[Seminar5] Synch Netw

B11 MR1 Ed1.x / Ed2.x

Seminar of GSM Network Engineering

Network Synchronization of Radio Timeslots Cristian IntaMarch 2010

Alcatel-Lucent 2008, d.r., XXXXX

AgendaTheoretical overviewFeature activation & compatibility with previous HWTelecom parameters, counters & IndicatorsTest strategyReference documentation


* | B10 mCCCH | September 2008 1Theoretical Overview


* | B10 mCCCH | September 2008 Operators got limited frequency spectrum:face continuously traffic capacity increaseNeed to improve spectrum efficiency, without big impact on:Network dimensioningNetwork planningB11 Solution Synchronized NetworksAdvantages:up to 10% capacity gainsno MS dependencyfewer collisions between signals and interferers improved C/IDrawbackneeds a common time reference in all cells (B11 solution - GPS)

Theoretical Overview


Theoretical OverviewCase without synchronization (without feature activation)Cell1 and Cell 2 use the same frequencyTS2 of cell1 interfers with TS2 and TS3 of cell2TS3 of cell2 interfers with TS2 and TS3 of cell1One call interfers two TS!

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

FN = 10

FN = 11

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

FN = 25

FN = 26


Theoretical OverviewCase with synchronization (with feature activation)Cell1 and Cell 2 use the same frequencyTS2 of cell1 interfers with TS2 of cell2TS3 of cell2 interferes with TS3 of cell1

One call interferes only one TS!

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

FN = 10

FN = 11

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

FN = 25

FN = 26


Theoretical OverviewSynchronized networksIn timeIn Frame Number (FN)Expected issues due to TDMA frames synchronizationOn radio procedures (linked to synchronized interference on air interface)On BSS dimensioning (more linked to TC)


Theoretical OverviewReminder of TS and TDMA frames

TDMA frames are numbered by Frame Number (FN)FN incremented at end of each TDMA frameFN cyclic, range 0.. FN_MAX (2715647) one cycle one hyperframe

TS0

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

TS1

TS2

TS3

TS4

TS5

TS6

TS7

TB3

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

Time slot

TDMA Frame

1

26 bit training sequence

1

57 data bits

57 data bits

TB3

Multi Frame

Superframe

Hyperframe

2048 superframes of 6.12 s duration

51 multiframes of 120 ms duration

3h 28m 53s

6.12 s

120 ms

4.615 ms

0.577 ms


Theoretical OverviewMultiframe definitionControl channelsFollows a 51-cycleDuration: 235.4 msecConsists mostly of four consecutive blocksSynchronization with FCCH and SCHTraffic channelsFollows a 26-cycleDuration: 120 msecPDCH ChannelsFollows a 52-cycleDuration: 240 msec

B0

B1

B2

B3

B4

B5

B6

B7

B8

B9

B10

B11

T

X

T

X

PDCH


Theoretical OverviewTDMA frame synchronization expected impact on radio proceduresBTS sends BCCH info and frequency and timing synchronization in the same timeBSIC identification more difficult Increase the time of neighbor identificationall SACCH sent simultaneouslyHigher interference higher error rateDTX MS side effect on SID frames (silent descriptor frame)SID frames sent in a pre-defined TDMA frame

all FR and EFR MS send SID in the same timeall HR MS send the SID in the same timeIssue not found for AMR and WB-AMR as no more pre-defined set of TDMA frames is used

Channel TypeTDMA frame subset always to be transmittedTDMA frame number (FN) modulo 104TCH/Full Rate52, 53, 54, 55, 56, 57, 58, 59TCH/Half Rate, subchannel 00, 2, 4, 6, 52, 54, 56, 58TCH/ Half Rate, subchannel 114, 16, 18, 20, 66, 68, 70, 72


Theoretical OverviewTDMA frame synchronization expected impact on radio proceduresSACCH and SID sent simultaneously interference degrade MS/BTS measurements less accurate for:Power controlHOChannel adaptation HRFRImpact independent on transport mode (IP or TDM in ALU BSS)Multiframe synchronization is avoided by using a FN offset on cell level (avoid sending signalling in the same time)ButImpact only on MS using the same and adjacency frequencyNot seen in co-site cells (already synchronized)Impact expected to be higher for a wide area of synchronized cells


Theoretical OverviewTDMA frame synchronization expected impact on BSSBTS sends 4 TDMA frames to TC each 20msEach BTS sends speech frames to TC at the same timeImpact may be faced both in TDM and IP modeBut TC is able to support such load TDM and IP mode: as each link BTS-TC has a different delay (between 1-2 ms)IP mode a different delay is expected (due to Abis and Ater bandwidth)Solution to overcome radio and BSS impactApply a FN offsetMethod to plan the FN offset to avoid al the expected impactBased on existing network and frequency planningApply certain rules


Theoretical OverviewFN Offset planningFor synchronized cells the FN Offset should respect the following rules:

IssueOffset to be avoidedBSIC Decoding 0, 10, 20, 30, 40, 1, 11, 21, 31 or 41 modulo 51SACCH collision0 modulo 13SID (FR only)8 frames modulo 104Load Spreading0, 4, 5 or 9 modulo 13


