radio fine tuning

BSS B11 Radio Fine Tuning Introduction - Page 1All Rights Reserved Alcatel-Lucent 2010

All Rights Reserved Alcatel-Lucent 2010

GSM B11BSS B11 Radio Fine Tuning

Introduction

STUDENT GUIDE

TMO18097 D0 SG DEN I1.0 Issue 1

All rights reserved Alcatel-Lucent 2010 Passing on and copying of this document, use and communication of its contents not

permitted without written authorization from Alcatel-Lucent



BSS B11 Radio Fine Tuning IntroductionGSM B112

Empty page

Switch to notes view!

This page is left blank intentionally




Terms of Use and Legal Notices

Switch to notes view!1. Safety WarningBoth lethal and dangerous voltages may be present within the products used herein. The user is strongly advised not to wear conductive jewelry while working on the products. Always observe all safety precautions and do not work on the equipment alone.

The equipment used during this course may be electrostatic sensitive. Please observe correct anti-static precautions.

2. Trade MarksAlcatel-Lucent and MainStreet are trademarks of Alcatel-Lucent.

All other trademarks, service marks and logos (Marks) are the property of their respective holders, including Alcatel-Lucent. Users are not permitted to use these Marks without the prior consent of Alcatel-Lucent or such third party owning the Mark. The absence of a Mark identifier is not a representation that a particular product or service name is not a Mark.

Alcatel-Lucent assumes no responsibility for the accuracy of the information presented herein, which may be subject to change without notice.

3. CopyrightThis document contains information that is proprietary to Alcatel-Lucent and may be used for training purposes only. No other use or transmission of all or any part of this document is permitted without Alcatel-Lucents written permission, and must include all copyright and other proprietary notices. No other use or transmission of all or any part of its contents may be used, copied, disclosed or conveyed to any party in any manner whatsoever without prior written permission from Alcatel-Lucent.

Use or transmission of all or any part of this document in violation of any applicable legislation is hereby expressly prohibited.

User obtains no rights in the information or in any product, process, technology or trademark which it includes or describes, and is expressly prohibited from modifying the information or creating derivative works without the express written consent of Alcatel-Lucent.

All rights reserved Alcatel-Lucent 2010

4. DisclaimerIn no event will Alcatel-Lucent be liable for any direct, indirect, special, incidental or consequential damages, including lost profits, lost business or lost data, resulting from the use of or reliance upon the information, whether or not Alcatel-Lucent has been advised of the possibility of such damages.

Mention of non-Alcatel-Lucent products or services is for information purposes only and constitutes neither an endorsement, nor a recommendation.

This course is intended to train the student about the overall look, feel, and use of Alcatel-Lucent products. The information contained herein is representational only. In the interest of file size, simplicity, and compatibility and, in some cases, due to contractual limitations, certain compromises have been made and therefore some features are not entirely accurate.

Please refer to technical practices supplied by Alcatel-Lucent for current information concerning Alcatel-Lucent equipment and its operation, or contact your nearest Alcatel-Lucent representative for more information.

The Alcatel-Lucent products described or used herein are presented for demonstration and training purposes only. Alcatel-Lucent disclaims any warranties in connection with the products as used and described in the courses or the related documentation, whether express, implied, or statutory. Alcatel-Lucent specifically disclaims all implied warranties, including warranties of merchantability, non-infringement and fitness for a particular purpose, or arising from a course of dealing, usage or trade practice.

Alcatel-Lucent is not responsible for any failures caused by: server errors, misdirected or redirected transmissions, failed internet connections, interruptions, any computer virus or any other technical defect, whether human or technical in nature

5. Governing LawThe products, documentation and information contained herein, as well as these Terms of Use and Legal Notices are governed by the laws of France, excluding its conflict of law rules. If any provision of these Terms of Use and Legal Notices, or the application thereof to any person or circumstances, is held invalid for any reason, unenforceable including, but not limited to, the warranty disclaimers and liability limitations, then such provision shall be deemed superseded by a valid, enforceable provision that matches, as closely as possible, the original provision, and the other provisions of these Terms of Use and Legal Notices shall remain in full force and effect.




Blank Page






Course Outline

About This CourseCourse outlineTechnical supportCourse objectives

1. Topic/Section is Positioned HereXxxXxxXxx

2. Topic/Section is Positioned Here






1. B11 Radio Fine Tuning

1. Typical Radio Problems 3JK12201AAAAWBZZA

2. Idle Mode (Re)Selection 3JK12202AAAAWBZZA

3. Radio Measurements Principles 3JK12203AAAAWBZZA

4. Radio Link Sup and Power Control 3JK12204AAAAWBZZA

5. Handover Algorithms 3JK12205AAAAWBZZA

6. Resources Allocation Management 3JK12206AAAAWBZZA

7. Optimization Methodology 3JK12207AAAAWBZZA

8. Case Studies 3JK12208AAAAWBZZA

9. Annexes 3JK12209AAAAWBZZA

10. Solutions 3JK12210AAAAWBZZA




Course Outline [cont.]






Course Objectives


Welcome to BSS B11 Radio Fine Tuning Introduction

Upon completion of this course, you should be able to:

By the end of the course, participants will be able, for conventional networks, to: - Characterize the usual radio problems and decide on the appropriate maintenance team; - List and describe BSS radio algorithms and related parameters;List radio parameters and check

conformity with Alcatel-Lucent standards; - Estimate the qualitative impact of an algorithm parameter change; - Propose algorithm parameter setup to solve typical radio problems. Note: Hierarchical, dual-band, frequency hopping and GPRS networks are covered in other trainings.




Course Objectives [cont.]






About this Student Guide

Switch to notes view!Conventions used in this guide

Where you can get further information

If you want further information you can refer to the following:

Technical Practices for the specific product Technical support page on the Alcatel website: http://www.alcatel-lucent.com

Note Provides you with additional information about the topic being discussed. Although this information is not required knowledge, you might find it useful or interesting.

Technical Reference (1) 24.348.98 Points you to the exact section of Alcatel-Lucent Technical Practices where you can find more information on the topic being discussed.

WarningAlerts you to instances where non-compliance could result in equipment damage or personal injury.




About this Student Guide [cont.]






Self-assessment of Objectives

At the end of each section you will be asked to fill this questionnaire Please, return this sheet to the trainer at the end of the training


Instructional objectives Yes (or globally

yes)

No (or globally

no) Comments

1 To be able to XXX

2

Contract number :

Course title :

Client (Company, Center) :

Language : Dates from : to :

Number of trainees : Location :

Surname, First name :

Did you meet the following objectives ?Tick the corresponding box

Please, return this sheet to the trainer at the end of the training




Self-assessment of Objectives [cont.]


Instructional objectives Yes (or Globally

yes)

No (or globally

no) Comments

Thank you for your answers to this questionnaire

Other comments

Section 1 Module 1 Page 1

All Rights Reserved Alcatel-Lucent 20103JK12201AAAAWBZZA Issue 1

Do not delete this graphic elements in here:


Module 1Typical Radio Problems

3JK12201AAAAWBZZA Issue 1

Section 1B11 Radio Fine Tuning

GSM B11BSS B11 Radio Fine Tuning Introduction





GSM B11 BSS B11 Radio Fine Tuning IntroductionB11 Radio Fine Tuning Typical Radio Problems1 1 2

Blank Page


First editionLast name, first nameYYYY-MM-DD01

RemarksAuthorDateEdition

Document History





Module Objectives

Upon completion of this module, you should be able to:

Characterize typical radio problems in order to trigger an intervention of the appropriate team





Module Objectives [cont.]






