Bay Level Offsets

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Bay Level OffsetsVer.1.b

Peter A Norris

This document is intended as a guide to maintenance and installation engineers to

give a better appreciation of the importance of Bay Level Offsets and to give a'rule of thumb' for checking the results of Bay Level calibration.

This document is not a part of Customer Documentation and if any doubt exists

the published Customer Documentation takes precedence.

Questions on this document should only be directed to the author.

References: a. W43: Installation & Configuration: BSS Optimization

b. W37: BTS Maintenance Information

c. W23: Command Reference

1. The need for Bay Level Offsets

Bay Level Offset calibration is necessary in order for an RCU to correctly reflect the

actual mobile stations uplink signal level in measurement reports passed to the

Handover Detection and Power Control (HDPC) process. In any RF path within a

cabinet there will be variations in performance depending on frequency due to

tolerances of the equipment and components, both passive and active. There will be a

number of gains and losses which need to be taken into consideration. Bay Level

Offsets calibration allows these variations to be vectored into the uplink signal strength

calculation thus maintaining the accuracy of measurements across the frequency range

of the RCU. Bay Level Offsets are unique to a specific radio/cabinet rf path and ifanything in this combination changes re-calibration is required.

2. Method.

During Bay Level Offset calibration, a reference signal is measured relative to a

reference point in the system. The difference between the actual signal strength,

measured within the RCU, and the reference signal strength, at the reference point, is

the receive path gain which is calculated and entered in an offset table. The process is

repeated for predetermined frequencies across the appropriate frequency band of the

RCU. The reference point used is the top of the cabinet and the reference signal is

-65dB.

During normal operations, the offset is then applied to measurements of uplink signals

from mobile stations before they are passed to HDPC.

i.e. INPUT SIGNAL: X dB + Y dB = Z dB

MEASUREMENT REPORTED: Z dB - Y1 dB = X dB

Where: X = MS signal strength at the reference point

Y = Receive RF path gain

Y1 = Receive path gain from Bay Level Offset table

Z = MS signal strength at the AIC

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3. When should RCUs be calibrated.

RCUs should be calibrated in accordance with current Customer Documentation, this

includes the following:

a. When a RCU has been swapped (only the new RCU needs to be calibrated)

b. When a RF front end unit has been changed/added/removed (all radios fed by thatunit need to be calibrated)

c. Cabinet has been reconfigured.

d. Long Term Path Balance statistics vary between radios in the same cell.

4. Bay Level Calibration procedure

It is vital that the procedure contained in the BSS Optimization manual is followed

precisely, failure to do so can give poor results. This is the most important factor, and

is far more important than adherence to any predicted calibration ranges as they are

only a general guide.

5. Impact of bad calibrationBad calibration data may have the following impacts on call processing:

a. Handovers may occur when there is no need causing loss of quality during

handover.

b. Handovers may not occur when needed causing poor quality or dropped calls

c. IOI may be incorrectly represented leading to timeslots being in the wrong

interference band.

d. Path Balance will be incorrect indicating a rf fault

6. Preserve Cal Data feature

The Preserve Cal Data feature should be used to store a RCUs calibration data in the

CM database. This allows a defective RCU to be replaced at any time and the

previously stored cal data to used until such time as the RCU can be calibrated. This

ensures that service can continue at a site with minimal interruptions during peak

hours.1 Calibration data between RCU will have a maximum difference of 2 dBs,

therefore, the impact on service will be small.

7. Table values

The values in the table contained on the following pages are calculated values only. If a

sector falls outside of these values it does not necessarily indicate a fault. Other

indicators, such as Path Balance should be referred to. The tables are valid for sectors

within a single cabinet only where the receive antenna is fed to that cabinet.

8. Invalid calibration data

A calibration value of 80 is invalid. All other values within the range 81 to 7F are

considered valid, however, although a value may be in the range where it is considered

to be valid, the calibration data may not be appropriate for the cabinet in which the

radio is installed and so the calibration is bad. Each figure represents 0.1dB in the

range 4.8dB to 30.2dB.