Theoretical OverviewFrequency Planning aspects:No impact on NH and BBH planning, while a slight reduction of interference is expectedNew method to deploy for Fractional Reuse and DFH Not Synchronized Synchronized

Synchro on network: MAIO and HSN planning done on area MAIO/HSN cluster are created to ease the frequency planningCollision probability only at MAIO/HSN borderSynchro only on site level: MAIO and HSN planning done on siteFrequency Plan based on a collision probability


Theoretical Overview ND StudiesNetwork Design view on feature:Synchronized networks offers the potential for increased capacity in GSM:in combination with tight frequency reuse and fractional loadingtight network synchronization maximizes the effects of other features such as SAIC or Rx diversity.Simulations have been carried out to check the benefit of the feature:Takes into account the time of TS interference overlap. In ideal synchronized networks should be 0.No ramping considered (all TS starts and ends sharply)No continuous fading taken into accountEffects of other duties not taken into account (measurement, signaling, etc)Simulation takes into account:Ideal network design (hexagonal design with 1 or max 2 neighbor cyclesEach interferer mobile can be in one of the 4 states: no activity / GSM / GPRS / EDGEMonte Carlo simulation (more that 10000 iterations)


Theoretical Overview ND StudiesNetwork Design OutputX axis. C/IY axis BER =0 same BER but a lower C/I


Theoretical Overview ND StudiesDue to lower C/I at the same BER, traffic capacity has been modeled as shown (Fractional Reuse 1 has been used):

Gain of 24% for EFRGain of 16% for AMR-HRGains are to be confirmedNew simulation results expected from ND!


* | B10 mCCCH | September 2008 2Feature activation & Compatibility withprevious HW


* | B10 mCCCH | September 2008 The feature is optionalactivation is done on BTS levelFeature can be activated on a large area (several BSC or subset of one BSC)Locked on per TRX basis (all TRX of the impacted BTS)Activation by setting GPS-Synchronized TrueIf GPS is not available on BTS side parameter ignored

Feature Activation


* | B10 mCCCH | September 2008 Compatibility with previous HW generationEvolium BTS equipped with SUMx with GPS receiverSlave BTS does not need SUMx, as synchronization is done by the master BTS

Restrictions & LimitationsMaster BTS without SUMx with GPS receiver

Compatibility with previous HW generation and restrictions


NE Tool readiness for feature9955Synchronization already available in tool (main application)C/I computation takes into account the synchronization (main application)To developMethod for MAIO/HSN cluster planning (9155 AFP)Method for FN Offset planning (9155 AFP)Method for 9155 import from OMCR (PRCG, main application)LASER NPO and/or Legacy 5 new alarms for GPS synchronizationSMART MCT/CARO New BTS parameters to handle

NE Tool Impact AMTNo DeutripNo QvoiceNo Caro/SMART MCTYes QoS databaseNo AnaQoSNo LaserYes RMSATNo RNO/NPONo NEMONo NITRONo 9955Yes PianoNo CompassNo DMSNo


* | B10 mCCCH | September 2008 3Telecom Parameters, Counters, Indicators


* | B10 mCCCH | September 2008 Telecom Parameters

1 3 reserved for future usage


* | B10 mCCCH | September 2008 New CountersNo PM counter monitor this feature

Modified CountersNo impact on existing PM counters

Telecom Counters


* | B10 mCCCH | September 2008 4Test Strategy


* | B10 mCCCH | September 2008 On B11 pilot, two categories of tests are planned to be performed:Unitary testsHandover success and durationGPRS/EDGE re-selection durationVoice Quality testsData performance tests (FTP/PING)

Statistical testsNon regression testsCheck the KPIs for improvementStability analysis for corresponding H/W (GPS receiver)

Test Strategy


Test Strategy Unitary tests (1/5)Requirements4 cells of two BSC which are synchronised (belonging to at least 3 different sites (Trace) Mobile stations:MS with NACC/PSI capabilitiesAir interface protocol analyzerConditionsMobilityStaticModesCS, GPRS and/or EDGEApplicationsLong call for HO testing (mobility)Long FTP for re-selections (mobility)VQ tests (static and mobility)PING/FTP in static condition

Inter BSC

Intra BSC

Intra BSC

Inter BSC


Test Strategy Unitary tests (2/5)Unitary tests4 cells belonging to 2 BSCGPS-Synchronized = FalseEN_NACC=EnabledEN_PSI_STATUS=Enabled

Mode: Mobility:CS long call for HO testing and voice qualityFTP long transfer for cell re-selectionStatic (in one of the cells):VQ static testFTP / PING tests in medium radio conditions

(Trace) Mobile station:Release 04 MS


Test Strategy Unitary tests (3/5)Unitary tests (cont.)Test cases:GPS-Synchronized = False (1st reference test)1 x CS call session + VQ mobility 50 InterBSC and 50 IntraBSC HO (25 routes)1 x DL FTP session 20 InterBSC and 20 IntraBSC reselection (10 routes)3 x VQ static in one cell (1000 samples each point)10 x FTP DL/UL in EDGE in static condition with medium radio conditions (-65

[Seminar5] Synch Netw

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