Table of Contents

Switch to notes view! Page

1 Presentation 72 Coverage Problem 93 Interference Problem 184 Unbalanced Power Budget Problem 325 TCH Congestion Problem 386 Deducing the Right Team for Intervention 43





Table of Contents [cont.]







1 Presentation





1 Presentation

Justification

Several sources of information can alert RFTM team: QoS indicators Customers complaints Drive tests Other teams information (NSS statistics)

As many symptoms are common to several causes, it can be necessary to: Consolidate standard sources of information Carry out specific examinations Deduce the appropriate team for intervention





2 Coverage Problem





2 Coverage Problem

Definition and Symptoms

Definition: Bad coverage A network or cell facing coverage problems presents a bad RxLev and RxQual

at the same time on some areas.

Symptoms: Customers complain about dropped calls or/and no network OMC QoS indicators TCH failure rate Call drop rate Low proportion of better cell HO High rate of DL quality HO

A interface indicators High rate of Clear Request messages, cause radio interface failure

No information is available on non-covered parts of the network, as there are non-mobiles making calls over there!

Nevertheless, cells in border of non-covered zones do have a particular behavior:

Cell A will mainly perform Better Cell handovers towards its neighbors, whereas cell B, bordering the non-coverage area, will perform emergency handovers for MSs exiting the network.

For these MSs, mainly DL Quality HO will be triggered:

DL because MS antenna is less efficient than BTS one, Quality rather than Level since Qual has a greater priority in Alcatel-Lucent HO causes.

AB





2 Coverage Problem

Examination

Depending on the information sources you have: Radio Measurement Statistics (RMS) (RxLevel , RxQuality) matrix Radio Link Counter S vector Number of calls with DL/UL bad coverage (bad RxLev, bad RxQual)

Abis interface (for example with COMPASS) bad quality > 5% bad level RxLev < - 95 dBm and RxQual > 4

OMC-R or A interface unexpected high traffic, induced by call repetition

Billing information High recall rate detected

RMS:

Provides statistics from any area in the network which are available at any time. Cost-effective. Easier and cheaper to perform than Drive test or Abis Trace. The operator can tune 54 parameters (based on RxLev, BFI, C/I, Radio Link Counter S, Path Balance, etc.) to

define up to 16 templates (depending on cell type rural, urban, etc. for example).

Trigger from the OMC-R.

NPO can save up to 15 days of RMS for the complete network. Templates can be designed in NPO. Default result reports are available in NPO.





2 Coverage Problem

Typical Causes

If the actual coverage is not the one predicted by RNP tools: check antenna system increase or decrease antenna down-tilt check BS_TXPWR_MAX to be increased if value different from RNP power budget

If the actual coverage is OK compared to the predicted ones: indoor traffic, to be handled by specific means if black spot close to cell border, ease outgoing HO





2 Coverage Problem

Investigation with Abis Trace

Example of an Abis trace analysis

TRX index RxLev_UL RxLev_DL RxQual_UL Path_loss_UL Path_loss_DL delta_Path_loss Delta_quality AV_MS_PWR Nb_of_samplesRxQual_DL

TRX index Qual0 Qual1 Qual2 Qual4 Qual5 Qual6 Qual7 Bad_QualityQual3

TRX index Qual0 Qual1 Qual2 Qual4 Qual5 Qual6 Qual7 Bad_QualityQual3

1 -89.29 -84.67 0.42 123.82 123.67 0.15 -0.01 34.53 30740.43

2 -89.77 -89.09 0.41 124.87 128.09 -3.21 0.03 35.11 10 2530.38

3 -83.15 -79.15 0.17 116.05 121.22 -5.16 -0.16 32.9 53390.33

DISTRIBUTION OF UPLINK QUALITY

1 86.50% 3.19% 2.50% 1.92% 2.08% 0.98% 0.26% 3.32%2.57%

2 88.11% 1.82% 1.91% 2.14% 2.17% 1.15% 0.19% 3.51%2.51%

3 77.70% 4.30% 4.30% 3.56% 3.56% 1.70% 0.17%4.36%

1 88.29% 1.82% 2.05% 1.30% 1.46% 1.76% 0.94% 4.16%2.37%

2 87.50% 2.98% 2.60% 2.11% 1.14% 0.74% 0.50% 2.38%2.43%

3 71.30% 3.82% 4.02% 4.16% 4.30% 4.23% 3.16%4.89%

DISTRIBUTION OF DOWNLINK QUALITY

5.43%

11.73%

It could have been coverage problems if this trace was made for 3 mono-TRX cells. In this case, the 3 lines are uncorrelated. Anyway, delta path loss of frequency 111 is greater than 5dB, showing a problem on this TRX.

If this is a 3-TRX cell, it cannot be a coverage problem as the three TRXs are not impacted. It will be either interference or malfunction of one TRE.

If the trace is done on 3 mono-TRX cells, in that case, it could be a coverage problem. Be careful when interpreting this result table: even if average levels in the UL and the DL are high and a lot of Quality problems are seen, nobody can say that samples with bad quality have a good level! The level seen is just an average

One should have a look at the next slide





2 Coverage Problem

Investigation with Abis Trace [cont.]

Example of an Abis trace analysisThresholds

Bad Coverage RxLev -95 RxQual > 4

Interference RxLev > -95 RxQual > 4

3-88.0063-95.3331-71.0031-80.0061-80.003 -80.003

571111212

Number_UL: 10 253Number_DL: 10 253

Int_UL: 2BC_UL: 358Int_DL: 0%

0.02%3.49%

67-104.64

2048-

107.5051

Number_UL: 5339Number_DL: 5339

Int_UL: 0BC_UL: 290Int_DL: 0%BC_DL: 626

0.00%5.43%

SamplesBSIC63-101.542

SamplesBSICNeigh_Cell_Nb

SamplesBSICNeigh_Cell_Nb

= -102.17 dBm3.74%BC_DL: 115

57-100.532045-98.7121034-98.036533-98.6137

= -106.56 dBm

BC_DL: 244 2.38% = -106.17 dBm

Frequency: 92

Frequency: 111

11.73%Neigh_Cell_N

b10

All samples are Bad Coverage samples (BC). None is interference, showing that this cell is not facing any interference problem.

By the way, if the cell is:

mono-TRX, this is a coverage problem. 3 TRXs, this is a malfunction of the TRE (shown also by the high value of delta_path_loss).





2 Coverage Problem

Investigation with RMS

Suspecting a cell coverage problem Distribution of samples per RxQual value and RxLev band

Distribution of samples per RxLev band

012

45

7

[-110,-104[

[-104,-98[

[-98,-92[

[-92,-86[

[-86,-80[

[-80,-74[

[-74,-68[

[-68,-62[

[-62,-56[

[-56,-47[

RxQuality (Nb)

RxLevel(dB)

[0, 14 793]]14 793, 23 446]]23 446, 29 586]]29 586, 34 348]]34 348, 38 239]]38 239, 41 529]]41 529, 44 378]]44 378, 46 892]

Out of RangeX

Interval of numberof samples

Downlink Samples Matrix in log scale

3

6

Not acceptable coverage limit:too low level

too bad quality

A coverage problem is observed when a significant amount of the traffic of a cell is suffering from both low level and bad quality (RxQual).

To confirm, distribution of samples per RXLEV band should be also considered to know the proportion of calls which are experiencing a low signal level.

If a lot of samples of low level and bad quality are observed for only a sub-part of the TRXs (can be one only) then a BTS hardware problem or a problem on the antenna should be suspected.