1GSR 5.1 feature

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EXPECTED RCU CALIBRATION RANGES

MCELL2/6 1800(HIGH POWER,HIGH SENSITIVITY)

GAIN

Lower limit upperlimit

LNA 19 25.5 Guideline 1. All radios in the same cabinet and in the same sector should calibrateno greater than 2 dB difference

Connectors -2.22 -2.32

Radio -1 1 Guideline 2. The difference between the two RX branches of radios in the samesector should be no greater than 9dBs

Overall range 15.78 24.18 Expected calibration range EEh to 42h

Calibration steps 84.0

MCELL 2/6 1800

LNA 8.5 15.5 Guideline 1. All radios in the same cabinet and in the same sector should calibrateno greater than 2 dB difference


Radio -1 1 Guideline 2 The di fference between the two RX branches of radios in the same sector should be no greater than 9 dBs

Overall range 5.28 14.18 Expected calibration range 85h to DFh.


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MCELL 6 900

DLNB 13 15 Guideline 1. All radios in the same cabinet and in the same sector should calibrateno greater than 2 dB difference

IADU 0 6

Connectors -0.69 -0.84 Guideline 2. The difference between the two RX branches of radios in the samesector should be no greater than 9dBs

Radio -1 1

Duplexer -1 -1

Overall Range 10.31 20.16 Expected calibration range B8h to 1Ah


MCELL 2 900

DLNB 13 15 Guideline 1. All radios in the same cabinet and in the same sector should calibrateno greater than 2 dB difference

IADU

Connectors -0.69 -0.84 Guideline 2. The difference between the two RX branches of radios in the samesector should be no greater than 4 dBs

Radio -1 1

Duplexer -1 -1

Overall Range 10.31 14.16 Expected calibration range B8h to DFh


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INCELL 900

DPP 11.8 18 Guideline 1. All radios in the same cabinet and in the same sector should calibrateno greater than 2 dB difference

Duplexer -1 -1

Radio -1 1 Guideline 2. The difference between the two RX branches of radios in the samesector should be no greater than 9 dBs


Overall Range 8.94 17.14 Expected calibration range AAh to FDh

Calibration Steps 82

INCELL 1800

LNA 8.5 15.5 Guideline 1. All radios in the same cabinet and in the same sector should calibrateno greater than 2 dB difference


Radio -1 1 Guidel ine 2. The difference between the two RX branches of radios in thesame sector should be no greater than 9dBs

Overall range 5.28 14.18 Expected calibration range 85h to DFh


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INCELL 1800 HIGH POWERHIGH SENSITIVITY

LNA 19 25 Guideline 1. All radios in the same cabinet and in the same sector should calibrate nogreater than 2 dB difference

Connectors -2.22 -2.32Radio -1 1 Guideline 2. The difference between the two RX branches of radios in the same sector

should be no greater than 8dBs

Overall range 15.78 23.68 Expected calibration range EEh to 3Eh


HORIZON MACRO (1800 SURF)

SURF 10.9 18.5 Guideline 1. All radios in the same cabinet and in the same sector should calibrate nogreater than 2 dB difference

HARNESS (est) -1 -1

Radio -1 1 Guideline 2. The difference between the two RX branches of radios in the samesector should be no greater than 10dBs

Overall range 8.9 18.5 Expected calibration range AAh to 0Ah


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HORIZON MACRO (900 SURF)

SURF 9 18 Guideline 1. All radios in the same cabinet and in the same sector shouldcalibrate no greater than 2 dB difference

HARNESS (est) -0.5 -0.5

Radio -1 1 Guideline 2. The difference between the two RX branches of radiosin the same sector should be no greater than 11dBs

Overall range 7.5 18.5 Expected calibration range9Ch to 0Ah


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Hex Value Reference Point Gain Value Comments

