Inter Layer HO Procedures

Telecom Traffic When handovers are triggered

Handovers Interference Handover’s When the receiving quality is lower than the interference quality threshold and receiving level is higher than the interference level threshold, it is considered that interference exists in serving cell, so interference handover is triggered.

Bad Quality Handover’s When the receiving level of a MS or a BTS is lower than the quality threshold, bad quality handover will be triggered.

Telecom Traffic Change the default interference handover parameters to the new one Interference HO Receiving Quality

Old Value

New Value

RXQUAL1

60

50

RXQUAL2

50

40

RXQUAL3

49

39

RXQUAL4

48

38

RXQUAL5

47

37

RXQUAL6

46

36

RXQUAL7

45

35

RXQUAL8

44

34

RXQUAL9

43

33

RXQUAL10

42

32

RXQUAL11

41

31

RXQUAL12

40

30

RXLEVOff

5

5

Telecom Traffic Change the default quality handover parameters to the new one Bad Quality HO Non-AMR HO DL Qual. Threshold from 50(60) → 40 UL Qual. Threshold from 50(60) → 40

AMR HO DL QuaLimit AMRFR from 65 → 55 UL QuaLimit AMRFR from 65 → 55 DL QuaLimit AMRHR from 60 → 50 UL QuaLimit AMRHR from 60 → 50

Telecom Traffic Change the default edge handover parameters to the new one

EDGE HO Edge HO Allowed --> yes Edge HO UL RX_LEV Threshold 12(-98dBm) Edge HO DL RX_LEV Threshold 17(-93dBm)

Telecom Traffic Layer HO Layer HO watch Time(s) 3 Layer HO valid Time(s) 2 Inter-Layer HO Threshold from 25dB(-85 dBm) → Depends on situation 0 to 63 is corresponding to -110 dBm to -47 dBm If the DL receive level of a cell is lower than the Inter-layer HO Threshold, the cell is listed in the candidate cells based on the receive level. The cell takes a low priority for handovers • Actual Inter-layer HO Threshold of a serving cell = configured Inter-layer HO Threshold - Interlayer HO Hysteresis • Actual Inter-layer HO Threshold of an adjacent cell = configured Inter-layer HO Threshold + Interlayer HO Hysteresis of an adjacent cell – 64. Inter-Layer HO Hysteresis from 3dB

→ Depends on situation

Adjacent Cell Inter-layer HO Hysteresis 67

→ Depends on situation

Telecom Traffic Layer HO conclusions 1. 2. 3.

Increase of HO hysteresis = decrease the possibility to make ping-pong HO Increase of adjacent HO hysteresis = increase the RxLvl of the adjacent cell to enter the HO process (decrease the probability of a adjacent cell to make HO) Increase of HO threshold = increase of the RxLvl to enter the HO process (decrease the HO occurrence)

Cell A default parameters HO hysteresis = 3 Adjacent HO hysteresis = 67 HO threshold = 25 Cell B default parameters HO hysteresis = 3 Adjacent HO hysteresis = 67 HO threshold = 25 Default: Actual threshold of serving = 25 – 3 =22(-88dBm) Actual threshold of adjacent= 25+67-64=28(-82dBm)

Exp a) Make easier only HO from A Æ B Serving RxLvl A = -89dBm Best neighbor RxLvl B = -84dBm A parameters HO hysteresis = 3 Adj. HO hysteresis = 64 HO threshold = 25

B parameters HO hysteresis = 3 Adj. HO hysteresis = 67 HO threshold = 25

A point of view Actual threshold of serving = 25 – 3 =22(-88dBm) Actual threshold of adjacent= 25+64-64=25(-85dBm) B point of view Actual threshold of serving = 25 – 3 =22(-88dBm) Actual threshold of adjacent= 25+67-64=28(-82dBm)

Telecom Traffic

Problem 1: Call is passed from 1800 to 1800 Reason 1800 Layer has bigger priority. Inter layer parameters Hardware solution Down tilt 1800 cells Software Solution Change BQ HO, Interference HO, 1800 site HO hysteresis = 3 Adjacent HO hysteresis = 67 HO threshold = 40

Actual threshold of serving = 40 – 3 =37(-73dBm) Actual threshold of adjacent= 40+67-64=43(-67dBm)

900 site HO hysteresis = 3 Adjacent HO hysteresis = 71 HO threshold = 25


Telecom Traffic

Problem 2: 1800 cells have more traffic than 900 cells Reason 1800 Layer has bigger priority and less down tilt Hardware solution Down tilt 1800 cells Software Solution 1800 site HO hysteresis = 3 Adjacent HO hysteresis = 67 HO threshold = 40




Telecom Traffic

Problem 3: Call is passed from 900 to 1800 easy even if 900 is a better cell and 1800 cell pass it to 1800 cell due to layer priority Reason 900 cell has less priority and HO in the same layer is easier according to HO parameters. Hardware solution Down tilt 1800 cells Software solution 1800 site HO hysteresis = 5 Adjacent HO hysteresis = 67 HO threshold = 40




Inter Layer HO Procedures

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