If all the TRXs are experiencing a lot of samples of low level and bad quality then a coverage problem must be suspected.

These RMS indicators are provided on the NPO tool per TRX, per Cell:

Matrix of Number of Measurement Results per DL RxQual value and per DL RxLev bandRMQLDSAM = RMS_DL_RxQuality_RxLevel_sample

Vector of Percentage of Samples per DL RxLev bandRMQLDLVDV = RMS_DL_RxLevel_distrib

Vector of Percentage of Samples per DL RxQual bandRMQLDQUDV = RMS_DL_RxQuality_distrib





2 Coverage Problem

Investigation with RMS [cont.]

Suspecting a cell coverage problem Average TA values per RxQual value and RxLev band

16.00%14.00%12.00%10.00%8.00%6.00%4.00%2.00%0.00%

01/1

2/20

01

01/0

1/20

02

02/0

1/20

02

03/0

1/20

02

04/0

1/20

02

05/0

1/20

02

06/0

1/20

02

07/0

1/20

02

08/0

1/20

02

09/0

1/20

02

10/0

1/20

02

11/0

1/20

02

12/0

1/20

02

13/0

1/20

02

14/0

1/20

02

109876543210

%N > TA thres TA max

Maximum Timing Advance and TA > threshold

N > TA thresTA maxTA thresholdAcceptable

coverage limit:sufficient level and

good quality

Not acceptablecoverage limit:

too low level andtoo bad quality

% of TA valueover TA threshold

has also to beconsidered

012

45

7

[-110,-104[

[-104,-98[

[-98,-92[

[-92,-86[

[-86,-80[

[-80,-74[

[-74,-68[

[-68,-62[

[-62,-56[

[-56,-47[

RxQuality (Nb)

RxLevel(dB)

[0, 2]]2, 4]]4, 6]]6, 8]

Out of Range

Interval of averageTiming Advance

Uplink average TA Distribution

3

6

X

Down

In order to know if the coverage problem is due to a big amount of traffic at the cell border or rather to indoor calls, the average TA value per RXQUAL value and RXLEV band as well as the Percentage of TA values over TA threshold should be observed:

Matrix of Average TA per UL RxQual value and per UL RxLev bandRMQLUTAM = RMS_UL_RxQuality_RxLevel_TimingAdvance

Rate of Measurements Results whose TA is greater than the TA thresholdRMTAGTR = RMS_TimingAdvance_greater_threshold_rate

Maximum TA value of all values reported in Measurement Results RMTAMXN = RMS_TimingAdvance_max





2 Coverage Problem

Investigation with RMS [cont.]

Suspecting a local cell coverage problem RxQual and RxLev per TA bands

5

4

3

2

0

1

2.5

[0,5[ [6,11[ [55,63[[49,54[[43,48[[37,42[[31,36[[25,30[[19,24[

[12,18[

-47

- 60

- 70

- 80

- 110

- 90

- 59

[0,5[ [6,11[ [55,63[[49,54[[43,48[[37,42[[31,36[[25,30[[19,24[

[12,18[

Bad qualityand bad Level

for a specific TA band

Coverage problem

In order to know if the coverage problem is due to a big amount of traffic at the cell border or rather to indoor calls, the average TA value per RXQUAL value and RXLEV band as well as the Percentage of TA values over TA threshold should be observed:

Matrix of Average TA per UL RxQual value and per UL RxLev bandRMQLUTAM = RMS_UL_RxQuality_RxLevel_TimingAdvance

Rate of Measurements Results whose TA is greater than the TA thresholdRMTAGTR = RMS_TimingAdvance_greater_threshold_rate

Maximum TA value of all values reported in Measurement Results RMTAMXN = RMS_TimingAdvance_max





3 Interference Problem







Definition: Interference A network facing interference problems presents good RxLev and bad RxQual

at the same time on some areas.

Symptoms Customers complain about bad speech quality (noisy calls) and/or call drops OMC QoS indicators: SDCCH/TCH Drop Low proportion of better cell HO High rate of DL/UL quality HO and interference HO Low HO success rate


DL/UL depends on the way on which the interference is present.

Mainly, interferences are in the DL, due to bad frequency planning introducing interferences in the network. And this problem will not change till the frequency plan is not returned

Sometimes, interference can be in the UL in very dense area (for example, microcell area), since MSs are very close.

Finally, sometimes interferences are not coming from BS or MS but from another radio equipment, either in the UL or the DL.






Examination with RMS

Radio Measurement Statistics (RMS) RxQual/RxLev matrix CFE/RxLev matrix C/I vectors for neighbors C/I vectors for MAFA frequencies MAFA is a new standardized GSM feature for mobiles MAFA mobiles can provide C/I measurements from non-neighbor cells

Number of calls with DL/UL interference (good RxLev, bad RxQual) Number of noisy calls (bad RxQual) with bad voice quality (bad FER) A high rate use of the most robust AMR codecs also denounces interferences

problems. But be careful, this can also be due to a pessimistic choice of the thresholds used for codec change.

The feature Radio Measurement Statistics (RMS) is designed to make far easier the work for planning and optimization of the network by providing the operator with useful statistics on reported radio measurements.

In fact these statistics give directly the real cell characteristics by taking into account the MS distribution.

Thanks to this feature, the operator is able to:

detect interfered frequencies. assess the quality of the cell coverage. detect and quantify cell unexpected propagation. assess the traffic distribution in the cell from statistics on reported neighboring cells. evaluate the voice quality in the cell. etc.

In regards to the RTCH Measurements Observation (measurement type 11), the Radio Measurement Statistics feature (RMS) brings the following advantages:

smaller report files. the report files always have the same maximum length no matter what the measurement duration is. every measurement is taken into account (no sampling). no more need for measurement post-processing tools for statistics. Directly available with NPO.






Examination with RMS [cont.]

Suspecting a cell interference problem Number of samples per RxQual value and RxLev band

Quality problems are obvious at any level of RMS data

Interference highlighted Network fine tuning needed

012

45

7

[-110,-104[

[-104,-98[

[-98,-92[

[-92,-86[

[-86,-80[

[-80,-74[

[-74,-68[

[-68,-62[

[-62,-56[

[-56,-47[

RxQuality (Nb)

RxLevel(dB)

[0, 14 793]]14 793, 23 446]]23 446, 29 586]]29 586, 34 348]]34 348, 38 239]]38 239, 41 529]]41 529, 44 378]]44 378, 46 892]

Out of RangeX


Downlink Samples Matrix in log scale

3

6

Average RxQual value per RXLev bandhas also to be considered

0123456

[-110,-104[

[-104,-98[

[-98,-92[

[-92,-86[

[-86,-80[

[-80,-74[

[-74,-68[

[-68,-62[

[-62,-56[

[-56,-47[

RxQuality (Nb)

RxLevel(dB)

Downlink average RxQuality per RxLevel

RxQualityAverage

5

Average DL RxQuality = 2.81







Suspecting a Voice Quality problem Number of samples per BFI band and RxLev band

0123456

[-110,-104[

[-104,-98[

[-98,-92[

[-92,-86[

[-86,-80[

[-80,-74[

[-74,-68[

[-68,-62[

[-62,-56[

[-56,-47[

Average CFE

RxLevel (dB)

Uplink average Consecutive Frame Erasure per RxLevel

78

Average RxQual

0

1

2

3

4

5

6CFEAverage

RxQualityAverage

Consecutive Frame Erasure (BFI) is a measurement based on loss of consecutive

speech frames over one SACCH mw.

It is directly linked to Voice Quality.

