Layer3 Function in TEMS

Layer 3 Function in TEMS(15 minutes)

Layer3 Messages

Signaling Layer3

Radio Network Planning and Optimization

The flow of layer3 messages in TEMS can be seen in Layer3 messages widows from menu Presentation Signaling Layer 3 Messages. Messages which can not be decoded are shown in Error Report. In TEMS version lower than TEMS8, detail of layer3 message can be locked and open more than 1 message at the same time.


Layer3 Messages

Layer 3 Control In TEMS version5 or lower, Layer 3 message can be manipulate and ask mobile to send, delay or discard specific layer messages.

From the windows, we can see the available messages in DL and UL, unfortunately not all messages that we can modify.


Layer3 Messages

Practice1. What is the Error Report?

2. There are some layer 3 messages that can not use in the operation sequence, please mention them.

Answer : Synchronization Channel InformationHandover AccessRandom Access

Answer : The messages that can not be decoded successfully by mobile station.


Layer3 Messages

Case Study and Practices(2 hours)


Layer3 Messages

Case Study #1 (Emergency HO observation) In order to observe the situation after Emergency Handover, instead of going out for drive test we can modify layer 3 messages. The modification report the BSC that the current radio condition is bad and at the same time we can setup the different of the RxLevel between Serving and neighbors.

Please find the value of penalties time after BQ Handover.


Layer3 Messages

Case Study #1 (Emergency HO observation)Methodology:

Open specification 44.016, section 9.1.21 and 10.5.2.20 to see the content of measurement report.

Answer: 15 seconds


Layer3 Messages

Practice #1 (Timer 3105, and T3124) Timer 3105 is used for the repetition of the PHYSICAL INFORMATION message during the synchronism handover procedure. After network receive HANDOVER ACCESS, it will send PHYSICAL INFORMATION which contains new timing advance used at target cells. Maximum number of PHYSICAL INFORMATION send to mobile station, NY1, is set by network operator. However this procedure are also control by T3124, which is hard coded in mobile station. After T3124 expired MS will setup the old channel in layer 2 and send Handover Failure to old cell.

Please find the value of T3105 and T3124 and How many PHYSICAL INFORMATION send from BSC before T3124 expired.


Layer3 Messages

Practice #1 (Timer 3105, and NY1)Methodology:

Answer: T3105 = 7 msT3124 = 320 msNumber of PHY INFO = 3-4


Layer3 Messages

Case Study #2 (Foreign cell in Kirkuk) From idle mode drive test in Kirkuk, we found the a lot of Immediate Assignment Reject when MS try to camp on one foreign cell. This cell broadcast the frequency of Asiacell band which BCCH 113, BSIC 15.

Please find the following parameter of foreign cell from layer 3 messages.

CGICell Reselection HysteresisRXLEV-ACCESS-MINBA ListMaximum RetransmissionT3212SDCCH TSAverage TA


Layer3 Messages

Case Study #2 (Foreign cell in Kirkuk)Methodology:

Item Find from valueCGI System Information Type3 418-05-7412-64090

Cell Reselection Hysteresis System Information Type3/4 6 dB

RXLEV-ACCESS-MIN System Information Type3/4 1 dB

BA List System Information Type2 none

Maximum Retransmission System Information Type2/3/4 7 times

T3212 System Information Type3 1 deci-hour

SDCCH Time slot Immediate Assignment TS 1-6

TA Immediate Assignment 6

Practice #2 (Foreign cell in Mosul)


Layer3 Messages

From idle mode drive test in Mosul, we found the a strange cell not belong to Asiacell network. This cell broadcast the frequency of Asiacell band which BCCH 124, BSIC 00.

Please find the following parameter of foreign cell from layer 3 messages.

CGIMS-TXPWR-MAX-CCHRXLEV-ACCESS-MINBS-PA-MFRMSTX-IntegerCROATT flagRADIO-LINK-TIMEOUT

Practice #2 (Foreign cell in Mosul)


Layer3 Messages

Item Find from valueCGI System Information Type3 418-05-7421-777

MS-TXPWR-MAX-CCH System Information Type3/4 0

RXLEV-ACCESS-MIN System Information Type3/4 37/38 dB

BS-PA-MFRMS System Information Type3 3

TX-Integer System Information Type2/3/4 32

CRO System Information Type3/4 126

ATT flag System Information Type3 YES

RADIO-LINK-TIMEOUT System Information Type3 36 SACCH

Methodology:

Case Study #3 (Wrong BSIC decode)


Layer3 Messages

From the drive test on highway, we find bad quality and drop call problem.

Please find possible problem and solution for this case.


Layer3 Messages

Case Study #3 (Wrong BSIC decode)

-When mobile served by 74(46) it can receive Signal Strength of 86 but in TEMS show BSIC 44.-But now move near to 86(11) What happen?

-We have 2 Assumptions

1.86(44) Overshoot and MS can decode SCH from it.

2.MS is not decode 86(11) and use 86(44) that used to perfectly decode so long time.

Analysis:

Solution:1.Look from Synch Channel Information for see that which place is the last time

that MS can decode 86(44)

-If near 86(11) you should tilt down 86(44) because it overshoot coverage

-If far from 86(11) you should so this case MS remember old BSIC !!

-Neighboring Optimization

-Change BCCH pattern

Practice #3 (Wrong BSIC decode)


Layer3 Messages

We have another problem case found in the highway, the problem is bad quality and drop call.

Please find possible problem and solution for this case.


Layer3 Messages

Practice #3 (Wrong BSIC decode)

-Mobile go along the road by camp on 75(47) before experience bad quality

-Mobile never measure 94(75) the suitable cell that it should to camp on

-So it should to choose new cell that stronger than 75(47).that is 81(72) or 86(47)

-But mobile decode wrong BSIC from these two frequency 81(75) and 86(72)

-After that BSC command mobile to HO and HO fail

-Add Measurement frequency and neighbor from 75(47) to 94(75)

-Change BCCH of either 81(75) or 81(72)

-Change BCCH of 86(72) or 86(47)

Analysis:

Solution:

Layer3 Function in TEMS

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