(Multiples of 0.1) dB

7F 127 30.2 Maximum gain compensation

7E 126 30.1

7D 125 30

7C 124 29.9

7B 123 29.8

7A 122 29.7

79 121 29.6

78 120 29.5

77 119 29.4

76 118 29.3

75 117 29.2

74 116 29.1

73 115 29.0

72 114 28.9

71 113 28.8

70 112 28.7

6F 111 28.66E 110 28.5

6D 109 28.4

6C 108 28.3

6B 107 28.2

6A 106 28.1

69 105 28.0

68 104 27.9

67 103 27.8

66 102 27.7

65 101 27.6

64 100 27.5

63 99 27.4

62 98 27.3

61 97 27.2

60 96 27.1

5F 95 27.0

5E 94 26.9

5D 93 26.8

5C 92 26.7

5B 91 26.6

5A 90 26.5

59 89 26.4

58 88 26.357 87 26.2

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56 86 26.1

55 85 26.0

54 84 25.9

53 83 25.8

52 82 25.7

51 81 25.650 80 25.5

4F 79 25.4

4E 78 25.3

4D 77 25.2

4C 76 25.1

4B 75 25.0

4A 74 24.9

49 73 24.8

48 72 24.7

47 71 24.6

46 70 24.5

45 69 24.4

44 68 24.3

43 67 24.2

42 66 24.1

41 65 24.0

40 64 23.9

3F 63 23.8

3E 62 23.7

3D 61 23.6

3C 60 23.5

3B 59 23.4

3A 58 23.339 57 23.2

38 56 23.1

37 55 23.0

36 54 22.9

35 53 22.8

34 52 22.7

33 51 22.6

32 50 22.5

31 49 22.4

30 48 22.3

2F 47 22.22E 46 22.1

2D 45 22.0

2C 44 21.9

2B 43 21.8

2A 42 21.7

29 41 21.6

28 40 21.5

27 39 21.4

26 38 21.3

25 37 21.2

24 36 21.1

23 35 21.0

22 34 20.9

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21 33 20.8

20 32 20.7

1F 31 20.6

1E 30 20.5

1D 29 20.4

1C 28 20.31B 27 20.2

1A 26 20.1

19 25 20.0

18 24 19.9

17 23 19.8

16 22 19.7

15 21 19.6

14 20 19.5

13 19 19.4

12 18 19.3

11 17 19.2

10 16 19.1

0F 15 19.0

0E 14 18.9

0D 13 18.8

0C 12 18.7

0B 11 18.6

0A 10 18.5

09 9 18.4

08 8 18.3

07 7 18.2

06 6 18.1

05 5 18.004 4 17.9

03 3 17.8

02 2 17.7

01 1 17.6

00 0 17.5

FF -1 17.4

FE -2 17.3

FD -3 17.2

FC -4 17.1

FB -5 17.0

FA -6 16.9F9 -7 16.8

F8 -8 16.7

F7 -9 16.6

F6 -10 16.5

F5 -11 16.4

F4 -12 16.3

F3 -13 16.2

F2 -14 16.1

F1 -15 16.0

F0 -16 15.9

EF -17 15.8

EE -18 15.7

ED -19 15.6

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B7 -73 10.2

B6 -74 10.1

B5 -75 10.0

B4 -76 9.9

B3 -77 9.8

B2 -78 9.7B1 -79 9.6

B0 -80 9.5

AF -81 9.4

AE -82 9.3

AD -83 9.2

AC -84 9.1

AB -85 9.0

AA -86 8.9

A9 -87 8.8

A8 -88 8.7

A7 -89 8.6

A6 -90 8.5

A5 -91 8.4

A4 -92 8.3

A3 -93 8.2

A2 -94 8.1

A1 -95 8.0

A0 -96 7.9

9F -97 7.8

9E -98 7.7

9D -99 7.6

9C -100 7.5

9B -101 7.49A -102 7.3

99 -103 7.2

98 -104 7.1

97 -105 7.0

96 -106 6.9

95 -107 6.8

94 -108 6.7

93 -109 6.6

92 -110 6.5

91 -111 6.4

90 -112 6.38F -113 6.2

8E -114 6.1

8D -115 6.0

8C -116 5.9

8B -117 5.8

8A -118 5.7

89 -119 5.6

88 -120 5.5

87 -121 5.4

86 -122 5.3

85 -123 5.2

84 -124 5.1

83 -125 5.0

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82 -126 4.9

81 -127 4.8

80 -128 4.7 Invalid Transceiver Calibrationalarm

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Bay Level Offsets

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