RxQual to be compared with CFE since Bad RxQual does not always mean bad VQ.

[0, 1[[1, 2[[2, 4[

[6, 8[[8, 10[

[14, 18[

[-110,-104[

[-104,-98[

[-98,-92[

[-92,-86[

[-86,-80[

[-80,-74[

[-74,-68[

[-68,-62[

[-62,-56[

[-56,-47[

CFE (Nb)

RxLevel(dB)

[0, 14 793]]14 793, 23 446]]23 446, 29 586]]29 586, 34 348]]34 348, 38 239]]38 239, 41 529]]41 529, 44 378]]44 378, 46 892]

Out of RangeX


Consecutive Frame Erasure Matrix in log scale

[4, 6[

[10, 14[

[14, 18[[14, 18[[22, 25[

[18, 22[

[14, 18[


Matrix of Number of Measurements Results per CFE band (or BFI band) and per UL RxLev band RMFEM = RMS_UL_ConsecutiveFrameErasure_RxLevel_sample

Vector of Average number of Consecutive Frame Erasure per UL RxLev bandRMFEBFAV = RMS_UL_ConsecutiveFrameErasure_avg_per_RxLevel

Vector of Average UL RxQual per RxLev bandRMQLUQUAV = RMS_UL_RxQuality_avg_per_RxLevel







Suspecting a local interference problem RxQual and RxLev per TA bands

5

4

3

2

0

1

2.5

[0,5[ [6,11[ [55,63[[49,54[[43,48[[37,42[[31,36[[25,30[[19,24[

[12,18[

Bad qualityand good Level

for a specific TA band

interference problem

-47

- 60

- 70

- 80

- 110

- 90

- 59

[0,5[ [6,11[ [55,63[[49,54[[43,48[[37,42[[31,36[[25,30[[19,24[

[12,18[


Matrix of Number of Measurements Results per CFE band (or BFI band) and per UL RxLev band RMFEM = RMS_UL_ConsecutiveFrameErasure_RxLevel_sample

Vector of Average number of Consecutive Frame Erasure per UL RxLev bandRMFEBFAV = RMS_UL_ConsecutiveFrameErasure_avg_per_RxLevel

Vector of Average UL RxQual per RxLev bandRMQLUQUAV = RMS_UL_RxQuality_avg_per_RxLevel






Typical Causes

GSM interference co-channel adjacent

Non-GSM interference other Mobile Networks other RF sources






GSM Interference: Adjacent Channels

Adjacent channel interference +6dB are sufficient to interfere (9dB according to GSM)

Level

Frequency

F(BTS1)

6 dB

F(BTS2)F(BTS1) = F(BTS2)+1






GSM Interference: Adjacent Channels [cont.]

Adjacent channel interference: Symptom Usually downlink interference High rate of quality HO, call drop (due to HO but mainly due to radio) and TCH

assignment failure

Examination Neighbor cells in Abis trace (only for BCCH) Non-neighbor cells in RMS (MAFA frequencies) Frequency planning C/(I adjacent) < -6dB

Correction Downtilt increase of interferer, or even change of antenna orientation Reduction of BS power if necessary, Change of frequency (best solution) Concentric cell implementation (1 extra TRX needed if traffic cannot be supported

by Outer+Inner configuration)






GSM Interference: Co-Channel

GSM Interference Co-Channel interference -12dB are sufficient (-9dB according to GSM) by Outer+Inner configuration

Level

Frequency

F(BTS1)

-12 dB

F(BTS2)F(BTS1) = F(BTS2)






GSM Interference: Co-Channel [cont.]

Co-channel interference Symptom Usually downlink interference High rate of quality HO, call drop and call failure

Examination Neighbor cells in Abis trace (only for BCCH) Non-neighbor cells in RMS (MAFA frequencies) Frequency planning C/I < 12 dB

Correction Downtilt increase of interferer, or even change of antenna orientation Reduction of BS power, Change of frequency Concentric cell implementation (1 extra TRX needed if traffic cannot be supported

by Outer+Inner configuration)






GSM Interference: cellular

GSM interference: cellular

BTS1: ARFCN 5 BTS2: ARFCN 6

MS1 indoor RxLev_UL: - 90 dBm

MS2 outdoor, connected to BTS2 1: no level on BTS1

(BTS 1 under-roof) 2: - 80 dBm on BTS1:

interferer UL/DL 3: no level on BTS1 cell algo prevents BTS2->BTS1 HO

MS 1(indoor)

MS 2(outdoor) 1

2

3

BTS 1(Micro)

BTS 2

When interferences are created by frequency planning, its not so hard to detect them. But frequency planning tools mainly consider DL C/I and coverage.

Some problems are more difficult to predict. For example, lets consider a microcell layer:

A and B are 2 microcells with the coverage described before in dense urban environment.

Even if both cells A & B are using adjacent frequencies (5 and 6), the overlapping area is far from cell A antenna. Thus, in this area C/I is lower than 6 dB.

A red MS is connected to cell A. When the MS starts its call, it transmits full power and a PC algorithm quickly reduces MS power as the received level is very good (microcell coverage). When MS A enters the building, it faces a loss of signal of 20 dB. Then, the MS power increases to MS_TXPWR_MAX.

A second mobile B is connected to cell B and moves down in the coverage area of cell B. The MS power of B decreases quickly down to MS_TXPWR_MIN as the MS is close to the antenna. But when MS B arrives outside the building where A is sitting, A and B are close and transmitting on adjacent frequencies Then B has to increase its power to avoid dropping its call. By the way, global level of freq B is increased in all cell B creating interference in the UL.

AB






GSM Interference: Forced Directed Retry

GSM Interference: Forced Directed Retry The MS should connect to cell2, but no TCH

available The MS connects to cell 1 with forced

directed retry The MS is emitting at high level (far from

BTS1) UL interference for BTS 3

BTS 1 is emitting at high level DL interference at BTS 3

Cell 2: 4 5

C ell 3: 23

Ce

ll 1:

2

4

MS

BTS 2

BTS 1

BTS 3

Another more difficult case of interference: FDR

When examining the preceding situation of planning tool: no problem of C/I. No risk of interference. The FDR algorithm allows an MS connected on an SDDCH on a cell without any free TCH to make an SDCCH-TCH handover (cause 20) so that it takes a TCH on its neighbor. As seen from the user, this is not a handover (call establishment phase, no impact on speech quality), and this algorithm is very efficient to avoid cell congestion cases.

This algorithm is mainly based on neighbor level compared to parameter L_RXLEV_NCELL_DR (n). If the level greater than this threshold, the TCH is to be seized on neighbor.

FDR is mandatory for dual layer or dual band networks (and very easy to configure in this case), since we have capture handovers. Capture handovers send traffic to lower or preferred band cells. In case these cells are congested, calls may not be established, even if upper or non-preferred band cells are free (due to MS idle mode selection, advantaging microcell for example). With the FDR algorithm, the MS takes an SDCCH in the preferred cell, and FDR is used to take a TCH on the non-preferred cell in case of congestion. This situation highlights a good network behavior, since the MS is at the same time in the coverage area of both cells (preferred and not preferred).

The situation described on the slide corresponds to the usage of FDR in a single layer network. This is in that case a heavy-to-tune algorithm presenting of lot of interference and bad quality call risks, since the mobile will be connected to a cell when being not in its service area.

umbrella

microcellFDRcapture






Non-GSM Interference

Other mobile networks: TACS/AMPS/NMT900 Inter-modulation with GSM BS/MS receiver Spurious RACH for AMPS (AMPS Tx bands close to GSM uplink band) Examination TASC: coverage hole with 600 m from TASC BTS

AMPS => 50% reduction of range if AMPS/GSM BTS collocated

Other RF interferers (Radar, shop anti-theft mechanisms, medical device, etc.)

