OLD HO percentageshave improved.

DCR Causes 2100H

0

0.5

1

1.5

22.5

3

3.5

4

4.5

0 9 - 0 1 - 2 0 0 4 : 2 1

0 9 - 0 4 - 2 0 0 4 : 2 1

0 9 - 0 7 - 2 0 0 4 : 2 1

0 9 - 1 0 - 2 0 0 4 : 2 1

0 9 - 1 3 - 2 0 0 4 : 2 1

0 9 - 1 6 - 2 0 0 4 : 2 1

0 9 - 1 9 - 2 0 0 4 : 2 1

0 9 - 2 2 - 2 0 0 4 : 2 1

0 9 - 2 5 - 2 0 0 4 : 2 1

0 9 - 2 8 - 2 0 0 4 : 2 1

1 0 - 0 1 - 2 0 0 4 : 2 1

1 0 - 0 4 - 2 0 0 4 : 2 1

1 0 - 0 7 - 2 0 0 4 : 2 1

1 0 - 1 0 - 2 0 0 4 : 2 1

1 0 - 1 3 - 2 0 0 4 : 2 1

1 0 - 1 6 - 2 0 0 4 : 2 1

1 0 - 1 9 - 2 0 0 4 : 2 1

1 0 - 2 2 - 2 0 0 4 : 2 1

1 0 - 2 5 - 2 0 0 4 : 2 1

1 0 - 2 8 - 2 0 0 4 : 2 1

1 0 - 3 1 - 2 0 0 4 : 2 1

tch_act_fail_call

tch_lapd_fail

tch_netw_act

tch_user_act

tch_bts_fail

tch_bcsu_reset

tch_a_if_fail_old

tch_a_if_fail_call

tch_tr_fail_old

tch_tr_fail

tch_abis_fail_old

tch_abis_fail

tch_rf_old_ho

tch_radio_fail





HO failure rate hasimproved much much morewith static traffic after AHwas implemented.

HO Failure Rate 2100H

0

5

10

1520

25

30

35

40

0 9 - 0 1 - 2 0 0 4 : 2 1

0 9 - 0 4 - 2 0 0 4 : 2 1

0 9 - 0 7 - 2 0 0 4 : 2 1

0 9 - 1 0 - 2 0 0 4 : 2 1

0 9 - 1 3 - 2 0 0 4 : 2 1

0 9 - 1 6 - 2 0 0 4 : 2 1

0 9 - 1 9 - 2 0 0 4 : 2 1

0 9 - 2 2 - 2 0 0 4 : 2 1

0 9 - 2 5 - 2 0 0 4 : 2 1

0 9 - 2 8 - 2 0 0 4 : 2 1

1 0 - 0 1 - 2 0 0 4 : 2 1

1 0 - 0 4 - 2 0 0 4 : 2 1

1 0 - 0 7 - 2 0 0 4 : 2 1

1 0 - 1 0 - 2 0 0 4 : 2 1

1 0 - 1 3 - 2 0 0 4 : 2 1

1 0 - 1 6 - 2 0 0 4 : 2 1

1 0 - 1 9 - 2 0 0 4 : 2 1

1 0 - 2 2 - 2 0 0 4 : 2 1

1 0 - 2 5 - 2 0 0 4 : 2 1

1 0 - 2 8 - 2 0 0 4 : 2 1

1 0 - 3 1 - 2 0 0 4 : 2 1

%

ho_fail_inter ho_fail_intra ho_fail threshold1 threshold2

EFL was relatively thesame. EFL 2100H

0

2

4

6

8

10

12

14

16

0 9 - 0 1 - 2 0 0 4 : 2 1

0 9 - 0 4 - 2 0 0 4 : 2 1

0 9 - 0 7 - 2 0 0 4 : 2 1

0 9 - 1 0 - 2 0 0 4 : 2 1

0 9 - 1 3 - 2 0 0 4 : 2 1

0 9 - 1 6 - 2 0 0 4 : 2 1

0 9 - 1 9 - 2 0 0 4 : 2 1

0 9 - 2 2 - 2 0 0 4 : 2 1

0 9 - 2 5 - 2 0 0 4 : 2 1

0 9 - 2 8 - 2 0 0 4 : 2 1

1 0 - 0 1 - 2 0 0 4 : 2 1

1 0 - 0 4 - 2 0 0 4 : 2 1

1 0 - 0 7 - 2 0 0 4 : 2 1

1 0 - 1 0 - 2 0 0 4 : 2 1

1 0 - 1 3 - 2 0 0 4 : 2 1

1 0 - 1 6 - 2 0 0 4 : 2 1

1 0 - 1 9 - 2 0 0 4 : 2 1

1 0 - 2 2 - 2 0 0 4 : 2 1

1 0 - 2 5 - 2 0 0 4 : 2 1

1 0 - 2 8 - 2 0 0 4 : 2 1

1 0 - 3 1 - 2 0 0 4 : 2 1

%

HoppingEFL/Cell





8.2 Performance Trends

DCR_8C shows at least 20% gain in DCR performance

0.00

0.50

1.00

1.50

2.00

2.50

0 2 4 6 8 10 12 14 16

EFL

D C R

8 c

Baseline (before)

AH

Baseline (after)

15 BCCH

20% gain





Uplink FER was trending better

93.00

94.00

95.00

96.00

97.00

98.00

99.00

100.00

0 2 4 6 8 10 12 14

EFL

G o o d F E R

Baseline (before)

AH

Baseline (after)

15 BCCH





DL RXQUAL has no significant change

87.00

88.00

89.00

90.00

91.00

92.00

93.00

94.00

95.00

96.00

97.00

98.00

0 2 4 6 8 10 12 14

EFL

G o o d R X Q U A L D L

Baseline (before)

AH

Baseline (after)

15 BCCH





Uplink RXQUAL was trending better with AH

94.00

95.00

96.00

97.00

98.00

99.00

100.00

0 2 4 6 8 10 12 14

EFL

G o o d R X Q U A L U L

Baseline (before)

AH

Baseline (after)

15 BCCH





Preliminary results show small but consistent improvement in the SDCCH Success Rate. Moreimprovement was seen with a reuse of 15 on the BCCH.

98.00

98.20

98.40

98.60

98.80

99.00

99.20

99.40

99.60

99.80

100.00

0 2 4 6 8 10 12 14

EFL

%

Baseline (before)

AH

Baseline (after)

15 BCCH





8. KNOWN ISSUES WITH ANTENNA HOPPING

Transmission outage causes some TRXs in a BTS to trigger “TRX faulty” alarm incorrectly causingthe TRXs to become blocked out of service until a BTS reset was performed. This issue has beenbrought up with Nokia Product Line for resolution.

9. CONCLUSION AND RECOMMENDATION

Downlink diversity provided by AH helps minimize the impact of fast fading on non-hopping TRXs and

stationary users. With the feature we can gain roughly about 20% drop call performance. Cluster leveltesting indicates that there is an over all improvement with mobile (1700H) traffic and stationary(2100H) traffic – albeit the impact is much more significant on the stationary traffic. The gains on theBCCH are reflected with the improved HO success rate and Drop Call rate. HO related drops havebeen reduced because of better BSIC decoding.

Spectrum limited areas would benefit with AH as shown on the performance trends with 12 BCCHreuse. The benefits would also extend to the non-hopping layer if the available frequencies in the MAlist have high correlation.

antenna hopping guidelines

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