Other RF interferers:

medical devices: GSM equipment disturb them more than the opposite! anti-theft mechanisms. Example:

The Microcell is showing a very high call drop rate. On one frequency, very small call duration.

No problem seen in the frequency plannig. No potential interferer.

Abis trace:

The Spectrum analyzer connected on the antenna feeder highlights a peak on GSM freq 6 in the UL Anti-theft mechanism turned off: no more problem

shop

Microcellantenna

Qual

Level

Qual

Level

DL UL

interference





4 Unbalanced Power Budget Problem







Definition: Unbalanced power budget A cell facing unbalanced power budget problems presents a too high path-

loss difference between UL and DL (often DL>UL) Rule: try to have delta as small as possible to avoid access network possible

only in 1 direction (usually BTS->MS: OK and MS->BTS: NOK) Symptoms: OMC QoS indicators High rate of Uplink quality Handover causes Low incoming HO success rate (no HO Access triggered on the uplink) Degradation of TCH failures and OC call drop indicators


O&M Alarms Voltage Standing Wave Ratio BTS Alarm (VSWR) TMA Alarm (in case of G2 BTS or Evolium BTS with high power TRE)

UL Quality HO is triggered:

UL since the problem is in the UL. Quality as Quality has greater priority than level.






Examination

RMS: Path Balance vector per TRX Number of calls with abnormal bad FER (good RxQual & bad FER)

Abis monitoring: |delta path-loss| > 5dB Check if problem is occurring for 1 TRX or all

Problem on 1 TRX: FU/CU or TRE problem or ANY problem or cables connected to this equipment.

All TRXs: problem on antenna, feeder, jumper or common equipment (e.g., ANX, ANC).






Abis Trace

Example of an Abis trace analysis

106 -94.52 -87.19 0.43 127.55 130.19 -2.64 0.18 33.03 20660.25

Frequency Qual0 Qual1 Qual2 Qual4 Qual5 Qual6 Qual7 Bad_QualityQual3

Frequency Qual0 Qual1 Qual2 Qual4 Qual5 Qual6 Qual7 Bad_QualityQual3

89 -84.29 -75.17 0.65 115.32 118.17 -2.85 0.21 31.03 20010.44

118 -90.75 -83.36 0.46 123.22 126.36 -3.14 0.04 32.46 31930.41

124 -88.89 -85.30 0.29 120.48 128.30 -0.37 31.59 29310.67

DISTRIBUTION OF UPLINK QUALITY

106 84.75% 4.07% 3.68% 1.36% 1.50% 0.92% 0.53% 2.95%3.19%

89 81.41% 1.70% 2.95% 6.35% 2.55% 1.30% 0.10% 3.95%3.65%

118 83.62% 4.23% 4.23% 1.57% 1.79% 0.97% 0.25%3.35%

106 90.27% 3.44% 2.08% 0.92% 1.36% 0.34% 0.05% 1.74%1.55%

89 80.16% 6.45% 7.00% 1.50% 0.50% 0.45% 0.10% 1.05%3.85%

118 86.78% 2.72% 3.95% 1.41% 1.13% 1.19% 1.00%1.82%

DISTRIBUTION OF DOWNLINK QUALITY

3.01%

3.32%

Frequency RxLev_UL RxLev_DL RxQual_UL Path_loss_UL Path_loss_DL delta_Path_loss Delta_quality AV_MS_PWR Nb_of_samplesRxQual_DL

-7.82

124 90.79% 1.06% 2.18% 1.77% 1.30% 0.48% 0.07%2.35% 1.84%

124 77.14% 4.37% 5.87% 3.48% 1.36% 0.82% 1.02%5.94% 3.21%






RMS Data

Suspecting a TRX hardware problem Average Path Balance

A fair average Path Balance at Cell level can hide a bad value for one TRX

0500

10001500200025003000

[-110,-20[

[-20,-10[

[-10,-6[

[-6,-3[

[-3,0[

[0,3[

[3,6[

[6,10[

[10,20[

[20,110[

Nb Samples

PathBalance(dB)

NbSamples

PathBalance Distribution

Average Cell Path Balance = - 0.9 dB


Vector of the Number of Measurement Results per Path Balance bandRMPBV = RMS_PathBalance_sample

Average Path Balance valueRMPBAN = RMS_PathBalance_avg






Typical Causes

Antennas or common RF components, TMA (pb common to all TRXs of the BTS)

TRX RF cables/LNA ... if problem located on only 1 FU

Every BTS has its proper architecture and the diagnosis must be adapted.





5 TCH Congestion Problem







Definition: TCH Congestion TCH Congestion rate (TCH Assignment Phase) is too high (more than 2%) Rule: try to meet the offered traffic (asked by users) by providing the right

number of resources (TRX extension) Symptoms: Customers complain about Network busy OMC QoS indicators High TCH Congestion rate Low incoming Intra/Inter BSC HO success rate (no TCH available) High Directed Retry rate if activated

A interface indicator: BSS Congestion failure in OC High rate of Assignment Failure messages, No radio resource available






Examination and Typical Causes

Examination: TCH Congestion On a per cell basis examination, check the evolution of the TCH Congestion

rate. Typical causes: Special events: Foreseeable: football match, important meeting

Activate some TRXs already installed (and use Synthesized FH) Add special moving BTSs

Not foreseeable: car crash on the highway

Cells on wheel operational by several operators around the world for special events coverage & capacity:

IRMA (SFR) connected to Caens BSC. Orange coverage / Football WC 1998 for Paris Stade de France : Specific cells covering Paris Stadium. During games, only small capacity (using joker frequencies). During

breaks, some TRX off-cells around are turned off, and frequencies are reused for stadium cells.






Typical Causes

Daily periodic problems At peak hour, the cell is not correctly dimensioned.

Hardware solution (refer to Annex)

Estimate the offered traffic: At OMC-R level: Traffic in Erlang/(1- TCH Congestion rate)

Use the B-Erlang law to estimate the number of TCHs required for a 2% blocking rate, thus the target configuration

Add TRXs to reach the new target configuration and find joker frequenciesand / or implement concentric cells

Warning: offered traffic is not the capacity delivered by the system but the traffic asked by the users.






Typical Causes [cont.]

Daily periodic problems At peak hour, the cell is not correctly dimensioned.

Software solution Use specific densification features Half Rate Forced Directed Retry Traffic handover Fast Traffic handover Candidate Cell Evaluation (FREEFACTOR / LOADFACTOR)

Half rate may not only mean SW solution. Need of G2 BSC/TC, Evolium TRE or G2 DRFU.





6 Deducing the Right Team for Intervention






Process

Problem characterization

Make assumption causes

Check the tuning of default radio parameters

Consult the config. db Choose an (other) classical algo

Identify the tunable parameters

Impact estimation

Standard setting ?

No

Yes

Yes

No

No

Yes

Call expert

- Microcell, multiband- Concentric

=N

No

Yes

No

Yes

No

Yes

Parameters modificationDatabase updating

Impact simulation of aparameter modification

No

- Hopping- Marketing

Yes

QOS alarm on the network,on a BSC or some cells

- Indicators (% call drop)- Field measurements/planning- Subscriber complains

QOS team

DHCPEND

Drive test team

DHCPEND

Dimensionning team

OK

Correctionaction

Maintenance team

Planning team

NOK

Cell corrected ?Neighbor cell ?

RFT team - Interferences- Coverage (indoor)- Power budget- Congestion (TCH, SDCCH)- BSS problemInvestig problem ?

Planning/BSS causes

Standard parameters ?

Onpurpose

Systemproblem ? SimulationOK ?

Recurrent problem ?

N timesCheck ?

With QOS ?






Coverage Problem

In case of coverage problem: If the field reality does not match the RNP prediction Maintenance team to change physical configuration (tilt, azimuth, antenna height,

etc.) and drive test team to check it

If the field reality matches the RNP prediction Deployment team to add sites (tri-sector, micro cellular, indoor cells)






Other Problems

In case of interference problem: Planning team to identify the interference source and correct it (joker

frequency, new frequency planning, etc.)

In case of unbalanced power budget problem: Maintenance team to check the impacted BTS (antennas, TMA, RF cables,

LNA, diversity system, etc.)

In case of TCH congestion problem: Traffic team (theoretically always in relation with the marketing team) to

manage the need of TRX extension, densification policy, etc.






Exercise

Match the symptoms listed below with the corresponding problem.

High rate of UL QUAL HO causesGood RxLev and Bad RxQual

VSWR alarm (OMC-R) (Voltage Standing Wave Ratio)

Bad RxLev and Bad RxQual

OMC QOS indicators: % TCH ASS failure high % call drop high

% QUAL HO % call drop % call failure

Unbalanced Power Budget Bad coverage Interferences

TCH Congestion

High Path-loss difference between UL and DLLow incoming HO success rate

Time allowed: 10 minutes






Radio Fine Tuning Team

When the detected problem does not concern another team (Networkdesign and frequency planning, Dimensioning, Radio engineering, Maintenance) or when the other teams cannot give any solution (too tight frequency planning, no additional TRX available, no financial budget for new sites, etc.), the Radio Fine Tuning team has to find acompromise between: High traffic density (Erl/km/Hz) High quality of service (Call drop, CSSR, Speech quality, indoor, etc.)

Its role will be to take charge of radio resources management process This process can be fully described by the following algorithms: Idle Mode Optimization Cell Selection and Reselection

Dedicated Mode Optimization: Radio Link Supervision and Power Control Handover

Ressources Allocation and Management

In-depth knowledge of these algorithms is required for tuning





Self-assessment on the Objectives

Please be reminded to fill in the formSelf-Assessment on the Objectivesfor this module

The form can be found in the first partof this course documentation





End of ModuleTypical Radio Problems





Module 2Idle Mode (Re)Selection








GSM B11 BSS B11 Radio Fine Tuning IntroductionB11 Radio Fine Tuning Idle Mode (Re)Selection1 2 2

Blank Page




Document History





Module Objectives


Describe the Cell Selection and Reselection Algorithm List the associated parameters





Table of Contents


1 Idle Mode Cell Selection and Reselection 7





1 Idle Mode Cell Selection and Reselection






Selection and Reselection Principles

At startup (IMSI Attach), the MS selects a cell with: best C1 once camped on one cell (in idle mode)

the MS can decide to reselect on another one if: C1 criterion is too low the MS cannot decode downlink messages the current cell is becoming forbidden (e.g. barred) the MS cannot access the cell there is a better cell, regarding C2 criterion

Idle Mode Status null: the Mobile Station (MS) is off Status search BCCH: the MS searches a broadcast channel with the best signal level (cell selection and

reselection) BCCH list: up to 36 BCCH frequencies plus BSIC can be saved on SIM per visited network. Look if frequencies of the BCCH list can be used. No entries in the BCCH list, or the location is completely different: scan frequency band.

Status BCCH: the MS is synchronized on a BCCH. The MS camps on a cell. The BTS sends the neighbor cells list (BCCH allocation BA) on BCCH in System Information (SI) 2, 2bis and

2ter if BSS parameter EN_INTERBAND_NEIGH in dual band networks: GSM900 serving cellGSM900 neighbor cells put into SI 2GSM1800 neighbor cells put into SI 2ter/2bis

GSM1800 serving cellGSM900 neighbor cells put into SI 2terGSM1800 neighbor cells put into SI 2/2bis

The MS measures RXLEV from BCCH of the serving and neighbor cells. Camping on a cell is performed using C1 criterion only (the chosen cell is the one with the best C1)

The MS needs to have access to the network. The MS needs to be accessible by the network.

Reselection is done using the mechanisms referenced above. handover algorithms in idle mode






C1 Criteria

C1 ensures that, if a call was attempted, it would be done with a sufficient

downlink and uplink received level based on 2 parameters, broadcasted on BCCH RXLEV_ACCESS_MIN [dBm] MS_TXPWR_MAX_CCH [dBm]

evaluated every 5 sec (minimum) C1 = A - MAX(0,B) > 0 A = RxLev - RXLEV_ACCESS_MIN B = MS_TXPWR_MAX_CCH - P If A > 0 & B < 0 OK, if B > 0, it can be compensated by A A >> 0 means that the MS is closer to the BTS

RXLEV_ACCESS_MIN [dBm] = minimum level to access the cell

MS_TXPWR_MAX_CCH [dBm] = maximum level for MS emitting

A = RxLev - RXLEV_ACCESS_MIN

assess that the MS received level is sufficient

B = MS_TXPWR_MAX_CCH - P

P maximum power of MS assess that the BTS received level will be sufficient






C2 Criteria

CELL_RESELECT_PARAM_IND= not present THEN C2=C1 else C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET (T)

(if PENALTY_TIME 31) if T > PENALTY_TIME, TEMPORARY_OFFSET(T) = 0 used to avoid locating on transient cell CELL_RESELECT_OFFSET used to favor cell among other (e.g. micro-cell vs. umbrella,

once T > PENALTY_TIME)

Or C2 = C1 - CELL_RESELECT_OFFSET(if PENALTY_TIME = 31)

CELL_RESELECT_OFFSET used to handicap some cells among others One reselection criterion is compared to C2s C2neighbor > C2current if cells belong to same LA C2neighbor > C2current+Cell_Reselect_Hysteresis if cells from a different LA

Note: CELL_RESELECT_OFFSET: from 0 to 126 dB, step 2dB PENALTY_TIME: from 0=20s to 30=620s, step: 20s; 31=infinite TEMPORARY_OFFSET: from 1=10dB to 6=60dB; 7 = infinite

The use of a second formula (Penalty_time = 31) is restricted to very special cases, as we do not like to penalize a cell. If a cell is parametered with PT=31, it will be penalized compared to ALL its neighbors. To penalize a cell compared to one neighbor, one should better boost the neighbor cell (using the first formula).

The first formula is very useful for favoring indoor cell or microcell.

Cell Selection and Cell Reselection Considering CELL_BAR_QUALIFYIn case of phase 2 MS and CELL_RESELECT_PARAM_IND=1, it is possible to set priorities to cells

CELL_BAR_QUALIFY

Two values:

0 = normal priority (default value) 1 = lower priorityCELL_BAR_QUALIFY Interacts with CELL_BAR_ACCESS (barring cell)

A phase 2 MS selects the suitable cell with the highest C2 (C1>0) belonging to the list of normal priority.

If no cell with normal priority is available then the MS would select the lower priority cell with the highest C2 (C1>0).






Exercise 1

On this network example List the parameters involved in the selection / reselection process

Time allowed:

5 minutes

Cell

Sectorized cell

CI=6169GSM900

Concentric cell

(8564, 1964)

(8564, 6169)

(8557, 1823)

Cell

CI=6271GSM900

CI=6270, GSM900

CI=1823GSM900

CI=1964GSM900






Exercise 2

Find the selected cell by the MS

Cell 1

Cell 2

CI=6169GSM900

Cell 3

(8564, 1964)

(8564, 6169)

(8557, 1823)

Cell

CI=6271GSM900

CI=6270, GSM900

CI=1823GSM900

CI=1964GSM900

Measurements RxLev (cell 1) RxLev (cell 2) RxLev (cell 3)12345

-80-84-88-88-89

-96-90-90-87-85

-104-100-87-82-78

The same parameters setting is applied in all the cells:

Rxlev_Access_min = -103 dBm for all cells

Cell_Reselect_Offset = 0 dB

Temporary_Offset = 0 dB

Penalty_Time = 0 (20 s)

Cell_Reselect_Hysteresis = 6 dB





Self-assessment on the Objectives

Please be reminded to fill in the formSelf-Assessment on the Objectivesfor this module

The form can be found in the first partof this course documentation





End of ModuleIdle Mode (Re)Selection





Module 3Radio Measurements Principles








GSM B11 BSS B11 Radio Fine Tuning IntroductionB11 Radio Fine Tuning Radio Measurements Principles1 3 2

Blank Page




Document History





Module Objectives


Describe the Radio Measurements Principles List the associated parameters





Table of Contents


1 Radio Measurements 72 Radio Measurement Data Processing 20





1 Radio Measurements






Radio Measurement Mechanisms

MS connected (TCH or SDCCH) The serving cell gives the MS the list of the neighbor cells to listen to Every SACCH, the MS reports to the serving cell via a measurement

report message: Received level of 6 best cells

(which can change) DL level and quality

of serving cell

Best

cellBes

t cell

B est cell Bes t c ellC ell

C ell

Best cell

Cell

Best cell

Se

rvin

g cell

SYS_INFO_5message (list)

MS reporting

The BTS sends a SYS_INFO_5 message that contains the list of neighbor cells for connected mode (The SYS_INFO_2 message contains the list of neighbor cells for idle mode).

Sys info 2bis, 2ter, 5bis and 5ter are also used for multiband networks. MS reporting depends on EN_INTERBAND_NEIGH and on MULTIBAND_REPORTING parameters.

The MS may report:

6 strongest cells of any band (MULTIBAND_REPORTING=0), or

5 strongest cells of the serving band + 1 strongest cell of another band (MULTIBAND_REPORTING=1), or

4+2 (MULTIBAND_REPORTING=2), or

3+3 (MULTIBAND_REPORTING=3).

RXLEV Range: [-110dBm, -47dBm] Binary range: [0, 63]; 0=-110dBm, 63=-47dBm The higher the physical or binary value, the higher the receiving level

RXQUAL Range: [0.14%, 18.10%] Binary range: [0, 7]; 0=0.14%, 7=18.10% The lower the physical or binary value, the lower the bit error rate, the better the quality 0-2=excellent; 3=good; 4=ok; 5=bad; 6=very bad; 7=not acceptable






Radio Measurement Mechanisms [cont.]

For each MS connected to the BTS (TCH or SDCCH) UL received level and quality is

measured every SACCH The Timing Advance (TA) is

computed The UL information is gathered

into the measurement report This is the message result sent by

the BTS to the BSC

BSC

MS

DL mea

surements

UL+D

L measurements

BTS

Measurementreport

Measurementresult

Candidate cellevaluation

Measurements Active channelpreprocessingCandidate cell

evaluationHO & PCdecision

Candidate cellevaluation

PC execution

HO execution

The BSC is computing algorithms usually using average value (sliding window) of these measurements

The BTS starts sending MEASUREMENT RESULT messages as soon as it receives the RL ESTABLISH INDICATION message from the MS.

The BTS stops sending MEASUREMENT RESULT messages upon receipt of one of the two following messages: DEACTIVATE SACCH RF CHANNEL RELEASE

Every SACCH multiframe, the BTS: receives the MEASUREMENT REPORT message from the MS. For power control and handover algorithms, this message

contains downlink measurements and, in the layer 1 header, the power used by the MS. does uplink measurements. reports the uplink and downlink measurements to the BSC in the MEASUREMENT RESULT message. Input flows

Uplink radio signal: radio signal received on the Air interface. BS_TXPWR_CONF: BS transmit power currently used by the BS. DTX_DL: indicator of downlink DTX use.

Output flows: Abis MEASUREMENT RESULT message Internal flows:

Radio measurements. Air MEASUREMENT REPORT message (DL) containing DL MS radio measurements. Uplink radio measurements (quality and level) and a flag indicating whether DTX was used in the downlink (DTX/DL). Timing advance: last TA calculated by the BTS. MS_TXPWR_CONF: last reported value of MS power (reported by the MS). BS_TXPWR_CONF: value of the BS transmit power currently in use. BFI_SACCH: bad frame indicator of the SACCH block produced every SACCH multiframe (# 480ms):

0 = SACCH frame successfully decoded 1 = SACCH frame not successfully decoded






Structure of a Measurement Result

CHAN_NUMBER_IEID

FREQ(5) / BSIC(5) / RXLEV_NCELL(6)

Meas_result_number_IEIDMeas_result_numberElement IdentifierLength

{2} / RXLEV_UL_SUB_{2} / RXQUAL_UL_FULL / RXQUAL_UL_SUBBS_POWER_IEID{3} / BS_POWERElement IdentifierMS_TXPWR_CONF / R{3}TOA / R{2}Element IdentifierLengthLength

BA_USED / DTX_UL / RXLEV_DL_FULL0 / MEAS_VALID / RXLEV_DL_SUB0 / RXQUAL_DL_FULL / RXQUAL_DL_SUB / NO_NCELL_MNO_NCELL_M / RXLEV_NCELL(1)FREQ(1) / BSIC(1)BSIC(1) / RXLEV_NCELL(2)RXLEV_NCELL(2) / FREQ(2) / BSIC(2)BSIC(2) / RXLEV_NCELL(3)RXLEV_NCELL(3) / FREQ(3) / BSIC(3)BSIC(3) / RXLEV_NCELL(4)

0 / Message Type{7}

RXLEV_NCELL(5) / FREQ(5)


SACCH_BFI / DTX_DL{1} / RXLEV_UL_FULL

CHANNEL_NUMBER


MSG_TYPEMSG_DISK

TI {4} / Prot. Disc{4}

BSIC(4) / RXLEV_NCELL(5)

FREQ(6) / BSIC(6)

L1 Info

L3 Info:

Measurementreport from

the MS

Basically, the MEASUREMENT RESULT message is composed of:

L1 info: SACCH Layer 1 header containing MS_TXPWR_CONF and TOA. L3 info: MEASUREMENT REPORT from the MS. This message contains the downlink measurements and neighbor

cell measurements.

Uplink measurements performed by the BTS. BTS power level used.

SUB frames correspond to the use of DTX:

if the mobile is in DTX, the rxlevsub or rxqualsub is used to avoid measuring the TS where there is nothing to transmit in order not to distort measurements.

else rxlevfull is used that is to say all TSs are measured.

MS TXPOWER CONF: which is the actual power emitted by the MS.

TOA is timing advance.

SACCH BFI: bad frame indicator; 2 values 0 or 1; 0 means that the BTS succeeded in decoding the measurement report.

How the neighbor cells are coded:

BCCH1 index in BA list / BSIC1; BCCH2 index in BA list / BSIC2 why? because it does not receive LAC/CI (too long) but BCCH and replies with BCCH/BSIC






Extended Measurement Reporting (EMR)

Extended Measurement Reporting mechanisms Extended Measurement

Order includes the MAFA frequencies the MS is asked to measure

EMO sent once to the MS on SACCH after TCH seizure

Extended Measurement Results include the average signal level measured on each MAFA frequency over one SACCH mf duration

EMR received once per call on SACCH

Channel Activation Acknowledge

Assignment RequestPhysical Context Request

Physical Context Confirm

Channel Activation (TCH)(EMO included)

TCH ESTABLISHMENTTCH

Assignment CompleteAssignment Complete

Assignment CompleteSACCH

SACCH

SACCH

SACCH

SACCH (EMO)(MAFA Freq. List)

SACCH (EMR)(MAFA Freq. RxLev)

TCH ASSIGNMENT (OC or TC)

MS BTS BSC MSC

When the BTS receives a CHANNEL ACTIVATION with the Extended Measurement Order (EMO) included, it must send this information on the SACCH to the corresponding mobile only once.

When the BTS has to send this information, it must replace the sending of system information 5, 5bis, 5ter or 6 by this information. At the next SACCH multiframe, the BTS must resume the sending of this system information by the replaced one.

The EMO must be sent after 2 complete sets of SYS_INFO5 and 6, i.e. after the 2nd SYSINFO 6 after the reception of SABM. This guarantees the MS has received a complete set.

Then, the BTS normally receives from the MS an EXTENDED MEASUREMENT RESULT with the level of the frequencies to monitor. The BTS must make the correlation between these levels and the frequencies contained in the latest EMO information, after having decoded them, according to the order of the ARFCN. The EXTENDED_MEASUREMENT_RESULT is NOT forwarded to the BSC, instead a MEASUREMENT_RESULT with indication no_MS_results is sent to the BSC.

In particular, the BTS must identify the level of the BCCH frequency of the serving cell (which must always be part of the frequencies to monitor) and apply it as the RXLEV_DL in the Radio Measurement Statistics. The other frequencies will be considered in the same way as the BCCH frequency of neighbor cells: they will be linked to the neighbor level and C/I statistics.






Repeated SACCH and Repeated DL FACCH B11

Optional feature EN_REP_DL_FACCH EN_REP_SACCH

Available only for AMR calls Whatever the type of AMR FR or HR NarrowBand or WideBand

Gains Repeated SACCH: Extended Coverage & reduction of call drops Repeated DL FACCH: Improves handover reliability of AMR calls

MS 3GPP release Repeated SACCH is only supported by Rel 6 MS Repeated DL FACCH is mandatory for Rel 6 MS, but can be applied to legacy

MS

Improved voicecoverage with AMR

Signaling coverage

Call drop

Improved coveragewith RepeatedFACCH/SACCH

When AMR speech codecs were introduced, the same ACCH (Associated Control Channels) as those used for traditional TCH/FR and TCH/EFR were re-used The consequence is that, in poor radio conditions, the more protected AMR speech codecs have now better performance (in terms of error rate) than the associated control channels. This results in an imbalance between voice and signaling.

The SACCH is used mainly for the transmission of the radio measurement data. SACCH is also used for SMS transfer during a call.

The BTS sends cell specific information (periodically SYS_INFO 5, 5bis, 5ter, 6) to the MS using SACCH.

A FR TCH uses one TS per TDMA frame, for each frame of the multiframe, except the frames 12 and 25. The TDMA frame 12 is used to carry the SACCH and the TDMA frame 25 is an idle frame.

The SACCH multiframe / block is composed of four SACCH frames/bursts; thus the SACCH period is equal to 480ms.

The FACCH is associated with a TCH, and is required to support the high-speed signaling needed during call establishment, and HO management.

The occurrence of the FACCH is not fixed in the multiframe, as it is for the SACCH Rather, the FACCH occurs on a TDMA frame that is reserved for a TCH.

The multiplexing of TCH and FACCH is possible by means of the frame stealing. This means that a speech frame carried over a TCH can be replaced by a FACCH frame.

Additional flag: REP_DL_FACCH_LEGACY_SUPPORT

0: repeated DL FACCH enabled only for the AMR mobile stations having indicated the support of the feature by repeated ACCH Capability bit = 1

1: repeated DL FACCH enabled for all AMR mobile stations This parameter is relevant only if repeated downlink FACCH (EN_REP_DL_FACCH) is enabled.

Function available on BSC Evolution only.

The value 1 is used to tackle early implementations, ie for MS with repeated ACCH Capability bit=0 or MS without Repeated ACCH Capability bit (legacy MS).






Repeated DL FACCH: principle B11

Each DLFACCH frame is sent twice with exactly the same content In case of these 2 DLFACCH frames are not decoded, they are soft-

combined to succeed the decoding

FACCH n FACCH n+1

40ms

TCH fram

e

TCH fram

e

FAC

CH

n+2,1

TCH fram

e

FAC

CH

n+1,2

TCH fram

e

TCH fram

e

FAC

CH

n+3,1

TCH fram

e

FAC

CH

n+3,2

TCH fram

e

TCH fram

e

FAC

CH

n+1,2

TCH fram

e

FAC

CH

n+1,1

TCH fram

e

TCH fram

e

FACCH n,2

TCH fram

e

FACCH n,1

TCH fram

e

ok

Nok

Nok

Nok

ok

NO

K

okok

FACCH n+2 FACCH n+3

FACCH n+3,2

FACCH n+3,1

Soft Combining

Rel-6 MS

TDMA MultiframeAMR call

LAPDm

BTSFACCH n+4

FACCH n+4,2FACC

H n+

4,1

outcome of the decoding

process

In case of TCH/FR the transmission of the repeated FACCH is done by leaving one TCH frame between the two LAPDm frames.






Repeated DL FACCH: dynamic activation B11

The FACCH frame is effectively repeated if EN_REP_DL_FACCH = 1 or 2 AND AMR codec mode request (CMR) REP_DL_FACCH_THRES_AMR_XX XX = FR or HR or WB

codec threshold

FACCH N

Repeated FACCH N

4,75 kbit/s5,90 kbit/s

7.95 kbit/s

10,2 kbit/s

CMR

EN_REP_DL_FACCH = 1: enabled for LAPDm command frames.

EN_REP_DL_FACCH = 2: enabled for LAPDm command frames, and also for LAPDm response frames (valid only for the MS having indicated the support of the feature by Repeated ACCH Capability bit=1).

Dynamic activation is done as long as codec mode request CMR






Repeated DL SACCH: principle B11

If the MS can not decode correctly a DL SACCH, the BTS will resend it To indicate to the BTS the DL SACCH has to be repeated, the MS set the

SRR bit to 1 in the UL SACCH frame

480ms

SACCH

n+2

SACCH

n+3,1

SACCH

n+3,2

SACCH

n+4

SACCH

n+1,2

SACCH

n+1,1

SACCH

n

Rel-6 MS

TDMA Multiframe

LAPDm

BTS

SACCH

SACCH

SRR=1

SACCH

SRR=1

SACCH

SACCH

SRR=1

SACCH

Soft CombiningSoft Combining Soft CombiningSoft CombiningSoft CombiningSoft Combining

Rel-6 MSoutcome of

the decoding process

UL

DL

SRR: SACCH Repetition Request






Repeated UL SACCH: principle B11

If the BTS can not decode correctly a UL SACCH, the MS will resend it To indicate to the MS the UL SACCH has to be repeated, the BTS set the

SRO bit to 1 in the DL SACCH frame480ms

radio fine tuning

Documents